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Old 19-01-2010, 05:32   #16
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In the one design offshore racing world it is fairly common to have float lines.

An owner could empty the boat, weigh it, and then mark these float lines but maybe they really don't want to know?

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Originally Posted by David M View Post
Its too bad yachts do not come with stability and trim tables, like ships do. Then we would know the displacement by where the waterline is at the bow and the stern. Its a pretty easy calculation to make with the right info. Any idea why yacht manufacturers do not provide this data?
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Old 19-01-2010, 07:12   #17
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Displacement is not the weight of the boat
It is how much the boat would weigh to push it down to its DWL (design Water Line)

So, there should be an empty weight for a vessel when you buy or build it, with basic gear to make it work and it would float high on its lines.

Then there would be a loaded weight, with all the stuff, which would = displacement of vessel, which would push it down onto its lines.
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Old 19-01-2010, 07:17   #18
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IDon't expect a light boat to carry a large load.
Though it is possible

For example take a 50 ft cat with a displacement (full load) of 10,000kg

Make one from steel
and one from foam ,kevlar, epoxy

Which can carry the heavier load / more cruising gear?
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Old 03-02-2010, 09:13   #19
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The PDQ 36 was reported to weigh 8,000 pounds empty, based on original calculations. Simon Slater told me it was several years later that a boat was actually weighed on a well calibrated crane, and the actual weight was IIRC 1500# heavier. Mine is over 10,000 pounds with a huge generator and four batteries that each weigh more than one of my motors!. While this is still light compared to other production boats of similar size, the point is that you haven't a clue how much any boat weighs until you weigh it.
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Old 03-02-2010, 12:33   #20
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Quote:
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Its too bad yachts do not come with stability and trim tables, like ships do...
... Any idea why yacht manufacturers do not provide this data?
Perhaps, because typical yachts are sold for under (oftimes well under) a million dollars, and producing those tables might cost upwards of $10K ?
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