[PCW] Foils and roll motion

[Robert Deering]

John,

Could you define 'skinny' a bit more?  What L/B ratio do you feel is
optimal, or is there another 'measurement' that you are using?

Bob Deering
Juneau, Alaska


On 11/18/09 12:31 AM, "John Winter" <john at adventurebay.co.nz> wrote:

> Personal Observations on Foils and Skinny Hulls.

> 3.       But by just adding Foils on a slim hull cat will miss a large part
> of the hull improvement opportunity. Adding fullness above waterline in the
> bows helps reduce bow tunnel pounding and a foil will soften landings on
> fast boats, hence our new hull shape was developed after 6 months pounding
> across the Pacific in skinny hulls bruising the crew black and blue. We and
> the crew of boat-builders all decided future boats will have less tunnel
> entrance, 2 months in Tahiti repairing tunnel delamination and core shear
> gave us time to think this over. (Composite originally engineered by a
> leading composite design house might I add)
> 
> 4.       Further to the crews bruising was the snappy roll motion of skinny
> hulls in beam seas. A 16 day voyage from Marquesas to Galapagos with a naval
> architect, an engineer and 2 boat-builders aboard gave us time to reflect.
> Skinny hulls are for harbour crossings, not real time, confused ocean seas.
> Wide hulls we think have slower immersion rates so they don't sink down
> quickly to the tunnel buoyancy and stop dead, snapping back when the arched
> tunnel is reached. They immerse slower, finish their roll softer and some
> weight aloft also helps slow the end of the roll.