[PUP] PPM - Stability Curves (was Let's design the perfect...)

[Mike Maurice]

>     These graphs of vanishing stability aren't generally available from the 
> major production manufacturers. At least I can't get them from Nordhavn.
> 
>     Do you have access to such things for popular boats, or know how they 
> can be calculated with the kind of data we routinely have available for 
> production trawlers? Are such calculations usually accurate, or does this 
> take tank testing (which nobody is going to do, except on a model).

These stability numbers are easy to calculate using a computer program. 
I have been using DelftShip. You have to create a table of offsets to 
input to the computer, but after that it will generate most of the 
numbers with little more effort.


I used this on a sailboat for which I had the drawings. The generated 
numbers that came from the computer generally matched what I expected 
after examining the designers notes.

The table of offsets is not as hard to infer from the actual built hull 
as you might expect. You can easily measure off some crude offsets with 
a tape measure. Input them to the program and then smooth the displayed 
lines to match what you see in reality.

As for the thickness of the windows. Big windows means thick ones to 
withstand impact. Frankly, I have real doubts about big windows being 
very realistic.

Mike

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Capt. Mike Maurice
Tigard Oregon(Near Portland)