Flats Stalker 18

10. Fiberglassing the Seams

Bill of Materials
1. The Strongback
2. The Pencil
3. Wood Butchering
4. Transom
5. Joining Panels
6. Round Chine Option
7. Jig Assembly
8. Stitching it all together
9. Tabbing & Filleting
10. Fiberglassing the Seams
11. Glassing the Hull Bottom
12. Fiberglassing the Sides
13. Fairing Slurry
14. Fairing - A Strategy
15. Fairing the Outside (Cont'd)
16. Skeg
17: Rubrails
18. Primer
19. Hull Flip
20. Inside Taping
21. Inside Cloth
22. Stringers & Knees
23. Installing Frames
24. Sole
25. Rod Holders
Photo Album
Contact Me

Fiberglassing Seams (~4 hours - one person)


This is the 1st of several fiberglassing steps on this boat. This is probably the easiest one also. Before beginning anything, make sure that all of your seams have a 1/2" or larger radius - No Exceptions! I unrolled and cut the required 6" wide, 12 oz biaxial tape for all the seams. The keel, keel to transom, and side to transom intersections all get 2 layers of tape. The chine seams get one layer. Basically you just lay the tape over the seam and at each end allow for about 3" or 4" of excess. After I cut the tape necessary for each seam I rolled it back up and labeled it with a piece of LIGHTLY applied tape. Here's some of the tape on the chine seams prior to adding epoxy...

I unrolled and cut the 50" wide, 12 oz, biaxial fiberglass cloth and cut it to length - Just in case I got industrious and had enough time to do the entire bottom fiberglass lamination schedule in one session, . I rolled 18'+ piece onto a cardboard tube and set it aside. Here's a shot of it on the hull after I cut it to length.

The bottom cloth isn't wide enough to cover the entire side of the boat and design doesn't require the side panels to be completely fiberglassed. The only requirement is that the wide fabric cover or overlap the chine seam by 6". The best solution (but more expensive) would be to buy twice as much cloth as listed in the Bill of Materials. I decided to compromise and use 50" wide 6 oz, biaxial cloth on the sides to add a little extra strength, along with some abrasion, and impact protection. This extra cloth will add more weight, require more fairing time, and obviously more epoxy and fairing compound than the original design. I decided to cut this cloth out while I had the chance. I unrolled enough for the length of the boat and then split the cloth into two, 25" wide pieces - one piece per side. I rolled those onto a cardboard tube and set aside for later. I also measured the 60" wide peel ply I had on hand to apply to the cloth after laminating. (Click here to review the benefits of peel ply - Peel Ply).Now it's time to prepare for laminating the fiberglass tape!

The first step is to mix up a small amount of epoxy and precoat the seam areas on the plywood that will be covered with tape. I used a 2" chip brush to "paint' some epoxy over the seam area and then I used a squeegee/spreader to evenly apply the epoxy across the wood surface. This needs to sit for at least 20 minutes to allow the wood to absorb the epoxy. It's done to insure the wood doesn't absorb epoxy from the cloth and create a resin starved area which would be a weak spot in the lamination.

The next step is to roll out the tape over the seams. I chose to do the keel seam 1st so I wouldn't have to reach over any wet chine edges to get access to the center of the hull. Since I hadn't worked with this particular cloth before, I decided to just do one layer of tape to see how things went. (When applying overlapping layers of tape or cloth you should offset the edges 1"+ to create a transition instead of the abrupt edge you would get with two layers placed directly on top on each other.) Here's a shot of the keel tape just before I started. The shot next to it shows the keel finished and a chine seam with dry tape.

The technique I used for applying epoxy is to saturate the cloth with excess epoxy to drive out any air and to make sure there is enough resin. Then I use a spreader at a low angle to scrap or squeeze excess resin out of the cloth and move that excess towards a dry section. You have to play around to get a feel for how much pressure you can apply without moving the cloth, but the excess resin needs to be removed for the lamination to have optimum strength. Ideally, a good lamination should have a 50/50 resin to cloth ratio by weight or less. At a certain point, too little resin will have a negative impact on strength as well. For laminating I generally mix about 8 oz to 12 oz of mixed resin per batch using the slow speed hardener. I like the extra pot life of the slow hardener because it gives you plenty of time to apply the resin, work it in to saturate the cloth, and then remove the excess. After the first couple of batches you'll get a system down and then basically it's just working your way down the length of the hull, one batch of resin at a time.

I was working by myself, so taping the entire outside of the hull took me several hours since I had to stop after each batch a mix up another one.