Stability issues

[kitcat]

Mac X's and M's are notoriously unstable for the first 10 degrees or so of heel, until the water ballast starts making itself felt, which means that they are very tender boats in gusty conditions, the sort I regularly encounter in estuary sailing, and I noted that there was some discussion about putting permanent ballast into the bottom of the hull, but that will only detract from the on road trailing performance when it needs to be relatively light.

So thinking about this, and wanting some extra ballast to counteract the tenderness, it seems that if one stores a load of anchor chain [more than you would normally carry] around the d'board housing it could be more useful than keeping it in the front anchor locker, but still be useable if stored carefully. Taking this one step further, how about using some purpose built moveable weights, the sort that are routinely bolted to tractors to counteract implements at the other end, which could be tied or strapped down in the same area, but not permanently bonded in, so they could be removed for trailing, launching or recovering. Of course it is a given that they would need to be found a home off the boat during this time.

Can anyone come up with some other ideas to stabilise the ballast with non permanent weights somehow? It would certainly give me a happier Admiral in gusty conditions, when the boat can suddenly heel to over 30 degrees before the main can be eased!

Paul

[Crikey]

Sounds like you're still answering your original premise of not wanting more weight, with more weight. Not quite the same when it's moved over to the vehicle, but you're still paying for it.
Wouldn't bladder, or container storage for extra ballast water, located in the areas you mentioned, be better in the sense that you could fill and empty - on site - before hauling on the road? A bilge pump would facilitate the water in or out and I bet you could get at least a couple of hundred of pounds in real easy.

Ross

[kitcat]

Yep, water bladder of some sort could work, and as you say Ross, there is already a pump handy, it may be possible to attach a permanent bladder or tank low down. Good thought, thanks

Paul

[bscott]

My wife has control of gusty conditions by being in charge of the traveller, and you should control the main halyard. Once she has control of heeling, things will be better.

Bob

[Crikey]

Paul, now you've really started a lost night of sleep here!
Perhaps it would even be possible to make two centrally located higher lateral tanks, sacrificing compartment storage space, connected by a valved large diameter pvc tube. Fill one completely full, pumping to the high tack side (to avoid sloshing), and valve drain to the low just before coming about. Repeat. Some incredible high speed transfer pump could avoid valve work below decks if single handing.
OK.... perhaps getting a little stoopid here but at least with the static single tank idea you could easily experiment by adding enough pre-filled water bottles to the general area, until you arrive at the basic extra weight you want to stay with. I think it would be still important, similar to the main ballast system, not to have any unwanted movement of the liquid weight.

Ross

[bartmac]

We have 2 x 150 litre bladders,one each side under the forward lounge seat and lengthway seat).A balancing valve which I open each night to keep things on a even keel.All done not so much for stability but more for general water usage.Its envisaged our tow vehicle will have a water tank and pump to fill prior to launching so as to keep our tow weight down.Two starting batteries and two "house" batteries installed 2 aside further add to our ballast.Due to rules and laws governing grey water we will install another bladder to capture this waste......interested to see our all up weight

[Highlander]

Just bring lots of Beer on board & as long as nobody P's O/B u'll maintain the ballast !

J

[Crikey]

Therefore size of bladder = angle of heel

[mastreb]

You could fill the ballast tank with glycerin. Pure glycerin is a non-toxic food-grade carbohydrate used as a low-hypoglycemic index sugar substitute. It has a syrupy consistency and is 25% heavier than water, which means that a ballast tank full of it will add 300 lbs. of additional ballast over the weight of water.

It's safe and legal to dump at sea. Because of it's high viscosity, it won't slosh around in the tank, and because its miscible in water it would be easy to wash out of the the tank by just filling it and dumping it.

Crude glycerin is a byproduct of biodiesel production. It can't be used in food because it's contaminated with vegetable oil, small amounts of methanol, and saponified fats, but the toxicity is so low that there's little to no environmental regulation of it in small amounts. There's a huge market glut of it, and you can often obtain it in 55 gallon drums just by paying for the drum or even offering to haul it away from small biodiesel producers. While there are certainly places you wouldn't want to dump it just to avoid questions, it's not an environmental hazard and can be eaten safely by fish and other wildlife.

Glycerin can burn (like sugar can) but it's difficult to start on fire and is not explosive unless its mixed with an oxidizer. I'm not sure what the effects in the ballast tank might be in terms of algae or mold growth promotion--likely it would prevent it because the tank would not contain the necessary water. However it may eventually putrify--I'm not sure about that. It is used as a preservative and would certainly last longer than most other food-grade compounds.

It would take a while to drain the tank if it would drain at all on its own (which would be a safety measure but inconvenient)--it may be necessary to hose it out of the ballast tank. Probably you would want to leave it permanently in the ballast tank and use an upgraded dual-axle trailer to haul your now 5000 lb. boat. You'd want to wash out the ballast tank at the end of the season and leave it open to drying out.

[seahouse]

That's a very interesting idea, mastreb!

Glycerin is also an environmentally-friendly anti-freeze. So you wouldn't have to empty the ballast for that reason, but might want to use it when (and where) freezing might be a threat.

-Brian.

[Crikey]

Not sure what homeland security would have to say about 1200lbs of floating glycerine. Sounds like a path for a waterborne binary explosive!

[Boblee]

Water has to be the best as you can move it in or out reasonably easy depending how you do it, we carry a 150l bladder under the rear berth but it only holds 100l and two 50l tanks in the bow under the v berth, both tanks are fairly low so should and do work as ballast.
Any extra lead is just too heavy for transport but the spare anchor and chain would help (slightly) until you needed it as an extra anchor we do keep any weight, cans etc as low as possible but doesn't stop the wife going white knuckle when the sails go up

[phil kelly]

Does anybody have any idea just how much extra ballast we could add without seriously diminishing the main feature that attracted us towards a Macgregor - IE it's unsinkability ?

[Tomfoolery]

Probably not much. There's not much boat exposed when it's flooded, as per the pics on MacGregor's web site, and for neutral bouyancy when submerged, you would add the weight of the additional water you need to displace to fully sink it. Doesn't look like much to me.

On the issue of stability, I have a feeling that the hull shape has a lot to do with its initial tenderness, along with the very high ballast location (high CG overall). With such a short moment arm at small angles of heel, I don't see where adding ballast high up (relatively speaking, as there is no keel) is going to have much of an effect on initial tenderness. At high angles of heel, when the center of bouyancy is far to one side and the boat's CG is far (sort of) the other way, there's lots of restoring moment, but with that shallow vee in the back and the ballast way up high, I suspect hull shape is doing most of the moment arm generation there, at least until it's predominantly on one side or the other.

[Mac26Mpaul]

My wifes in charge of healing... If the wind picks up or gets gusty, the sailing ends! LOL Its probably our primary reason for owning the Mac. Its a h@ll of a lot better powered cruiser than all those other trailer sailers and since I know I will have to power most of the time when the family is aboard, I might as well have the best powering sailboat LOL

well maybe I'm wrong, but I would think that no matter how much extra water ballast you add in there, its still going to be a tender boat for that first 10 degrees or so. I know its not what you want but I would think, the only way to make it less tender, is to add weight to the board........