drop leaf table on centerboard trunk

[JMAC]

I've made the 2 leaves and am wondering how best to hinge them and to support them while in use. The trunk's sides are of 1/2" fir marine ply and there is a 1" mahogany cap. The leaves are 25" long and 12" wide. Any photos of this kind of set-up out there? This is for the community sailing boat "Ponder", a 1957 AR True Rocket.http://farm4.static.flickr.com/3268/2773346690_303af0ac6c.jpg?v=0

[BBSebens]

oh man.. thats a nice picture. looks like an awesome little weekender.

I see no reason to go more complicate than a piano hinge and a folding knee brace. Lift the leaf, and swing the brace out into position, done. as long as your not expecting to put several hundred pounds, like more than a person, i would think that the 1/2" ply would support it.

[Bob Smalser]

http://www.whitechapel-ltd.com/images/tech/dropped.jpg

Google "rule joint" and browse. Rockler and others carry router bit sets these days that make them child's play. There are several options, swing-out legs being the most common and most stable. And no method is as strong as the rule joint....and if using plywood for the top you should edge it with solid wood anyway.

http://www.taunton.com/finewoodworking/SkillsAndTechniques/SkillsAndTechniquesPDF.aspx?id=2041

http://home.comcast.net/~cdhepler38/Notes/RuleJoint.pdf

http://www.whitechapel-ltd.com/tech/drop_leaf_table_hinge.shtml

[Andrew Craig-Bennett]

Bob is right; the rule joint is the correct one here.

Lesser woodworkers than Bob have gotten away with lesser joints, however. Indeed, it is very much the done thing, if going on board a boat where you know the custodian has built the cabin table, to notice a rule joint, if present, and compliment him/her on making it! ;)

I respectfully differ from Bob on using swing out legs on a cabin table - it is indeed the most rigid ashore but in a small boat's cabin there is too much of a risk of someone's leg contacting it and accidentally shutting it and you cannot "lose" the leg against the centrecase sides when closed. I would suggest a pair of hinged knees on each side.

Before going further, a couple of questions:

1. Are you intending the table to go over the centrecase capping (and be secured down to it in a temporary or a permanent manner) or will you incorporate the capping into the table top and hinge the leaves off the capping?

2. How will you access the centrecase from the top in order to clear it if the slot gets bunged up with mud, stones or critters?

3. How wide is the centrecase?

[P.I. Stazzer-Newt]

I'm not sure that the rule joint is any stronger than its simpler cousins - but there is no open gap to trap your fingers.

[Bob Smalser]

I'm not sure that the rule joint is any stronger than its simpler cousins....

http://www.whitechapel-ltd.com/images/tech/raised.jpg

Compared to a butt joint and brass piano hinge fastened by half-inch, #6 screws with unsupported leaf ends? I'm sure.

But I'm just providing the traditional solutions out there to look at. Without seeing the trunk and its space, I can't offer much. Just a couple notes.

As Andrew states, the tabletop must be easily dismantled to get at the trunk cap. Fastening the center leaf to the cap using bunged screws is simplest.

Andrew's "hinged knees" will work if sufficiently strong. The table should support most of a person's weight in heavy seas without collapsing, and half-inch fir trunk sides aren't strong enough to take that amount of point load without a reinforcement system. In the worst case, buggering the trunk sides in a bad fall could interfere with the operation of the board, and CB trunks have enough problems in their old age without hanging unnecessary loads on them. Either way, any supports can be accommodated by the width of the center leaf and hidden beneath an apron on the table top.

[Thorne]

I made a set of removable dropleaf table sides for the CB case in my SJ21. Epoxied thin metal fittings on the sides of the case, then had hinges on the two sides which the exposed end fit into the thin metal fitting on the CB case. Had swing-out legs as recommended above. Small coamings on most of the edges seemed to help keep stuff on the table.

[Andrew Craig-Bennett]

I agree with Bob. Good point about taking weight. You can make the swing out leg secure in the "out" position with a silent hook fixed to the bunk front.