Question for the Engineers here, regarding ballast weight

[Sheppie62]

I have a question for the engineers on the site, or someone that can answer this. Does splitting weight say 50lbs on left side floor and 50lbs on right side floor help the self righting of the boat? Or would 100lbs in the middle be best? (same height). To further complicate this, the center mounted weight would be on top of the ballast tank say maybe 4” higher. I’m trying to get weight up front in my 26x, I am thinking about a couple of agm batteries on each side of the ballast tank (see pictures).

[Tomfoolery]

Splitting extra weight between the two sides is exactly the same thing as having a single lump at twice the weight in the middle, assuming the elevation off some reference plane (like design water line, but any plane will do) is the same for both.

There's a tendency for folks to think of individual weights and locations and such, but in the end, it's the total weight of the boat and the location of the center of mass of the boat, including all ballast (water ballast too) that counts. As long as all the parts are stuck together so they can't move, including water ballast (no air space in the ballast tank), then the boat and ballast are just one big lump.

[Jimmyt]

I would add the virtually insignificant point that the arrangement that gets the most weight lowest in the boat is best. Generally, the lower the center of gravity in the boat, the greater the righting tendency increase as the boat starts to heel.

If you were talking about significant weight, you might be able to feel a difference. But, 100 lbs located a few inches up or down probably won't be noticeable.

[NiceAft]

In order to keep the weight as low as possible, you may want to look into this.
https://macgregorsailors.com/mods/index ... tem&id=460

It won't bring the weight further forward than amidship, but it should help considerably with self righting.

[Sheppie62]

Ok I looked up battery weights. The group 31 batteries weigh about 70lbs each. So 3 about 225lbs, if I added another to balance weight , 2 each side (I happen to have another ) then about 300lbs. I originally wanted to put 2 batteries in most forward Vee Berth (the one with the foam), but it’s even higher above the water line.

[NiceAft]

Sheppie said:

but it’s even higher above the water line.

Jimmy said earlier:

the lower the center of gravity in the boat, the greater the righting tendency increase as the boat starts to heel.

and

If you were talking about significant weight, you might be able to feel a difference. But, 100 lbs located a few inches up or down probably won't be noticeable.

You are now thinking of adding 300lbs more weight, 4" higher in the boat. My belief is that this does not contribute to more self righting. I like the idea of more weight closer to the bow though.

The other aspect is 300 lbs will be there when you are trailering also. That may create too much tongue weight for safe trailering.

[Sheppie62]

Thanks NiceAft and the others for your responses. And I like the weighted keel idea, I’ll have to look into that. I should have said “hypothetically” for the 100lbs, I was using that as an easy round number for calculations/ discussion only. Sorry, I wasn’t clear about that. I can move the 2 house batteries up there without hooking them up and see if it makes any difference. And I actually need trailer tongue weight to off set increased motor weight and setback ( I was planning on sliding the tandem axles back 6-9”, but this extra bow weight might be enough.

[Tomfoolery]

If you want three batteries, put the single battery on the low side. Every 26X I've seen lists a little, one way or the other at the dock but usually to port.

[Be Free]

In order to keep the weight as low as possible, you may want to look into this.
https://macgregorsailors.com/mods/index ... tem&id=460

It won't bring the weight further forward than amidship, but it should help considerably with self righting.

That's tickling some old brain cells...

There was someone years ago who made a weighted keel. As I recall the rope broke while he was under power, dropped the keel (with terrifying results) and the keel then fell out of the boat and was lost. I don't remember if he reported any significant improvement under sail before the board was lost.

Anyone else remember this one?

[BOAT]

Yeah, I remember - that's the issue with all these board mods is that they never give you real quantifiable stats on the performance before and after. BWY and the MacGregor factory got together on a project black boat where they did all kinds of crazy mods to a M boat including a weighted daggerboard and you can read bout it but in the end it had very little effect on sailing performance, actually made the boat SLOWER under power, but it did reduce heel angle but only slightly unfortunately though the reduced heel angle reduced some of the speed of the boat.

Weighted swing keels have been around forever and the big problem with them is controlling the center of lift. We sailed swing keels in the 70's and noticed the boat going from a lee helm to a weather helm with just a slight change in the angle of the keel.

As for ballast - the daggerboard on the M boat has holes so it fills up with water so the M daggerboard is already "ballasted". Water might not be as heavy as lead, but it's still 'ballast'. I find that in heavy winds the boat will heel less if the daggerboard is fully extended so it's fully 'ballasted'.

The location of the batteries in the M boat is also a good hint on battery placement: they are in the middle at the lowest point you can get above the ballast tank in the boat. If you can find a really low spot in your boat put the heavy stuff THERE.

[NiceAft]

BOAT,

The only thing I disagree with in the above post, is about the daggerboard in the M being ballasted by the water that is inside when the daggerboard is lowerred. That water doesn’t become a ballast; while submerged, it is the same weight as the water around it. That submerged fin is what gives resistance to movement. The water in the actual ballast tank does not become a factor until it is higher than the water surface surrounding it.

[Sheppie62]

If you want three batteries, put the single battery on the low side. Every 26X I've seen lists a little, one way or the other at the dock but usually to port.

Yes, 3 batteries would work very good as my boat now lists to port side, so 2 on starboard side. Regarding weighted keel, I already have made the boat go faster than it probably should under power, so any more stress on keel while motoring probably isn’t a good idea. I don’t really have a heeling problem, but I have already added alot of weight above water line so any reduction I think is a good idea.

[BOAT]

BOAT,

The only thing I disagree with in the above post, is about the daggerboard in the M being ballasted by the water that is inside when the daggerboard is lowerred. That water doesn’t become a ballast; while submerged, it is the same weight as the water around it. That submerged fin is what gives resistance to movement. The water in the actual ballast tank does not become a factor until it is higher than the water surface surrounding it.

You correct 0 ballast is not the right word for me to use zero ballast is neutral - the flooded daggerboard is as heavy or even heavier than anything else your going to put down there that is not made of steel - it's just not a huge difference

The black boat project actually had a weighted bulb version that worked the best under sail but it added a LOT of weight to the boat and made motoring performance really bad.

The biggest problem with a 25 foot waterline displacement sailboat is hull speed - no matter what you do the hull speed is still 6.9 knots. As we have all learned the hard way the best way to deal with heeling is to reef sails. The MAC already carries too much sail for it's weight. It's a tall rig (I can only speak for 'boat' - not sure how tall the X is) and tall boats heel a lot. That's why people like the Catalina 38 - a big heavy fat boat low in the water that has a short strong stubby mast. That boat can sail through a hurricane.

A MacGregor 26 will never be a Catalina 38 and no one should ever think they can turn the MAC into one. The boat is what it is.

When people start comparing things like that you end up with the kind of idiot youtube videos that were posted about the X boat on the other post about ballast. People have all kinds of expectations for these boats that are not realistic.

I always say, if you wanted to sail a boat that performed like a CAT38 why in the hull did you buy a MAC26???

[NiceAft]

Is the Black Pearl the black boat you refer too?

[Be Free]

Yes, 3 batteries would work very good as my boat now lists to port side, so 2 on starboard side. Regarding weighted keel, I already have made the boat go faster than it probably should under power, so any more stress on keel while motoring probably isn’t a good idea. I don’t really have a heeling problem, but I have already added alot of weight above water line so any reduction I think is a good idea.

The keel should not be down when you are going fast under power (but you already knew that ).