# Hydrofoil talk.



## HialeahAngler (Dec 18, 2008)

To the more knowledgeable folk. :biglaugh: Over the weekend I installed a SE 300 Sport hydrofoil on my boat. I thought it looked a little suspect when I saw how far out it was extending but I installed it as recommended, and it said it should fit everything except Volvo. NOT TRUE! I have a 50hp 1995 Johnson and it apparently doesn't work with these style engines. This is what it looked like before and after the install.









When I tried running it Sunday morning in flamingo it would not get speed and it would make the engine rev very high. It seems like a problem with too much pressure/water in the prop area. So I removed it and returned it. I exchanged it for the Doel-fin hydrofoil which is smaller and doesn't cover any area over the prop. Do any of you have any experience with the doel-fin? Has it worked well for you? I have 4 holes in my cavitation plate now 1/4" thick. The Doel-fin also uses 1/4" but I doubt the holes will line up from the last drill. Man do I hope I can get enough area to drill if it doesn't line up! Comments welcome.


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## noeettica (Sep 23, 2007)

Doel is an OK foil Good for the money ... Probibly Ideal for your application ...

There are other list members with More experiance with your Type of boat ...

....Dave


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## HialeahAngler (Dec 18, 2008)

here's the deal. I wanted to be able to plane faster, limit bow rise, maybe save some fuel, and run a bit smoother. I'm trying not to spend a lot but what do you think. Is there something that might work better for me. 16 ft Baycraft Bay skiff, 1995 50hp Johnson that runs great.


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## Brett (Jul 16, 2008)

If trim tabs are too costly, then the easiest way to improve performance is simple.
Cut down on the amount of equipment you carry, and balance the load.
A stern heavy hull will never perform properly, rearrange your gear so the hull floats level.
That's floating level with you at the helm.

Then save up for a good set of electric trim tabs.


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## TomFL (Oct 2, 2007)

It sounds like your trim angle is wrong; you mentioned that the boat would not get up to speed and the motor revs high, a possible sign of cavitation, maybe caused by too high a trim angle?

Don't forget when you install a hydrofoil it will change the characteristics of how your motor performs at different trim angles. 

I've run the doel-fin on a ton of different motor/engine combinations, from a 5hp 2-stroke on a 13' gheenoe to 225hp on 23' boats, and have never been let down. I like them and I'm sure the google-search-master-Brett can find some of my old posts on them. 

But that's not to say that the SE Sport was the problem. 

I think you're missing something in the setup with the SE, I just don't see it causing that problem. Could also possible be a hub slippage problem??

-T


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## Brett (Jul 16, 2008)

previous posts:

http://www.google.com/#hl=en&q=doel-fin+site%3Amicroskiff.com&btnG=Google+Search&aq=f&oq=doel-fin+site%3Amicroskiff.com&fp=Li-R6mbKWrc


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## HialeahAngler (Dec 18, 2008)

> It sounds like your trim angle is wrong; you mentioned that the boat would not get up to speed and the motor revs high, a possible sign of cavitation, maybe caused by too high a trim angle?
> 
> Don't forget when you install a hydrofoil it will change the characteristics of how your motor performs at different trim angles.
> 
> ...



no hub slippage or bbad trim angle. the SE Sport doesn't go into the motor far enough due to the metal strip above the cavitation plate. it doesn't set up on my engine where it should. I'm looking forward to using the doel-fin. thanks.


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## beavis (Dec 11, 2006)

It looks like it fits on there fine.  I have one on my boat and it runs great.


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## HialeahAngler (Dec 18, 2008)

so how can I check if my hub is messed up? once I removed it and ran the boat it ran great as usual. now i'm frustrated. :-X


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## beavis (Dec 11, 2006)

Just hearing what the circumstances are about how it is acting, I would have to second the trim angle suggestion.


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## HialeahAngler (Dec 18, 2008)

well as soon as I had the problem I tried it with the trim all the way down, and with it slightly angled also. no angle helped. still over rev'd and didn't go anywhere. it would pick up to about 5-8 mph and then vrrrrrrrrrr, over rev.


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## beavis (Dec 11, 2006)

just curious since I noticed your prop. What pitch are you running it. 

When I was experimenting with props. I tried one that had to much pitch and what you described is kinda what happened to me. The prop would ventilate for a while and take forever to hook up if I punched it. I would have to accelerate slowly and that is no fun. I brought the pitch down 2 inches and my boats gets it now.


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## boggob (Feb 20, 2007)

> well as soon as I had the problem I tried it with the trim all the way down, and with it slightly angled also. no angle helped. still over rev'd and didn't go anywhere. it would pick up to about 5-8 mph and then vrrrrrrrrrr, over rev.


Sounds like a hub problem.


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## HialeahAngler (Dec 18, 2008)

> just curious since I noticed your prop.  What pitch are you running it.
> 
> When I was experimenting with props.  I tried one that had to much pitch and what you described is kinda what happened to me.  The prop would ventilate for a while and take forever to hook up if I punched it.  I would have to accelerate slowly and that is no fun.  I brought the pitch down 2 inches and my boats gets it now.


truthfully I have no idea what pitch I'm running but the person I bought the boat from said that he had already experiment and had this prop spec'd to him for the boat. thanks. 

If I had a hub problem wouldn't I not be able to run at all? I ran all day at 30mph.


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## Brett (Jul 16, 2008)

Easy to check for a spun hub:

http://www.mercstuff.com/spunprop.htm


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## TomFL (Oct 2, 2007)

> It looks like it fits on there fine.  I have one on my boat and it runs great.


X2. I think we can delete that as a possible cause here. 

Gotta be prop hub or trim/tilt. 

Or.... could be the motor is not installed at the right height. The SE or Doel-Fin will lift the stern of the boat, and may be lifting it out of the water enough to cause the prop to cavitate/slip. By looking at the pics you posted I can't tell for sure. 

Is the boat bow-heavy?

The only issue I ever had with the doel-fin was on a 15 hi-sider and 5hp 2-stroke. I had my buddy (235 lbs) sitting up front along with the trolling motor, group 27 battery and his fishing gear. Behind him was the cooler and ice (read: very bow heavy). When I'd give the boat gas, the front end would want to plow under the water, I think from having such a light motor on the rear, all the heavy stuff up front including him (outweighing me by an easy 60lbs), and mostly from having the doel-fin on there lifting the stern. So for sure they produce a good bit of lift. Having my buddy sit at the middle seat was the only way to alleviate the problem. Moving more weight to the back and/or having him drive and me sit up front would probably have cured the issue, but we were having too much fun fishing to worry about it that day.

See if you can shift more weight to the stern of the boat either by having a buddy sit back there, you move back, etc and see if that helps it get any better and you may find out what the problem is for free. 

Also you may want to have a buddy look at the motor while attempting to get up on plane and see if the SE is out of the water as the prop begins to slip or if it's still under water. 

-T


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## HialeahAngler (Dec 18, 2008)

> Easy to check for a spun hub:
> 
> http://www.mercstuff.com/spunprop.htm


thanks Brett. I will paint it next time out.

believe me that the boat is stern heavy. the 12 gallon gas tank is back there and we both sit side by side, as well as a starting battery. The bow is also heavy. 2 deep cycle in the front hatch and one under the console. Now that you mention it the sound did seem as if the prop was coming out of the water. It would quickly lose pressure and over rev. you guys are a lot of help. so now what the heck do I do? do I just not use anything or should I give the doel-fin a try? don't want to put too many holes in the plate. :'(


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## TomFL (Oct 2, 2007)

You're kinda stuck here. You have 2 holes drilled that match the SE, but you took it back in exchange for the doel-fin. 

I would see if the doel-fin hole spacing matches the ones already drilled in your cav plate, in which case I would just use it; it's cheaper and does the job fine. 

If it doesn't I would probably go back to where you bought the SE from and see if they would swap you again and try to get it running properly. 

Or just leave both off and take it from there. Not a fan of turning your cav plate into swiss cheese. 

-T


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## HialeahAngler (Dec 18, 2008)

I feel kinda stupid for returning it so soon. I didn't know about painting the hub to check for slippage or the bow for weight. I'm going to check where the Doel-fin lines up and decide whether I am going to install it. Can the holes be covered if there was a problem with some welding or something? sorry about all the questions. I will update with the doel-fin pics.


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## paint it black (Nov 3, 2007)

> well as soon as I had the problem I tried it with the trim all the way down, and with it slightly angled also. no angle helped. still over rev'd and didn't go anywhere. it would pick up to about 5-8 mph and then vrrrrrrrrrr, over rev.


Are you sure you weren't getting grass caught on the motor? It happened to us on chris's boat quite a few times since all the floating sea grass. We'd have to power down, tilt motor, clean it off, tilt down, and start up. His boat was doing the same thing when there was grass on it. 

His motor ended up acting up though. Something to do with the carbs, or gas. It was acting as if it didn't have any gas. We thought we were going to have to trolling motor all the way back to the ramp. But chris took the cowling off and manually rev'd the carb as I started the motor and it cranked up. Seems like he might have an adjustment issue or something. We kept having problems starting up the motor since then. Or it might have been flooded really bad or something.


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## HialeahAngler (Dec 18, 2008)

definitely not a grass issue.


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## HialeahAngler (Dec 18, 2008)

good morning. Finally installed the Doel-fin this weekend, and I ran the boat at Holiday Park for a bit yesterday during the storms. The boat ran great, planed very fast, and did not lose any top end. I can say it's the best $36 I've spent. Once the boat is under way and trimmed a bit the doel-fin is actually out of the water. I was still able to push out 31mph from my little 50.  The problem that is now obvious is that the SE 300 hydrofoil comes out way past the prop, and that was causing way too much lift and hence lifting my prop out of the water and causing the blowout. Can't wait to give it a shot in mingo and see how it handles when taking of shallow. Thanks to all that help with suggestions. I also installed a new stern light. Maybe I'll put some pics up later.


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## beavis (Dec 11, 2006)

good to hear you are up and running




> problem that is now obvious is that the SE 300 hydrofoil comes out way past the prop, and that was causing way too much lift and hence lifting my prop out of the water and causing the blowout.


this would go back to the trim angle


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## TomFL (Oct 2, 2007)

> good morning. Finally installed the Doel-fin this weekend, and I ran the boat at Holiday Park for a bit yesterday during the storms. The boat ran great, planed very fast, and did not lose any top end. I can say it's the best $36 I've spent. Once the boat is under way and trimmed a bit the doel-fin is actually out of the water. I was still able to push out 31mph from my little 50.   The problem that is now obvious is that the SE 300 hydrofoil comes out way past the prop, and that was causing way too much lift and hence lifting my prop out of the water and causing the blowout. Can't wait to give it a shot in mingo and see how it handles when taking of shallow. Thanks to all that help with suggestions. I also installed a new stern light. Maybe I'll put some pics up later.


Awesome, glad to hear it. Sucks being frustrated after spending $$, and it's a great feeling to fix the issue $ overcome that frustration. Doing so and saving $$ at the same time is icing on the cake. 

I took the liberty of highlighting a good statement from you in your post above. 

I second that notion.

-T


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## HialeahAngler (Dec 18, 2008)

no doubt man. and I thought buying the most expensive one would be best, lol. thanks.


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## paint it black (Nov 3, 2007)

> good morning. Finally installed the Doel-fin this weekend, and I ran the boat at Holiday Park for a bit yesterday during the storms. The boat ran great, planed very fast, and did not lose any top end. I can say it's the best $36 I've spent. Once the boat is under way and trimmed a bit the doel-fin is actually out of the water. I was still able to push out 31mph from my little 50.   The problem that is now obvious is that the SE 300 hydrofoil comes out way past the prop, and that was causing way too much lift and hence lifting my prop out of the water and causing the blowout. *Can't wait to give it a shot in mingo and see how it handles when taking of shallow. *Thanks to all that help with suggestions. I also installed a new stern light. Maybe I'll put some pics up later.



let me knowwwwwww. ;D


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## HialeahAngler (Dec 18, 2008)

see what happened to you yesterday for ignoring your phone. lol. better not ignore it when that mingo call comes in. being that I'm a pro and all. :


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## paint it black (Nov 3, 2007)

> see what happened to you yesterday for ignoring your phone. lol. better not ignore it when that mingo call comes in. being that I'm a pro and all. :



Try calling next time. lol That text message shit wont wake me up. My phone only says "New Message" once. lol And I got your text mixed in with 6 texts from Miami Pescador I was ignoring his texts. lol I didn't even notice yours till after.


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## HialeahAngler (Dec 18, 2008)

and I thought you guys were best friends. lol. will do bro.


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## paint it black (Nov 3, 2007)

> and I thought you guys were best friends. lol. will do bro.


lol nah bro. I only fish with him once every few months if even that. The people I usually fish with on a weekly basis is Bernard(brakish1) and Chris(chris83).


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## HialeahAngler (Dec 18, 2008)

the doel-fin has performed great. took my dad out today in some less than favorable weather and had a great ride. some install pics:




























Went ahead and installed a new stern light while I was at it.




























I'm truly impressed with the least expensive of all the hydrofoils.


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## 1BadPFS (Aug 18, 2007)

the SE foil is way to long, has nothing to do with trim angle. This is why the little cast aluminum bobs foils do so well, they might be narrow, but they stick out past the rear of the cav plate. For a big boat with a v6, the SE might be the ticket, but on these things its like a water brake.


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## 1BadPFS (Aug 18, 2007)

Oh, looks like I'm a day late and 2 dollars short with my reply, glad to see you got it working. [smiley=1-thumbsup1.gif]


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## TomFL (Oct 2, 2007)

> the SE foil is way to long, has nothing to do with trim angle. This is why the little cast aluminum bobs foils do so well, they might be narrow, but they stick out past the rear of the cav plate.  For a big boat with a v6, the SE might be the ticket, but on these things its like a water brake.


Possibility there, I had an SE 300 on a 225 poptimax pushing a 23 seacraft. Heavy hull, and even with trim tabs the SE made a very noticeable difference. Of interest is that I had originally purchased a 23 seacraft and had some issues with it, and seacraft made me another one. I had installed the SE 300 on the first hull. 

10 months later, they delivered my new boat/motor. I pulled the new one off the trailer, drove the old one onto it and waved goodbye to the driver from the water. 

As soon as I hit the throttle on the new boat, I could feel the difference big time. within a week I had a new SE on the new boat/motor and I was happy with it's performance. 

So your point might be valid there. 

-T


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## HialeahAngler (Dec 18, 2008)

no doubt. it's just too much foil for a small engine. thanks.


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## Kemo (Jun 22, 2008)

Smaller, less expensive boats, smaller less expensive motors, = less expensive everything!  Simpler, too.  I always try them first (less expensive), then try to make my own.  Only spend the big bucks after everything else fails (and after pondering all the incredible and extremely useful advice you'll find on this forum).  

Kemo   

PS - Duh, sometimes try to make my own first.  Not always a good idea.


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## 1BadPFS (Aug 18, 2007)

DK - I've made my own foils... My conclusion is that the ones you buy are stronger than they look. :-[


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## ducktrooper (May 6, 2008)

I'm now thinking of putting on a Hydro Shield, which acts like a hydrofoil, but also installs UNDER the skeg to protect the prop. Made out of heavy, thick plastic and bolts thru the skeg.

This in theory will help my planing and handling while also protecting my prop in fresh water where I flyfish and duckhunt. Has anyone heard about or used these?

www.hydro-shield.com


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## TomFL (Oct 2, 2007)

> I'm now thinking of putting on a Hydro Shield, which acts like a hydrofoil, but also installs UNDER the skeg to protect the prop. Made out of heavy, thick plastic and bolts thru the skeg.
> 
> This in theory will help my planing and handling while  also protecting my prop in fresh water where I flyfish and duckhunt. Has anyone heard about or used these?
> 
> www.hydro-shield.com



If I'm not mistaken someone on here posted test results using one of these and was horribly disappointed. 

I think it killed the top-end. Like 20-30% off the top end. Basically it's in the water at all times, which means more hyro drag. Which is... well.. a drag. 

Someone please correct me if I'm wrong but I think it was this version.


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## ducktrooper (May 6, 2008)

Seems like a great concept but you may be right Tom. I did quite a search and found only a few posts...most were good buit posts were generally vague. 

I'd be interested as well to hear from others. I may ultimately go Doelfin and add a Mac's River Runner Prop protector for the rivers and small water bodies I'll be in.


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## TomFL (Oct 2, 2007)

> Seems like a great concept but you may be right Tom. I did quite a search and found only a few posts...most were good buit posts were generally vague.
> 
> I'd be interested as well to hear from others. I may ultimately go Doelfin and add a Mac's River Runner Prop protector for the rivers and small water bodies I'll be in.


Brett, any possibility you can work some 'net mojo and find that test result I was thinking of?


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## Brett (Jul 16, 2008)

Took a look on site for hydro-shield
not much in the way of results.
Maybe on one of your other forums, Tom.
The web runs pro and con for all the different types of foils.
No real comparisons posted.
I guess the question goes back to lift versus drag.
Do you need the lift more than you need to worry about the drag?


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## Tom_W (Oct 23, 2008)

The way I see it these devices can provide more than one function.

They're Anti-Cavitation plates

They provide stern lift

and 

They can be used for exagerating the engine trim to improve your hole shot.

All can affect speed, handling, hole shot and fuel economy.

IMO

Anti-Cav plates need to be wide and infront of the prop and might even have vertical sides to keep water in and air out.

Stern Lift (doel fin) need to stay submerged at most speeds.

Trim and hole shot units are usually narrow and behind the prop and usually ride free once at speed.

Of course most of the units can and do perform more than one function so you need to determine your requirements before selecting type of unit. 

Not to mention that every boat, motor and prop combo can react differntly to the same device.

There was a very large detailed thread on Texas Flats Fishing forum a while back dealing mostly with high powered cat type tunnels but interesting reading none the less.

As they say YMMV.

Tom W


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## HialeahAngler (Dec 18, 2008)

if you're talking about a small skiff I would recommend the Doel-fin without hesitation. I was out on the skiff again this weekend and I ran at different speeds. I was able to keep the boat on plane at a mere 14 mph, and a steady ride at even 8 mph. It has definitely changed the way my skiff handles and you can't beat it for under $40. Much easier than trying to invent something. lol.


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## TomFL (Oct 2, 2007)

> if you're talking about a small skiff I would recommend the Doel-fin without hesitation. I was out on the skiff again this weekend and I ran at different speeds. I was able to keep the boat on plane at a mere 14 mph, and a steady ride at even 8 mph. It has definitely changed the way my skiff handles and you can't beat it for under $40. Much easier than trying to invent something. lol.


 [smiley=1-thumbsup3.gif] [smiley=1-thumbsup3.gif] [smiley=1-dancingchief.gif]


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## DuckNut (Apr 3, 2009)

After breaking my skeg off not once but three times on oyster bars or something else under water I installed a Mac' River Runner more than 5 years ago. I did not bother fixing the skeg the last time and got three bolts through it.

To help Duck Trooper out, I duck hunt all over from Canada and usually average 7 different states every year and have not had a single problem with the device. I did not have a GPS on the boat before it was installed but I can tell you that if I lost any speed it is not noticed. I have a 16 footer with a Merc 25 4 stroke.

I have no idea if the device acts as a hydrofoil, because in reality, I do not care. I was simply tired of paying to fix skegs and props. This product has run aground more times than I have hair on my head and has not allowed any damage to my lower unit or the prop since it was installed. It works for me and I am sticking with it.

Before choosing the River Runner I looked at the one in the link above and came to the same conclusion that something that big might have negative impact and then decided to go with the smaller one. I might suggest trying the River Runner and if you do not like it you can take it off and have a prop shop fill in the 4 small bolt holes if you choose too.


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## TomFL (Oct 2, 2007)

> After breaking my skeg off not once but three times on oyster bars or something else under water I installed a Mac' River Runner more than 5 years ago.  I did not bother fixing the skeg the last time and got three bolts through it.
> 
> To help Duck Trooper out, I duck hunt all over from Canada and usually average 7 different states every year and have not had a single problem with the device.  I did not have a GPS on the boat before it was installed but I can tell you that if I lost any speed it is not noticed.  I have a 16 footer with a Merc 25 4 stroke.
> 
> ...


Well there you have it; great info. Glad to see there are more than a few duckers on here now...

-T


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## ducktrooper (May 6, 2008)

I simply couldn't ignore the many testimonials for the Doel Fin so I got one yesterday for $30 at store. I plan to install a Mac's Prop Protector as well....have heard they are absolutely essential for the type of rivers and water I'll be on. 

Thanks to all for their in depth comments....especially Tom.


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## TomFL (Oct 2, 2007)

> I simply couldn't ignore the many testimonials for the Doel Fin so I got one yesterday for $30 at store. I plan to install a Mac's Prop Protector as well....have heard they are absolutely essential for the type of rivers  and water I'll be on.
> 
> Thanks to all for their in depth comments....especially Tom.


Gawd I hope it works... Just kidding!!

Good to hear it, and post your findings!

-T


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