Gardner,
Your Mainecat/5200 idea is safe with me. I'm building a plywood dory
this summer and will be doing the same thing. Even if it doesn't work,
the theory is comforting.
So now you're basically tripling your submerged foil area for a 1.5'
depth: two rudders at normal width, and two mini keels that I'm
assuming would each be twice as wide as a rudder. You won't have ideal
steerage and leeway prevention, but my guess is that this is a moot
point. Either you have two rudders, or you have rudders plus dagger
boards or mini keels. Anything you do beyond the rudders will likely
help.
I'd try keeping the keels as close to each other, though. This
wouldn't be idea for beaching, but as Rob pointed out, tires are
probably better than keels anyway -- that way there's no risk of gravel
sanding off your bottom paint, or of bouncing in the surf taking your
keels off. In keeping the keels close together, almost like Rudolph's
tandem keel, the keels shouldn't impact steering that much, and could
even conceivably help. Two keels far apart, on the other hand, might
make it harder to shunt, particularly when you don't have as much
rudder in the water as you'd like.
At least you'll have the option of two counter-rotating rudders.
That's definitely going to help steering in minimal depths when
compared to a cat.
- Mike
On 6/21/2010 1:53 PM, Gardner Pomper wrote:
Hi,Yes, your description of when to use mini-keels is what I had in mind. I would rather not build them, but I am unclear as to what the minimum rudder area needed when sailing in light winds. Here is the scenario I have in mind:In the chesapeake, or the bahamas, there are many spots that are 2-3 feet deep that I would like to glide along in relatively light winds. The waters are sheltered, and therefore flat, and the wind is likely to be less than 10 knots. When doing this, I would like to have a draft of 2' or less. I can't have my rudders extended to 4 or 5' depth to get the requisite 2% of sail area, so I thought that fixed minikeels, maybe 1' deep, would give the boat a 1.5' draft. That, plus the rudders raised to 18" draft would give me more foil area than the rudders alone. I would not be looking to sail at > 5 knots under these conditions, because i really don't want to hit anything.In that scenario, with a boat about the size of a harry, or a harrigami, would I be able to steer with just the rudders (total submerged area of 3 sq ft, vs 400 sq ft of sail)? Would I be better off with an additional 3 sq ft of mini-keels?My Maine Cat 30 had the mini-keels attached with 5200, for precisely the reason you mentioned.. in a severe collision, the keels were supposed to break off without ripping open the bottom of the hull. I have no idea if that would have worked or not, but it gave me peace of mind to believe it, so please don't contradict the idea <grin>.- Gardner
On Mon,