Stopping the prop!!??

[Sneaky Pete]

Can't you just pop it in reverse before you stop the engine. Not sure if it still holds with a hydraulic gearbox but I think it does. I have done that on many boats in the past and it's no problem. I've never had a problem restarting in gear either.

I am with you here, I always put the gearbox in reverse after turning off engine. Shaft stops. Hydraulic box not sure about only way to find out is try it.

 

[sailorman]

I am with you here, I always put the gearbox in reverse after turning off engine. Shaft stops. Hydraulic box not sure about only way to find out is try it.

the prop will spin

 

[Scomber]

now thats a pleasant and concise response-my 3 blade knocks 1/2 kt off sailing speed every time i lock it in reverse

Well said Marsupial - simple minds need simple, catch-all answers, so the rather complex hydrodynamics are reduced to "Fixed props cause drag" - which all the Soton research proves to be a half-baked, half-correct answer.
Long-keelers with small prop orifices are the worst culprits (usually no room to fit a feathering or folding prop) and wear out gearboxes in short order, making an awful din when underway. If one has to have a fixed prop a two-blader aligning behind the deadwood is best fixed NOT rotating - saildrives and P-brackets folders of self-feathering (but the latter still need a fixed shaft to feather).

 

[macnorton]

I fitted a mountain bike disc brake to the shaft on a friends boat, the brake cable is attached to the engine stop pull so the brake is released when the engine is started.

 

[SimonD]

I fitted a mountain bike disc brake to the shaft on a friends boat, the brake cable is attached to the engine stop pull so the brake is released when the engine is started.

Oi, that was my idea a few posts ago! Did you fit the disc around the shaft? Got any pics?

 

[macnorton]

Oi, that was my idea a few posts ago! Did you fit the disc around the shaft? Got any pics?

Between the gearbox and propshaft flanges, made a bracket to fit the caliper to the gearbox case.
Will try to find the pics. (sorry didn't see your post)

 

[owen-cox]

I am with you here, I always put the gearbox in reverse after turning off engine. Shaft stops. Hydraulic box not sure about only way to find out is try it.

I think the secret is to stick it in reverse before stopping the engine then it does stop it as the hydraulics only operate the clutch.

 

[owen-cox]

You are incorrect

Actually you are incorrect. It depends on the type of gearbox as some use the hydraulic pressure to hold the gearbox in gear and some do not so it could be either way.

 

[nauticalnomad]

Got any references to back that statement up? A little googling seems to suggest the reverse is true.[/QUOTE

How much does the boat slow down when you put 2 x hands in the water either side whilst sailing?

 

[RichardS]

How much does the boat slow down when you put 2 x hands in the water either side whilst sailing?

Bit of an old thread ..... but as RAI's post was about the difference in drag between having a fixed prop and a freely-rotating prop, I'm not sure how you're going to simulate the freely-rotating prop scenario with your hands? Could be very painful

Richard