Monday, July 02, 2007

Hull Fiberglassing Details

Saturday morning and part of today were spent working on the fiberglassing of the port hull. The second keel reinforcing strip I added Friday was cured by Saturday morning, as was the final pass of filler epoxy around the stem to hull joints. I began by sanding and fairing the stem into the hull panels, then laminated a reinforcing strip of glass cloth cut on the diagonal over and around the stem. This strip goes from the sheer to the keel, overlapping the keel strips.

The photo below shows the detail of the stem to keel joint with the glass cloth over it and all excess epoxy squeegeed out.

Another area that I wanted to reinforce with an extra layer of cloth is the skeg to hull joint. This wide strip on each side of the skeg joins the keel strip and wraps around the leading edge of the skeg from both sides.

After the epoxy on these extra strips was cured, I sanded the entire hull and pre-coated it with a thin layer of epoxy applied with a foam roller. I've found that precoating a hull prior to laminating the glass cloth works really well and prevents any chance of the wood soaking epoxy away from the glass cloth and creating a dry laminate.
I let the precoat dry overnight and then sanded it this morning in preparation for laminating the cloth on one side. Since I'm doing this the easy way and laying up the cloth with the hull on its side so I won't be fighting gravity, I can only work on one side at a time, so today I did the port side of the hull.

After the hull was sanded and then wiped down with alcohol, I draped on the glass cloth and prepared to mix up large quantities of epoxy for wetting it out. It's already hot here this time of year at 8:00 in the morning, so I'm having to work with slow hardener and moderate sized batches of epoxy to keep it from going off before I can get it spread and squeegeed.

The wetting out was done with a combination of brushing and pouring and spreading with a squeegee. This is a big fiberglass job, especially when you have to work fast because of the heat. To get such a large piece of cloth to lay down evenly without wrinkles or trapped air bubbles, it is necessary to start in the midships section and work out towards the bow and stern. One detail that worked out really well was the angle I cut on the bottom edge of the upper topside stringer. This angle combined with a small fillet to the topside panel and a small radius on the bottom edge of the stringer allowed the glass cloth to lay down nicely and transition smoothly from the hull to the sheer. This detail will pay off in the long run, I think, with reduced chance of rot getting into this stringer, which is a common problem on the Tiki designs.

Below is the hullside with the second, filling coat of of epoxy applied after the first coat dried to a tacky state. Laminating this hullside took more than a half gallon of epoxy and the corresponding amount of hardener. Tomorrow if this coat is completely cured, I hope to flip the hull over and glass the other side. I'm leaving town in a little over a week to do a big teak carpentry job in south Florida, so I'm trying to get as much done on the boat as possible before I have to go. In addition to this work on the port hull today, I also finished joining the other lower hull panels for the starboard hull, and glued on the stringer. These panels will be ready for assembly after another sanding and second coat of epoxy on the inside surfaces.


kim whitmyre said...

Element II is looking really good, Scott!


Scott B. Williams said...

Thanks Kim. I'm sure glad I decided to go ahead and buy those plans when I did. This has been a great experience and I'm enjoying every minute of it.