CONTESSA 32 ASSOCIATION Homepage
Forum Home Forum Home > Technical Help > Engine, Gearbox, Stern Gear, etc
  New Posts New Posts RSS Feed: Gear Reduction Ratio
  FAQ FAQ  Forum Search   Calendar   Register Register  Login Login

Gear Reduction Ratio

 Post Reply Post Reply
Author
Message
Zoom 495 View Drop Down
CO32 Members
CO32 Members


Joined: 29 Sep 2014
Location: BC Canada
Online Status: Offline
Posts: 42
Post Options Post Options   Quote Zoom 495 Quote  Post ReplyReply Direct Link To This Post Topic: Gear Reduction Ratio
    Posted: 26 Nov 2015 at 5:00am
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
Back to Top
moongirl View Drop Down
CO32 Members
CO32 Members


Joined: 23 Aug 2009
Location: SOUTHSEA
Online Status: Offline
Posts: 232
Post Options Post Options   Quote moongirl Quote  Post ReplyReply Direct Link To This Post Posted: 29 Nov 2015 at 6:25pm
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 


COLIN
Back to Top
Brigitte View Drop Down
CO32 Members
CO32 Members


Joined: 11 Sep 2013
Online Status: Offline
Posts: 32
Post Options Post Options   Quote Brigitte Quote  Post ReplyReply Direct Link To This Post Posted: 30 Nov 2015 at 4:52pm
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 by Brigitte - 30 Nov 2015 at 4:55pm
Back to Top
 Post Reply Post Reply

Forum Jump Forum Permissions View Drop Down