|Subject: [harryproa] Re: Schooner v. Unarig|
|From: "jjtctaylor" <email@example.com>|
|Date: 12/7/2006, 10:41 AM|
You will have to choose your fudge factors for sail force. It isn't
just load to capsize..... I am not an expert but a really long
discussion can be found at:
Whole books have been written on rig planned loads. Even without
stays..... forces are dynamic so a whole bunch of engineers and
experts cannot yet agree on how much engineered strength (loads)is
enough. The sea is dynamic, wind is dynamic and boat motion as
well. FEA may tell you what may fail first.....but not the
conditions that caused it. So have to make a bunch of
variables. Thus make your planned limit then add something for for
NO matter what... impractical to design for all possibilities, so if
designed to function adequately well it be lost under some extreme.
Choose your limit, you won't be right or wrong.
--- In harryproa@yahoogrou
> Ah, I take your point. So the relative force on the mast due to
> size is largely irrelevant.
> So we will gain strength due to the shorter masts, but weight will
> governed by breaking strength. Need to do some more research.
> Thanks for straightening me out.
> Best regards
> --- In harryproa@yahoogrou
> > ----- Original Message -----
> > From: Herb Desson
> > To: harryproa@yahoogrou
> > Sent: Friday, December 01, 2006 5:27 PM
> > Subject: [harryproa] Re: Schooner v. Unarig
> > I am not quite sure what to make of the smaller sail area, but
> > it is clear that in any given weather there will be less force
> > mast for the schooner than for the single mast of the sloop.
> > Agreed, but the design load is still that force required to
> capsize the boat, so they have to be as strong as the single
> The same applies to the hull reinforcing. Supporting each mast at
> end of the beam is very easy. However, if only one sail is doing
> work, the hull has to be strong enough to transmit this load to the
> other beam, so ends up the same as if the mast was in the middle.
> > I look forward to seing the results of your calculations. I
> > costs money, but would it be possible to include an analysis of
> > exactly the same sail shape to get comparability? I am not sure
> > comparable a jibless schooner is to a balestron sloop from a
> > point of view. My first thought is that it wouldn't make much
> > difference, but clearly my first thoughts are not very reliable
> > these matters.
> > You ain't kidding about the cost of FEA! I can't afford to get
> into sail shape anaysis. We engineer the mast based on the
> it sees. The ballestron rig and the schooner would be pretty close
> the same weight.
> > Best regards
> > Herb
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