Transmission Rules

[davidpm]

Did a lot of docking practice tonite. No wind.
Is it OK to be running at 1/2 throttle.
Drop throttle to idle
Move transmission from forward to reverse
all in a couple of seconds.
It doesn't sound bad but I'm not sure the shaft has time to stop turning?
Any rules on this?

I could just have someone watch the shaft but I didn't think of it at the time.

[sailboy21]

Your tranny should be fine shifting at idle repeatedly. The shaft & prop inertia even if it is still turning a few revs is very small in comparison to the engine torque. Most conventional clutch type transmission will let you know (i.e. really hard to shift) if your are doing something they don't like before you do any real damage.

[sailingdog]

Besides, a prop spinning in water tends to shed speed very, very rapidly, since the force required to keep a prop spinning is pretty significant. A prop spinning in water tends to slow far more than wheels on a car rolling on flat pavement.

[Valiente]

It's not a problem. Say "one-potato" when the engine is in idle if you are worried about it.

Shifting with a feathering prop, on the other hand, can produce some horrendous clunking, which is why I'm installing a thrust bearing and a coupler that will isolate the gears from the shaft via a universal joint.*

*this is overkill for a Catalina 30 unless you are using it as a tugboat.