: . . . I want to use 1/8 on
: the sides and deck to save weight - the whole thing out of 1/4 seems a bit
: too heavy. I think I will buy a 2 gallon kit of epoxy - that should be
: more then enough for the extra glassing I will have to do.

Two issues here still bother me. One is trying to get a lighter boat by using thinner materials and then trying to reinfoce them to get the necessary strength, and the second is what I see as an inherent waste of materials by using two different thicknesses of plywood.

Personally, I am no where near being considered "light" in weight, so I probably have a slanted viewpoint on the relative value of lightweight boats. I don't mind "heavy" when it is on the water, and I really like "light" when I have to portage.

Saving two or three pounds is not always worth the time, effort or cost. If you NEED an ultralight boat then you'll want to build with special materials -- and those are not cheap -- or make a smaller boat -- and that may not be as useful as a larger one.

Going with thinner materials just to save 5 or 10 pounds does not make a lot of sense to me. What you save on the weight of the boat is rather trivial compared to the total payload you'll be moving.

Let's suppose I can carry 40 pounds comfortably. Minimal gear: A 2-liter bottle of water, baling sponge, paddle and PFD add up to about 10 pounds. If I build a 40 pound boat I'll make two trips to the shore -- one with the boat, and one with the gear. If I build a 30 pound boat I can throw in 10 pounds of gear, make it weigh 40 pounds, and carry everything in one trip.

Now add a 150 pound paddler and your total weight is either 190 or 200 pounds. In a race this might make a difference, but for recreational paddling it is trivial. With a larger paddler (and I would meet that description) or more gear, the difference is even less.

Looking at the more efficient cutting pattern for the chesapeake 17, it is obvious that the wood in this boat is going to weigh less than the weight of 1 1/2 sheets of plywood. With 1/4 inch lauan that is just not very much.

If you go with 1/8th inch for the sides you would indeed save half the weight for that component. But then you are adding your reinforcement strip, and some (4 ounce?) glass cloth and the resin that goes with it. By the time you are done, your difference in weight will not be significant. Maybe only a pound or two. For all the work and expense, you'll only save the weight of 2 or 3 cans of soda.

If you can get away with using just a gallon of epoxy to seal the inside, and glass the hull exterior, your costs will be cut dramatically. and the boat you build will still be light enough to manage by yourself.

As I figure it, except for solo portaging, anything under 60 pounds is a good weight for a personal boat. That is about what a 17' Grumman aluminum canoe, or a solid fiberglass canoe weighs. A 16' canvas covered wood canoe is probably around there. And almost every wood kayak I've seen or heard of is lighter than this.

On my last canoe trip my cedar strip canoe was the lightest, and the most desireable one to portage -- and we did 2 or 3 portages a day. But it was still about 40-45 pounds -- and that is quite manageable.

When people talk about kayaks that weigh in at 32 pounds and say that they are upset that they didn't build it lighter, I kinda roll my eyes. Back in the recesses of my memories I see images of 12-year-old Boy Scouts who barely weighed 90 pounds themselves lugging around those old Grumman canoes. Most of the time it took two scouts per canoe, but they got the boats in the water and had a good time.

You'll be building a boat that is far lighter than that. While 5.5 mm ( nominal 1/4 inch) lauan is heavier than 4mm okume, the difference is not much, and your boat will be light enough.

If you want a lighter boat, though, don't use any 1/4 inch plywood, and just build with 1/8th inch plywood. You can use scraps from your glass cloth to add reinforcement where needed. Or, buy the extra glass cloth and resin and reinforce the full length of the hull. A sandwich of 1/8th inch lauan plywood between layers of 4 ounce or 6 ounce glass cloth is going to be more flexible and stronger than plain 1/4 inch lauan plywood.

And if you want a real light boat, look at skin-on-frame construction. With Dacron or some other polyester fabric for a skin, and a bare skeleton of lightweight wood a S-O-F boat is hard to beat for light weight.

Hope this helps

PGJ