Clicking / tapping coasting down noise

[Herman Melville]

At WOT my daughter managed to pull out the kill switch. At least I know it works...

Anyway this was interesting because although I put it into gear when it's on the hose as part of pre season check I am doing so with the engine on (loudly) but in this case the ignition was of course cut.

So the boat is now decelerating in forward gear.

The water is pushing against the prop.

The water pressure was enough to turn the prop and since it was in gear then it must have been turning the crankshaft.

It wade a ticking / clicking noise as the revs dropped off. like a very loud tappit rod for those of your who remember them.

I have never been able to hear this before.

Can anyone help me with what is happening?

Is this a normal noise? was the engine being driven somehow backwards? Was it back pressure against the reeds? was if gearbox? I really don't have any idea which is why I am posting.

I am worried that it signals a problem but the engine seems healthy, uses about the amount of oil, has good power revs freely, starts easily etc.....

Any comment much appreciated.

Cheers,

[chipko]

The noise you are hearing is probably being made by the ratchet mechanism of the outboard motor gear box. When you rapidly pull back the throttle, the engine speed drops in response. However, the boat speed decreases more slowly due to momentum, and for a while the pressure of the water on the propeller blades will turn the propeller shaft faster than the drive shaft is turning. This causes the ratchet mechanism of the dog clutch in the gear box to emit a click as each tooth of the ratchet slips over the drive shaft.
You should be able to duplicate the sound when the engine is not running by putting the throttle and shift into forward and turning the propeller blade by hand. You will hear a click as the ratchet mechanism works.

Hope that helps.

[Herman Melville]

cheers that sounds bang on very helpful