Which way does my prop turn?

J

jammyhl1

New Member
Joined
17 Oct 2013
Messages
1
Visit site
It's a silly question but please bear with me. I have a Volvo Penta TAMD31A mated to a MS4A gearbox. Engineer has told me the engine rotates clockwise when viewed from the front. Does the gearbox change the direction of the prop rotation or does it turn same direction as the engine? If it does turn in the same direction then viewed from the rear my prop would be anti-clockwise and therefore Left Handed?

I'm unable to get onboard for a few weeks to verify in situ so wondered if anyone could help me resolve it here?
 
Sorry for the lame video, but skip to 1:33 and you'll see the shaft turning and stopping:

Counterclockwise as seen from the engine


Engine runs clockwise seen from the front according the users manual.
 
Last edited:
I have 2 TAMD41a engines and in fact one engine shaft runs RH and the other LH simply by virtue of the fact that the gear cables are reversed at the lever end. Depends on which gearbox you have but assuming it is the same ratio in both directions I guess it does not matter. It is usual with a single engine that the gearbox runs the same direction as the engine ( I think) but you won't be able to tell for sure without being on board. Sorry!
 
jammyhl1 said:
It's a silly question but please bear with me. I have a Volvo Penta TAMD31A mated to a MS4A gearbox. Engineer has told me the engine rotates clockwise when viewed from the front. Does the gearbox change the direction of the prop rotation or does it turn same direction as the engine? If it does turn in the same direction then viewed from the rear my prop would be anti-clockwise and therefore Left Handed?

I'm unable to get onboard for a few weeks to verify in situ so wondered if anyone could help me resolve it here?
Click to expand...

Would normally be RHand prop on single, when fitting a pair its the port that is swapped round for counter rotation
 
aquapower said:
Would normally be RHand prop on single, when fitting a pair its the port that is swapped round for counter rotation
Click to expand...
While I agree with your first sentence, I think it's a bit confusing to say that port engine is swapped round for LH rotation.
I mean, in the context of the OP question (engine vs. prop rotation), actually it's in the stbd engine that the gearbox changes the engine rotation.
It's in port engine that the shaft and engine rotation is the same, in spite of the fact that the other way round is considered "standard"...
 
On my previous boat, both props turned the same way (clockwise), Merc diesels on Alpha Gen 2 stern drives. Never caused me a problem, and in fact made things easier as I only needed 1 spare prop.
 
You're saying that as if it were normal... May I ask what boat are you talking about :confused:
I've seen many twin outdrive boats during the years, and I mean MANY, but the only one I saw with two r/h props (also with Merc Alpha, btw) was due to the fact that the owner had to replace the port drive after a grounding, and his Merc mechanic offered him a good deal on a r/h drive.
And incidentally, with the Merc Bravo the problem wouldn't have existed, because there aren't two different versions, it's just a matter of reversing the shifter cables.
 
rafiki_ said:
On my previous boat, both props turned the same way (clockwise), Merc diesels on Alpha Gen 2 stern drives. Never caused me a problem, and in fact made things easier as I only needed 1 spare prop.
Click to expand...

Sounds like a conversion can't have been factory supplied.
 
You must log in or register to reply here.

Share this page

Top