C-Forum

I took my latest creation out for a test paddle yesterday afternoon. It seems like all the cool kids are paddling short boats so I built it 8'7" long and 30" wide. As you can see, it has a ton of tumblehome and rocker. Instead of airbags, both ends are watertight compartments with hinged hatches. It has a simple saddle but no straps or braces (yet). It weighs around 33 lbs and cost less than $200 (thank you, Ebay!). However, it was very labor intensive (especially for an amateur working in his basement). The river you see (Cahaba) is Class II+, maybe III at its worst so this boat is suitable for my purposes. Time will tell.

Paddle On,
JC

This is awesome! What materials did you use to build it?

Thanks! Fiberglass 6oz ($52 on Ebay for 50'), Epoxy resin ($57 on Ebay), sheet foam ($30 Home Depot). Hatches, webbing, and foam pad brought the total close to $200. I built my first OC1 out of Kevlar for around $600. Sadly, I made a few errors that caused it to be flimsy with odd stability. It was a costly learning project. I saw the picture below and thought "why not?" Many people are leery of foam core boats because of repair concerns. However, the hull on this new boat is incredibly solid and stiff. It's probably not bomb-proof like a PE boat but it should meet my needs.

Looking good!

Looks great! I hope paddling it puts a huge smile on your face (it should!)

road_warrior64 wrote:I saw the picture below and thought "why not?" Many people are leery of foam core boats because of repair concerns. However, the hull on this new boat is incredibly solid and stiff.

Well done! Could you tell a bit about the building process? Did you work with stations and foam strips?

Steps to building a composite foam core boat:

#1. Spend hours thinking about how you want the finished product to look. Build it in your mind several times and try to anticipate problems. Helpful hint: Nod your head occasionally and mutter "uh huh" so that your wife thinks your paying attention.

#2. The idea of composite construction is pretty simple. Build any shape you want, cover it cloth, wet it out, let it dry. Ta-da! Instead of using station molds (which I used on my first boat), I only used two bulkheads and the shape of the bottom. Whitewater boats are so short and my design was pretty linear so this worked well.

#3. A mistake I made on my first boat was an incredibly wide, flat bottom hull. It also had vertical sides. Despite three layers of Kevlar and one layer of fiberglass, it was incredibly flimsy. Strong...but very flexible. Unless you want your boat to feel like a waterbed, put some structure and shape into it. My new boat is more narrow across the bottom with soft chines and flared sides. This gives me great initial and secondary stability. It wants to sit flat but pushes back as you begin to lean over. To get soft chines, I glued foam interior chine logs inside the hull then used a rasp to shape the chines.

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#4. Sheet foam comes in 8' sheets so I added foam to each end (for extra length and aesthetics) and shaped it with a rasp. Some may ask, "How do you make it perfectly symmetrical?" I'm not sure. I marked where I wanted the curves to stop with a marker, shaped it with the rasp, then felt for symmetry with my hands. It turned out pretty well.

#5. Cut and fit the deck. Add foam to any voids. Shape, sand, fill with thickened epoxy. Cover everything with cloth. My saddle is a few pieces of foam glued together, shaped with a rasp, and covered with a piece of foam exercise mat. The hatches were purchased off Ebay and the handles are thick nylon webbing bolted through the deck with big washers. Use epoxy for added strength and waterproofing.

A few tips: Cover the foam with a thin layer of epoxy and let it dry before you lay down your cloth. In my experiments, fiberglass did not always adhere to bare foam. Use color pigment in your epoxy. It's simple, cheap, eliminates the need to paint, and gives color all the way through. Fiberglass everywhere! Foam is incredibly weak on its own. My boat has at least one layer on the inside of the hull, deck, sides, cockpit. The exterior of the deck has two layers and the hull has three. One last thing. Some instructions I've read tell you to wet the work surface with epoxy before you add your cloth. It's supposed to help ensure complete saturation. I've tried this and it was very frustrating. Unless you have an assistant to help you carefully roll the cloth onto your project, you will end up with a rats nest of soggy, wrinkled, useless cloth. Instead, I laid the cloth on my dry work surface and used plastic body filler spreaders to work the resin into the cloth. 6oz fiberglass is fairly thin and you can tell when it's fully saturated.

I've already got some ideas on how to simplify construction, lighten, and strengthen my next iteration. First, we'll have to see how this boat holds up. Thank you for your interest.

JC

JC,

thank you for the writedown and for the pics - I am curious about your impressions paddling your creation. Hope you have tons of fun with it!

gerrit