# basic skiff design questions



## Sam K (Apr 24, 2020)

Hi everyone,
I'm an engineering student and I'm spending some free time this summer designing (and maybe building) a small poling skiff. It's 15 ft long and 56 inches wide. If I try to build it, I plan to keep it super low cost and just stitch and glue with plywood, then finish it so it won't just rot immediately. I've never built a boat before so simplicity is very important. 
I wanted to ask about the bottom design. I would love to just keep the bottom flat for ease of construction, but I see that a lot of skiffs have a reverse chine design. Would I be wasting my time building a flat bottom boat? Second, I think I should put in poling strakes to help it track well. How long are typical poling strakes and how far do they usually protrude from the bottom? Lastly, how tall from the bottom to the deck would be ideal? Seems to me you want to keep it low profile to avoid wind issues, right now its 15 inches. 
Also, what's the best place to buy exterior or marine plywood in sufficiently large pieces? I'm near orlando. 
Not looking to produce a world class skiff, just a fun project. I have looked at some stitch and glue plans out there and nothing really fits what I want perfectly, plus attempting an original design is part of the fun for me. When I'm ready to build I'll appraise whether or not I want to buy plans or attempt to build my own design. Any suggestions and advice are greatly appreciated. A couple CAD screengrabs from what I've whipped up so far are included. I still plan to add more structural pieces in the middle cockpit area, but I am still deciding exactly how I want to integrate those without getting in the way of the rod holders. 
Sam


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## BassFlats (Nov 26, 2018)

Boat builders central in Fort Pierce should have everything you need. Check out of their boat plans, it might help with your design.


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## DuckNut (Apr 3, 2009)

Sam,

You have asked a lot of questions. But more importantly the questions cannot be answered by anyone other than yourself.

All of the possible answers are opinions.

What I see in your design above says - build it just like that!

There is no right or wrong way for your build. Only an unsafe build is wrong.


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## Sam K (Apr 24, 2020)

@DuckNut Thanks for your advice. You're right that the answers are opinions but I definitely value the opinions of those better informed than me. Since yesterday I've decided to add a mild reverse chine and 3 degrees of deadrise throughout. Also rounded off the nose. Definitely adds complexity to the build but hopefully will be possible and worth it.


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## DuckNut (Apr 3, 2009)

@Sam K 

Don't become blind by overthinking it. Look at all the pics and draw it up and build it.

There are guys on here that have bought plans from one of the most respected skiff designer in the world and changed them to suit their needs. If there was only one way we would all have the same skiff.

I think it's great you made a couple small changes, now post those up as well.


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## JC Designs (Apr 5, 2020)

I am in full agreement with @DuckNut! It’s your baby, treat it as such.

I will add this as well and will probably start WW3 over it but here goes...
You would be amazed at how long properly sealed exterior plywood will last if maintained! Most of the commercial well boats/mullet boats you see are made of exterior ply and get abused day in and day out for many years with only the seams being glassed with csm and poly resin and painted with porch paint! Many many production builders that used or are still using plywood use exterior plywood with poly or vinyl ester resin. Ask me how I know, Build it how you want, with the materials you can afford or justify the cost of just build it strong and safe. Happy building, James!


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## Sam K (Apr 24, 2020)

Will 


DuckNut said:


> @Sam K
> 
> Don't become blind by overthinking it. Look at all the pics and draw it up and build it.
> 
> ...


I definitely need to stop designing and redesigning because it’s hard to know for sure unless I build it. I was thinking of looking into doing some simulations though for hull efficiency etc. I am lucky to have access to a lot of great software for free. Will post the final design before I build and post a build log if I end up doing it.


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## Sam K (Apr 24, 2020)

JC Designs said:


> I am in full agreement with @DuckNut! It’s your baby, treat it as such.
> 
> I will add this as well and will probably start WW3 over it but here goes...
> You would be amazed at how long properly sealed exterior plywood will last if maintained! Most of the commercial well boats/mullet boats you see are made of exterior ply and get abused day in and day out for many years with only the seams being glassed with csm and poly resin and painted with porch paint! Many many production builders that used or are still using plywood use exterior plywood with poly or vinyl ester resin. Ask me how I know, Build it how you want, with the materials you can afford or justify the cost of just build it strong and safe. Happy building, James!


Thanks for the encouragement. It’s funny you mention the workboats, I have looked at the work boats in the lagoons and thought if they are wood, wood can’t really be as evil as a lot of people claim. I think there is a market for low cost, budget shallow water poling skiffs at a gheenoe price point if it’s possible. So many companies building amazing boats, but not everyone can afford cutting edge. Any opinions on rotomolding as a hull manufacturing process for something similar to this in size?


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## JC Designs (Apr 5, 2020)

Sam K said:


> Thanks for the encouragement. It’s funny you mention the workboats, I have looked at the work boats in the lagoons and thought if they are wood, wood can’t really be as evil as a lot of people claim. I think there is a market for low cost, budget shallow water poling skiffs at a gheenoe price point if it’s possible. So many companies building amazing boats, but not everyone can afford cutting edge. Any opinions on rotomolding as a hull manufacturing process for something similar to this in size?


Would be cost prohibitive for most and not really the best material for a skiff IMO


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## K3anderson (Jan 23, 2013)

Foam core is way easier to use than wood IMO. Cost is more than the cost of the material. It's the cost of how much more time you use too. Core can be cut with a razor and shaped with a few swiped of the longboard.


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## loganlogan (May 8, 2020)

Did you say you are an engineering student? I couldn't tell. That's not a negative, but you have that mindset for planning.


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## DuckNut (Apr 3, 2009)

Sam K said:


> So many companies building amazing boats, but not everyone can afford cutting edge.


A company will not stay in business if they use basic plywood. The boats will last a couple years and then they will get bashed to smithereens on the internet because the cheap bastards who bought them think they should last a lifetime.

The boating industry has demonized wood and any boat made with it is automatically a hunk of crap. Boat stringers are a perfect example. If you use wood for a stringer and it rots away, who cares because the wood is not the stringer. The wood was used as a form to build the stringer out of the glass placed over top.


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## Sethsawyer (Apr 5, 2019)

Make sure your bow has some v in it a most flat bottom boats will not turn well on pole. You want a poling skiff to have enough v so that the bow has added drag “usually deeper in the water” when turning. The stern will turn nicely on pole while the bow sticks in place. It will also naturally turn into the wind and the v also helps tracking. A totally flat bottom boat can pole ok if the hull tapers to a nice point think stumpknocker. Especially if it is a little bow heavy. Again the bow has more drag in the water than the stern. 

Plywood covered in glass and resin will last a long time if you take care of her.


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## Sam K (Apr 24, 2020)

DuckNut said:


> A company will not stay in business if they use basic plywood. The boats will last a couple years and then they will get bashed to smithereens on the internet because the cheap bastards who bought them think they should last a lifetime.
> 
> The boating industry has demonized wood and any boat made with it is automatically a hunk of crap. Boat stringers are a perfect example. If you use wood for a stringer and it rots away, who cares because the wood is not the stringer. The wood was used as a form to build the stringer out of the glass placed over top.
> [/QUOTE





Sethsawyer said:


> Make sure your bow has some v in it a most flat bottom boats will not turn well on pole. You want a poling skiff to have enough v so that the bow has added drag “usually deeper in the water” when turning. The stern will turn nicely on pole while the bow sticks in place. It will also naturally turn into the wind and the v also helps tracking. A totally flat bottom boat can pole ok if the hull tapers to a nice point think stumpknocker. Especially if it is a little bow heavy. Again the bow has more drag in the water than the stern.
> 
> Plywood covered in glass and resin will last a long time if you take care of her.


thanks for that advice, I’ve added a bit more v to it but I will add more. I see what you mean looking at the bow of most poling skiffs. I’ve added a lot of nuance to the bottom since those pics but the basic dimensions have stayed mostly the same


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## Sam K (Apr 24, 2020)

loganlogan said:


> Did you say you are an engineering student? I couldn't tell. That's not a negative, but you have that mindset for planning.


Yessir. Mechanical going into my senior year at UF


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## Vertigo (Jun 3, 2012)

There are considerations when designing a skiff that go beyond basic function. Cost is the first and most obvious, but there are others such as the availability of work space, tools, and materials, the properties of the available materials, and even safety and environmental concerns and timing. Make sure you give plenty of thought to these concerns or your build might end in disappointment. There are lots of unfinished projects for sale on Craigslist that prove this point.

My only criticism of the design as I see it here is that a square transom is going to be a pain in the butt if you intend to hang an outboard from it.


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## State fish rob (Jan 25, 2017)

I would think rounded stern corners would be worth the effort I admire your “want to”. Enjoy the process. Good luck


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## Sam K (Apr 24, 2020)

Vertigo said:


> There are considerations when designing a skiff that go beyond basic function. Cost is the first and most obvious, but there are others such as the availability of work space, tools, and materials, the properties of the available materials, and even safety and environmental concerns and timing. Make sure you give plenty of thought to these concerns or your build might end in disappointment. There are lots of unfinished projects for sale on Craigslist that prove this point.
> 
> My only criticism of the design as I see it here is that a square transom is going to be a pain in the butt if you intend to hang an outboard from it.


Thanks for this criticism, I notice now most skiffs have transoms that angle inward a few degrees. Is this what you mean? That’s easy enough to change.


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## Sam K (Apr 24, 2020)

State fish rob said:


> I would think rounded stern corners would be worth the effort I admire your “want to”. Enjoy the process. Good luck


Thanks!


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## Vertigo (Jun 3, 2012)

Sam K said:


> Thanks for this criticism, I notice now most skiffs have transoms that angle inward a few degrees. Is this what you mean? That’s easy enough to change.


Yes. Easy to change, but does introduce more complexity getting all the angles right. Another point. Compound curves in plywood are very difficult to manage. Your bow section looks like it could be a problem area. Here's a simple layout that shows how to get around that problem. The bottom is in two halves down the center with a few degrees of deadrise. There are no compound bends in the bottom or the hull sides. There are more sophisticated ways to avoid compound bends, but this should give you some ideas.


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## Sam K (Apr 24, 2020)

so far so good. Some trimming and gap filling to do then it’s time to epoxy. Going to change the transom angle too


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## Sam K (Apr 24, 2020)

she floats! Looking for advice on what outboard to hang. With all the savings of building instead of buying, Im thinking I’ll go with a new Suzuki or tohatsu. At the low end I’m thinking the 81 lb tohatsu 9.8, and at the high end I’m thinking 97 lb Suzuki 20. Shes 15 ft by 54 in beam, flat bottom that tapers to a point (going to probably knock my teeth out when running in chop i know). Any advice on what you’d hang is appreciated.


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## Sam K (Apr 24, 2020)

Going to add a poling platform, center box, and grab bar this week along with finishing it and making it all pretty.


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## WhiteDog70810 (May 6, 2008)

FWIW, my very similar hull is 16’x54” across the gunnels (40” across the chines) at center station; I have a 2 stroke Nissan 8 HP and get about 16 mph. This is actually a very comfortable speed for a light flat bottom skiff; I think a 10 HP would be perfect. Even at 16 mph, when you get in open, windy areas, you’ll feel the hull get blown around a bit. I want a bit more HP for when I carry a heavier load, not necessarily for the speed, although I’d like to cruise at about 20 mph in protected areas. I do like how light this 2 stroke is though.

Nate


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## Sam K (Apr 24, 2020)

WhiteDog70810 said:


> FWIW, my very similar hull is 16’x54” across the gunnels (40” across the chines) at center station; I have a 2 stroke Nissan 8 HP and get about 16 mph. This is actually a very comfortable speed for a light flat bottom skiff; I think a 10 HP would be perfect. Even at 16 mph, when you get in open, windy areas, you’ll feel the hull get blown around a bit. I want a bit more HP for when I carry a heavier load, not necessarily for the speed, although I’d like to cruise at about 20 mph in protected areas. I do like how light this 2 stroke is though.
> 
> Nate


Thanks this is great advice, I got a great deal on a Yamaha 9.9 this morning and that will do for now, possibly for the long term.


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## Sam K (Apr 24, 2020)

jackson man said:


> Are you planning on that motor board on the transom to hold that 20hp. Zuke?


That transom has been reinforced with another half inch plywood, supports, and fiberglass since that picture. Did some force analysis with the computer model and a 20 should be fine I think. Glad I’m going with a 9.9 for now until it’s proven itself structurally sound.


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## Sam K (Apr 24, 2020)

Might need to add another half inch of ply so it clamps properly, I read most transoms are 1.5 in


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## DuckNut (Apr 3, 2009)

Great job Sam.

I think you learned a lot through this process. I know for sure if you continued to work on the computer for the perfect skiff you would not be on the deck practicing your poling.

Super job!


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## Sam K (Apr 24, 2020)

DuckNut said:


> Great job Sam.
> 
> I think you learned a lot through this process. I know for sure if you continued to work on the computer for the perfect skiff you would not be on the deck practicing your poling.
> 
> Super job!


Thanks! Painting her right now, excited to hang my outboard on her and head out across the lagoon


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## flyclimber (May 22, 2016)

Sam K said:


> Yessir. Mechanical going into my senior year at UF


Awesome! That's where I graduated from! I opted to start with a paddle board and foam. Validate process before jumping into a larger build.


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