Sunday, 19 September 2010
Transom Extension
The first time I sailed on the Honcho I noticed that the transom was immersed as we motored out of the harbor, dragging a small wave along with it�. Not good. Later, under sail, even with the boat heeled ten degrees, there it was, a little wave following the transom around everywhere we went. That little wave was telling me that Honcho�s transom sucks. I mean it sucks a little wave along behind it, squandering energy that could and should be used to make the boat go. For a yacht designer this simply won�t do.
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?Later, another problem became apparent. There is a very stylish recess in the transom that serves as a step and a place to bolt on the boarding ladder. It�s very French. That is to say that it looks good but, mon amie, it does not work so well. There is a nice recess for the ladder, but no place to put stuff or stand if the ladder is not deployed. Having an inconvenient boarding ladder is, well, inconvenient. But having a transom that sucks, that's just wrong.
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| Beneteau 36s7 with Immersed Transom Trouble |
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So I decided to build a small transom extension that will do three things. First it will stop the transom suckage (an industry term). Second it will provide a place to put stuff and stand on when boarding the boat from the dinghy or just checking the transom, which I do periodically. Third, it will increase the sailing waterline length by about a foot. As all students of yacht design know, the theoretical hull speed of any boat is 1.34 times the square root of its waterline length. I�ll save you the math, on the Honcho that translates to an increase of approximately one tenth of a knot in theoretical hull speed. Putting it another way, Honcho with the extension will go roughly two miles further than Honcho without the extension in a 24 hour run. Let�s face it, that�s not much�.But, I�ll be a lot more relaxed over the next 10,000 miles, or however many we sail, whenever I look over the transom and see a nice, clean, non sucking wake behind us. After all, cruising is supposed to be relaxing, right?
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| Here is a J/44 with Transom Trouble that was vastly improved by adding an extension. In this case we added a very substantial extension that included engine exhaust, cockpit drains and bilge discharge thruhulls. Honcho's modifications will not be nearly as extensive as these |
Over the next week or so, I�ll explain how to build a transom extension.
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