Composite Rowboat

Hello All,

Just signed up to your site hoping to get some helpful advice on a boat project I'm planning to under take this winter.

I'm an avid fisherman and enjoy camping and have worked on many different projects through the years.

My last camping trip to the Adirondacks just reminded me how my age is finally catching up with me and so I need to invent my way out of the problem.

I'm trying to create a boat that is stable, but very light weight in the form of a flat bottom rowboat in the rear 8ft then tapering down to a canoe type swept up front for the forward 4 to 6 feet.

The width in the rear at the floor will be 42 inches and the side walls 18 inches.

My plan was to create the mold shape out of pink foam board and then cover it with polyethylene heat shrink boat wrap to be able to then lay carbon fiber / Kevlar layers to make the hull.

I have worked with fiberglass before but not Kevlar or carbon fiber.

Looking for confirmation on my plan and what materials would best be suited for this project. Where to purchase materials. General layering steps (alternate layers, use Kevlar as final layer, etc.). How many layers would provide sufficient strength for 1000 pounds of total load people plus gear.

Any other suggestions to make my project a success.

Note: I'm not necessarily planning to make a number of these from the mold. If I can manage to get more than one for a friend, great but my goal is just to make one for me.

Thanks in advance for all the advice.
Scott M.

 

Welcome to the Forum Scott.

Can you post any sketches of what you have in mind please?

Re your proposal, before you jump into building it, it would be worthwhile looking at as many boat plans on line as possible - google is your friend here.
And don't be embarrassed about buying a set of plans if you come across a boat design that you like.

The cost of the plans will be insignificant in relation to the cost of the materials (especially so if you start lavishing carbon and kevlar on the construction of it), and (dare I say it) the plans will probably give you a much better boat design than what you are currently proposing above.

 

I have been looking on line for some time for a concept like I described but most people don't invest the time and money to fabricate a rowboat style boat out of carbon fiber/kevlar. But a typical 12 foot aluminum rowboat weighs around 100 pounds.

I have a bad back and so trying to place that boat on top of a roof rack of a full size pickup by yourself is basically impossible.

But a custom made carbon fiber/kevlar boat will weigh approx. 50 to 60 pounds.

I realize my concept is something totally new but the goal of the boat is to be stable (wide back/flat bottom), be rowable like a canoe/kyack (why the tapered front to canoe style point) and sweep up in front like a skiff to be able to go into water with a slight chop without having to worry about nose going under small waves.

For the most part my plan is to use the boat primarily for fishing with a trolling motor to power it around.

I will draw up some sketches to post to help people get a better idea of my project.

I agree 100% on doing research, research, research that is why I'm here on this forum. Time and researching is cheap, kevlar/carbon fiber and epoxy not so much.

Thanks
Scott M

 

You mean you want this: Recreational rowing boats | Liteboat - Light, stable, easy rowing boats https://www.liteboat.com/recreational-rowing-boats/

Forget the kevlar, use carbon only. But use it as a sandwich, with either foam or balsa.

 

Another study case for you https://www.storerboatplans.com/faq...a-canoe-experiment-strip-planked-12lbs-5-5kg/

 

Took a look and those are more specifically geared for rowing only.

For mine take a typical 12 ft jon boat, chop the front 4 feet off and put a swept up canoe front and connect the two.

Light, great to fish from and still rowable like a rowboat with two oars or like a kyack with a single paddle.

May make a quick small scale model out of foam block and take photos to post.
Thanks for link.
Scott M.

 

What you describe sounds a bit like a 29er (which is a bit like a smaller 49er) performance sailing dinghy, re the broad run aft, and a fine bow.
So I went looking for info on the 29er - and I found this Falco from Wooden Boat, which is similar in some ways.

FALCO https://www.woodenboat.com/boat-plans-kits/falco



She has a lot of flare on the hull topsides which gives you good reserve stability, yet makes for a relatively narrow waterline when you are rowing (which I am sure you will enjoy - rowing is addictive if it is fun).
I am thinking that you would probably want to increase the sheerline a bit up forward?
They mention a hull weight of 90 lbs in wood / epoxy - if you went high tech with a carbon / epoxy foam sandwich construction you could reduce this hull weight drastically.
Especially if you reduce the length to 12' from 14'.

 

Wow, this is almost exactly what I'm thinking of doing.

The only main difference is to sweep the front upward as well to provide more wave resistance and then not close in the front top side to allow more open space for 2nd fisherman and gear.

Seeing that it won't be a sailboat (at least initially, you never know I might get bored) at the rate of speed traveling with a trolling motor, the inside should stay dry even in a chop.

If that only weighs 90 lbs. At 14 feet, making something out of carbon fiber should be close to half.

Question: why are you and the other person saying to sandwich carbon and foam. Is this better than just all carbon layers or is it a cheaper way to go (less carbon material needed) and get just as strong of results?

Glad to see something is out there which is seaworthy that is close to my concept. Gives me a lot of confidence that mine will be doable and functional.

Thanks for finding that.

Hope to make a 1 foot model in the next day or two.
Thanks,
Scott

 

1000 pounds is beyond safe operation of a 12 foot, 42 inch wide boat, for mine.

 

Scott, you mention that you do not want to 'close in the front top side to allow more open space for 2nd fisherman and gear.'
However it would be prudent to have buoyancy compartments on the boat, in case you get flooded, and this bow area is a good place to have some buoyancy.
You will also need some buoyancy at the aft end, perhaps tanks along the gunwhales that can double as seats.

Re making a foam sandwich hull, this will be stiffer and less weight probably than a single skin hull.

I will endorse Mr E's comment re how 1,000 lbs is way too much for a boat this size - even a rectangular brick shaped boat that is 12' x 4' in plan area will sink by 4" if you uniformly load it with 1,000 lbs, and one with a pointed end will more likely sink by 7 or 8 inches.
Not to mention that the stability will not be happy.

 

Yea, I was just thinking about two men and adding gear to port to a campsite, not necessarily to operate the boat. Definitely over shot with that one, probably closer to 600 lbs.

My plan for added buoyancy was to make the seats that go across the width for where to sit would be made of the thick 2" foam board covered in carbon but be removable and pinned in place so that I could take them out when I put the boat on top of truck to reduce weight.

What type of foam would you have to use NOT to react with the epoxy resin. I know there is other epoxy that is safe for foam but it is much more expensive.

Also how thick would you make the foam layer?

I would assume you would lay down a single inside layer over the mold, then stick on the foam board, let that cure and then add two layers of carbon over the foam.

Thanks
Scott M.

 

Certainly sandwich seems the way to go, the only snag with it might be a susceptibility to damage from point impact, but overall I think the right solution, and of course you get positive buoyancy as a bonus. I don't think you really need carbon or kevlar, spend the money you save with S-glass woven fabrics, on the foam core. You could also save the weight of the internal "furniture" of the boat by making it removable, so you can more easily lift the boat.

 

Can you elaborate more on the S glass.
I most likely will only do this once and so I don't want to scrimp on materials to save a few hundred bucks. That being said I don't want to just waste money if there is going to be no significant benefit ( lighter, stronger, stiffer, puncture resistant, etc.)

 

Epoxy does not react with anything, only poly and vinylester melt EPS and XPS, but you would not use that for the hull anyway. Foam sandwich is lighter and stiffer then single skin fiberglass. But I think Mr. Efficiency is right, carbon is not needed, practical things like point impact will define the laminate, by the time you get there even S-glass is a waste, E-glass will be more then adequate. It's all a question of how thin you dare to go on the skins, meaning how much you are prepared to baby the boat.

 

SM,
From what I've read so far on your thread, I would recommend buying an existing hull that most closely matches your desires.
However, if this is not an option, consider stitch and glue construction.
It's fast, easy, simple, and strong given the weight.
If you feel comfortable taking on a foam build project, then go for it!
BB