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Mpetri · 02-02-2021, 01:52

Good morning to all
I post the tread also here because I think it should be a typical multihulls problem...
I would like to mount a right hand propeller (Volvo folding propeller 3 blades) on a left hand sail drive (Volvo 130s) in one of the two engines of my catamaran.

Volvo don't give me any written permission, but I know people that did it without any problems during years... My trusted mechanic (Volvo) said to me nothing is wrong in doing that seeing all the tech documentation.

Is there anybody can help me in taking that decision?

Thanks a lot in advance!

**Pete7** · 02-02-2021, 02:47

There are some shaft Volvo gearboxes that can drive either way, our MS2 is like that. We only found out by comparing the Volvo Penta 2003 installations in different Moody models. Some like mine have a left hand shaft drive and others right hand, for no obvious reasons. Prop shaft is offset slightly to the same side to extract past the rudder, so that's not it.

You really need to find an exploded gearbox diagram for a stern drive to see what is going on. Something like the sales brochure attached which shows cut aways of the gearbox.

Pete

**hlev00** · 02-02-2021, 03:24

I believe that multihulls should have counter rotating props to reduce prop walk. So supporting a gearbox that can be adjusted for which ever side it is installed on would make sense.

Harry

**Tupaia** · 02-02-2021, 08:00

Quote:

Originally Posted by hlev00

I believe that multihulls should have counter rotating props to reduce prop walk. So supporting a gearbox that can be adjusted for which ever side it is installed on would make sense.

Harry

On a power cat yes.

On a sailing cat there is no benefit in having contra-rotating props in most cases you are likely only using one engine when cruising.

Having them both rotate the same way when maneuvering in harbour may give you a preferential direction of boat rotation. With engine so far apart this is negligible.

In fact many sail drive props are only made in one direction of rotation.

Most saildrives have the same gearing forward and reverse so prop rotation is just a matter of swapping the control cable to the other end of the lever.

Compass790 · 02-02-2021, 12:24

Quote:

Originally Posted by Mpetri

Good morning to all
I post the tread also here because I think it should be a typical multihulls problem...
I would like to mount a right hand propeller (Volvo folding propeller 3 blades) on a left hand sail drive (Volvo 130s) in one of the two engines of my catamaran.

Volvo don't give me any written permission, but I know people that did it without any problems during years... My trusted mechanic (Volvo) said to me nothing is wrong in doing that seeing all the tech documentation.

Is there anybody can help me in taking that decision?

Thanks a lot in advance!

I dont know if this helps but we have been using reverse as forward on our Yanmar shaft drive gearbox due to having an opposite hand prop for a few years with no problems.
I had the gearbox apart for inspection at engine rebuild time & could see no reason not to do that.
As previous poster said look at exploded view of gearbox.

adjo · 02-02-2021, 12:28

Yanmar sail drives can operate in both directions. I don't know about Volvos.

Paul Howard · 02-02-2021, 13:14

I had Volvo 2002 engines with saildrives on my former catamaran and had them set up with counter-rotatiing Maxprops, starboard engine right hand rotation and port engine left hand rotation. I had an original Volvo saildrive two bladed fixed saildrive propellor, left handed pitch, that I carried as a spare. One of the Maxprops got damaged, the one with right handed rotation, and I put the left handed prop on that right handed rotation saildrive. There was no problem with the operation of the saildrive, as the gear ratios for the Volvo saildrive is the same in forward and reverse and the installer makes the choice as to how to install the cables.
The worse and most confusing was getting used the change in the use of the shifting levers. With one engine the lever was forward for forward, the other shifter in reverse position for forward. It took a couple months before I got the prop repaired and was almost used to it by then. Of course I could have changed the cables around on the shifter mechanism, but did not.
I disagree with Tupaia, counter-rotating props on a catamaran is important in close quarter manoeuvring. Also, when running on one engine when in open water the autopilot did not like the slight angle of the boat running on one engine rotation (and the dragging non-powered hull).

Mpetri · 02-02-2021, 14:53

Thanks to all!
What I am thinking about, now, is which configuration I have to make:
1. left engine with left.hand props rotation & right engine with right-hand props rotation --> external props rotation
OR
2. left engine with right.hand props rotation & right engine with left-hand props rotation --> internal props rotation

The difference between the two configuration are quite important: that first one is better during maneuvering (docking situations where is really important to steer for example with strong wind against), the second a little better for long cruising distance with two motoring ongoing (this configuration is the one that airplane have when 2 props in the wing).
I think I will probably make the 1. configuration.

Shrew · 02-02-2021, 14:57

Counter rotating drives on twins allow you to use prop walk to your advantage when docking. Reversing STBD kicks stern to Port. Reversing Port kicks stern to STBD.

Docking with a single would be awkward. IMHO having either engine in reverse walking the stern in the same direction would also be awkward. But that is probably because I come from decades of powerboats where counter rotating is common on twins.

Squanderbucks · 03-02-2021, 04:46

Many transmissions do not care which way they turn and all you do is just switch the control cable hookup in your shifter/throttle control. Works that way with my ZF and previous 502’s. Check your operation and installation manual.

manitu · 03-02-2021, 05:00

The 130s gearbox is unidirectional.
Remember to set the gearbox in your new reverse direction when sailing.

http://bavariayacht.org/downloads/en...%207742984.pdf
.manitu

Mpetri · 03-02-2021, 07:50

Excuse me Manitu, I want be sure to understand well: so by your info I CANNOT put a right-hand propellers in the left-rotating 130s by simple inverse the cable of commands??