GL: Denser Water Wes: Roll Causes Yaw?

[Ralph Yost (home)]

Joe
Of course you are correct. The subject of what creates boat motion is very 
complex, and I hope I didnt appear to describe it fully with my short 
synopsis.
We were discussing boat characteristics and I wanted to point out the most 
commonly known and obvious.
R.

----- Original Message ----- 
From: "joe" <joseph.pica at gmail.com>
To: "'Ralph Yost (home)'" <Ralph at AlphaCompServices.com>; "'KevinR'" 
<kfredden at verizon.net>; "'Bill Donovan'" <trailersource at mindspring.com>
Cc: "'Great-Loop List'" <great-loop at lists.samurai.com>
Sent: Friday, February 20, 2009 6:30 PM
Subject: Re: GL: Denser Water Wes: Roll Causes Yaw?


> Ralph,
> I am not a naval architect but by experience know that this issue is more
> complicated than that.  The use of "gentle and snap" is a little 
> misleading
> with regard to hard chined heavy displacement vessels with very low 
> centers
> of gravity and great residual buoyancy.  Obviously, roll is also a 
> function
> of wave size, period, steepness and direction of travel. The roll
> sympathetic frequency of the hull has a huge impact as to the degree that 
> it
> rolls and to what extent in small versus larger waves at differing 
> periods.
> I agree that a deep keel sail boat with the leverage of a sail array has a
> great stabilizing effect...under load.  The sail has little if any effect 
> at
> anchor or under way in no or a foul wind.  In those conditions you at the
> mercy of the "roll monster" .  Hence the reason for all the various anti
> roll devices from active to passive on round hull trawlers(sail less 
> boats)
> and at anchor mono-hull sail boats.  Non stabilized round bottom hulls can
> pendulant in a beam sea in a very frightening and uncomfortable fashion.
> Again not a naval architect but have experienced all of the above and
> greatly prefer (find most comfortable) the hard chined (flat bottom) heavy
> displacement trawler design.
>
> Joe
> "Carolyn Ann" N37