# Micro-cat



## Davalos

Hello everyone. My name is David. I am a back yard boat builder from Orlando Florida. You can quite often find me tooling around the North Indian River Lagoon on weekends. I am introducing a new type of microskiff. It is actually not a small skiff, but a small outboard powered catamaran. When I cruise the Indian River Lagoon on a day with moderate chop, I get pretty beat up in my Boston Whaler 13 classic. My microcat will hopefully offer a smooth ride in moderate chop. It will also offer more stability when you stand on any side of the boat. I am obviously sacrificing looks for performance with this boat. The hard corners don't look great, but they add stability and maximum planing surface. I hope to start trial runs soon. I will post my latest pic below.


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## bryson

Do you have any napkin sketches? I like cats in most sea conditions. You will sacrifice draft for ride, but most will absolutely slice through chop with how sharp the bow entry usually ends up.


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## NealXB2003

My experience with cats has been with bigger boats, so may not be relative here.  The ones I've been around needed to pack air in the tunnel to achieve peak performance. That phenomenon usually started to occur around 60 or 70 mph on the bigger boats. Below that, they tended to run wet. Can a smaller cat pack enough air at low speed to capitalize on the benefits of a cat hull?
Neat concept by the way. Im not criticizing the idea, just curious.


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## Davalos

bryson said:


> Do you have any napkin sketches? I like cats in most sea conditions. You will sacrifice draft for ride, but most will absolutely slice through chop with how sharp the bow entry usually ends up.


I have better than that. I am almost done with the prototype. I will be updating my first post with the new pics.


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## Davalos

NealXB2003 said:


> My experience with cats has been with bigger boats, so may not be relative here. The ones I've been around needed to pack air in the tunnel to achieve peak performance. That phenomenon usually started to occur around 60 or 70 mph on the bigger boats. Below that, they tended to run wet. Can a smaller cat pack enough air at low speed to capitalize on the benefits of a cat hull?
> Neat concept by the way. Im not criticizing the idea, just curious.


What you are describing sounds more like a 3 point hydro. I was not aware that ocean going catamarans were capable of going speeds in excess of 60 mph. What kind of engines and prop pitches are used on these catamarans that you are describing? In any event, my microcat is not designed for air induction, and we'll have a price point about 1/100th of the price of the catamarans that you are describing.


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## NealXB2003

Lol, not talking top fuel hydros, but id love to take miss Budweiser for a spin. 

Take a look at Lanier Custom Boats. 20' cat typically powered by a 250 or 300 hp outboard. Depending on layup and setup, those run from 80 to 100+ mph.


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## whoislang

Plenty of offshore catamarans running 70-80+ nowadays. Dont get me started on cats . Good luck with your mini cat. Could be a market depending on how she turns out. Post some photos, apparently they're worth 1000 words


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## Davalos

Okay. I know what you're referring to now. That is a high performance cat. Mine is styled more like an ocean going catamaran. The type that fisherman would use. I would consider what I am building to be a cross between a planing hull and a displacement hull. For instance, it is nearly impossible to keep my 13 ft Boston Whaler classic going about 14 miles an hour. My boat does not like that speed because it is not planing and 13 is too fast to follow the laws of a displacement hull. All the way that's just in theory right now, I believe my hull will be able to achieve cruising speeds and still ride smoothly. We shall see.


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## Davalos

whoislang said:


> Plenty of offshore catamarans running 70-80+ nowadays. Dont get me started on cats . Good luck with your mini cat. Could be a market depending on how she turns out. Post some photos, apparently they're worth 1000 words


I will certainly do that. Thanks


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## Sublime

Look at some of the haulover inlet vids on YouTube. Lots of 40-60 foot cats with quad 300s or 400s . Those can all do 60 mph easy.

Now back on subject. There are bay boats they call "catamarans" here in Texas. They are just flat bottom hulls with essentially a huge tunnel from one end to the other. Planing hulls only.

There was a company way back in the day here in Texas that took old Hobie catamaran hulls and put outboards on them. I bet they ran smooth but they probably also hunted the waves pretty bad with those sharp entries.


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## KWGator

David,
I grew up on the Banana River and still to this day have my 8.5 ft. long fiberglass catamaran boat. My parents purchased it in 1986 as my Christmas present in Cocoa, FL from the builder who had the molds. As I remember it, he had molds for 8ft., 10 ft., and 12 ft. versions but my memory is a bit foggy since I was much younger then. My boat is called a Seaworthy but the decals on the sides of the boat are long gone at this point. It kind of looks like you are driving a bathtub when out on the water but I have so many fond memories from using that boat. My boat was rated for a 6hp and I remember my max speed was about 22-24 mph with a 6ph Evinrude back when I was much lighter in weight. Very stable, took chop great, and was great for cruising around uninhabited spoil islands on the river as a kid. Overall weight for the empty boat was around 110 lbs but I am sure it is a bit heavier now as we have had to add some reinforcement to the transom over the years.

The boat is now stored in my neighborhood HOA lot for use on the lakes up here in Tallahassee with my son. It now only gets use of a trolling motor since the HOA forbids anything else but my brother-in-law still has my 1986 Evinrude 6hp in his garage (hasn't been started in years but I bet we could make it work with a few hours of TLC). I am looking forward to what you come up with for your design and might be able to offer you some thoughts on the pro/cons of my boat if you are interested.
Keith


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## Davalos

KWGator said:


> David,
> I grew up on the Banana River and still to this day have my 8.5 ft. long fiberglass catamaran boat. My parents purchased it in 1986 as my Christmas present in Cocoa, FL from the builder who had the molds. As I remember it, he had molds for 8ft., 10 ft., and 12 ft. versions but my memory is a bit foggy since I was much younger then. My boat is called a Seaworthy but the decals on the sides of the boat are long gone at this point. It kind of looks like you are driving a bathtub when out on the water but I have so many fond memories from using that boat. My boat was rated for a 6hp and I remember my max speed was about 22-24 mph with a 6ph Evinrude back when I was much lighter in weight. Very stable, took chop great, and was great for cruising around uninhabited spoil islands on the river as a kid. Overall weight for the empty boat was around 110 lbs but I am sure it is a bit heavier now as we have had to add some reinforcement to the transom over the years.
> 
> The boat is now stored in my neighborhood HOA lot for use on the lakes up here in Tallahassee with my son. It now only gets use of a trolling motor since the HOA forbids anything else but my brother-in-law still has my 1986 Evinrude 6hp in his garage (hasn't been started in years but I bet we could make it work with a few hours of TLC). I am looking forward to what you come up with for your design and might be able to offer you some thoughts on the pro/cons of my boat if you are interested.
> Keith


Thanks Keith. I appreciate the assistance. When I am not building boats, I am out on the North Indian River Lagoon in my 1971 Boston Whaler 13


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## firecat1981

So is it a design following a Livingston or Twinvee?


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## Davalos

Certain aspects of it is like a Livingston. I don't want to give it all away now because I haven't finished building the prototype yet. My boat has a couple of twists that correct deficiencies that I feel many planing hulls have. The transom has a tendency to dig deep into the water and sort of just plow through the water. And the bow on some of these microskiffs serve no function at all while underway.







I am going to see if I can improve upon that. And in doing so, hopefully improve upon efficiency. Like I mentioned, it is all theoretical at this point.


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## whoislang

This something along the lines of what I am envisioning yours being like, maybe I'm way off. I hate to endorse this thing as this company got its roots in completely copy and pasting the Freeman, but this little thing may have potential. To me its like a mini version of a race cat, built with a fishing/skiff layout. kind of like a new take on an old twin vee. Probably not going to be ideal as a poling skiff but may have some benefits for the inshore angler.


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## Davalos

whoislang said:


> This something along the lines of what I am envisioning yours being like, maybe I'm way off. I hate to endorse this thing as this company got its roots in completely copy and pasting the Freeman, but this little thing may have potential. To me its like a mini version of a race cat, built with a fishing/skiff layout. kind of like a new take on an old twin vee. Probably not going to be ideal as a poling skiff but may have some benefits for the inshore angler.
> 
> View attachment 170961
> 
> 
> View attachment 170962


You are correct in saying that you are way off. I already own several boats that have the profile of the one in your picture. It is basically a classic Boston Whaler 13-footer. I have three of them in my backyard right now. What I am building is different. And I'm building it so that it can be pushpoled through the shallows. Here are pics of my Boston Whalers.


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## Labsrule

And another - Flats Cat Boat : 17 foot Shallow Water Catamaran Flats Fishing Boat


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## makin moves

Hull slap? Seems like it would be a noisy boat unless the open center is below waterline. What type of boats do you already build?


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## paint it black

Live Watersports has their L4Expedition which a lot of guy's are running outboards on. And the L2Fish. Great catamaran paddle crafts. Make for awesome fishing vessels.


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## Davalos

paint it black said:


> Live Watersports has their L4Expedition which a lot of guy's are running outboards on. And the L2Fish. Great catamaran paddle crafts. Make for awesome fishing vessels.


I just saw the promo. I didn't see a single picture of one of those boards with a 9.9 horsepower outboard on it. 


Labsrule said:


> And another - Flats Cat Boat : 17 foot Shallow Water Catamaran Flats Fishing Boat
> View attachment 170971


I thought this website was about microskiffs. There's nothing micro about the boat in your picture in my opinion.


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## firecat1981

A microskiff is defined as 18ft or less and a max of 70hp.


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## Davalos

firecat1981 said:


> A microskiff is defined as 18ft or less and a max of 70hp.


Thanks for that definition. Just to clarify, I thought this web site was for boats similar to the 3 boats that are featured on this web sites home page. My bad.


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## MatthewAbbott

Post some pics of your design.


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## Caddis

I'm interested to see what you come up with too.


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## georgiadrifter

Pichers?


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## 994

What niche are you trying to fill? I’m only the 25th post and I’ve seen Miss Budweiser, a few old Boston whalers, and heard talk about a “microcat”.


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## Xcapnjoe

mosquitolaGOON said:


> What niche are you trying to fill? I’m only the 25th post and I’ve seen Miss Budweiser, a few old Boston whalers, and heard talk about a “microcat”.











Micro Cat for micro water


Every boat ever built was designed to suit a particular purpose. Whether it is a centre console for sport fishing, a 27m super yacht for relaxing and impressing, or an 18’ skiff for harnessing the wind’s raw power, each was built with a specific use in mind.




www.fishingmonthly.com.au




GIT SUM!


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## 994

Xcapnjoe said:


> Micro Cat for micro water
> 
> 
> Every boat ever built was designed to suit a particular purpose. Whether it is a centre console for sport fishing, a 27m super yacht for relaxing and impressing, or an 18’ skiff for harnessing the wind’s raw power, each was built with a specific use in mind.
> 
> 
> 
> 
> www.fishingmonthly.com.au
> 
> 
> 
> 
> GIT SUM!
> View attachment 171007
> View attachment 171008
> View attachment 171009


Looks tippy


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## Smackdaddy53

Hovercraft


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## Xcapnjoe

mosquitolaGOON said:


> Looks tippy


It's a glorified LayZBoy!

Displacement is a lost art.


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## Smackdaddy53

What the hell is going on here?


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## Smackdaddy53

Those Flats Cats are terrible hulls. At one point they were offering an aluminum version. They ran skinny but did everything else horribly. My buddy had the smaller one with a Yamaha 90.


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## Xcapnjoe

Smackdaddy53 said:


> Those Flats Cats are terrible hulls. At one point they were offering an aluminum version. They ran skinny but did everything else horribly. My buddy had the smaller one with a Yamaha 90.


I don't know what's happening. I think my caustic nature is exposing the bare mettle. 

Plus I hate cats. They steal your soul while you sleep.


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## Mark H

Smackdaddy53 said:


> Hovercraft


That would be a shallow water capable craft though poling might be an issue. 😁


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## Davalos

MatthewAbbott said:


> Post some pics of your design.


It's still in the development stage. Not much to see yet.


Xcapnjoe said:


> Micro Cat for micro water
> 
> 
> Every boat ever built was designed to suit a particular purpose. Whether it is a centre console for sport fishing, a 27m super yacht for relaxing and impressing, or an 18’ skiff for harnessing the wind’s raw power, each was built with a specific use in mind.
> 
> 
> 
> 
> www.fishingmonthly.com.au
> 
> 
> 
> 
> GIT SUM!
> View attachment 171007
> View attachment 171008
> View attachment 171009


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## Davalos

This board is a bit tricky. Nothing like Facebook.


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## Davalos

Xcapnjoe said:


> Micro Cat for micro water
> 
> 
> Every boat ever built was designed to suit a particular purpose. Whether it is a centre console for sport fishing, a 27m super yacht for relaxing and impressing, or an 18’ skiff for harnessing the wind’s raw power, each was built with a specific use in mind.
> 
> 
> 
> 
> www.fishingmonthly.com.au
> 
> 
> 
> 
> GIT SUM!
> 
> 
> mosquitolaGOON said:
> 
> 
> 
> Looks tippy
> 
> 
> 
> My dad was approached by Craig at (that company that strapped 2 surf boards together and called it a boat) They asked him for a quote on fabricating the sponsons. My dad did not bid on it because they wanted to pay him close to nothing, and he does not produce garbage. As far as what need I am trying to fill, I don't know why anyone would be concerned about that. Everyone should do their own thing and I will do the same.
> View attachment 171007
> View attachment 171008
> View attachment 171009
Click to expand...


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## Davalos

Xcapnjoe said:


> Micro Cat for micro water
> 
> 
> Every boat ever built was designed to suit a particular purpose. Whether it is a centre console for sport fishing, a 27m super yacht for relaxing and impressing, or an 18’ skiff for harnessing the wind’s raw power, each was built with a specific use in mind.
> 
> 
> 
> 
> www.fishingmonthly.com.au
> 
> 
> 
> 
> GIT SUM!
> View attachment 171007
> View attachment 171008
> View attachment 171009





mosquitolaGOON said:


> Looks tippy


My dad was approached by Craig at (that company that strapped 2 surf boards together and called it a boat) They asked him for a quote on fabricating the sponsons. My dad did not bid on it because they wanted to pay him close to nothing, and he does not produce garbage. As far as what need I am trying to fill, I don't know why anyone would be concerned about that. Everyone should do their own thing and I will do the same.


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## Davalos

mosquitolaGOON said:


> What niche are you trying to fill? I’m only the 25th post and I’ve seen Miss Budweiser, a few old Boston whalers, and heard talk about a “microcat”.
> 
> I don't know why anyone would be concerned about that. Everyone should do their own thing and I will do the same.





makin moves said:


> Hull slap? Seems like it would be a noisy boat unless the open center is below waterline. What type of boats do you already build?


Mosquitolagoon; I am not doing this by myself. It is a colaborative effort between me and my brother. My dad, my brother and myself have all worked for Robalo and Cobia. I worked at Regal Marine. My dad owned LA Marine Works. And my brother did the tooling and fabrication for a competition ski boat for Joseph Vlasic, the Vlasic pickle maker guy. I have been repairing and messing around with boats for a long time. I thought it was time that I made my own, because I don't like what is out there.


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## whoislang

Davalos said:


> You are correct in saying that you are way off. I already own several boats that have the profile of the one in your picture. It is basically a classic Boston Whaler 13-footer. I have three of them in my backyard right now. What I am building is different. And I'm building it so that it can be pushpoled through the shallows. Here are pics of my Boston Whalers


If you think that boat is similar to a whaler then I'm not sure we are both thinking of the same thing when we say catamaran.....

Whaler more of a "W" hull

The TAG is a 19ft
Cat with two sponsons separated by a tunnel running throughout






























I think what would benefit the skiff community more than that TAG is a boat like the SCB or Simmons but smaller so it can be powered by a 70 or less. And pushable like you said. Needs to be quiet as well. Not sure a cat is right for those requirements. Interesting to see if it would be feasible.

Looking forward to seeing your boat in the future.

They claim an 9" draft at rest with this 1400# 24'. Seems like a scaled down one could do even better. 
















'


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## Davalos

Thanks for your reply. And thank you for the schematics and photos. They are very helpful. My design is somewhat similar to the profile of the boat in your photo. But with a significant difference. I should be done with my prototype by the middle of next week. I can then show you actual photos as supposed to just describing it. If I would have just described it in words right now, the only thing that would happen is a bunch of folks would pile on and criticize it. That is why I would rather post a photos than describe it in writing. Thanks again.


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## Sublime

This is what I was talking about. A dude here in Tx tried something like this 30 years ago. It is Hobie cat hulls given a more narrow beam. A couple things come to mind. It would be smooth in lots of conditions, super stable and it would sucketh to stuff either one of the those bows.


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## Davalos

Sublime said:


> This is what I was talking about. A dude here in Tx tried something like this 30 years ago. It is Hobie cat hulls given a more narrow beam. A couple things come to mind. It would be smooth in lots of conditions, super stable and it would sucketh to stuff either one of the those bows.
> 
> View attachment 171039


That Hobie Cat hull is the closest thing to the design that I have. The only difference is that my hulls are wider to act a little more like a planning hull, and for added buoyancy. In addition, my boat is being made of 1088 Lloyd's rated Meranti marine plywood. So it is lighter and stronger than rotomolded plastic.


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## Davalos

Davalos said:


> That Hobie Cat hull is the closest thing to the design that I have. The only difference is that my hulls are wider to act a little more like a planning hull, and for added buoyancy. In addition, my boat is being made of 1088 Lloyd's rated Meranti marine plywood. So it is lighter and stronger than rotomolded plastic.


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## NealXB2003

Davalos said:


> That Hobie Cat hull is the closest thing to the design that I have. The only difference is that my hulls are wider to act a little more like a planning hull, and for added buoyancy. In addition, my boat is being made of 1088 Lloyd's rated Meranti marine plywood. So it is lighter and stronger than rotomolded plastic.


I can't wait to see pics and performance numbers. 

No worries about building with wood when so many other builders are going all composite?


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## Davalos

My prototype is being built out of marine plywood. I haven't quite decided yet what my production boats will be built out of. All I know is that Riva started out building their yachts out of all mahogany. They haven't done too bad.


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## Davalos

(X)


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## bryson

Keep the pictures coming-- would love some from further away to help visualize the design, as well as some idea on how you are addressing the deficiencies you mentioned earlier on. This is a pretty good group of guys here, and you're likely to get some decent feedback.

What's the projected draft? The narrow sponsons should give a nice ride but I'd worry about waves slapping the underside of the tunnel if it sits a little lower in the water. Looks like a step behind the vee to a flat bottom aft? And a small pod in front of the prop? Would love to see a sketch to piece it together. 

I had a semi-displacement 26' cat (basically a SeaCat SL5) for a few years and loved the way it rode. Biggest downside was the fact that it would stuff the bow at trolling speeds in big (short period) seas, since the sides of the sponsons were basically vertical and there was no rise to the bow to help out either. The semi-displacement hull was nice in that it helped what you're describing in the transition where you're getting onto plane -- it didn't seem terribly "unhappy" at that awkward speed like a true planing hull does.


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## Davalos

bryson said:


> Keep the pictures coming-- would love some from further away to help visualize the design, as well as some idea on how you are addressing the deficiencies you mentioned earlier on. This is a pretty good group of guys here, and you're likely to get some decent feedback.
> 
> What's the projected draft? The narrow sponsons should give a nice ride but I'd worry about waves slapping the underside of the tunnel if it sits a little lower in the water. Looks like a step behind the vee to a flat bottom aft? And a small pod in front of the prop? Would love to see a sketch to piece it together.
> 
> I had a semi-displacement 26' cat (basically a SeaCat SL5) for a few years and loved the way it rode. Biggest downside was the fact that it would stuff the bow at trolling speeds in big (short period) seas, since the sides of the sponsons were basically vertical and there was no rise to the bow to help out either. The semi-displacement hull was nice in that it helped what you're describing in the transition where you're getting onto plane -- it didn't seem terribly "unhappy" at that awkward speed like a true planing hull does.





bryson said:


> Keep the pictures coming-- would love some from further away to help visualize the design, as well as some idea on how you are addressing the deficiencies you mentioned earlier on. This is a pretty good group of guys here, and you're likely to get some decent feedback.
> 
> What's the projected draft? The narrow sponsons should give a nice ride but I'd worry about waves slapping the underside of the tunnel if it sits a little lower in the water. Looks like a step behind the vee to a flat bottom aft? And a small pod in front of the prop? Would love to see a sketch to piece it together.
> 
> I had a semi-displacement 26' cat (basically a SeaCat SL5) for a few years and loved the way it rode. Biggest downside was the fact that it would stuff the bow at trolling speeds in big (short period) seas, since the sides of the sponsons were basically vertical and there was no rise to the bow to help out either. The semi-displacement hull was nice in that it helped what you're describing in the transition where you're getting onto plane -- it didn't seem terribly "unhappy" at that awkward speed like a true planing hull does.


Wow Bryson. You know your stuff. Ok. I failed to mention the following. I am designing the boat specifically for mild to moderate chop of Floridas Intracoastal, the IRL and Mosquito Lagoon, and to also go idle speed in 8" of water through the mangroves of the North IRL without tearing up the bottom. I know what the boat WILL NOT do. It will never truly plane like a skiff. It will never accomodate a 30 hp 4 cycle. It will never meet the expectations of these guys talking about going 80 mph. Now I need to find out what the boat WILL do. As far as hull slap, I am hoping that the piece of hull that sits in front of the anti-cavitation plate will mitigation hull slap somewhat. In addition, my hull bottom in that area consists of 5/8 1088 Meranti marine plywood sandwiched between layers of 1708 biaxial cloth. If hull slap continues to be a concern, I will modify the tunnel until hull slap is gone or greatly reduced. I am banking on a fine entry and built in trim tab boxes to balance the boat and delivery the ride I am looking for.


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## Davalos

Davalos said:


> Wow Bryson. You know your stuff. Ok. I failed to mention the following. I am designing the boat specifically for mild to moderate chop of Floridas Intracoastal, the IRL and Mosquito Lagoon, and to also go idle speed in 8" of water through the mangroves of the North IRL without tearing up the bottom. I know what the boat WILL NOT do. It will never truly plane like a skiff. It will never accomodate a 30 hp 4 cycle. It will never meet the expectations of these guys talking about going 80 mph. Now I need to find out what the boat WILL do. As far as hull slap, I am hoping that the piece of hull that sits in front of the anti-cavitation plate will mitigation hull slap somewhat. In addition, my hull bottom in that area consists of 5/8 1088 Meranti marine plywood sandwiched between layers of 1708 biaxial cloth. If hull slap continues to be a concern, I will modify the tunnel until hull slap is gone or greatly reduced. I am banking on a fine entry and built in trim tab boxes to balance the boat and delivery the ride I am looking for.





Davalos said:


> Wow Bryson. You know your stuff. Ok. I failed to mention the following. I am designing the boat specifically for mild to moderate chop of Floridas Intracoastal, the IRL and Mosquito Lagoon, and to also go idle speed in 8" of water through the mangroves of the North IRL without tearing up the bottom. I know what the boat WILL NOT do. It will never truly plane like a skiff. It will never accomodate a 30 hp 4 cycle. It will never meet the expectations of these guys talking about going 80 mph. Now I need to find out what the boat WILL do. As far as hull slap, I am hoping that the piece of hull that sits in front of the anti-cavitation plate will mitigation hull slap somewhat. In addition, my hull bottom in that area consists of 5/8 1088 Meranti marine plywood sandwiched between layers of 1708 biaxial cloth. If hull slap continues to be a concern, I will modify the tunnel until hull slap is gone or greatly reduced. I am banking on a fine entry and built in trim tab boxes to balance the boat and delivery the ride I am looking for.


Bryson, I didn't answer your question about draft. I haven't done exact calculations yet. But my experience tells me that the draft is going to be somewhere in the range of 4 inches. And because the boat and rider will be balanced, the boat should sit flat in the water. That means that the bottom of my tunnel will sit about 2" off the water while the boat is at rest.


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## Davalos

Update on my project. Progress update: I got my sponsons tacked into place. This project uses a combination of frames, stitch and glue, and tortured ply. I can easily lift either end with very little effort. Next step is to remove the painters tape, finish running my fiberglass tape at all angles inside and out, do my fillets, and then fill the sponsons with 2 lb foam.


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## Sublime

Looks good.


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## bryson

Look forward to following along. Different is fun. Sharp entry will slice though light chop like a dream.


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## Davalos

Bryson, that is the idea. And I am hoping that my oversized built in trim tab boxes keep the bow down so they can do their job properly. And I have sacrificed looks for extra stability. I have some plans for the design to take the focus off those hard corners.


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## Davalos

bryson said:


> Keep the pictures coming-- would love some from further away to help visualize the design, as well as some idea on how you are addressing the deficiencies you mentioned earlier on. This is a pretty good group of guys here, and you're likely to get some decent feedback.
> 
> What's the projected draft? The narrow sponsons should give a nice ride but I'd worry about waves slapping the underside of the tunnel if it sits a little lower in the water. Looks like a step behind the vee to a flat bottom aft? And a small pod in front of the prop? Would love to see a sketch to piece it together.
> 
> I had a semi-displacement 26' cat (basically a SeaCat SL5) for a few years and loved the way it rode. Biggest downside was the fact that it would stuff the bow at trolling speeds in big (short period) seas, since the sides of the sponsons were basically vertical and there was no rise to the bow to help out either. The semi-displacement hull was nice in that it helped what you're describing in the transition where you're getting onto plane -- it didn't seem terribly "unhappy" at that awkward speed like a true planing hull does.


I am going to update my first post to keep things simple.


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## m32825

Are the hulls interchangeable or is there a "left" one and a "right" one?


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## devrep

things like this is what Microskiff used to be all about. small boats with small power. keep plugging away at it, ignore the ignorant and listen to constructive criticism. all you can do.


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## Davalos

devrep said:


> things like this is what Microskiff used to be all about. small boats with small power. keep plugging away at it, ignore the ignorant and listen to constructive criticism. all you can do.


Thanks. To quote James Dyson (the vacuum cleaner guy), I just think things should work properly. Quite frankly, I don't like 90% of what is out there. Most of the smaller boats being manufactured today look pretty. And they are designed so that they come on plane easily. But lets see how stable they are, and how comfortable they are at full throttle in a moderate chop . Case in point. My '71 Boston Whaler 13 turns heads wherever I go. But get her going 28 mph in moderate chop when my wife is on board and.....Well, you get the picture. I wanted to construct a stable, comfortable boat. This one is not a pretty boat that will go 60 mph. There are already plenty of those on the market already.


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## Davalos

m32825 said:


> Are the hulls interchangeable or is there a "left" one and a "right" one?


My hulls are symmetrical. The cats that have asymmetrical hulls are built for speed. They are designed to keep as much of the hull as possible out of the water. My micro-cat is designed to keep the bow in contact with the water at all times.


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## Davalos

My numbers are in. I just calculated my draft and freeboard. The hull itselft will draft about 4". Since it is a cat, I can set my anti-cavitation plate about 3" higher than the bottom of the sponsons. So... my total draft should be about 9". My freeboard should be about 10 inches.


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## firecat1981

Is there a deflector in front of the motor to smooth out water? If not you might run into issues and have to run the motor lower to get into clean water.

For low HP in calm waters this can be a cool platform to drift fish from or have a trolling motor on. One thing I'd caution is if you are making the sharper entry to cut through any kind of chop then I'd avoid a bow down attitude with tabs. The one huge drawback of cat designs are the lack of forward buoyancy. This is why the bow rises so much in offshore designs and why the pontoons avoid being super sharp, instead giving them a more stubby appearance. With only 10" of freeboard and heavily tabbed you have the risk of submarining trying to cross a boats wake. I think I would model it in 1/4 scale and play with it.


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## m32825

Clueless about cats so educate me: where do you mount the outboard and the trolling motor?


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## firecat1981

Depending on the design you can mount the outboard in the center, or have twins mounted behind each hull. The trolling motor usually needs to be mounted as centrally as possible in the front to avoid crab walking.


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## MatthewAbbott

firecat1981 said:


> Depending on the design you can mount the outboard in the center, or have twins mounted behind each hull. The trolling motor usually needs to be mounted as centrally as possible in the front to avoid crab walking.


If this doesn’t have 6hp motors on the cats then it’s a bust. Lol


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## Davalos

firecat1981 said:


> Is there a deflector in front of the motor to smooth out water? If not you might run into issues and have to run the motor lower to get into clean water.
> 
> For low HP in calm waters this can be a cool platform to drift fish from or have a trolling motor on. One thing I'd caution is if you are making the sharper entry to cut through any kind of chop then I'd avoid a bow down attitude with tabs. The one huge drawback of cat designs are the lack of forward buoyancy. This is why the bow rises so much in offshore designs and why the pontoons avoid being super sharp, instead giving them a more stubby appearance. With only 10" of freeboard and heavily tabbed you have the risk of submarining trying to cross a boats wake. I think I would model it in 1/4 scale and play with it.


Thanks for your observations. Yes on the deflector. I plan on placing the deflector 1.5" deeper than the transoms waterline when fully loaded. But I am open to any suggestions concerning deflector depth. As for the one huge drawback of [most of the] cat designs, i.e. the lack of forward buoyancy, and the bow rise; I am well aware of these deficiencies, as I have been investigating hull configurations for many years, including cats. It stands to reason that if you take a long, skinny hull with a narrow bow, and then put a huge, heavy chunk of metal (an outboard) at the transom, and then submit it to 3 - 5 foot seas, the bow is most certainly going to rise and fall excessively because the hull is not balanced. That is no mystery to me. It is simply the laws of physics. My hull design is different than your typical offshore cat in terms of weight distribution, aspect ratios and intended usage. If for whatever reason, I am not comfortable with the amount of bow rise, I have a trick up my sleeve (see attached photo). A wing off the lower inside of each bow. It would be the hydraulic equivalent of shock absorbers on a car. Remember, I am not out to design a pretty boat AT THIS TIME. I am designing a functional boat. Something different.









As for getting swamped by a passing boat, #1: I am not really designing this one to navigate around marked channels. This boat would be most at home on the quiet backwaters of the IRL. In areas where the big boys dare not go. #2. I plan on placing a 8" tall wave deflector towards the front of the deck. It would have a dual purpose as a foot rest when fishing off the bow. Thanks again.


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## Davalos

m32825 said:


> Clueless about cats so educate me: where do you mount the outboard and the trolling motor?


Outboard is mounted in the centerline of the boat, 18" forward of the end of each sponson. As for the trolling motor, my outboard is my trolling motor. I would explain, but I feel that I am already giving away too much info.


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## NealXB2003

Davalos said:


> Outboard is mounted in the centerline of the boat, 18" forward of the end of each sponson. As for the trolling motor, my outboard is my trolling motor. I would explain, but I feel that I am already giving away too much info.


Torqeedo?


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## Davalos

NealXB2003 said:


> Torqeedo?


Why would I spend $4,000 on an electric motor, and then add about 140 pounds of batteries to my boat when I can buy a brand new 5 hp propane powered outboard for $1700?


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## Davalos

bryson said:


> Do you have any napkin sketches? I like cats in most sea conditions. You will sacrifice draft for ride, but most will absolutely slice through chop with how sharp the bow entry usually ends up.


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## Davalos

firecat1981 said:


> Is there a deflector in front of the motor to smooth out water? If not you might run into issues and have to run the motor lower to get into clean water.
> 
> For low HP in calm waters this can be a cool platform to drift fish from or have a trolling motor on. One thing I'd caution is if you are making the sharper entry to cut through any kind of chop then I'd avoid a bow down attitude with tabs. The one huge drawback of cat designs are the lack of forward buoyancy. This is why the bow rises so much in offshore designs and why the pontoons avoid being super sharp, instead giving them a more stubby appearance. With only 10" of freeboard and heavily tabbed you have the risk of submarining trying to cross a boats wake. I think I would model it in 1/4 scale and play with it.


OK. Here is my micro-cat update with a wave deflector in place. In essence, I just added 6 inches of freeboard to the boat, but only added 5 more lbs. to the total weight.


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## Smackdaddy53

Definitely different!


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## NealXB2003

Davalos said:


> Why would I spend $4,000 on an electric motor, and then add about 140 pounds of batteries to my boat when I can buy a brand new 5 hp propane powered outboard for $1700?


I agree with you there, but your comment about the big motor doubling as your trolling motor had me thinking you were leaning electric.


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## Davalos

NealXB2003 said:


> I agree with you there, but your comment about the big motor doubling as your trolling motor had me thinking you were leaning electric.


Yes. I probably would have thought the same thing you did.


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## Davalos

Smackdaddy53 said:


> Definitely different!


Ok. I am taking that crazy wave deflector off! I don't know that I want it to be different to the extreme.


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## firecat1981

If the boat nose dives to the point that deflector actually gets impacted you have much bigger problems! Plus it's just a wind sail.

Also the deflector I was referring to needs to be under the boat in front of the motor.


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## Smackdaddy53

Davalos said:


> Ok. I am taking that crazy wave deflector off! I don't know that I want it to be different to the extreme.


Do what you want, I was just making a comment. Get your build on!


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## Davalos

firecat1981 said:


> If the boat nose dives to the point that deflector actually gets impacted you have much bigger problems! Plus it's just a wind sail.
> 
> Also the deflector I was referring to needs to be under the boat in front of the motor.


Yes. I have one in front of the anticavitation plate. My design has roughly the same freeboard as a Solo skiff. So it should be fine. And my entire deck is self bailing.


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## Sublime

I’m using the Carbon Core PE 80. Here is a little 4” x 12” piece I laid up and drove over with my Dodge Cummins. Very little compression.


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## Davalos

Sublime said:


> I’m using the Carbon Core PE 80. Here is a little 4” x 12” piece I laid up and drove over with my Dodge Cummins. Very little compression.
> View attachment 171705





Sublime said:


> I’m using the Carbon Core PE 80. Here is a little 4” x 12” piece I laid up and drove over with my Dodge Cummins. Very little compression.
> View attachment 171705


I feel that what I am using comes fairly close to the specs of the synthetic boards out there on the market, but without the hefty price tag. I am using Lloyd's rated 1088 Meranti marine plywood. In case you are not familiar with that, the 1088 standard means that there are no voids or footballs allowed in the plywood, and it has also passed the 10-hour boil test for no delamination. And this type of marine plywood comes in widths from 1/8 of an inch to 3/4 in. I know my boat is going to end up slightly heavier, but so will my wallet LOL.


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## KWGator

Not sure if you will have this problem but on my little 8.5 ft. cat, at top speed on plane with my 6hp Evinrude, water tends to hit the front of the outboard shaft and splash up the front of the motor shaft between motor and transom and come over the transom a bit between the two motor clamps on transom. I think a slightly wider motor deflector and a slightly different exit design at rear of cat hulls might improve or eliminate this problem. At lower speed it is not a problem. I know you mention that this is only for going shallow on the IRL (like where I spent most of my younger days) but you know a top speed test will be done at some point so I hope this helps in your design thinking.


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## Davalos

KWGator said:


> Not sure if you will have this problem but on my little 8.5 ft. cat, at top speed on plane with my 6hp Evinrude, water tends to hit the front of the outboard shaft and splash up the front of the motor shaft between motor and transom and come over the transom a bit between the two motor clamps on transom. I think a slightly wider motor deflector and a slightly different exit design at rear of cat hulls might improve or eliminate this problem. At lower speed it is not a problem. I know you mention that this is only for going shallow on the IRL (like where I spent most of my younger days) but you know a top speed test will be done at some point so I hope this helps in your design thinking.


I appreciate the information. I do know water splashes around quite a bit back there between the motor and the transom no matter what kind of boat you have. The fact is that my transom cause all the way up to the bottom of the motor clamp and is 3 ft wide in that area. The diverter I have at the bottom of the transom is going to be dead even with the anti-cavitation plate. I am just not visualizing right now how water could possibly splash into the boat. I am not saying you're wrong. I'm just saying I don't know how water could get into the boat with my transom setup


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## KWGator

Davalos said:


> I appreciate the information. I do know water splashes around quite a bit back there between the motor and the transom no matter what kind of boat you have. The fact is that my transom cause all the way up to the bottom of the motor clamp and is 3 ft wide in that area. The diverter I have at the bottom of the transom is going to be dead even with the anti-cavitation plate. I am just not visualizing right now how water could possibly splash into the boat. I am not saying you're wrong. I'm just saying I don't know how water could get into the boat with my transom setup
> View attachment 171709


Here is a photo I borrowed from the internet of a very similar outboard to mine, since my 6hp is 5 hours away from boat so I cannot show it on my boat. Arrow points to where water flows over my transom when at full speed on plane.









I hope your design doesn't have this problem but I wanted to point it out in case it helps.


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## Davalos

I understood that water is coming over your transom from between the clamps as you stated in your post. But I am not understanding is how is the water getting there to begin with. I would love to see a picture of your anticavitation plate in relation to the bottom of your hull or diverter. I would bet my right arm that something is not lining up properly and causing that water to come over your transom.


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## KWGator

I will try to get some photos of hull this weekend and share. It is filthy and needs a good cleaning anyway.


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## Davalos

bryson said:


> Do you have any napkin sketches? I like cats in most sea conditions. You will sacrifice draft for ride, but most will absolutely slice through chop with how sharp the bow entry usually ends up.


Update: got my biaxial fiberglass layer up. Hoping to do some test runs this weekend.


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## Davalos




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## KWGator

Weather was bad last weekend so I was not able to take any photos of my hull. I will try to this weekend.
Hope your tests are successful and maybe can include some videos for how she performs.


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## Davalos

KWGator said:


> Weather was bad last weekend so I was not able to take any photos of my hull. I will try to this weekend.
> Hope your tests are successful and maybe can include some videos for how she performs.


I will do my best to get her ready. I am anxious to see what she will do in terms of what I am trying to accomplish.


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## MudSkipper

Nice looking and interesting rig. It seems like that front spray shield could be added or removed as needed. If I could put a 50 on it, I'd be happy just zipping around.


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## Davalos

MudSkipper said:


> Nice looking and interesting rig. It seems like that front spray shield could be added or removed as needed. If I could put a 50 on it, I'd be happy just zipping around.


Thanks. I already took that spray shield off permanently. As for the 50 hp 4 stroke Tohatsu outboard, there are at least 200 boat manufacturers that do a really good job at making go-fast boats between 15 and 17 feet that you would feel right at home in. I don't want to compete against them. I am trying to create something that IMHO does not exist, or that there are very few of.


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## Davalos

Davalos said:


> Thanks. I already took that spray shield off permanently. As for the 50 hp 4 stroke Tohatsu outboard, there are at least 200 boat manufacturers that do a really good job at making go-fast boats between 15 and 17 feet that you would feel right at home in. I don't want to compete against them. I am trying to create something that IMHO does not exist, or that there are very few of.


Getting ready to round off my inside corners. I make my own profiling tools, so I can easily do whatever shape of radius I want.


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## Sublime

Davalos said:


> Getting ready to round off my inside corners. I make my own profiling tools, so I can easily do whatever shape of radius I want.


Yep, but for those reading that haven't done much of this, the angle at which you hold whatever tool you come up with can greatly change the size and thickness of the fillet. Definitely some technique involved.


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## firecat1981

Sublime said:


> Yep, but for those reading that haven't done much of this, the angle at which you hold whatever tool you come up with can greatly change the size and thickness of the fillet. Definitely some technique involved.


Absolutely, no one likes a wavy fillet. I usually keep a variety of craft sticks around to do it at about a 75 degree angle.


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## Davalos

firecat1981 said:


> Absolutely, no one likes a wavy fillet. I usually keep a variety of craft sticks around to do it at about a 75 degree angle.


No wavy fillets here. And I apologise to the poly people for violating your rules. That poly based fairing putty I used on my boat is sticking to everything. To epoxy, my shoes, the aluminum mixing board, acrylic, small children...
Filleted and sanded the entire bottom of the boat in 3 hours. Not bad.


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## Davalos

Davalos said:


> No wavy fillets here. And I apologise to the poly people for violating your rules. That poly based fairing putty I used on my boat is sticking to everything. To epoxy, my shoes, the aluminum mixing board, acrylic, small children...
> Filleted and sanded the entire bottom of the boat in 3 hours. Not bad.
> View attachment 172451


Question: has anyone put their polyester fairing putty in the fridge prior to use? I used a 100:1 MEKP ratio, and still only get 3 minutes working time. I was working in the shade, and it isn't too hot today in Central Florida. Obviously, I can't use any less than 1% MEKP. Looking for some advice here.


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## firecat1981

Mix it up and spread it out thin quickly. If you have it in a pail or cup it will kick fast.


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## Copahee Hound

Davalos said:


> Question: has anyone put their polyester fairing putty in the fridge prior to use? I used a 100:1 MEKP ratio, and still only get 3 minutes working time. I was working in the shade, and it isn't too hot today in Central Florida. Obviously, I can't use any less than 1% MEKP. Looking for some advice here.


I had success putting poly RESIN in the fridge before mixing in q cells, so I don't see why putty would be any different. I'm also not very experienced with poly, so take my opinion with a grain of salt


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## Davalos

firecat1981 said:


> Mix it up and spread it out thin quickly. If you have it in a pail or cup it will kick fast.


I did that. I had it off my board and onto the hull within 1 minute. Kind of like I do when I am working with 5 minute drywall mud. But some of it started kicking before I could even fair it out completely. I really like that fairing compound. It is just a bit too fast for me.


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## Davalos

Copahee Hound said:


> I had success putting poly RESIN in the fridge before mixing in q cells, so I don't see why putty would be any different. I'm also not very experienced with poly, so take my opinion with a grain of salt


Thanks. I don't have a ton of experience with poly either. But I can tell you that I would much rather fair and do cosmetic repairs with poly than with epoxy. It is ready to sand in 15 minutes. And it sands like a dream. I will never do non-structural repairs with epoxy again.


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## MudSkipper

Davalos said:


> As for the 50 hp 4 stroke Tohatsu outboard, there are at least 200 boat manufacturers that do a really good job at making go-fast boats between 15 and 17 feet that you would feel right at home in. I don't want to compete against them. I am trying to create something that IMHO does not exist, or that there are very few of.


Hey man, again nice job. I was not asking you to change anything on your boat and there is no need for you to compete with others. I just want to hang a 50 and go for a ride. That's all. Zoom Zoom.


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## Davalos

MudSkipper said:


> Hey man, again nice job. I was not asking you to change anything on your boat and there is no need for you to compete with others. I just want to hang a 50 and go for a ride. That's all. Zoom Zoom.


Mudskipper, once I finish with this project, I think you are going to like the next one even better. It's my outboard version of a 1/3 scale Riva Aquarama 44. It's my dream boat. Since I don't have $750,000 or somewhere to park a 44' yacht, I am going to do the next best thing.


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## Davalos

Got my Water diverter framed out. If someone knows what the proper name of that part is please, let me know.


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## MudSkipper

Davalos said:


> Got my Water diverter framed out. If someone knows what the proper name of that part is please, let me know.
> View attachment 172707


Doohickey, thingamajig, whachamacallit! I think you should name it yourself.


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## Smackdaddy53

Davalos said:


> Got my Water diverter framed out. If someone knows what the proper name of that part is please, let me know.
> View attachment 172707


Hydrosplitter


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## MudSkipper

I'm having a little trouble understanding why such a device is needed. I'm anxious to see out it works. Is its bottom level with the two cat hulls? Sort of hard to tell in the photo. Keep the photos coming and thanks for sharing your build.


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## Davalos

Smackdaddy53 said:


> Hydrosplitter





Smackdaddy53 said:


> Hydrosplitter


Sorry that one is already taken. A hydrosplitter is a fitting used in septic tank drain fields


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## Davalos

MudSkipper said:


> I'm having a little trouble understanding why such a device is needed. I'm anxious to see out it works. Is its bottom level with the two cat hulls? Sort of hard to tell in the photo. Keep the photos coming and thanks for sharing your build.


You need to have an understanding of how tunnel hulls work. The section of hull where the diverter is located is 6 inches above the bottom of the pontoons. The bottom of the diverter itself is 3" about the bottom of the pontoons. The cavitation plate on my outboard is going to be 2.5 inches above the bottom of the pontoons. The diverter is there to supply a steady flow of undisturbed water to the prop. All these numbers are specific to this 11.5' hull. All these numbers would increase as my hulls get bigger. Long story short, it is a way for me to be able to raise my outboard up higher than the bottom of the hull, thus allowing my Boat to draft 8" of water while going full speed. I am sure I did a horrible job of explaining it. I hope to be able to show you a video soon


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## MudSkipper

Davalos said:


> You need to have an understanding of how tunnel hulls work. The section of hull where the diverter is located is 6 inches above the bottom of the pontoons. The bottom of the diverter itself is 3" about the bottom of the pontoons. The cavitation plate on my outboard is going to be 2.5 inches above the bottom of the pontoons. The diverter is there to supply a steady flow of undisturbed water to the prop. All these numbers are specific to this 11.5' hull. All these numbers would increase as my hulls get bigger. Long story short, it is a way for me to be able to raise my outboard up higher than the bottom of the hull, thus allowing my Boat to draft 8" of water while going full speed. I am sure I did a horrible job of explaining it. I hope to be able to show you a video soon


I get it. Good explanation. Nothing further needed except to run it to see if the math, etc yields what your looking for.


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## Davalos

Update on my micro-cat build. I am a bathroom renovation contractor by trade. Lately, getting time off from work to finish my boat has been like pulling eye teeth. 

I have been doing a lot of thinking. I now believe there is 0% chance I will ever be able to break into the technical skiff market in any significant way, no matter how good my build performs or looks. Brand loyalty is everything. The guys dropping $30,000 on these boats are buying a brand. I don't think anyone is interested in a $10,000 off brand skiff.

I am going to continue developing my micro-cat. But as a fun, stable, novel looking, light, reasonably priced boat for Bubba and his beer drinkin' buddies. I may also develop a kit in the future for a 14 footer with a 20 hp.


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## jonterr

Davalos said:


> Update on my micro-cat build. I am a bathroom renovation contractor by trade. Lately, getting time off from work to finish my boat has been like pulling eye teeth.
> 
> I have been doing a lot of thinking. I now believe there is 0% chance I will ever be able to break into the technical skiff market in any significant way, no matter how good my build performs or looks. Brand loyalty is everything. The guys dropping $30,000 on these boats are buying a brand. I don't think anyone is interested in a $10,000 off brand skiff.
> 
> I am going to continue developing my micro-cat. But as a fun, stable, novel looking, light, reasonably priced boat for Bubba and his beer drinkin' buddies. I may also develop a kit in the future for a 14 footer with a 20 hp.
> Seriously???
> So , that’s it?
> I just spent 15 min reading this thread and now you bail???😳


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## Davalos

Where did you get the impression that I am bailing? If I were bailing, I would not have bothered giving the update. I will continue to post updates as soon as additional information becomes available.


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