Prop rotation-gctid360080

[Guest]

Hey guys,

I have a 85 Contessa Sunbridge 280 sp, what prop rotation will be better?

[2850Bounty]

The 280, 285, 290, SP all offer a decent trim fin/torque tab arrangement for either rotation propeller.

This means that prop torque can be controlled fairly well.

The 27/275 does not offer this as well.

LH props place an unlift on the vertical shaft.... RH = download.

If running a LH, make sure that your transmission vertical shaft split ring keeper has not expanded any.

If time for a re-seal, this can be checked and/or replaced.

So.... you can pretty much run either hand prop with those caveats.

[Guest]

I find props that rotate in a circular motion tend to be the best...:kidding

We either need more information, or rephrase your question. When you push the throttle forward on a single engine, your prop shaft only spins one way.

If you have twins, one rotates to starboard, one rotates to port, so not sure what the question is...

Dutch

[2850Bounty]

Spinaxis wrote:
1.... I find props that rotate in a circular motion tend to be the best...:kidding

We either need more information, or rephrase your question.

2.... When you push the throttle forward on a single engine, your prop shaft only spins one way.

If you have twins, one rotates to starboard, one rotates to port, so not sure what the question is...

1... Fully agree! This is why Maytag and Kenmore had issues with their first stern drives! Back/forth/back/forth... it was awkward!

2... Dutch, for any Dog Clutch drive, that would be true, but not with the Volvo Penta.

The transmission is in the upper unit.... and the lower unit hypoid gears are bi-directional.

The design is such that it makes no difference as to which way you spin a single prop drive for fwd propulsion.

Also, there is no RH Reverse Rotation engine for these in a twin engine scenario.

[Guest]

New at this guys, sorry for the lack of onfo. Can't afford DP so I'm turning the old SP LH that I have right now. Just want to know if there will be any differance getting on plane or slow maneuvering with changing from LH to RH rotation?

The prop is 16x15.

[boatworkfl]

bfalzara wrote:
New at this guys, sorry for the lack of onfo. Can't afford DP so I'm turning the old SP LH that I have right now. Just want to know if there will be any differance getting on plane or slow maneuvering with changing from LH to RH rotation?

The prop is 16x15.

Whichever direction your propeller turns right now is the one to stick with, unless you want to spend a lot of money changing parts or running in reverse to go FWD.

[2850Bounty]

Actually, the cost to do this is ZERO!

The transmission main drive gear turns two "driven" gears.

Either driven gear can be FWD or REV.

The s/p lower unit hypoid gears are designed to deliver power during either rotation... although from a highly technical view point, the gear cut would appear to be best for a LH prop.

This is how Volvo does the Stbd RH rotation on twin engines boats.

Port drive transmission linkage rotates the eccentric piston CW (lower "driven" gear) for FWD gear engagement (as seen in this image).

Stbd drive transmission linkage rotates the eccentric piston CCW (upper "driven" gear) for FWD gear engagement.

The engine and the s/p lower unit don't know the difference.

Here's a 290 set up to use the lower driven gear for FWD.

If single prop, this one would be using a LH propeller.

If Duo Prop, there is no choice.... the lower "driven" gear must be used.

NOTE:

• the vertical linkage piece is always pulling down for FWD gear.... regardless of which hand prop is being used.
• the shift cable always "extends" at the drive for FWD gear.... again, regardless of which hand prop.

Shown here is a FWD engagement.

Shift cable is extended...... bell crank is swung towards AFT... linkage has been pulled down.... eccentric piston has been rotated CW.



Merc BI and BII drives, I believe, are LH RH capable also.

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