Glassing the Hull, Fitting the Deck

Up to this point, most of the steps have been small and tedius. Things change radically now–glassing the outside of the hull is a big step, both emotionally and as a task. You want the hull to be as smooth as practical. As you drape the glass, it will catch on every small snag and pull the weave, creating odd patterns and even open gaps.

Make Sure the Hull is Smooth!

Your first decision is “am I confident that where I’ve decided to cut will provide enough length to properly wrap the stern and bow, yet not so much as to leave insufficient glass for the following steps?” So you make the first big cut. Once you’ve got the glass cut and smoothed to the hull, you’re ready to wet it out. Don’t cut the slits for the bow and stern until you’ve wet the glass almost all the way to each end–you’ll be surprised to see that the cloth moves in expected ways as you wet it out. It’s not stretching–it’s just getting a good tight fit and you will see that even though you thought you had smoothed it tightly to the hull, there is still a lot of movement. I wet the glass far enough into the bow and stern that I have to cut wet glass with my scissors–they wipe clean, or can be cleaned with a little acetone. Waiting until this point allows me to immediately lay the wet glass back on the hull and smooth it down, so I know immediately if I’ve made the cut long enough. I then continue wetting one side and wrapping it around, then wet down the other side and overlay it without causing a wrinkle in the underlying first wrap. You may have to peel the top layer back one or twice to get it right.

When the Deck is Wired, You Can Make a First Check of Alignment

OK, now that the hull is glassed and strong, it’s time to wire the deck together, using the hull and frames as your form. Don’t worry about the fit of the edges (yet). I had to use a couple of supports near the bow and stern, two spring clamps on the edge of the hull, to temporarily hold the deck panels from slipping off, until I could get a few wires into the upper edges of the two deck panels that form the sheer. In the end, you’ll finally get it all wired together. Now you can begin to get  a good sense of whether you have any alignment problems. This boat went together really well for me (my Tern had a real vertical and width problem matching the deck and hull back near the stern). The only discrepancy I noted was the gap (see photo) between the frame(s) and deck. I think you will find some variability in your boat–panels not exactly right when they were originally joined, too much chamfering of the seams, etc. As long as our discrepancies are small and symmetrical, you’re doing fine.

You're Going to See Some Anomalies

Once you’re satisfied, glue the deck seams and fit it back on the hull to ensure alignment (remembering to put the plastic wrap on top of the forms, of course). If you’re constrained for space in your shop or garage, now is the time to get rid of the second 16′ work bench top. Replace it with a sling. This not only opens up your space, but will be tremendously handy when you begin to permanently attach the deck, and for many steps thereafter.

A Sling--The #2 Best Idea Ever

Yay! The sling. This is the #2 best idea in kayak building. Do it. Once you get the boat together permanently, the sling will allow you to reach inside and apply tape, etc., with the boat in the best orientation for the resin.

Easily Put the Boat in Any Orientation You Want

Smoothing the Inside Seams

The deck will slow you down a lot more than you expect. There are many steps in getting it taped and reinforced. While you are waiting for the resin to cure in each of these steps, you can get a jump on the schedule by scraping and sanding the inside of the hull. The inside has to be as smooth as the outside in order to drape the fiberglass cloth properly. This is where the #1 best idea in kayak building comes in–the Bahco scraper (see it on the “Best Tips” page and here in the middle of the hull). However, when you’re scraping the inside seams, you have to be careful not to cut through the resin and into the glass. The Bahco is amazingly sharp and the corners of the blade will cut down into the resin with ease. Use a grinder to relieve the corners slightly, maybe 0.03″. Just put a bit of a “round” on them. You can still do damage, but the risk is reduced by 97% (I did a study, to be published by the Harvard Press real soon now). I scrape all the joints and smooth down the tape edges, too, especially the thick side. You want to be able to run your hand along the entire inner surface and not feel any sharp roughness–in the hull so you can drap the glass and in the deck so that there won’t be any abrasion sources for ruin your dry bags later.

Skew the Glass to Get Two Big Remnant Triangles

Glassing the inside of the hull is a good bit more difficult than any step so far. My first tip is to drape the cloth with the help of a few spring clamps to hold the orientation as you smooth the glass. Second, turn the cloth so that you have a large triangle on one side of the bow and on the other side of the stern. This won’t make it any easier to wet it out, but when you trim the cloth you’ll have two relatively large triangles rather than four small ones. These larger pieces will come in handy later. Note: when you layout and trim off the excess cloth, be careful to leave more margin than you might expect, maybe 3″–the cloth will shift sideways as you wet it out, unless you’re very lucky or very careful.

Cut the Ends After the Glass is Wetted Out

Notice that the cloth is bunched up at the bow (same at the stern, but out of view of the photo). You will have to cut it and overlap it, but don’t cut it until you’ve wet out the cloth almost all the way to the ends (same as when wetting out the cloth on the outside of the hull). You can make the appropriate trims once you’ve wet the cloth out all the way to the bow/stern. Clean the scissors later.

Very Happy with the Outcome, Even Though the Margins Went to Zero

Notice that the glass is smooth and conforms to the inner shape, even in the pinched bow and stern. You will have your gloved hands in the resin a lot, and you’ll be handling your scissors a lot, too, so have paper towels ready to clean your gloves often.  One thing to notice in this photo is that there was zero margin in the cloth in several places near the bow and stern. I thought for sure I had estimated enough extra width, but as I wetted out the cloth, I found the edges being pulled right up to the edge of the hull and even inside a little bit. You’ll have only an inch of so of margin in the middle of the boat, but the cloth doesn’t move much there, since you start wetting in the middle.