Puget Sound Pounder
Join Date: Nov 2008
Location: Bainbridge Island, Port Madison, WA
Thanked 8 Times in 8 Posts
Rep Power: 8
Re: overpropped vs underpropped
Kelly- what is your engine manufacturers spec for WOT. Full governed rpm is the rpm at full throttle in neutral, the governor controls the maximum rpm to prevent damage to the engine. If you were able to reach the max governed speed under load you were either way underpropped, or you have a lot of hp. Sounds like by increasing pitch you actually put the engine under load which would make a difference in sound.
Yanmar 4JH5E naturally aspirated (non-turbo). Yes, we are hitting the governed rpm rate (3400 rpm). Prior to making the prop pitch change we easily hit the governed rate under load. So our yard, who does all the warranty work for Beneteau, agreed that increasing the pitch would be a worth while activity. The two degree increase really helped my speed at cruising rpm. My Max Prop actually allows 1 degree pitch changes, the yard actually thinks it could go another 1 degree, but I am happy where we are. The engine sounds happy, so I am happy. So under load WOT is 3250 from a max no-load of 3400, sounds good to me.
4JH5E is 54 hp and we have an SD50 saildrive. Beneteau Oceanis 45. 23,500 lbs.
Last edited by kellysails; 12-15-2012 at 09:53 PM.
Reason: added fyi