Shawn,

Boy, you gadda set don n' figur o' What cher doin.

A propellor will stay working until it aspirates (sucks air in from the
surface). This is not a real big problem for trolling motors and not
even a big issue to IC outboards until SHP gets up there (~50). Not to
mention that you are trying to mix three completely different animals.

Now,
Are you investigating 1-Wing in ground effect, 2-surface piercing
hydrfoil or 3-fully submerged foil with active control??

The motors of electric powered cars are not a lot of horsepower, but the
starting torque is real good and that almost does not matter to the
propellor. Electric machines tend to be "made out of heavy" and
batteries won't help you out there either.

I think you might think about this a little longer.

Matt Colie
An ex-engine professional, licensed marine engineer, naval architech and
builder of very strange things


Shawn Gibbs wrote:
In article , "D MacPherson"
writes:


The answer to that question depends on the application - type of propeller,
power loading, operating speeds. Can you tell us a little more?


I'm playing with the base design for a hydrofoiling semi-wing-in-surface-effect
craft; electric, solar-electric, hybrid-electric; semi-kayak-ish main hull with
proa-like outriggers. The motors (probably Minn Kota but haven't ruled out
using more efficient motors used in electric vehicle competitions) will be
located at the base of either V-type wave-piercing or T-type fully submerged
foils, so part of my current task (and the basis for my admitedly
vague/nebulous question) is to make sure that the props stay at a functional
depth as the foils rise. Current design allows me to vary the depths of the
foil-prop assemblies. I'll ask the question again after I've figured out how
light I can safely make the frame/hull, how many batteries I can pack and still
stay safely buoyant, which will finally lead me to foil, motor and prop
choices.

Warm Regards
Shawn