Weighted Keel

[Duane Dunn, Allegro]

I haven't seen this one posted here before.

Seems like someone would be able to adapt a similar system to the M. Check out the video.

http://seawardyachts.com/keel.html

[bubba]

What is the bulb weight ? We just recently put in 50 lbs of lead in our daggerboard and a 6 to 1 on the deck it works slick and stiffens up our M consertiable at about 10 deg heal.

[Duane Dunn, Allegro]

The 26RK carries 1200lbs of ballast and the 32RK carries 2500lbs of ballast. As the keel is the only ballast on these boats I would guess almost all of this is in the bulb and the lower section of the daggerboard. Obviously the key to managing this much weight is the 3:1 pulley system and the electric winch.

To compare, BWY had 430lbs in the bulb they had on the end of their M dagger board in Pearl Noir. They were able to easily sail without any water ballast on that specially constructed M.

Here's picture in 14 knots of wind with no water ballast


http://bwyachts.com/La%20Perla%20Noir/Pearl%20Home.htm

[Slamjammer]

Not an engineer, but I wonder about torsional rigidity with this keel design. The dagger board seems rather small (fore to aft) relative to the length of the bulb. The bulb would seem to be susceptible to side loads which could impart a twisting motion to the dagger board. These are otherwise very nifty boats, IMHO....saw one at the Chicago Sail Only show.

But, like I said.....not an engineer.

[bubba]

Remember the Black Pearl had all 300 lbs of fixed ballast removed during the molding of the hull to reduce the overall weight. It is a completely different dagger board not made of fiberglass. it also had a 6 to 1 setup to pull up the daggerboard and they still use the wintch.

[Terry]

What is the bulb weight ? We just recently put in 50 lbs of lead in our daggerboard and a 6 to 1 on the deck it works slick and stiffens up our M consertiable at about 10 deg heal.

There have been a few owners who have done this, I believe some have gone as higfh as 150 Lbs of leadshot. How is it that this mod does not create a weak spot where the leadshot ends. Would the daggerboard not snap off right at the point of fill when pressure is applied? Is there a submission somewhere that descibes this process so that others can duplicate it? I have read about a few others who have done this but I would need to read the step by step instructions to attempt it myself. It sounds more and more like a good idea every time I hear it mentioned. I'd like to try it. Is anyone able to provide the details?

[SRQBob]

It seems to me that people are making this unnecessarily complicated.
I would think the easiest (and possibly cheapest) way to add weight to the Mac centerboard (and probably the daggerboard), would be to remove the centerboard, take it to almost any steel fabrication shop, and ask them to create the same shape with 1/2", 5/8" or even 3/4" steel. The thickness would dictate what weight your new centerboard would be.
The centerboard on my 26X is probably 2" thick. I seriously doubt I could lift that size/shape made of 2" thick steel. Plus, it would put tremendous pressure on the pivot point.
The leading edge could be ground to create a hydrodynamic "blade". The steel would need to be primed and painted with appropriate anti-corrosion paint.
I think a second hole, lower on the board, might give a better board lifting angle (on my board, the centerboard line attaches about mid board). If the board lifting point is moved lower on the board, the board lifting line would probably have to be rerouted further aft. (And, I admit, I'm not sure where this would likely be... probably in the middle of the ballast tank. But, even so, with an empty tank and basic fiberglass skills, it seems solve-able. However, board raising/lowering would probably have to be done from the cabin from then on.)
Aluminum would be another possibility, but much more expensive.
Altering the board shape would be another possibility, thinner on top and full thickness on bottom-but made of thicker steel. This would achieve the weight you desire, but put more of it down low. I'd be cautious with this since the centerboard foil isn't just about weight, but also, preventing slippage.

[SRQBob]

I said, "thinner on top and full thickness on bottom-but made of thicker steel." I probably should have said, "NARROWER on top and full WIDTH on bottom-but made of thicker steel."

[bastonjock]

Ive been toying with the idea of fitting a plastic bush at the top of my centerboard to stop the side ways wobble,then my next idea is to fill the centerboard with 150lbs of lead and then fill the gap with epoxy,thus creating a solid centerboard.

[TexasDan40]

If less heeling over is the desire, I read that filling the water ballast while in reverse will make sure the tank is filled completely. The "poster" said the Mac sailed much better. I haven't tried this but will be sailing this week and will definately try it and post my performance prognosis.
thanks,
Te