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It still all comes down to the leverage (of the sail's force) that is trying to move the ballast around the center of gravity and boyancy as mentioned. A small puff could turtle a ton of lead if it is located close enough to the CG/CB (think a ton of lead in a narrow sealed tube long enough to support it, it would take much to make it roll) This all keeps making me wonder why the M does not have a weighted CB, (manufacturing costs?) I know that there are those who have done it and I am considering some combination of weight and skeg (for low speed motoring) myself.

tangentair wrote:It still all comes down to the leverage (of the sail's force) that is trying to move the ballast around the center of gravity and boyancy as mentioned.

Totally, but there's more . There's balance (COG's relationship to COB) and then there's intertia. I guess I was saying that I believe the macs have a decent ballast-to-displacent ratio (and sufficiently low COG), because the overall weight is kept to a mininum. I do think however, what makes macs more tender is the low displacement itself. Low displacement weight will always be tender even if the COG ridiculously low. It simply doesn't have the mass/interia to not get pushed around. IOW - compare two boats with the same righting moments (i.e. heel about the same for x sail area) - but one displaces twice as much as the other. The lighter boat will be much more tender in waves and short puffs. I think the macs are kinda like the latter.

~Bob

1. Replace our water ballast with the same weight of lead, iron, concrete or whatever, without moving the ballast's center of gravity, and we have the same resistance to heeling.
2. Lead is denser than water (or feathers) and so for a given weight is more compact, so takes less room on the boat, and so is more desirable as a ballast medium.
3. Replace our water ballast with the same weight of ballast located lower down (as at the bottom of a keel 5 feet below the hull), and we have increased resistance to heeling.
4. On a different point, there is a kind of direct proportionality relating wind speed to boat size. In general, given otherwise comparable boats and a rising wind speed, I would expect to reef the smaller boat earlier than the bigger boat. I seem to recall someone writing that the small boat sailor must reef in winds that barely move a fully canvased clipper ship.
5. Thus, we have to reduce sail area on our 26 foot Macs, while those 30+ foot keelboats are still flying main and genny without excessive heel.

On the other hand, our Macs trump those 30+ foot keelboats in other ways, e.g. trailerability behind the family van or SUV, low cost to buy and operate, gunkholing, etc.

Ron

ronacarme wrote:4. On a different point, there is a kind of direct proportionality relating wind speed to boat size. In general, given otherwise comparable boats and a rising wind speed, I would expect to reef the smaller boat earlier than the bigger boat. I seem to recall someone writing that the small boat sailor must reef in winds that barely move a fully canvased clipper ship.
5. Thus, we have to reduce sail area on our 26 foot Macs, while those 30+ foot keelboats are still flying main and genny without excessive heel.
Ron

Hi Ron,

This is pretty much what I was getting at. The difference is the overall weight/displacement/intertia. The smaller/lighter boats have a much faster reaction time and are unable absorb quick changes in wind and wave, like larger heavy boats - even if the heel averages to exactly the same amount for the conditions. I've heard nasty mac-skeptics relate the X and M to bobbing corks on the sea. It is kinda true, really. They react to right the boat just fine, but only after taking a good slapping in a large wave or puff.

Tangentair
I mentioned to our dealer about adding weight to the DB/CB and his reply was that they investigated this for the Mack 28 but the amount of lead that could be placed there made it unworthwhile and having less effect than moving a body around on deck (but still not convinced).
There is also the added problems of lifting it.
The more I use my boat the more I appeciate how well balanced it is.