1708 mat for stringers

[tartuffe]

Thats right. I went overboard and cut strips 4", 8", 10" and 12" but that was way overboard. You'll cut your stringers to size, I used spacers (my center bulkheads and barclamps to get my stringers the right distance apart as well as perfectly perpendicular and situated the stringers so everything lined up with all my measurements and marks I made prior to demolition. Once everything lined up inside the boat I traced the inside and outside of the stringers with a sharpie on the hull. Then I raised the whole assembly enough to put a thumb-sized bead of PB between the lines I traced under one stringer. Lowered it all back down on the bead. This gives you good contact and no hard spots. Take more PB and run a small bead on the inside and outside of the stringer and use a sponn to make a nice radius. Lay your first tab and wet it out. If its 6" wide then 3" on the hull and 3" on the stringer. Lay another over top of that one say 10" wide with 5" on the hull and 5" on the stringer. You can do another if you want but probably not necessary but I'm no marine engineer. Like I said, I did 4. Let that cure. Then repeat for the other.

The idea is that you want the fiberglass to dissipate shock loads from the immovable area (stringer) out to the very flexible area of fiberglass without any focus of forces leading to stress cracks.

Keep in mind the best results are to not allow the PB to harden before you get the fabric laid and wetted. Use the slow cure and mix many small batches. I large will cure in about 15 minutes even if it is slow cure.

[cterrebonne]

Thanks, really good info. I was plannig on going with the foam or 5200. As he bedding. That would give me as long as I needed. Unless you think the woody mix is much better

[tartuffe]

The foam is probably just as good but I would tab with the full 4 layers if you go that route. The PB is a mix of cabosil and resin. It isn't the wood flour.

Some people get all frothy mouthed about using 5200 versus foam versus PB for bedding. I read an awful lot and personally liked the PB bedding the most. They all have positives.

4 layers of biax is about 1/8" thick so you may have 1/4" of glass supporting your stringer. I figured if I'm buying high dollar 3/4" marine ply, I wanted the full strength transfer throughout my hull.

[tartuffe]

Here are a couple pics, one is before bedding and the other shows a test fit of the cap but you can see the layers of tabbing from the ink I marked the glass to cut the widths. See how nice that radius is....pretty proud of that

[cterrebonne]

Originally Posted by tartuffe

Here are a couple pics, one is before bedding and the other shows a test fit of the cap but you can see the layers of tabbing from the ink I marked the glass to cut the widths. See how nice that radius is....pretty proud of that

that is some nice craftsmanship you did right there. What did you use to apply the PB under and on the edges of the stringers?

[tartuffe]

Big zip lock bags with some duct tape on one edge then cut the corner off to make it like a pastry bag to squeeze out like icing. Smoothed the radius with plastic spoons.

[cterrebonne]

Originally Posted by tartuffe

Big zip lock bags with some duct tape on one edge then cut the corner off to make it like a pastry bag to squeeze out like icing. Smoothed the radius with plastic spoons.

makes sense. thanks. This is off topic for this thread but how many sheets of ply did you use for your transom?