Weight Distribution

[Mark Prouty]

I can tell you that the 150 lbs of dumbells I used to have at the very tip of the bow (in the flotation) made the boat plane off slightly faster but did not seem to make the top end any better...may even have been slower. They sure made the boat unstable though. The very first time I took my mac out and was getting hit broadside with a 12-15 mph short wavelength chop at anchor, I thought the fillings would come out of my teeth because the roll oscillations were so violent (it tossed a coiled up rope right out of my anchor locker to be lost forever). I almost sold the boat after that first day....glad I learned and kept her though. The biggest part of that incident was too much weight in the front...second biggest was no boards down.

Dimitri,
I don't understand why weight in the bow would make the boat more unstable. I'm concerned about this. I was thinking or stowing most of my heavier gear towards the bow assuming that it would improve the way the boat planes.

I was also interested in a mod with the fuel tank in the bow. http://macgregorsailors.com/cgi-bin/mod ... record=174

How much to you concern yourself on balancing gear port and starboard? Does 150 or 200 pounds more on one side cause a problem?

[greybird-M]

I have a 26M, 2003 model. My starter battery is aft, starboard also is the 'house'battery, the galley AND the porta-pottie. The boat leans to starboard, obviously, unless crew stays to the port side of the boat. It seems to me that the boat is designed starboard heavy and the dealer did not help by installing the 'house' battery on the starboard side either. It annoys me that I will have to add ballast to the port side of my boat, probably using weight set plates stored in large, heavy zip lock baggies. There has to be a better way but when the boat is designed in such a fashion, there is not much you can do EXCEPT to add compensating weight.

[Don T]

Hello:
The trick here is to add weight low in the boat. Any mass added above the center of gravity will decrease stability. And, in this case, the weight was also forward where the hull is very narrow causing the bow to dig in and the added weight to toggle.

Could you move your batteries and maybe a fresh water tank over to the port side to balance the boat?

[Chip Hindes]

I would strongly recommend against using any kind of compensating ballast (like weight set weights in baggies) which is not fastened solidly to the hull. In the event of a knockdown or even in heavy seas these things become lethal projectiles, and they only need to get up a little momentum to smash right through the flimsy interior pan. If the boat were to turtle these will end up on the cabin ceiling and help to keep the boat in its turtled condition.

[Dimitri-2000X-Tampa]

Dimitri,
I don't understand why weight in the bow would make the boat more unstable. I'm concerned about this. I was thinking or stowing most of my heavier gear towards the bow assuming that it would improve the way the boat planes.

I was also interested in a mod with the fuel tank in the bow. http://macgregorsailors.com/cgi-bin/mod ... record=174

How much to you concern yourself on balancing gear port and starboard? Does 150 or 200 pounds more on one side cause a problem?

Mark, I actually discovered the phenomenon the very first time I went out and anchored (stopped my forward motion in a decent blow) The boat didn't come with a manual, but later I downloaded it and I think it also warns about too much weight in the bow.

As with an airplane, you can be well under the payload of the craft and still have a lethal balance problem. On a Mac, it shouldn't be lethal, but it can put you into one hull of a roll oscillation or a wobble if you like. Who knows, that oscillation may even cause a capsize if there is a serious side-to-side weight imbalance disrupting the equilibrium. The boat is designed to "balance" on the flatter part of the hull further aft (otherwise, it will seesaw on a fulcrum). With 150 lbs of weights at the very tip of the bow (it was down low and I don't think that makes much of a difference for this particular problem), that was a very large amount of weight way forward of the center of longitudinal stability in relation to other weight on the boat (mostly me and the motor). If I had had another couple people on board sitting in the cockpit, it probably would never have happened.

So, the issue is balance, as long as there is enough weight to the rear to balance out what you are putting in front, you will be ok. There are ways to calculate that btw, you just have to figure out the CoS (same as CoG I believe) and then do calculations based on the weight and the distance from the CoS. Its part of pilot training when figuring out weight and balance before you fly an airplane.

If you don't have enough weight rear, I definitely would not recommend putting too much weight forward, and neither does the owners manual. It was damned near impossible to haul out the anchor with over 350 lbs on the bow causing the roll oscillations. My bigfoot is about 255# too. I would say the roll was going from one side to the other side in about half a second (1 second cycle with maybe 30 degrees of roll back and forth)...pretty freaky. With the weights out of the bow, I've never had that problem again, but I also put the boards down in situations like that too. Funny thing is that the dealer put the dumbbells in and was doing that with all the Macs they were selling. At least they were jammed into the foam and then covered with the screwed down hatch all the way forward in the V-berth...so they probably wouldn't have gotten loose.

[Dimitri-2000X-Tampa]

Your problem must have been due to your speed and hull design.

Just to clarify, my problem was with no forward speed when the boat was at anchor out in an open bay. It was one of those strange days when the wind was holding me mostly broadside to the chop. The chop was at the right height and length to throw the boat into the oscillation.

When under sail, powersailors can do a little better with some more weight in the bow in order to raise the square (powerboat like) transom a little higher out of the water causing less drag. The front half of the Mac26X is like a displacement hull and the rear half is like a planing hull. It would probably be a lot happier planing, but so far, the closest I've gotten to that under sail is surfing down some big waves (about 8.5 kn).