Collapsible daggerboard?

[garypete]

I'm making an 18' EM White Guide cedarstrip I built years ago into a dedicated sailing canoe. I want to incorporate a weighted daggerboard into the canoe in a watertight daggerboard trunk to give the canoe some extra stability under sail. I'll be using a loose-footed spritsail that Todd Bradshaw will be making for me.

To prevent ripping the daggerboard case out of the hull if I hit a submerged rock under speed, I'd need the lower 24" of the daggerboard to fold back against the hull on a pivot pin. I envision a threaded SS screw for the pivot pin so I can set the tension to a point where it won't swivel back under normal use, but will swivel if I hit an underwater obstruction.

I'm wondering if it wouldn't just be easier to build in a standard dropdown weighted centerboard in a trunk.

I've seen information on a folding fan centerboard for canoes, and that would also be a possibility that would preserve more of the interior storage area of the canoe. Either a daggerboard or centerboard trunk will take up quite a bit of room in the hull. My question on the fan centerboard for anyone having experience with the unit:

Is a fan centerboard heavy enough that it will add some stability to the canoe when deployed?

Gary

 

[Dan Miller]

The No. 2 Radix (middle size) weighs 10 pounds. The main advantages of the fan centerboards are the reduction of the centerboard trunk - these were invented during the period when folks were sleeping in their canoes. They create a lot of drag.

Why do you feel the need for extra ballast? Most sailing canoeists don't bother, relying instead on human ballast. As an historical footnote, it was the international races between Vesper and Pecowsic from the states and Nautilus and Pearl from across the pond that proved the superiority of unballasted sailing canoes over ballasted ones. 'Course, it was racing, and decked canoes, but still....

A little lead to counteract buoyancy of the board is sometimes used, but bungee cord works well too. If you are doing much shallow water sailing, you might consider leeboard(s) over a center- or daggerboard...

 

[Andre Cloutier]

leeboards

all the way, freeing up space in your boat and allowing you to pivot it at will to improve response under sail. John H will chime in soon about the virtues of leeboards. nice to have it moveable. Otherwise, have a look at a windsurfer with a retractable dagger, when I sailed a lot you would kick it up with your foot when on plane, and the trunk had gaskets that closed it off when you were fully retracted. would require an awfully high trunk in a canoe though

 

[Todd Bradshaw]

One option that's sometimes used is an over-sized (in the fore-and-aft direction) daggerboard trunk where a block of crushable foam (like syrofoam) is built into the aft end of the slot near the bottom of the hull. The foam takes much of the force on impact and slows the boat to a stop without destroying the trunk.

If you're feeling creative, there is at least one way to build a one-piece (solid slab of wood) daggerboard that will kick up if you hit something. You make the board in what is actually a chunk of a big circular arc. Inside the daggerboard case, you have blocking, guides or possibly even small rollers which are set to create a slot that is also a matching arc. This is a quick and dirty drawing of the cancept, but I think you'll get the idea. I haven't tried one, but do know that it's been used on some high-speed multihulls where a hard grounding at speed would likely destroy the hull.