Boat Building Forum

Find advice on all aspects of building your own kayak, canoe or any lightweight boats

Re: Coho Keel Strip
By:Paul G. Jacobson
Date: 4/2/2000, 6:14 pm
In Response To: Coho Keel Strip (Bruce Kahn)

> I have just glassed the hull of my Coho. Came out O.K., but next time I'll
> either borrow a few extra hands, work in cooler weather, or buy some slow
> set hardener.

Easier option: Mix batches that are half the size. Yes, you will be mixing more batches, but: The resin "kicks" or starts to suddenly set, at a faster rate in a larger batch. With smaller batches you can control material use better and save $ on resin, and weight. You will have "rolling deadlines", as you will finish applyng a small batch long before it "kicks", ad then when you mix the next batch, you can reset your workflow clock. For example: If you mix 16 ounces of resin, and it has a pot life of 20 minutes, then you will have to coat about 20 square feet of glass cloth in that time. That only gives you 1 minute per square foot. On the other hand, if you mix an 8 ounce batch, you'll have a slightly longer pot life -- maybe 22 minutes -- to do about 10 square feet. That is over TWICE the amount of actual working time. Then mix another 8 ounces and you have another 22 minutes to do another 10 square feet. (times and amounts of material covered are merely for example -- you may go much faster or much slower, but the princiuple is the same)

With your normal set hardener the first batch will kick a lot sooner, and thus be less likely to run or drip, than if you used a slow set hardener. The stuff is workable for only the pot life, so staying with a shorter pot life and doing smaler areas with smaller batches of resin becomes more efficient. You will need more small mixing cups, but that is about your only additionl cost for this, and you'll really appreciate the time reduction in sanding out runs.

> My question has to do with the keel strip. The Pygmy
> directions discuss applying the fill coats of resin on the hull, then
> glassing in the keel strip. Seems like the strip should go on before I
> layer in the fill coats. Any feedback?

I don't usually read minds, but it sounds to me like they want the first layer of glass finished so the keel strip lays on a flat surface, instead of a pock marked one. I can't see that the strength would be that much different, either way, but when you go to sand the edges on that keel strip, to blend them into the existing base, you'll probably appreciate having the base layer of closth covered with the extra resin. It will help keep you from damaging that first layer of glass cloth as you sand. That is, unless you get a bit rough with it. Seeme to me like you could just fill the weave and finish only an area a few inches on each side of the keel before putting on the keel strip, and then after blending in the edges of that strip you could go over the entire boat with filling and finishing coats -- but I can't see that this would save you any time or material. Go with the plans.

Hope this helps

Paul G. Jacobson

Messages In This Thread

Coho Keel Strip
Bruce Kahn -- 4/2/2000, 5:35 pm
Re: Coho Keel Strip
David -- 4/3/2000, 4:37 pm
Re: Coho Keel Strip
Chuck -- 4/3/2000, 1:00 pm
Re: Coho Keel Strip
Dean Trexel -- 4/3/2000, 7:51 am
Re: Coho Keel Strip
Paul G. Jacobson -- 4/2/2000, 6:14 pm