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Date Posted: - Monday - 08/ 8/05 - 3:18pm
Author: Chuck
Subject: The weight of a Mariner 40

Can anyone please tell me the actual dry weight of a Mariner 40 fiberglass version. It is important that I find this out. Appreciate any help. Thanks, Chuck

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Replies:

[> 26,500 lbs. -- Randall, - Wednesday - 08/10/05 - 3:33pm

According to the M40 factory specs on the MOA site, you displace 26,500 lbs. I'm assuming that factory displacement figures and "dry weight" are the same.

That the info you need?

RR

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[> [> Re: 26,500 lbs. -- Gene MS, - Wednesday - 08/10/05 - 5:40pm

Displacement and "dry" weight are definetly not the same.

Your displacement of 26,500 lbs is the weight of the water displaced by the presence of the hull in water. At 8.33 lbs per gal (3,181.273 gallons.

The actual weight of the vessel will be different and will also depend on the total weight of the vessel, its gear, tankage, fuel, water, waste the engine. etc.

I would tend to think the dry weight would be less than the displacement weight. No help here huh?

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[> Displacement vs Dry Weight -- Randall, - Wednesday - 08/10/05 - 10:19pm

Fun question as I really don't know the answer, but this is what I've learned tonight:
1. Dry weight always refers to the boat less fluids and also tends to refer to the boat as made by the builder before the addition of all the owner's stuff.
2. Dry weight is a term used mostly for small, powered pleasure craft that get towed by trailers or shipped on trucks because actual weight is easy to ascertain and material to shipping costs.
3. Displacement is based on a naval architect's formula "executed during the design process" and so is never exactly the same as "actual dry weight" or even actual displacement (i.e. no one ever measures the actual amount of water displaced by a boat post construction--though it's fun to contemplate how that might be done). But according to one authority, "the difference (between displacement and dry weight) is not enough to concern boat owners." Go here for a little more: http://www.docksidereports.com/boat_specifications.htm

Unless one of you've had your M40 on scales lately, I think Chuck is stuck with the 26,500 number.

But I can't find the answer to this interesting question: would 10 lbs of lead pounded out into a bowl that would float displace 10 lbs of water?

RR

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[> [> Re: Displacement vs Dry Weight -- Gene MS, - Thursday - 08/11/05 - 2:01pm

Chuck
If you are doing this to build a trailer or acquire one
A single axel can handle up to 16,000 lbs and a two axel
can handle up to 32,000 lbs

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[> The answer is "yes". -- Randall, - Thursday - 08/11/05 - 2:23pm

Being an English Major, my closest approach to a science class was Physics for Poets in which we analyzed sonnets whose rhyming structure was based on words like “velocity”, “lift”, and “vaccum”. They weren’t very exciting sonnets, by the way.

So, though it seems dead obvious that “displacement” must equal “weight”—otherwise the boat simply won’t float, duh!—I spent the entire morning trying to find one book in my sailing library that discussed the physics of buoyancy.

Only one did, and only briefly:

“According to the Archimedes’ principle, the buoyant force on an immersed object is equal to the weight of the fluid it displaces. This means that a boat is in equilibrium when the hole she makes in the water, so to speak, is the same in volume as the weight of water equal to the entire weight of the boat. For this reason, the weight of a boat is called her displacement.” –THE PROPER YACHT, Beiser

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[> [> Re: The answer is "yes". -- Chuck, - Thursday - 08/11/05 - 5:34pm

Great discusiion guys but the displacement is not the dry weight. We NEED the info for hauling purposes so I need to know how much the designed weight of the boat is if it were hung on a scale. Perhaps Bill might have the answer. Chuck

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[> [> [> Re: The answer is "yes". -- Bill Kranidis, - Friday - 08/12/05 - 6:52am

No difference, Chuck.

If you want to be safe, add another 2,000 lbs. to the 26,500 lb. spec (since Clair DID overbuild his boats) and you'll be well within the range.

So, starting at 28,500 add all your stores, water, fuel, ground tackle and so on and you'll get pretty close to cruising displacement.

Off the bat, I'd bet that your boat will weigh in at 32,000lbs right now (cruising mode).

Best,
Bill

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[> [> [> [> Re: The answer is "yes". -- Chuck, - Friday - 08/12/05 - 5:47pm

Many thanks Bill. I knew you had the answer.

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