Lead Ballast

[chockswahay]

My boat has a fair amount of lead pieces (loose) under the floor in the forecabin. I would like to tidy up and secure the lead and thought it might be a good idea to move the lead forward to the space (otherwise wasted) in front of the chain locker.

This will result in the lead now being above the waterline and about 8 feet further forward than it is now. If this resulted in lowering the waterline at the bow a little that would be fine as she sits about 4 inches high anyway.

However................................

Would the transfer of mass have any effect on boat handling? For example you could balance a caravan by placing weight at the front or back but the inertia around the pivot point (axle) can lead to instability and tendancy to swing and wagtail.

Sorry if this sounds a stupid question but I figure some one out there might have the answer.

Many thanks

Chox

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[PaulJ]

It is certainly not a stupid question and I suspect that since you have identified the problems you can also guess what the answer will be..... You have not said what type or size of boat nor how much lead we are talking about but assuming it is some kind of sailing boat, DO NOT move lead that is currently below the waterline to a position above the waterline.

Conventional wisdom has it that weight should be kept out of the ends and the theory behind that is pretty much what you have identified. However plenty of boats seem to get away with having considerable weight in the form of anchors,chains,windlasses and water tanks in the bows so I think I would worry less about that. If you want to change the fore and aft trim though, I think I would look for weight in the aft end that could be shifted forward rather than simply adding weight forward.

If you really want to do this then I would advise consulting the designer if at all possible, otherwise a naval architect or possibly a surveyor but the short answer is ..... don't do it.

Paul.

<hr width=100% size=1>I used to have an open mind but my brains kept falling out.....

 

[oldharry]

Ballast must be kept at the lowest possible point in the boat. Raising it will upset the stability of the hull, and if placed too high would cause serious instability and cause a capsize.

Moving it forward will alter the trim, and may make the boat difficult or even impossible to steer or handle. the back end will fail to grip the water properly and will wander uncontrollably. A sailing boat will 'gripe' badly if there is too much weight forward, and be pretty well unmanageable.

Try rowing a dinghy with someone sitting up forward - you get the same effect.

Finally, the ballast needs to be secured and mounted where the hull is designed to take the weight. Wrongly placed it could severely damage a wooden hull, and if inadequately secured could move or even fly around in a rough sea with disasterous consequences.

If the boat is badly trimmed and upo by the bows as you say, then tramsferring moveable weights from down aft is the only solution - water and fuel cans, spare gas, and other gear can easily be moved up temporarily to find out if you really do have a trim problem.

Many smaller boats I have owned have improved considerably after adding weight forward - but preferably not by shifting main ballast around, and certainly not if it raises the centre of gravity.

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[danera]

As the ballast is loose in the forcastle I would guess that it was placed by a previous owner to correct the trim, eg after adding a (heavier) engine. Moving (adding) ballast forward affects the handling of the yacht, decreasing weather helm - it's possible to achieve the same result by raking the mast forward. As other posters have suggested, I wouldn't move to where you suggested, but instead remove it to see how the boat behaves without it, you may find it more convenient to move/repaint the waterline. If you decide to leave it where it is make sure it is secured down as it could turn into lethal projectiles in the event of a knockdown!

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[chockswahay]

Thank you for your replies so far. I forgot to say that the boat is a 44ft ketch and weighs 12 tons empty with a registered tonnage of 17. The lead was indeed added to trim the boat, I would estimate about half a ton or so. The hull is epoxy with balsa core.

I am not too worried about the waterline (coz we will end up with loads of kit and provisions on the long hauls!) but I am certainly concerned about the potential damage in high seas or god forbid a knockdown.

Previous owner said never had a problem................but if it's gonna happen, it'll happen to me!

Any ideas on best way to secure the lead?

Chox

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[oldharry]

If you are going offshore, then prepare for the worst case scenario. A knock down may never happen, but it is well on the cards and the thought of lead ballast flying around if it did....

Even a boat that size, moving half a ton to a position above the waterline will affect the handling and stability - not enough to capsize, but probably enough to affect rough weather handling adversely.

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[danera]

If the lead is there for trim more than stability and you are heading offshore, have you considered locating a fuel or water tank there instead?

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[William_H]

Yes defineately the lead must be secured. Lots of epoxy resin under and around the lead may do the job. However weight in the bow and stern even though balanced will give a greater pendulum effect than mass near the middle of the boat. So if you can move weight out of the stern then either do without the extra lead balast or preferably mount it very low in the bilge near the middle of the boat.
Re caravans I don't know that weight at the front and back causes the pendulum type swing. Certainly a balanced van or trailer ia terrible danger. They should have 10% total weight on the draw bar ie definitely not balanced but front heavy to avert the tail wag. Good luck with your voyaging will

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[oldharry]

Caravans are notorious in their response to bad loading. Heavy weights placed any distance from the axle - even if the balance is correct for towing can make it almost unmanageable. Snaking starts at any sort of speed and even a skilled driver will have difficulty preventing his outfit from jacknifing with disasterous results in certain circumstances.

Same goes for boats being towed with heavy engines on the transom - unless the trailer is specifically designed to overcome the problem.



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