Weighted Keel

[delevi]

All this math is making my head spin. I guess the bottom line is that we're really talking about 100-200 lbs of rail meat equivalent=NOT WORTH THE TROUBLE.

Chip, I actually enjoy the heeling characteristics of a monohull and wouldnt dream of trading my Mac in for a cat. The fact of the matter is that a 15 degree angle of heel is fantasy land where I do the majority of my sailing. San Francisco Bay on a summer afternoon frequently gets winds of 25 knts+ Under such conditions when going upwind or even down to a beam reach, with reefed sails, it is difficult to keep the boat at 30 degrees or less. I have tweaked the rig enough to where I can withstand 35-40 degrees before the boat rounds up, unless I let out the main sheet and spill air quickly in a gust. Sailing at 30-35 degrees heel significantly slows down the boat, and becomes a bit uncomfortable, not to mention hard work constant trimming, etc. This is basically why I have pursued this whole mess.

Frank, I know you sympathize with my situation, since you sail in these winds.

All in all, I would have to agree with you Chip, that it would be unwise to err on the side of the notion that Macgregor overcompensated on the durability. I had my boat for just a year and had a number of things break, including a dagger board. I never had a collision or grounding. My dealer said that I probably left it down while in a slip and the boat sat on the DB at an angle during low tide & just snapped it. He is probably right. My new board is also getting dinged up at the top with various chips in the glass. This is the area which sits in the trunk for support when the board is down. My conclusion is that the board is not very strong. Having broken my first one, I looked at the inside and it is quite hollow with a cross section of glass in the middle. I was going on an assumption that filling the board with lead or shot would actually strengthen it, but I guess that assumption was false. Also, after getting a strong recommendation from Macgregor against doing the mod, I'm inclined to let it go and just deal with the proverbial "Every boat is a compromise."

[Graham Carr]

McGregor has a history of building sailboats with heavy swing keels.

V-17: 300 lbs. swing keel
V-22: 500 lbs. swing keel
V2-22: 500 lbs. swing keel
V-23: 600 lbs swing keel
V-25: 624 lbs. swing keel
M-24: 575lbs. swing keel
M-23: 600 lbs. swing keel
M-25: 625 lbs. swing keel

There are a few others I did not mention.

All of these keels are all lowered and raised by a winch similar to the one used to pull the boat on the trailer. To the best of my knowledge, none of them have any pulleys. I know the V-17 and M-25 does not have pulleys. Just last week I raised the keel on a M-25 and it was not hard at all. The swing keel pins are only 3/8 bolts. Based on MacGregor striving to keep cost down, I would imagine the new trunks are about the same design as the old ones. You only have to look at the history to see all the boats are about the same. They have a few different layouts. I guess you could say history repeats itself. Im not surprised the factory would not recommend making any changes. CYA so if someone does the change without beefing up the trunk, it would not come back on them. On the Potter 19 that I mentioned earlier in this post, Bill did beef up his trunk. The new keel trunk was glassed into the hull by laminating both the inside and outside to the hull. To prevent flexing the trunk had buttress installed on both sides extending from the top and angled down to the hull. He actually cut the old trunk out completely leaving a hole in the bottom of the boat. Of course the new trunk was installed over the hole. Is it worth it? Well The value of a mod is kind of like beauty is in the eye of the beholder.
Like I said before;
Rail meat may be fine if you have others onboard, but when you sail alone your out of luck. This is when I feel a modified weighted keel would be beneficial. The thing to keep in mind is this type of mod (depending on weight) would lead to beefing up the trailer.

Graham

[baldbaby2000]

The righting arm is the distance between the center of gravity and the center of bouyancy. The center of buoyancy shifts as the boat heels putting it towards the low side. This is because the shape of the boat in the water changes as it heels. Crew weight raises the center of gravity so as the boat heels it helps less and less and eventually makes things worse.

The effect of adding weight to the end of the dagger board would be to lower the center of gravity. I'll assume the center of gravity to be 2 feet above the bottom of the hull. If I assume the boat is 3900 lbs and add 100 lbs 6 feet lower than the CG, the new center of gravity is lowered by 6*100/(3900 + 100) which is just under 2 inches. This doesn't seem like much but maybe I'm missing something.

PS We routinely hit 30 degrees with our boat because of peak gusts and it's annoying. Rail meat is in short supply on our boat.

[Catigale]

...on lack of rail meat

...and telling the Admiral you have the Swedish Bikini Team on Board to help "the healing" will get an icy reception...

[delevi]

Arena Yacht sales will be working on a weighted keel mod this winter. They hope to bring it to market next year, after some testing on their boats. They will probably go with a small bulb around 150lbs over lead shot. I'm certainly looking forward to this development. I realize the trailier would need a small modification to accommodate the bulb at the bottom. I wonder, however, how much the additional drag will affect performance under power.

[Catigale]

How much bouyancy is there in an or ??

Will the boat still be positive flotation after adding 150 pound bulb??

Pos Floatation is big for Admiral (and me)

THis enables trips to Nantucket and Cuttyhunk, crossing 25 miles of ocean, knowing that even if holed, we will have something to hang on to.

Trying to answer my own question, I check out the factory page on the

I see 5 people on deck and probably a good 100 gallons of water volume above the water line....this would mean

750 pounds people
800 pounds water bouyancy

equals

1500 pounds less 1000 pounds of motor and stuff on a heavily loaded boat

...still 500 pounds reserve for that keel???

[ALX357]

.....Also note a "bulb" on the bottom of the M daggerboard would prevent you from raising it out of the boat, and the boats bottom could not be flush without making modifying the hull with a pocket fot the bulb., or making the weight have the same profile as the rest of the board.
Whereas on a X, a centerboard with a bulb would be unable to enter the trunk, without modifying the hull with a pocket, Note the pocket would reduce performance on either boat when the board was down, much more than the trunk itself, which was a big enough deal with MacGregor to use as a selling point for the X to M production change.

[NautiMoments]

delevi, it will be interesting how Arena Yachts makes out with this mod. What shape of small bulb he will use, torpedo style or round. The problem I see with using a bulb is that it could react to fore/aft movement. Tod tells me that the bulb on the prototype boat "clunks" in the trunk. This could be an issure to consider.

[mtc]

Adding mass to the dagger board would necessarily add significant stress to the glass for little gain. Even if the board withstood the pressure without cracking, not sure how all the rigging, which was designed to roll over in wind rather than stay upright, or with less heel, would tolerate the additional stress.

If you want to keep the boat going with less heel, get yourself some trapieze gear and hike out over the windward rail.

That'll do it.

Michael

[ALX357]

if a pig had wings it could fly....
somehow this saying seems to fit the Mac Lead Bulb concept.
I am a believer in the Mac, love my X, but it's heeling characteristics are built in to the extent that changing them with this weighted centerboard or daggerboard seems more of a re-design than practical...
2" lower center of gravity, in exchange for lots of work in fibergalss reinforcement, re-shaping a bulb hole in the bottom of the boat, modifying the trailer, both for shape and weight capacity, introducing new and unknown/untested factors of stress to the hull, and rigging.
Seems more possible in an M, where the board stays vertical all the time, maybe replace the lower half or so of the board with solid metal, etc, but impossible on an X to add a bulb, maybe just fill the hollow with lead, and see if the hangar and fittings can stand the extra stress.

[baldbaby2000]

Adding mass to the dagger board would necessarily add significant stress to the glass for little gain. Even if the board withstood the pressure without cracking, not sure how all the rigging, which was designed to roll over in wind rather than stay upright, or with less heel, would tolerate the additional stress.

If you want to keep the boat going with less heel, get yourself some trapieze gear and hike out over the windward rail.

Hiking out would stress the rigging just the same as if you added weight to the board to keep the same heel angle. In our case the fact is that there are only 2 of us and we don't weigh much; in fact I'm kind of a whimp. I don't see any warnings in the manual about not having 4 people on the high side so I assume the rigging could handle the effect of some weight on the bottom of the dagger board just the same. Also our Mac 25 had a 650 lb keel with similar rigging and we never broke anything. I think the main added stress to the board would be when there's no pressure on it and it's banging around.

BB

[Blue Max]

I guess it's a SF Bay (heavy wind) thing, that I don't get. If I were to add weight, even to the keel of my boat, and expect better performance, I would want to remove more weight from somewhere else.

This is why my first goal with a weighted keel would be to allow me to run my X or D without water ballast, at least in light to moderate winds. I have no problem holding the main sheet in my hand like on a Hobe-cat in case things start to lean over too far.

This is how I would expect to gain better performance. According to the Mac manual (not that it is gospel but still a valid reference), each additional person you bring aboard your boat (or 150 pounds of gear) will probably cause a reduction in speed of about 1 knot. If you are adding 150+ pounds to your boat, you need to overcome that math before you see any improvement. No one has mentioned that yet.

Can someone with a weighted keel respond about empty ballast tank performance? Thank you,

[Highlander]

No not yet that I know of but I have mentioned it several times as sand is an easily removed & disposible product if you were into a long trailer trip & I am thinking of trying it with a winged D/B
But I have to finnish of the mods I'm in the middle of first , then perhaps later !

J

[baldbaby2000]

I have about 60 lbs of lead in the bottom of mine and have sailed many times with no water ballast when the winds are below 12 knots or so. As far as speed I really don't notice a big difference between no water ballast and having water ballast. I've never really understood why.

[Blue Max]

Thank you for your responses!