Jeff Morris wrote:
After starting this little brouhaha I think I might have to modify my claim that my cat
has no prop walk.

Since the props are widely spaced (15 feet with an 18 foot beam) if I ever tried to back
on one engine the boat would "spin out" immediately. Although the boat is functional with
one engine in forward, it is rather crippled for maneuvers in reverse.

Understandable. With that spacing, you'd HAVE to expect "donuts", on one
engine astern, prop walk, or no prop walk.

Therefore, anytime I would be running one engine in close quarters, I would be also be
running the other, and likely balancing so that it would back true, or adjusting to turn
as desired. The only way I could tell that I had no prop walk would be to carefully
measure the RPMs, and this is beyond my instrumentation.

A simple test, would be both engines astern, equally. Since they are
both "left hand", your boat should immediately start backing to stbd.
How quickly and at what "turn rate", would indicate the degree of prop walk.
I'm guessing here, but I'm betting you can steer your boat astern by
just increasing/decreasing throttle on one or the other of the engines?


Thus, the net affect is zero propwalk, but I have no way to determine whether the
individual engines are generating propwalk.

Another way would be back on port engine and get a sense of "turn rate",
then back on stbd and compare (backing on stbd, could/should produce a
slower turn rate)

BTW, the builder claimed this was a non-issue, but when they started building larger
sailing cats, and the powercat, they used counter-rotating props, because it was an option
with the larger transmissions.

Your transmission/reverse gear is only built to turn in one direction?
Can't be built to turn opposite?

Overall, I'm guessing that the spacing of your props, andG as mooron
says, the fact you have folding props of relatively little "bollard
pull" means that for most maneuvers you do, prop walk will be there, but
not of enough significance, when compared to the reaction of your boat
to the spacing and thrust of your props, so, as the builders claim, it
will generally be a non issue.

otn