Left-Hand Propeller, Gearbox Recommendations ?

[Ara H28]

Hi, I'm re-powering my sailboat which has an left hand propellor that is offset on the port side of the keel, can anyone recommend a gearbox which is suitable for a 20-30hp engine. my shaft has a 8deg down angle.
I'm considering the following gearboxes any feed back would be very helpful.
TMC 60A (I'm not sure if this one can run both ways)
TMC 60E
PRM 150
ZF 10 M
Thanks

[NCboatrx]

The TMC60 is the only gear that you have listed that will handle a left hand or a right hand propeller.
This is only with the following ratios; 2:1 and 2.5:1.
When using this transmission with a LH propeller, you must fit the TMC oil cooler.
The other transmissions that you have listed (including the TMC60A) are all built for use with a RH propeller.
Any engine should be able to accept 8 degree stern down angle as a constant.
Stanley

[Ara H28]

Originally Posted by NCboatrx

The TMC60 is the only gear that you have listed that will handle a left hand or a right hand propeller.
This is only with the following ratios; 2:1 and 2.5:1.
When using this transmission with a LH propeller, you must fit the TMC oil cooler.
The other transmissions that you have listed (including the TMC60A) are all built for use with a RH propeller.
Any engine should be able to accept 8 degree stern down angle as a constant.
Stanley

Thank you for the information, The Vetus 27hp 3 cylinder engine is supplied with the ZF 10 M gearbox the shop said that they have checked and the gearbox can run either way continuously. it has 2.05:1 / 2.72:1 ratios which would mean using a 2.72 ratio as the ahead gear?
Please explain if you believe that this is not the case.
Thanks,

[GordMay]

Ratings apply to right hand turning engines ...
➥ http://www.tadiesels.com/transmissio...es/ZF_10_M.pdf

[NCboatrx]

The A position is forward. This ratio is 2.72:1
The B position is reverse. This ratio is 2.15:1
ZF publish full information in their literature and the shop that is advising you has not taken into account the differant shock factor that must be applied to get reliable service.

ZF 10
Position A is normally ahead.
These are the maximum ratings:
R: 2.045 38 hp @ 3000 3 cyl shock factor adjustment 38hp/1.15 = 33 hp
R: 2.722 27 hp @ 3000 3 cyl shock factor adjustment 27hp/1.15 = 23.5 hp

The intermediate gear will not survive constant power transfer. When used in the B position, the intermediate gear will be used and the bearing that this rides on will not work for long.

[jenny2]

Originally Posted by Ara H28

Thank you for the information, The Vetus 27hp 3 cylinder engine is supplied with the ZF 10 M gearbox the shop said that they have checked and the gearbox can run either way continuously. it has 2.05:1 / 2.72:1 ratios which would mean using a 2.72 ratio as the ahead gear?
Please explain if you believe that this is not the case.
Thanks,

ZF is one of few gears that you can run either way.

[NCboatrx]

Jenny 2. I suggest that you click on the attachment that GordMay supplied in his post. Read the attachment, this is the ZF publication on the ZF10M transmission, at the bottom of page 2 of the pdf you will see what ZF say about forward and reverse. Nowhere does it say that these positions are reversible. They go to pains to say that position A is for forward which will call for a right hand propeller. pos B is for reverse.