In "Shawn" writes:


Why would you want to stop the prop rotating?

First, to avoid the unnecessary wear in the bearings and sealings.

Secondly some gearboxes are properly lubricated only when they are
driven by the engine and hours and hours of propshaft rotating will
cause damage to them.

Third the resistance of the rotating prop is bigger than the resistance
of a feathered prop. This topic has been discussed here for ages, and no
unanimous agreement has been reached, because it depends on the pitch
and aspect ratio of the propeller and various other factors. The
discussion is mainly been around the fixed type propeller.

Fourth some props will make some noice while rotating "freely".

So here for starters, there might be more...

- Lauri Tarkkonen

(Lauri Tarkkonen) wrote:

In "Shawn" writes:


Why would you want to stop the prop rotating?

First, to avoid the unnecessary wear in the bearings and sealings.

Secondly some gearboxes are properly lubricated only when they are
driven by the engine and hours and hours of propshaft rotating will
cause damage to them.

Third the resistance of the rotating prop is bigger than the resistance
of a feathered prop. This topic has been discussed here for ages, and no
unanimous agreement has been reached, because it depends on the pitch
and aspect ratio of the propeller and various other factors. The
discussion is mainly been around the fixed type propeller.

Fourth some props will make some noice while rotating "freely".

With us, it was originally #3. We had/have a three blade prop and a
modified full keel.

And then after we'd sailed the boat some it became primarily #4. It
sounded like we were next to a freeway when under sail. It was awful
- almost more noise than the engine. We weren't at that point in a
position to sail more than about 6 hours at a time so #2 wasn't so
much of a concern.

It was one of the first major investments we made, and we have not
been sorry. We gain at least a half a knot under sail. We also found
when we went to install it that the shaft was scored, and we had to
replace that also.

So here for starters, there might be more...

- Lauri Tarkkonen

grandma Rosalie

Thanks for those tips and reminders! Right now I'm looking at Vari-Prop
fourblade followed by MaxProp, Luke and the rest in third place except I
tossed Autoprop from the list. Haven't factored in cost as of yet. The
differences in the prop are not so great but enough to try and pick the
closest one to my needs. One of the things we are doing is putting in a
reduction gear system on the shaft in order to make the power curve of the
engine match the possible boat speed of the hull more efficiently. Along
with this the fabricator added a metal collar with a notched index. With
engine in neutral and the prop and shaft spinning slowly it's easy to put a
locking lever into the index notch and saves messing about headfirst under
the cockpit sole with a set of vice grips.

M.




" writes:


Why would you want to stop the prop rotating?

First, to avoid the unnecessary wear in the bearings and sealings.

Secondly some gearboxes are properly lubricated only when they are
driven by the engine and hours and hours of propshaft rotating will
cause damage to them.

Third the resistance of the rotating prop is bigger than the resistance
of a feathered prop. This topic has been discussed here for ages, and no
unanimous agreement has been reached, because it depends on the pitch
and aspect ratio of the propeller and various other factors. The
discussion is mainly been around the fixed type propeller.

Fourth some props will make some noice while rotating "freely".

With us, it was originally #3. We had/have a three blade prop and a
modified full keel.

And then after we'd sailed the boat some it became primarily #4. It
sounded like we were next to a freeway when under sail. It was awful
- almost more noise than the engine. We weren't at that point in a
position to sail more than about 6 hours at a time so #2 wasn't so
much of a concern.

It was one of the first major investments we made, and we have not
been sorry. We gain at least a half a knot under sail. We also found
when we went to install it that the shaft was scored, and we had to
replace that also.

So here for starters, there might be more...

- Lauri Tarkkonen

grandma Rosalie

On 31 Jul 2004 10:24:40 GMT, (Lauri Tarkkonen)
wrote:

In "Shawn" writes:


Why would you want to stop the prop rotating?

First, to avoid the unnecessary wear in the bearings and sealings.

Secondly some gearboxes are properly lubricated only when they are
driven by the engine and hours and hours of propshaft rotating will
cause damage to them.

Third the resistance of the rotating prop is bigger than the resistance
of a feathered prop. This topic has been discussed here for ages, and no
unanimous agreement has been reached, because it depends on the pitch
and aspect ratio of the propeller and various other factors. The
discussion is mainly been around the fixed type propeller.

Fourth some props will make some noice while rotating "freely".

So here for starters, there might be more...

- Lauri Tarkkonen

What he said.

Brian W