John's Cedar Kayak
Page Seven: Fiberglassing the Hull
(Click photos for a larger image)
Epoxy takes a longer time to become a solid in cold temperatures, and I'm building in an unheated garage in winter. At least Dallas tends to have mild winters.
The temperature in my garage workshop tends to be about halfway between the outdoor temperature and a normal room temperature. I should be okay to apply epoxy when the garage temperature is near 60 degrees or above.
I applied a sealer coat of epoxy to the hull using a roller and squeegie, and was pleased by the appearance. No big glue blotches.
The next day, when the sealer coat was not tacky anymore, I filled some remaining little gaps with epoxy mixed with two parts wood dust to one part microspheres. It produced a reasonably good color.
Sanded lightly the next day.
We applied the epoxy by pouring it on from a cup and using a roller to spread it around. It was allowed to soak in for a few minutes, then we used a plastic squeegie to scrape off the excess epoxy.
The hull receives two layers of 6-ounce fiberglass, and just enough epoxy to fill the weave and give a smooth appearance.
Originally, I planned the second fiberglass layer for only the bottom area, including the chines and the keel stems, but the hull wall on this design is only about 4 inches wide so I decided to put the second layer of glass over the whole hull. It only adds an extra 8 or 10 ounces to the boat weight. Glassing all the way up to the sheer line also eliminates a lot of scraping and sanding to feather in the keel strips and bottom patch.
I am trying to keep the weight of the boat to a minimum every step of the way, and there are many trade-offs between strength and weight. If my boat is a half-pound too heavy I will know why.
This photo is a close-up of the hull after two coats of fiberglass. It also shows a glue line that should have been sanded out, staple holes, and a scarf joint. With more epoxy coats, the weave will become invisible.
Even though this is my second boat, I am still amazed at how the
white fiberglass cloth becomes clear when wet with epoxy.
Invariably, after applying an epoxy coat to the boat, I end up
with a little extra epoxy left in the cup. This is why I like to have a
few little items around that might benefit from an epoxy coating. I cut my seat back, and glued together strips that will form two hip
braces now, so I can use the surplus mixed epoxy to finish them.
I did some experimenting on the inside of the box, with not filling holes and gaps, and not smoothing, just to see how it looked after epoxy and fiberglass. This will help me know how careful to be on the boat.
Created: January 1, 2003