[PUP] Let's design the perfect passagemaker - Lets start ....

[Alan]

o;? o;? o;? o;?
Hey Mike -- right you are.  You made me go and search for Kasten's
Hydrostatic Report and check the large angle stability analysis and the
stability curve.

My boat has no region of negative stability.  In other words, it is fully
self-righting.

As you noted, the calculations ignore down flooding issues, so we'll keep
the doors closed in heavy weather!

Alan

-------Original Message-------

From: Mike Maurice
Date: 10/31/2008 3:27:33 PM
To: Passagemaking Under Power List
Subject: Re: [PUP] Let's design the perfect passagemaker - Lets start ....

> .  The boat I am building has a
> positive righting moment (think that is what it is called).  If knocked
over
> by "a big one" it will right itself.

Alan,
All boats have positive righting moment. If they did not they they would
immediately turn turn turtle.

The issue is how much righting moment to resist turning turtle, AND, At what
point does the righting moment vanish, also known as the point of vanishing
stability. The graph of this is a curve and is known as the Curve of
vanishing stability.

There are rough rules of thumb for the desirable number of degrees rolling
before this point is reached. A bluewater boat, sail or otherwise should
have at least 120 degrees and 140 is better.