[hpv-boats] Single person easily driven displacement hull / planing stabilizers

[Larry H. Smith]

On Jan 10, 2011, at 4:17 PM, Rick Willoughby wrote:
> I have found flat bottom stabilisers, 2m long and 100mm wide to be 
> about the best.  They achieve close to maximum stability as soon as 
> they hit the surface.

Hello Rick,

Though I mostly "lurk" in this forum these days, i always appreciate 
the contributions of you and others who have much more understanding of
the design use of math, computers, etc., than myself. Prop-stuff is way 
over my head. ;-)

Regarding your suggestion for stabilizer shape:  I am wondering whether 
facts related to "planing" conditions entered into your "flat bottom" 
decision, ...i.e. when visualizing the stabilizer as an independent 
hull, the speed/length ratio of the immersed portion of the stabilizer 
is very much greater than that of the main hull, and thus into commonly 
accepted "planing" territory. Also, as the main hull bow rises with 
speed, the stabilizer angle of attack may approach (or could be 
designed to approach) nearly ideal planing angles (4-5 degrees?)?

Of course choppy water changes the AofA constantly, but it seems likely 
that in calm water these observations would be pertinent.

Unless the hull is momentarily overly unstable, only the rearmost 
undersurface of the stabilizer should be in contact, so the aspect 
ratio of the contact area should also be in a favorable range for 
planing.

I'd value your thoughts,

PS - I remain in awe of your speed of implementation of ideas and 
fabrication of models!

Larry