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Saving money on a foam core boat

Posted by 2tcooke4 
Saving money on a foam core boat
January 01, 2019 08:38PM
I have a question regarding foam core boats. Plascore and Nida core 4X8 sheets are beastly expensive here in Montana, especially when including shipping.
Before I get started on my Beavertail I have been playing around with some scraps of Dow Blueboard insulation. Epoxy and glass fabric sticks to it just fine. It is waterproof and closed cell. With only one layer of glass over it seems to have good compression strength. It cuts nicely with a bread knife. Best of all it's around $20 for a 3/4 or 1" X 4X8 sheet and is available at Homedepot and my local lumber yard. Does most of the hull strength come from the layers of fiberglass? If so could I just add another layer of glass to the bottom?

Do you think it could make a good boat?

Any thoughts are welcome.
Re: Saving money on a foam core boat
January 02, 2019 01:26PM
I've used blue foundation foam for seat decks in the past. I found adhesion with epoxy is improved if you sand it lightly with 220 sand paper. That blue foam has a slick smooth finish it's best to scuff up a bit.

Core foam material manufactured as a fiberglass core material is no cheaper than Plascore. Nidacore tends to be even more expensive.

I wouldn't use foundation foam on the bottom. I haven't tried so I can't say from experience..........well I can. I've made seat tops with it and they were great for seat tops but too spongy for a hull bottom. You'd have to add a ton of glass.

Consider Plascore for the bottom only with 1/4" inch Meranti Hydrotech for the side panels. I have a now 11 year old boat built that way. I don't offer it as plan but I use the shite out of it and the bottom has been fine. Much much much better than a glass covered plywood bottom.

I built that boat with a relatively flat bottom so I could use it with my 20hp two stroke Mercury. It doesn't motor well and it's slow to turn as an oar powered river boat but it does do both. Well enough. I should have built more of a Rapid Robert. They are the best two way boats. But I have that boat and use it hard. The Plascore bottom was and is a big success.

Interesting side note: My flat bottomed two way boat (that I wish was a Rapid Robert) does have enough rear end rocker to keep the transom up out of the water (when not using the motor). People notice right away it is the easiest boat to slow down in a current. Easier than any other boat. It's drawback is turning speed. Because it is relatively flat it has too much chine in the water and it takes too much arm power to make it turn quickly in tricky water.

There is great value in failure.
Re: Saving money on a foam core boat
March 28, 2019 08:54PM
Do you mind sharing the rocker on that boat, Sandy? I’m working on a model to design my own 2 man fly fishing skiff that can be car topped. My first design worked out to be 10ft x 4ft wide with 6” of rocker in back and 3” in front. I’m concerned that it might still be like trying to turn a flat bottom Jon boat.
Re: Saving money on a foam core boat
March 30, 2019 03:37AM
I'm in Idaho driving home from Oregon. Towing a new trailer. Old people's retired life starts soon. Share the rocker profile on my two way motor or oared boat?

...don't know how. I didn't like the boat much, even though I still use it, so I didn't write down the dimensions. It's also buried under a snow bank. Or was when I left a week ago.

If you want a river/oared boat that can be motored build a rapid Robert. I tried to do better and ended up with worse. Dayum shame at that
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