RPM Problem

[Bill Andrews]

380 Aft Cabin with twin Mercruisers has lost significant RPm since Feb when pulled, cleaned, bottom painted, props and motor tuned. Diver carefully cleaned hull and props but still 600 RPM lost! Both engines indicate same loss of RPM. Non ethanol fule purchased at home marina where good volume of fuel sold. All suggestions welcomed.

 

[Kevin Smith]

PRM Loss

Assuming this is at wide open throttles with a normal load on board, it is a lot of rpm loss? You might want to Murphy Prop shop about your prop size and results you are getting.

The most qualified persons in VA that may be able to help are the folks at Murphy's Propeller in Norfolk VA. Here is the link.

http://www.murphyspropellers.com

You also might want to talk to the Sea Ray dealer in Prince William VA. They are one of the largest in North America and maybe the world. They sell a lot of larger boats and maybe they can offer you some assistance. Here is the link.

http://www.pwmarina.com

Kevin Smith
Richmond VA

 

[MarkD]

The props being "tuned" could be the key here. What do you mean when you say tuned? Cupped? If so, this might account for some rpm loss. Can you also elaborate on how much rpm?