LH to RH drive conversion

[hyperdog]

hi i opperate a twin prop 11 1/2 m passanger boat both engins opperate the drive to LH props could this be changed to a LH and RH prop system . i understand this would stop the boat crabbing

[gonzo]

What kind of drive or transmission do you have?

[CDK]

You got that right hyperdog.
All you need is a gearbox with the same fwd and reverse ratio, so you can put one in reverse while running forward. To achieve that, the bowden cable (or hydraulic cylinder if that is what you have) must be attached to the other side of the gear lever.

With a bit of luck, your gearboxes qualify. If not, you need the replace one of them. It is a good habit to cool that one because it has to dissipate more heat.

And you need a new prop for that side of course.

[hyperdog]

the trans are 1/1 ratio model 10/18/002 velvet drives

[CDK]

Beautiful, all you need to do is order a mirror image of the prop you have now.
If your boat is equipped with Teleflex or similar controls, you can simply transfer the gearbox cable to the other side of the lever.

[hyperdog]

ok CDK just one more i have been told that it is bad to run the gearbox in reverse as it will short the life of the box is that true or not ????????????

[hyperdog]

ps thanks for the other answer cheers

[CDK]

When gearbox makers point out which types have the same fwd/rev ratio so can be used in a ccw propulsion system it can't be that bad. There is an extra set of gears engaged, so there will be a bit more friction and wear.
I assume the main cause of gearbox damage is switching at high rpm or with improperly adjusted cables.

[hyperdog]

ok ????? but will it run at full power in reverse?????? cheers

[gonzo]

Velvet Drive transmissions should not be run backwards. It will destroy the transmission. You need a reverse turning engine and then the transmission will be fine.

[hyperdog]

thats what i thought cheers gonzo

[CDK]

Gonzo, maybe you know more about the product than the manufacturer.
Velvet says that with standard automotive input shaft rotation, the gearbox can drive RH or LH props with equal efficiency. The drive can NOT be used with a reverse turning engine because there will be no hydraulic pressure to operate the clutches.

http://www.velvetdrive.com/techinfo/...tybrochure.pdf
http://www.velvetdrive.com/techinfo/...ertyowners.pdf

[hyperdog]

ok so what your saying is that i can just change the cable on the morse control to select the reverse gear for forward propultion (ie with a RH prop) on my 1:1 ratio gear box and that will give me a LH prop and a RH prop with 2 engines that are both LH drive and it will run just the same on the RH box in reverse as it does on the LH box in forward ..... and wont DESTROY my transmission..................??????????????????? o and if the velvet drive wont run in full power in reverse can you sugest a box about the same size that will cheers

[Tahoerover]

Originally Posted by hyperdog

ok so what your saying is that i can just change the cable on the morse control to select the reverse gear for forward propultion (ie with a RH prop) on my 1:1 ratio gear box and that will give me a LH prop and a RH prop with 2 engines that are both LH drive and it will run just the same on the RH box in reverse as it does on the LH box in forward ..... and wont DESTROY my transmission..................??????????????????? o and if the velvet drive wont run in full power in reverse can you sugest a box about the same size that will cheers

You need a reverse rotation of one engine and adjust the oil pump in your velvet drive for the new direction. A V.D. uses a sun gear for reverse and it is not designed to consent use.

[CDK]

Please read the Velvet manual or brochure, the links are in post #12.

The manufacturer clearly states on page 1 than "both designs require a left hand engine and will turn a right or left propeller with equal efficiency".

The owner's manual also addresses another myth on page 6 by stating that freewheeling during trolling or sailing does not harm the transmission.