About the Bottom

Neglected by most, it is the most important speed contributor in sailing. Clean, and faired, and protected from fouling, and blisters. I strpped the bottom to gelcoat in 2009 using a mild stripper. I had to see what was going on underthe paint, check for blisters, and so on.

the paint was flaking in spots, hair thin in some areas and 1/8 mm thick in others. Clearly the boat had not been stripped in at least 10 or 15 years. I decided to tackle the monumentous task and started with a small test coupon on the rudder. The non-MEK, non-Methylene cholride solvent worked very well, and its slow action was a plus to reduce diffusion into the gelcoat, but it took four hours to soften the thicker areas. A quick sanding with 80 grit and four coats of interlux barrier coat epoxy should eliminate any risk of blistering. Additionally, I was told the boat has a exterior schedule of vinylester resin and the rest of the hull uses polyester. This, or some special polyester, keeps blisters down. I did not observe a single blister on the boat, though I did see a few gelcoat micro-blisters about 1/16 in diameter right at the waterline. The presumed reason for these was the heavly load of gear on the boat which kept the waterline under.

I did find one oddity in these boats. The brochure shows at least two available keel configurations for the Centurion 49. As it stands, the two keels had separate shapes. You can see this in the pictures below. Since the length of the keel stub is different in the two versions of the keel, the manufacturer used a mold insert to produce version A or version B of the boat. The Centurion 47 was 8 or 9 years in production and the original mold had been recycled into a Centurion 49, from a Centurion 47, by adding the transom extension and swim platform.. Building a new mold was a very expensive proposition for a five to six boat a year design. I was told by Mr. Dubois that the yard originally planned to build only 30 boats, and ended up building close to 80 or 100 of them. By the time the 49 model came along, it was uncertain how long its life would span. Wauquiez found a simple solution with the mold insert, only one mold would be used for the production. I don't have evidence of this, because I was unable to get technical data from the yard on the actual construction of the boat. Between the bankruptcy and the changes in staff and acquisition by Beneteau, original design specs are not to be found by the service department and frankly I gave up on their help. But the witness lines which were filled with fairing compound run exactly on a length that matches the longer keel design. I doubt this is coincidental; the only other explanation would be that my boat had received extensive damage, I discount this because there is a complete absence of any evidence of repairs inside the hull other than the ones I effected. So, there you go. I thought mold inserts were used only in plastics molds for injection molding or blow molding, but apparently some smart person figured out the value in a boat production yard too!

No more needs to be said about the bottom work, the pictures say it: It is dirty, annoying, tiring, and unpleasant. But sailing on a smooth bottom is bliss.