Clipper's Vera Cruise Build

Clipper's Vera Cruise Build

Sunday, July 5, 2015

Working On The Hull Exterior

With the completion of the skinning several weeks back, the next step is to get the hull ready for an exterior finish. This entails much more than simply painting it.

To start with, there is the skeg which must be fabricated and located. Briefly, the skeg is a piece of lumber, approximately 11 feet long, sort of like a short fin, that extends from the bottom of the boat. I bought the oak for that just last week.

Then there are spray rails which need to be fabricated and installed. These serve to keep water spray from traveling up the sides of the boat while underway and spraying the passengers. I'll cover both the skeg and the spray rails in a future posting.

But before these can be done, the hull needs to be covered in fiberglass and then smoothed out. This will also be covered in a future posting.

Prep work for fiberglass means insuring that the hull is smooth. This requires application of fairing compound, basically epoxy with an easily sandable filler mixed in, spread over any uneven sections and then sanded smooth with a long sanding board. I've just started applying the fairing compound and haven't sanded it yet. This is just one section and there will be others.

The sanding board is similar to what is used in auto body restoration to smooth out the surface of the automobile. It is basically a long board, slightly flexible with a handle and sand paper attached to the sanding surface. You can spend a bunch of money and buy these, but they are relatively easy to make. You can also custom make them to whatever size you might need. I have made one so far.

The design is fairly simple. The center upright was my idea for keeping the flexibility of the board from being excessive. I found that I had to shorten it a bit however. I bought two 10 yard rolls of self adhesive sandpaper from that are the width of the sanding board. I used 3M spray adhesive to glue a thin piece of rubber to the bottom side of the board as a cushion.  The rubber is tool box drawer liner available from Harbor Freight Tools for a small amount and is perfect for the job. The sandpaper wraps around the ends of the board and is held down by two blocks with machine screws and butterfly nuts.

I have yet to use this board so I am not absolutely positive it is the best design, but I will trying it out on the fairing compound in a few days. And yes, the entire boat has to be sanded, by hand, using a board like this, or possibly bigger. It is the only way to insure that it is smooth.

After the hull is smoothed out, a layer of fiberglass must be added using several applications of epoxy resin. This serves as an abrasion barrier for the bottom. It also insures that the hull is watertight. Finally, it provides a nice even surface, after sanding, for paint application.

Sanding did you say? Yes, the epoxy must be sanded, also by hand, also using the long sanding board. The goal is to get a nice, smooth, fair surface before applying the paint. As I said, all of that will be covered in the future.

However, before all of that, I have been working on the decorative finish on the transom. This is a layer of 1/4" mahogany that is epoxied to the exterior surface of the transom. It is applied in planks, approximately 4 inches in width.

Here they are laid out on the bottom so I can try and match up the grain. This is not a perfect process but I was trying to get them matched up in such a way that there are no funky transitions from one board to another. Due to the nature of the wood grain, and because I only have so many pieces to work with, there will still be some differences from one board to the next. However I am hoping the application of stain will even this out.

I had this lumber milled by my source of lumber and the price was fairly reasonable. Since I do not have access to a planer, this was the only way for me to accomplish this.

The lumber is applied to the transom, one plank at a time starting from the cutout edge (the eventual top of the transom). In order to hold them in place while the epoxy cures, I am using a pneumatic stapler I bought at Harbor Freight which is working fine so far.

The staples are shot through plywood washers and then through the mahogany into the plywood subsurface on the transom. Only the first plank was able to use clamps. All the subsequent planks required staples.

Once the epoxy has cured for a while, I removed the staples and the plywood washers. Removing these staples is not easy if you don't do anything special. What I found works for me is to apply a soldering iron tip to the end of the staple for a minute and then using an angled pair of needle nose pliers, I lever the staple out of the hole using the plywood washer to protect the mahogany.

This leaves a small set of holes for each staple. These can be handled in a variety of ways. One way would be to use a wood colored filler and then sanded. However, I wanted a nicer finish than that, so I am trying out a technique to swell the holes shut using steam. The second picture is after a trial run. Although not perfect, it is good enough for me to know that an improvement in the process will yield better results.

Basically what I did for the trial run was squirt water on the holes and then hold a steam iron on the hole briefly. I got good swelling using this technique, but I think it can be improved. When I get back to this, I am going to be using a wet wash rag and steam iron over the rag applying steam to the holes. I think the additional moisture will swell these completely shut. Once the entire surface is sanded smooth, the staple holes should be nearly, if not completely, invisible.

The outboard cutout in the transom is eventually going to be capped with a piece of solid wood. This will match up to the mahogany planking and give a nice finished look to the cutout. In order to mate the cap with the mahogany, the planking needs to be sanded back to the cutout surface. Here it is mostly completed. Only the bottom of the "U" needs to be removed and sanded smooth.

Since this photo was taken, I have applied two more planks, but will be taking a short break to spend the next several days with my family on a mini vacation. Once all the planks are glued on, I will clean up the glue lines and long board sand the mahogany for a final finish. Then I will probably stain it.

Once the staining is completed, and all of the hull is smoothed out, I will be applying the fiberglass cloth. The cloth will also cover this surface. I intend on using a low weight cloth (6 ounce) so that the wood finish is still visible. I know from others that this can be done.

So that is it for now. There is still a lot of work to be accomplished but I keep trying to spend time every day getting more done. Until next time, take care.

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