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Old 07-12-2012, 17:08   #16
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Re: fore and aft trim

thanks for your responses guys. what i really wanted to know was the theory on the distribution of ballast on the center line to get the correct fore and aft trim. less ballast closer to the bow or more ballast closer to the front of the keel ?? Im leaning towards removing about half the lead from the bow and fixing the other half to a center point just infront of the keel and adding 70 meters of chain(which may come in handy) to the bow secction under v berth. this should give me the same trim as i have now but
would be much safer.
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Old 08-12-2012, 04:36   #17
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Re: fore and aft trim

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Originally Posted by Alley cat View Post
thanks for your responses guys. what i really wanted to know was the theory on the distribution of ballast on the center line to get the correct fore and aft trim. less ballast closer to the bow or more ballast closer to the front of the keel ?? Im leaning towards removing about half the lead from the bow and fixing the other half to a center point just infront of the keel and adding 70 meters of chain(which may come in handy) to the bow secction under v berth. this should give me the same trim as i have now but
would be much safer.
Putting weight in the centre of the boat will do nothing other than slow it down. None of us here can help you, as we can't judge how the boat is trimmed.

I find it hard to believe that your boat was designed so badly that it requires such drastic trimming measures. My best advice is to lose ALL the lead (sell it and make some money!) then follow the advice on trimming using the water tanks, which is what many of us do anyway. Forget about the chain, that's a waste of time.

I repeat: Lose the lead, forget the chain, and stop worrying about trim!
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Old 08-12-2012, 05:39   #18
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Re: fore and aft trim

Nobody would put lead in a racing monohull except in the keel. Your boat was in a One-Design class, or something like that. They build the boats on the light side then ballast them to be identical. My OD race boat had a weight up the mast, by the upper spreaders, to make the mast legal. They balance the components both statically and dynamically. It makes a difference.

Take it out. Replace with stores. Maybe make a diagram of where they were. Any boat like that you want all weight centered over the keel. Nothing in the ends. Some misinformed cruisers have other opinions but they are wrong. After that it is better aft than forward because of your narrow bow and wide aft sections. Often when going downwind the race crew will move the heavy gear aft to keep the rudders in the water. Indeed, you will see the entire crew at the transom ... sometimes praying.

Weight in the ends increases pitching in seas. That slows a boat and is uncomfortable. It's is a inertia thing: Once the bow starts going up, it keeps going up. And vice-versa down. That's one reason why no modern design boat has the picturesque long overhangs or bow sprits and such.

Under many rules it is completely legal to shift ballast when racing. Often there is someone down below constantly moving sails and anchors to the windward side. It makes a difference.
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Old 08-12-2012, 10:38   #19
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Re: fore and aft trim

[QUOTE=europaflyer;1102619]Putting weight in the centre of the boat will do nothing other than slow it down. None of us here can help you, as we can't judge how the boat is trimmed.

I find it hard to believe that your boat was designed so badly that it requires such drastic trimming measures.
Actually, it's not real uncommon for one off boats, or the first in a series... "the architect nervously awaited the first splsahing of the hull.. will it sit on it's lines???"

My best advice is to lose ALL the lead (sell it and make some money!) then follow the advice on trimming using the water tanks, which is what many of us do anyway. Forget about the chain, that's a waste of time.

I repeat: Lose the lead, forget the chain, and stop worrying about trim![/QUOTE] yes
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Old 08-12-2012, 12:18   #20
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Re: fore and aft trim

Yeah forget the chain, you won't ever need it!!!!!

That has to be the worst pieces of advice ever put forth on this site. if you are going cruising, all chain rode is the only way to go. Yeah, it weighs a bunch but the piece of mind knowing that the anchor is securely attached to the boat is priceless. For occasional anchoring or marina cruising, all chain rode can be dispensed with. For real cruising where you'll be on the hook 24/7/365, it's the only way to go.
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Old 08-12-2012, 14:05   #21
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Re: fore and aft trim

Whatever you use, you need a system and need to understand it's limitations. All chain is the most idiot proof. On a light racing hull, maybe 40-50ft of chain with nylon backup is fine. Just manage your system. Dont anchor where sharp coral heads will cause problems etc. or be more careful how you anchor there. Was it Bob and Nancy Griffiths who sailed around the world (3X?) in Awahnee using flating 1" Poypropylene anchor rode..? ! I read their book, I think it was Bob....
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Old 08-12-2012, 15:27   #22
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Re: fore and aft trim

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Yeah forget the chain, you won't ever need it!!!!!

That has to be the worst pieces of advice ever put forth on this site. if you are going cruising, all chain rode is the only way to go. Yeah, it weighs a bunch but the piece of mind knowing that the anchor is securely attached to the boat is priceless. For occasional anchoring or marina cruising, all chain rode can be dispensed with. For real cruising where you'll be on the hook 24/7/365, it's the only way to go.
The OP was planning to dump a load of chain in the forecabin, to sort out a problem with his boat which probably doesn't even exist. I wasn't talking about anchor chain.
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Old 08-12-2012, 20:14   #23
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Re: fore and aft trim

One feature of a light boat like that is that changing the trim is easy. Moving just a few things changes the trim significantly. A friend across the anchorage can tell if we are up in the morning because the turn of the bow shows when the GF and I haul our 140 kilos out of the V-berth and aft to the area around the coffee pot. I judge the water remaining from the YC bar as she heals significantly with one empty tank. Level with both full or both empty.

Keeping her light in the ends does not necessarily mean getting rid of the anchor chain. You do what you must to get the job done. There's probably no good solution for chair forward. I do take the anchor off the bow for major passages.
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Old 08-12-2012, 20:29   #24
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Re: fore and aft trim

Ok guys, thanks for your thoughts! Imgoing to remove all the lead and try
Moving some stores and equipment from down aft to forward to retain present trim. This will improve safety and perhaps performance as well. Thanke again.
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Old 08-12-2012, 21:31   #25
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Re: fore and aft trim

Please don't take away from this that weight at the front is always a good thing! On most yachts, it is anything but. This is why all sailors should start in dinghies, you learn that to get the performance downwind you need to be leaning as far backwards as possible to help the boat hydroplane.

You might have a freakish boat that needs really odd trim, but unless you feel the stern is really dragging in the water stop worrying about your fore and aft trim. Only racers really obsess about trim. If you are planning to start racing, the key is to lose as much weight as possible, and keep what there is down low and in the centre (for most boats). Crew leaning off the rail upwind, and as far to the back of the boat as possible downwind. Only in light airs do you need to start worrying about getting weight forward; send the crew to relax on the foredeck!

I might be wrong, and you might have a one-off yacht which didn't quite turn out as intended. Somehow, I doubt it.

Have fun!
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Old 09-12-2012, 14:53   #26
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Re: fore and aft trim

Quote:
Originally Posted by Alley cat View Post
I have recently purchased a 41 ft fast cruising yacht a modern design with
a bulb keel, plumb bow and fairly wide aft section. During a recent internal clean and locker inspection I found that the boat has numerous lead ingots in lockers forward of the mast. these were not very well secured and i want to glass them onto the hull. My dilema is that i dont understand why the former owner/builder has placed this lead in three
diffrent positions. All on the center line but at least 4ft apart. Iam sure it
was added to counteract the weight of motor ,fuel tanks etc in the stern.
would i be better off using less weight and putting it further forward ?
OR even more weight and having it closer to but infront of keel? what are
implications ?? (total weight of ingots is aprox 200kg)
Any ideas?
If the boat is of a known design, I would strongly recommend contacting the designer and asking whether the lead is an integral part of the design.

It may well be that the lead is a necessary part of the design for trim, but it may be that it is not necessary at all. If the boat has previously been used for racing but will now be more cruising orientated, it may be possible to replace the "dead weight" if lead ingots with "useful" wieght of anchor chain, heavier anchor, tankage, batteries, etc., but without input from the designer I'd be very cautious of making significant changes to the trim.
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Old 09-12-2012, 16:09   #27
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Re: fore and aft trim

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Resin infusion made the hulls heavier?
With resin infusion it fills up every void such as the spaces between all the blocks of balsa etc with resin so yes it will be heavier than contact molded hull all other things being equal, however you are much less likely to end up with a waterlogged hull.

Steve.
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