Tuesday, November 2, 2010

Interior Finish

Flipping the boat over resulted in several revelations. The first was that all of a sudden the boat seems really big, surprisingly big, much bigger than we had imagined it when it was upside down. The second was that our planking looked pretty good, both the bottom and side planking had turned up well. The third was that we had been quite generous with our use of Sika to seal the planks. While it is tremendous to know that the boat is well-sealed and shouldn’t leak we didn’t quite know what to expect the interior would look like once we cleaned up the excess Sika. If you decide to follow our approach be forewarned that cleaning up the squeeze-out can be quite time consuming. We went at it with a variety of tools, chisels, cabinet scraper, exacto knife, and paint scraper. Each has its application and we found that no one tool was successful in all situations. But slowly but surely we eventually removed the entire squeeze-out. Whoo-hoo!

Transom prepped for staining
 And finally the fourth revelation was that we had over cut the width of the gains in some instances and while on the outside of the boat the planks were flush there was a small gap on the inside. To tidy this up we carefully selected gain and color matched mahogany planking cut-offs and cut and glued slivers of matching wood into the over cut gains. Another pain staking process that you just want to get over so that you can get on with the real work.
Bow prepped for staining

The real work was to set our hands to the construction of the centerboard and its case. But the more we thought about it the more set we became in our belief that now was also the time to finish the interior planking of the boat before it became cluttered up with side knees, and bench supports, and benches. Now was the last opportunity we would have to have complete and easy access to the side planks.

Of course the question was how to finish the interior? From our investigations there are as many ways to finish a boat as there are ships in the water it seemed. At first we had decided to go with an oil based solution. Lee Valley Tools sells a couple of products that seemed like good candidates, Deftoil (Marine or Exterior Finish) or Tung oil. A couple of years ago we had used Tung oil on our outdoor cedar planters and had been reasonably happy with the results. The nice thing about this product is that it has a smooth finish and you can really still feel the wood. We also liked the Deftoil because it has some dye in it that we thought would be good for evening out the differences in the natural coloring (some light and some dark) of our mahogany planking. But further reading about oil type finishes revealed that they have a tendency to turn black over time. And I can see this taking place on the planters now that they are two years old. I just couldn’t imagine sanding down the whole interior every 2 years and refinishing!

After considerable time spent investigating our other options we decided that we would first stain and then varnish the interior. Choosing the stain was pretty straightforward, a trip to the local big box lumber store provided us with all the ammo we needed to narrow the choice to a couple of stain colors. We bought both of them and stained both a light and dark plank to see how they would look. In the end we choose Minwax “Red Chestnut” for the stain. The process of staining the wood was really simple and quick—a quick application with a rag, wait, and then a light buff to pick any excess.

The choice of varnish was another long drawn out process as we had read a lot about Behr Spar Varnish and how wonderful it is—apparently an original formulation that has been made for years and years, inexpensive, and easy to apply. It is available at Home Depot in Canada but no longer available in the US, I do not know why. Our local store had 1 litre cans of gloss (we wanted to use gloss vs. satin because it has more UV protection and had decided to follow that with satin if we found the gloss too reflective) but no 4 litre cans, the pricing was $15/ 1 litre can and $35/ 4 litre can so naturally I wanted to get my hands on the 4 litre can. So I had them do an inventory check of all the surrounding stores. What followed was totally comical, the sales clerk would first check availability on the in-store computer and then phone a store that according to the computer had inventory only to discover that the product wasn’t actually in the store. He repeated this process for at least three of their stores until eventually he came back and basically said that it wasn’t available. On a whim a couple of days later I decided to hit a couple of the stores that the sales clerk couldn’t get a phone verification from because the stores were just too busy. The first store was a bust but at the next store I hit the mother load, they had 10 cans of the stuff—hoarding it no doubt!

By now I was all pumped up to start varnishing but needed to wait for the right weather, humidity below 60% and temperature above 60F as varnish can blush if the humidity is too high. And I needed a few consecutive days as the plan was to apply 8 coats and I needed at least 12 hours between coats but no more than 24 hours. In a perfect world 4 days would be sufficient. What followed was the coldest and wettest fall in ages. Every time it looked promising the forecast would change and the rain would come again—this went on for weeks. As it turned out I applied a couple of coats using a foam brush and then it rained. So I waited, then sanded. Sanding turned out to be a really time consuming process, each re-sand would take ~2.5 hours. All those copper roves look nice but really slow down sanding and the narrow planks make it difficult to use a powered sander so most of the work was done by hand. Here is how the work progressed, first I applied 2 coats then sanded, then another 2 coats and sanded, then another 2 coats and sanded, then I applied coat 7 and sanded and then finally coat 8. In the end I was happy with the way the finish looked and evened out the color differences in our boards—the scarf joints have all but disappeared. But in all honesty I can tell you the finish is not furniture smooth and silky but it should be functional—it is a boat after all! We still have bluff the transom with some really fine grit to smooth it out further but, that will have to wait for another day.

Finishing done, starting work on side knees

Note marks for location of molds and centerboard on green tape

Lessons learned:

1. Finish sand your planks before installing them as sanding around the roves is slow and painstaking work.

2. Mark location of molds on floor, chine, and top of planks (both sides or you will be wondering which is which).

3. If you have access to a sprayer, use it, the varnish will go on smoother—although for the cost the foam brush did a great job.

4. Get sand paper that will not load up quickly—I used 220 grit especially designed for sanding varnish.

5. The roves like to hold vanish and will eventually start a small run—I wish I had some sage advise on how to address this problem but, I do not, good luck!

The next post will cover the centerboard and its case, this work proceeded in conjunction with the finishing work.

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