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Displacement vs. safe payload capacity?

Posted: Sat Nov 24, 2012 2:08 pm
by greyrfox
I have got a question that I am wanting some useable information on concerning the estimated displacement of a hull design. I am leaning towards a Coronado design. I see the displacement is listed as 5900 lbs. With a hull weight of approximately 1500 deducted that leaves 4400 lbs for cabin, engine, fuel, equipment and passengers. But that is to the displacement level to which my understanding is just before it starts to sink when theoretically filled with that much in water weight. Since I have no intention of pushing the limit, what is a "safe load" calculation I can use for a "useable" payload for this vessel? It is also my understanding that if I push the length of this vessel to the full 10%, (28'-3") then I could add the extra volume of hull for a higher displacement estimate based on the extra weight of water in the stretched hull.
My concern is safety over speed.


Sorry for the long winded question. I hope someone gets my question? I just want to know how much before it's too much?
Rick

Re: Displacement vs. safe payload capacity?

Posted: Sat Nov 24, 2012 2:16 pm
by Soloboat
The best answer I can give is to read David Gerr The Nature of Boats. He probably has the most eruidite explanation of displacement and the weight carrying capacity of your boat. He takes all the variables that may influence capacity ,eg if you build light vs heavy.
Hope this helps

Re: Displacement vs. safe payload capacity?

Posted: Sat Nov 24, 2012 2:19 pm
by greyrfox
The best answer I can give is to read David Gerr The Nature of Boats.

Thanks Solo: So is there a possible link for this article or is it a book? I will do a word search and see what I come up with. Thanks for the tip.

Re: Displacement vs. safe payload capacity?

Posted: Sun Nov 25, 2012 6:56 am
by Bill Edmundson
In the USCG regs. There are a couplle of formulas. Based on your "sinking" number. Displacement is something like 1/5 of sinking. It is your safe capacity. Boat, motor, fuel people, gear everything.

Bill

Re: Displacement vs. safe payload capacity?

Posted: Sun Nov 25, 2012 5:12 pm
by greyrfox
Thanks Bill I was pleasantly surprised to hear that. I was thinking I may have to go "bigger".
Rick