jfm
Well-Known Member
Fine, OK!
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Prop direction
- Thread starter Dave_Knowles
- Start date
Alistairr
Well-Known Member
So how do the props on my bravo 3 counter rotate?
Are there 2 shafts??
Yours ever more confused.
Alistair..
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Petrol Rules..
Are there 2 shafts??
Yours ever more confused.
Alistair..
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BarryH
Well-Known Member
Re: Extract from Volvo manual
The following is from the official Volvo Workshop manual. Not the DIY manuals sold
in the swindlries. I was given the manual by a mate who worked for volvo.
Change of propeller rotation
The gear arrangement in the upper gear housing is so designed that no modifications are necessary in order to change propeller rotation. Only the linkage needs to be altered and this operation is a simple task.
With a standard left-hand rotating propeller the lower gear operates the forwardgear. In this case the shift rod is connected as shown in dia 4.
it then has a line drawing of the sterndrive
With a right hand rotating propeller the upper gear becomes the forward gear. Simply disconnect and move the shift rod to the opposite end of the eccentric piston arm as indicated.
Connect the rod to the opposite hole in the yoke. Do not rotate the rod while making this connection. The bend in the rod must face the same directiondirection for both installations.
If any adjustments are necessary, refer to Retaining Pawl adjustment.
So as you can see the the change in direction is carried out in the upper gear housing and not in the lower unit where the propshaft is. The thrust on the prop will alway be forward.The bearings in the lower unit are tapered roller. theres no "gears" in there.The only gears are bevel cut eliptical. So as long as the thing has been shimmed properly and the gear mesh is correct there'll be no issues regarding wear.
edited because of fat finger syndrome
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<P ID="edit"><FONT SIZE=-1>Edited by BarryH on 02/10/2003 11:15 (server time).</FONT></P>
The following is from the official Volvo Workshop manual. Not the DIY manuals sold
in the swindlries. I was given the manual by a mate who worked for volvo.
Change of propeller rotation
The gear arrangement in the upper gear housing is so designed that no modifications are necessary in order to change propeller rotation. Only the linkage needs to be altered and this operation is a simple task.
With a standard left-hand rotating propeller the lower gear operates the forwardgear. In this case the shift rod is connected as shown in dia 4.
it then has a line drawing of the sterndrive
With a right hand rotating propeller the upper gear becomes the forward gear. Simply disconnect and move the shift rod to the opposite end of the eccentric piston arm as indicated.
Connect the rod to the opposite hole in the yoke. Do not rotate the rod while making this connection. The bend in the rod must face the same directiondirection for both installations.
If any adjustments are necessary, refer to Retaining Pawl adjustment.
So as you can see the the change in direction is carried out in the upper gear housing and not in the lower unit where the propshaft is. The thrust on the prop will alway be forward.The bearings in the lower unit are tapered roller. theres no "gears" in there.The only gears are bevel cut eliptical. So as long as the thing has been shimmed properly and the gear mesh is correct there'll be no issues regarding wear.
edited because of fat finger syndrome
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BarryH
Well-Known Member
Yes there is 2 shafts. The forward prop shaft is actually tubular and the rearward propshaft is solid.
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Alistairr
Well-Known Member
So does that not make the outer shaft, quite weak?
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Petrol Rules..
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BarryH
Well-Known Member
Why, there sould be no lateral movement in it.If there is your bearing are shot. Its made of stainless anyway. Depends how you mean weak. It won't resist crushing like a solid one. I wouldn't worry about it. Mercruiser probably spent millions on R&D.
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Alistairr
Well-Known Member
Thanks Barry,
I was just curious..
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Petrol Rules..
I was just curious..
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andyball
Well-Known Member
why ?
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Chris_d
Well-Known Member
Dave, I had the same dilema some years ago now, my boat was heeling over to starboard excessively when planing and i was advised that this was because of the LH prop fitted. My boat had only been used on the river before I had it and had been built with the wrong prop.
A LH prop combined with a LH rotating engine were corkscrewing the boat over to starboard, fitting a RH prop canceled out the flywheel effect of the engine and made the boat run almost level. On my sterndrive the direction is reversable by swapping the gear cable over on the lever, but on some older Volvo and merc's this isn't possible because the gearing is different.
The RH prop certainly made a big difference on my boat and it handles much better, but only at planing speeds of 17knts+. Paddle wheel effect on sterndrives is not worth worrying about as you turn the drive to tuck the stern in anyway, but is useful on a shaftdrive boat to stop or move the stern in.
So unless your boat can go at more than 15knts forget the LH prop, but technicaly it should have a RH.
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A LH prop combined with a LH rotating engine were corkscrewing the boat over to starboard, fitting a RH prop canceled out the flywheel effect of the engine and made the boat run almost level. On my sterndrive the direction is reversable by swapping the gear cable over on the lever, but on some older Volvo and merc's this isn't possible because the gearing is different.
The RH prop certainly made a big difference on my boat and it handles much better, but only at planing speeds of 17knts+. Paddle wheel effect on sterndrives is not worth worrying about as you turn the drive to tuck the stern in anyway, but is useful on a shaftdrive boat to stop or move the stern in.
So unless your boat can go at more than 15knts forget the LH prop, but technicaly it should have a RH.
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