Prop rotation

[Adrian]

We have recently recon the gear box and have lost power in one engine, we think that we may not have the correct prop rotation. Should the props be set up as counter rotation? I.e starboard clockwise and port anti clockwise or both the same? Love to have your thoughts....

[mmwjr]

First I am assuming you have inboards and not I/Os and that you only recon 1 gear box, correct? Counter rotation helps a boat track staighter at slow speeds but doesn't affect power, therefore I don't think this is the issue.

What do you mean by lost power? lower RPMs, requires higher RPMs to track straight, ...

My first assumption is a recon gone bad, loosing power through the gear box

[pascavone]

all standard engine are LEFT rotation... counter clockwise.

I/O's and inboards.

A RIGHT rotation is a clockwise rotation.

The right and left is always viewed when facing the flywheel.

The Engine number will have an L or R in the block number.

[shrew]

Yes, MOST twins are configured to counter rotate. PROP rotation is as follows:

Starboard = Clockwise
Port = CounterClockwise

http://website.lineone.net/~alanann/propturn.htm

whether that is a result of the engine rotation or the transmission, I am not sure. I though this was handled in the transmission. In teh case of Outdrives, I thought that was handled in the drive. Hopefully someone with more knowledge will pipe-in to clarify.

[Huddo007]

Originally Posted by Adrian

We have recently recon the gear box and have lost power in one engine, we think that we may not have the correct prop rotation. Should the props be set up as counter rotation? I.e starboard clockwise and port anti clockwise or both the same? Love to have your thoughts....

Adrian
Both props spin in different directions, see attached photo of mine and see if your blade pitch is same direction

[Adrian]

Hi mike, yes they are inboard running through a v drive. We have lost power in the port engine, when throttle is pushed up full we can just reach 4000 rpm. The starboard engine we push the throttle we get about 4800rpms. any thoughts?

[Adrian]

hi mate, I hope that you received my private email last week?
Thanks for the pictures I will have a look when I am next under the boat. I went out on the weekend and caught some squid for dinner, and had a few beeers while we were out, I look forward to catching up with you and learning more about our boats. cheers

[Adrian]

thanks Shrew

[Adrian]

thanks Pascavone

[mmwjr]

Adrian,
I am assuming that both engines ran Ok prior to the gear box rebuild, correct. Was this an over the winter rebuild? Were the props removed? i.e are you sure the props are OK, did you get them reworked,... A bad or incorrect prop on the port engine may keep the rpms down. I don't know of any conditions how the v drive would result in a loss of rpms.

[pascavone]

V-drive and outdrive only have one gear forward and one reverse.

If you got 4,000 RPM out of it and it did not fly apart, I think your drive is fine.