Re: How much Flotation? And Where?

DAVID_KAUTZ@HP-Sunnyvale-om5.om.hp.com
Wed, 5 May 1999 15:34:32 -0700


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West Wight Potter Website at URL
http://www.lesbois.com/wwpotter/
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If it's a really old rule it may assume that the boat is made of wood,
which would have more buoyancy than fiberglass.


Dave Kautz
P-15 #1632 Tilly Lucy
Palo Alto, CA

______________________________ Reply Separator _________________________________
Subject: Re: How much Flotation? And Where?
Author: Non-HP-JBlumhorst (JBlumhorst@aol.com) at hp-boise,mimegw7
Date: 5/5/99 1:37 PM

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West Wight Potter Website at URL
http://www.lesbois.com/wwpotter/
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In a message dated 5/5/99 1:12:20 PM Pacific Daylight Time, cgula@innet.com
writes:

> Hi Judy, et al:
> The old rule of thumb for figuring the minimum floatation was used an
amount
> (figured @ 58#/cu. ft) equal to 100% of the ballast and 40% of the rest of
> the designed displacement. This should allow the average boat to float
> regardless of the amount of water aboard

Hi Mac,

Let me see if I understand you.

Keel weight /58---> 370/58= 6.4 cubic feet.
Designed displacement * 0.4 / 54 ---> 2000 *.4/58 = 13.8 cubic feet.
Total = 20.2 cubic feet.

I don't know what the designed displacement truly is, but I'm guestimating
that she'll be floating on her lines at 2000 pounds.

So you're saying that about 20 cubic feet of foam is all a P19 needs? I
figured it at about 30 cubic feet. Can you explain why this formula works?
If I understood the reasoning behind the formula, I could consider geting rid
of another 10 cubic feet.

Best, Judy B