Forums, Engine, Gearbox, Stern Gear, etc, Gear Reduction Ratio

Zoom 495 at 26/11/2015 05:00:40
Since the Beta 20 seems to be the engine of choice for the Contessa 32, what is the gear reduction that is most popular? And is there a corresponding ideal propeller as well?
Thanks,kris

moongirl at 29/11/2015 18:25:29
Hi Zoom. I believe the ‘standard’ ratio is 2:1 but you might want to check with Kit Rogers as he will know.
As far as props go a lot will depend on the type. The standard prop is 2 bladed, some people do fit a 3 blade and others use the DARGLOW feathering type. The cut-out in the rudder seems to vary slightly and will determine max diameter. A prop supplier will need HP, ratio, width of aperture from this data they will establish the pitch oh and of course they will need shaft diameter.
Hope this helps.
Regards

Brigitte at 30/11/2015 16:52:50
We’ve literally just replaced the prop on Brigitte. We inherited what I think is probably a pretty standard Norris 14" two blade prop which I’m sure was recommended for our Beta 20 engine.

We believe that a 14" prop is too big for our skeg aperture. It caused a lot of vibration and noise, and wore our shaft bearing into an oval hole which made the problem worse. We don’t race, (and never bothered to line the prop up with the skeg under sail), so decided we would risk a miniscule drop in performance (perhaps a couple of minutes on an 8 hour sail!) for a quieter life under engine. We fitted a Centaflex while we were at it.

Not wishing to take on the extra maintenance required for a Darglow, we’ve followed Keny’s lead and replaced it with a 3 blade, 12" Campbell Sailer from Canada, size recommended by them for the Beta 20. This might seem like sacrilege but we were amazed by how tiny it is next to our old prop. The weather has been so awful, we’ve yet to test it in open water, but it sounds great in the marina!

Edited: Brigitte on 2015-11-30 16:55:56