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From: Joe - G4XRZ (no email)
Date: Tue Aug 03 2004 - 12:22:42 EDT
Hello Robert, and many thanks for the kind reply. yes. thats how I
was calculating it. I was simply using a tried n tested method of
calculating area 'WL' from 'square area' - WL using a 'fudge
factor' - i.e - .7 to .8 depending on design.
Much appreciated Sir ! . I have never come across a formula so easy
to use.
Really good stuff, I really welcome your input and knowledge.
(ps, I was fudging for the "Westsail 32"... using a factor of 27 WL
* 9 beam with a 0.73 (severe 'made up' - 'fudge factor' for area
WL!)area conversion.)
Makes interesting reading, and really shows the wisdom in stowage. !
Joe n Jayne - UK... I will have a 'small' beer to you today Sir for
the education !
seriously good stuff.. you are one of the 'real' areas of interest
that make this forum so worthwhile.
J n J
--- In , "Robert Gainer"
<robert_gainer_2 at h dot dot dot > wrote:
> Joe,
> I did not have the lines to your boat so I just picked some
numbers for the
> area of the water line, beam etc that are probably in the
ballpark. For what
> you are doing it won't make much of a difference. The formula
is .35 times
> the area (in square feet) of the waterline squared then divide
that by the
> beam (in feet).
>
> Beam 10 feet, area of water line 150 sq ft so, 150 * 150 = 22500
* .35 =
> 7875 / by 10 = 787.5 foot lbs. or 1/2" up at the bow by moving
787.5 pounds
> one foot aft.
>
> I hope this helps,
> Robert Gainer
>
>
>
> >From: "Joe - G4XRZ" <captainslarty at n dot dot dot >
> >Reply-To:
> >To:
> >Subject: [world-cruising] Re: moving batteries to another spot
> >Date: Mon, 02 Aug 2004 12:39:13 -0000
> >
> >Hi Robert
> >Please can you clarify the formula ?
> >
> >is it ... "to trim 1" is .35(A(squared)/B)" ?
> >(as per my brackets ?)
> >I am using a rough conversion of actual area to wl area of (wl-l *
> >wl-b)*.7 to 0.8 depending on design (without getting the paper out
> >lol...). With that I seem to match your figures.
> >
> >Joe.
> >
> >
> >
> >--- In , "Robert Gainer"
> ><robert_gainer_2 at h dot dot dot > wrote:
> > > Tom,
> > > The approximate formula for moment to trim 1" is .35A
(squared)/B.
> >Where A is
> > > the area of the water line and B is the beam at the water
line. A
> >is
> > > squared. So if your WL length is 52 feet and your WL beam is 13
> >feet I get
> > > an approximation of 7,000 foot-pounds to trim 1". And that is
˝"
> >at the bow
> > > and ˝" at the stern. So 1,600 pounds moving 15 feet is 24,000
foot
> >pounds
> > > and divide that by the 7,000 foot pounds to trim 1 inch and you
> >will trim a
> > > total of 3.4 inches. Again divide that into trim at the bow and
> >stern so the
> > > bow will go up, 1-3/4 inch and the stern will go down 1-3/4
inch.
> >For the
> > > nitpickers out there the center of flotation is a little aft of
> >the center
> > > of the boat so the bow will trim up a little bit more and the
> >stern will
> > > trim down a little less. The difference is about 5% more at the
> >bow and 5%
> > > less at the stern. Check my math, and I am guessing at your
> >dimensions.
> > > All the best,
> > > Robert Gainer
> > >
> > >
> > >
> > > >From: "Je Ne Se Pas" <thomas dot stuifzand at c dot dot dot >
> > > >Reply-To:
> > > >To:
> > > >Subject: [world-cruising] moving batteries to another spot
> > > >Date: Fri, 30 Jul 2004 21:59:14 -0000
> > > >
> > > >Hi All,
> > > >
> > > >We are having currently 6 x 8D as the house battery and we are
> >about
> > > >to upgrade to some serious batteries (840 pounds).
> > > >
> > > >The new batteries weight approx. 1600 pounds and will not fit
in
> >the
> > > >old spot.
> > > >
> > > >The current batteries are about midship and about 1 foot in
from
> > > >starboard (not the best place you would think).
> > > >
> > > >We have space just after the engine room, right on the center
of
> >the
> > > >boat. beam wise we would move only a few feets, but length
wise
> >we
> > > >would shift a lot of weight about 15 feet further aft.
> > > >
> > > >Now... we are talking about a 35 metric tons 60 foot boat
here,
> >so in
> > > >my opinion it should not make to much a difference, but I
would be
> > > >really interested in your opinion.
> > > >
> > > >Thank you, Tom
> > > >
> > > >
> > >
> > >
_________________________________________________________________
> > > Is your PC infected? Get a FREE online computer virus scan from
> >McAfeeŽ
> > > Security. http://clinic.mcafee.com/clinic/ibuy/campaign.asp?
> >cid=3963
> >
>
> _________________________________________________________________
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