Can a Mac capsize?

[Jimnkathy]

I was sailing on Mark Twain Lake a few weeks ago. We were having a great day sailing. We had 15+ kt winds, it was the fastest wind I ever sailed my mac X in. We were sailing very fast I dont know the speed but we were actually leaving a nice size wake behind us.

The winds were gusting pretty fast from 15 to about 20. Our boat suddenly heeled to a scary point. There were some 30+ ft sailboats out there with us. They didnt reef there sails and they were staying at a steady heel. I thought I could do the same but I had a few scary moments where I thought we were going over. I decided to lower the sails and motor back to the ramp.

I guess my question is are the macs more likely to capsize compared to some other sailbaots?

[Harrison]

Based upon my limited sailing experience I’ll take a stab at this. To me, water ballasted boats are more tender at first due to the water ballast system. As you heel the boat over, the water ballast reservoir rises to a level higher than the water surface you are sailing in, thus creating the force to counteract your heel. Maybe I have a misunderstanding of the physics of a water ballasted boat, but I see it like this. . . Take a ziplock bag full of water and place it in water. It’s pretty much neutral. Doesn’t weigh practically anything. Offering very little weight/ballast (outside of the weight of bag). Now slowly lift it out of the water. As you get more of the contained water in the bag above the surface of the surrounding water, the bags weight increases. Maybe I got it wrong, but that’s how I see our water ballasted boats reacting. The more heel, the more weight/force we get, until we have the entire water ballast reservoir above the surrounding waters surface.

A permanently ballasted boat has approximately the same amount of force countering the heel at any degree. (as long as the ballast remains in the water)

To answer the question. . . I think any boat can capsize if the conditions exist. I certainly would rather be in my Mac than on a non ballasted keelboat on my local lake.

---Harrison

[eric3a]

..

[tangentair]

The issue of whether the ballast works in or out of the water is long debated here, I will not add to it at this point, however since I have both a keel boat and a Mac let me put my two cents in. Those keel boats likely have twice the ballast you have in their fin-like keels hanging well below their center of gravity (we will come back to this point) and their beam is at least 25% greater than yours. Like a narrow canoe, Macs can roll quickly because there is no change in the surface area presented to the water as it rolls. Now consider the center of gravity, the point around which the Mac wants to roll. It is only slightly above the water ballast and therefore the advantage of the wind upon the sail is far greater than a beamy keel boat where the iron/lead/cement is 3 to 4 feet below the C/G. I do not think the Mac will turtle, but it can give you a scare until you learn how close to the wind your comfortable with and how much sail you can comfortably carry. I think the only mistake you made was coming back in. But listening to me could just as well be your second.
However, you might consider, that the plastic baggy of water that is neutral in the surrounding water, weights 2.2 pounds per liter holding it in your hand in the cockpit, passing it to your mate while your standing in the cabin, or laying on the floor when she puts it down.

[vkmaynard]

Water ballasted boats are more tippy simple because the moment arm of the ballast is much less than that of a weighted keel boat. Put 2/3 of the water ballast total weight in lead, 4'-5' below the hull and the Mac would behave like a regular sail boat. Then you could add a real main sail and not reef most of the time for a comfortable crew sail.

But then you could not: launch the boat in our doubt ridden lake, beach the boat, easily trailer the boat, go wakeboarding, get to where you are going when the crew gets board, etc...

Victor

[Harrison]

Guys,

Good point regarding the CG and the hull shape. I have to agree with you that they are probably a bigger factor than the actual ballast weight itself.

---Harrison

[LOUIS B HOLUB]

Any boat can capsize given the right (wrong) conditions.

Capsizing from wind alone on a ballasted and properly loaded (ie not overloaded, proper repartition of weight) Mac is virtually impossible in my opinion.

I notice that my MacX and MacM DVDs show the boat pulled over on its side, with a quick response to upright when the mast weight is released. That and other safety features sold me on the Mac.

Im a novice fair weather sailor, which seems to be the case with many fellow Mac folks--exceptions granted to the more experienced as Eric, Frank, Chip, and others that I try to gain sailing 'know hows' from.

But, we novice sailors are suseptable to a "knock down" in my opion, simply because of inexperience. Knowing how to sail the boat isnt as difficult as reading the winds. But, Im still trying to learn.

[Harrison]

You know what, I’ve been thinking about this all afternoon. I’m wrong on the water ballast/water bag analogy. The reason the bag of water is neutral IN water, is because it displaces it’s own weight in water. (assuming the water is the same specific gravity IE: fresh water vs. salt water for example) When we raise the bag out of water we are no longer displacing the same amount, thus our bag is heavier, because it is no longer buoyed up by the displacing water pressure.

Our hulls displace more water weight, than they weigh, whether full of ballast or not. This is why they float. (bear with me, I’m thinking out loud) If our beams were shaped wider than they currently are, as our boat heels, we would start to displace more water due to the shape of the hull, thus the resistance to the opposing heel is increased. In turn, increasing stability. Tangentair you got me thinking with your canoe example. Thanks.

My apologies on my first post as I got focused on the wrong thing, then started typing before the brain kicked in!

---Harrison

[JonBill]

Jim,

It varies from boat to boat for the reasons mentioned above by the guys and for some other reasons, but to boil it down to a good rule of thumb for those 30 foot boats you mentioned because of their design, ballast and sail area my guess would be they need to reef at about 20 mph wind, but in the Mac X or M you need to reef a lot earlier than that. At around a 12-14 mph wind and it's past time to reef in an M or X. There are those who will disagree with me but these are just my rules of thumb.

Also on a related issue it's a good idea to reef early in the face of an approaching storm or squall line before it gets to you. Do this for safety sake as you never know what the wind condition will be until the storm has hit and then its too late, so this will also help to avoid the problems you mentioned. If you have consistent winds at 12mph or higher at the start of the day then go ahead and reduce sail before you go out in your X and you can always add sail area later if your boat can handle more sail in those conditions.

Squall lines are comprised of storms that organize into a linear structure and a squall line may be aligned into one or more segmented lines. It can be a long lasting multi-cell storm too. You need to learn to recognize approaching squall lines as they can be quite severe when they first hit on an otherwise peaceful day. If they catch you off guard with full sails flying you may have what's known as a knock-down experience. Actually capsizing is pretty rare but can happen.

There are other ways of managing sail in overly windy conditions. One way is in how you trim your sails. If you let the wind spill off from your point of sail then you can manage more wind but I prefer to reef early.

Kind Regards,
JonBill

[TAW02]

I have a MAC25 and a 26M. The M tends to heel quicker but stabilizes about 15 degrees. Meaning that after 15 degrees the M tends to hold a good trim and is less sensitive to wind gusts. I can run on a 20 knot wind with full sails if it is my MAC25. Not so on my M. At 20 knots I am reefing my main and running on a slightly reefed 135 headsail. I think the difference is high freeboard on the M. Both ships round up in wind gusts upward of 25 knots. Although I ran with a guy who had an identical MAC25 and he sailed reefed down to the poles in 40 knot winds and would make way nicely as if it were a summer day! He was an old salt, retired navy and singlehanded his MAC25 daily throughout his retirement years. He knew that boat like the back of his hand too. So I believe it has everything to do with how successful you are with the boat you sail. The more you sail your boat the better you are become with her.

[baldbaby2000]

It's not really so much the nature of the ballast--water, lead, etc. What matters is the location of the center of gravity (COG) and the center of bouyancy (COB). As the boat heels over, the center of bouyancy moves in a direction that puts force on a lever arm to keep the boat level. The COG shouldn't change unless the ballast is only partially full or gear starts shifting around; both bad things.

see COG link.

Having said that I agree that it's unlikely that a Mac would capsize strictly from the wind. Now if there are big waves that's another story.

Daniel

[NiceAft]

Jimnkathy,

I'm going to take a different approach. The above responses are answering your question about capsizing. I'd like to comment on your comfort level when heeling.

If you don't have one, install a Clinometer.


You will develop a sense of control when you gradually see the angle you are currently sailing as opposed to the angle you have experienced before. 15 degrees at first may be scary. When you hit it again, and realize that 15 is no big deal, you will be going to 20 and then greater. We have had Nice Aft beyond the limit on the scale (45degrees) of ours.

The placement of the device is another story. Some prefer dead center of the boat. Mine is far to the Starboard. It does not make a difference.

If, when you said

Our boat suddenly heeled to a scary point

I assumed you were new to the Mac's heeling tendencies. If I'm wrong, well then never mind.

Ray

[Don T]

OK I'll chime in,
The reason that water ballast is more tender is because of the ballast density. When it begins to heel, because of the low density, it takes a lot of angle to get enough weight off the center of bouyancy. Lead being way more dense has a lot more weight off center at less angle. The classic Macs have a ballast tank that is long, low and narrow so it stiffens quicker than the X & M which have higher wider tanks in front and behind the sole. It is one price we pay for standing head room. Another being windage.

Will it capsize? Of course but usually, with ballast in, the boat will round up righting herself. There have been cases where the ballast was enpty and the boat capsized filling with water. In that case it will stay on her side because the water centers itself between the two areas of bouyancy, the air in the ballast tank and the foam flotation. There was a picture in the paper of a Mac in just that scenario.

[LOUIS B HOLUB]

Will it capsize? Of course but usually, with ballast in, the boat will round up righting herself. There have been cases where the ballast was enpty and the boat capsized filling with water. In that case it will stay on her side because the water centers itself between the two areas of bouyancy, the air in the ballast tank and the foam flotation. There was a picture in the paper of a Mac in just that scenario.

In addition, another thing Ive learned from this site concerning the danger of having a full ballast, and an unforseen hull leak. There is a little (+ -) half inch hole below the cabin exit ladder, and its there for a reason. If water appears coming out of that hole, its an alert that the bilge has water which endangers a Mac when heeled--bilge water will act as a counter weight against the ballast and over the boat goes with the mast in the water. (When I first purchased the boat, I assumed that hole was a cabin floor drain hole a major opps.)

[Currie]

FWIW -

An interesting thing to note about water ballast, is that it can still provide a reasonably low COG if the boat as a whole is lightweight (a la 26X/M's). Keel boats have lead in them, but the construction of the ship as a whole (hull above waterline, deck, rigging, sails, etc.) is much, much heavier. Not say that Mac's aren't more tender, but they do have a very reasonably low COG using water-ballast, because of overall lightweight contruction.

~Bob