Tim,
Remind me... what's the trick with adjusting the crown of the deck beams as they go forward to get the right deck camber? Is it that the radius needs to increase as you go forward, or decrease?
I learned this a while back, but like all knowlege not used, it's lost from my mind. All of my boatbuilding texts are still packed up from the move, but you probably have all of yours committed to memory at the moment, so I figured I'd ask.
-MH
Crowning the deck beams
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Tim
- Shipwright Extraordinaire
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There was an article in Wooden Boat sometime last winter (02-03) covering this, called something like Ye Olde Deck Beams, or some such. The author's purported "right" method involved using some sort of wooden jig to loft each of the beams separately. Since I chose to use constant camber (as variable camber would have been wasted in this particular design), I did not study the technique that closely. It seemed overly fussy to me.
The basic premise is that beams of a constant camber, when combined with a traditional sheerline that dips amidships (or close thereto, for our purposes) would be too high amidships, creating a hogged appearance to the deck. This means, basically, that you need less camber (i.e. less or a rise per foot of beam) when cutting the amidships deck beams than those at the end. (I think.) While this theory seems sound on paper, and when exaggerated illustrative drawings showing the supposed "problem" are used, I think that in practice it is unnecessary. Most wooden boats, among them all the ones we love and cherish, were built with a single beam mold. In a truly flush-decked boat, lacking any cabin trunk, I think the variable camber idea could possibly have merit. For most designs with cabin trunks and cockpits taking up much of the deck, I think the so-called problem becomes even less evident.
I disposed of the magazine containing the article a long time ago, but a site reader sent it to me something after the fact. I might possibly still have the scanned article on my old computer. I could also run a copy of the printout I have and send it to you if you like.
The basic premise is that beams of a constant camber, when combined with a traditional sheerline that dips amidships (or close thereto, for our purposes) would be too high amidships, creating a hogged appearance to the deck. This means, basically, that you need less camber (i.e. less or a rise per foot of beam) when cutting the amidships deck beams than those at the end. (I think.) While this theory seems sound on paper, and when exaggerated illustrative drawings showing the supposed "problem" are used, I think that in practice it is unnecessary. Most wooden boats, among them all the ones we love and cherish, were built with a single beam mold. In a truly flush-decked boat, lacking any cabin trunk, I think the variable camber idea could possibly have merit. For most designs with cabin trunks and cockpits taking up much of the deck, I think the so-called problem becomes even less evident.
I disposed of the magazine containing the article a long time ago, but a site reader sent it to me something after the fact. I might possibly still have the scanned article on my old computer. I could also run a copy of the printout I have and send it to you if you like.
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