Old as Dirt!
Join Date: Nov 2008
Location: Tampa Bay Area
Thanked 142 Times in 135 Posts
Rep Power: 8
Re: How Hard To Push My Perkins
This may be a dumb question, but that has never stopped me before.
I have a 1994 vintage Perkins "Perama" 29 HP inboard diesel, with about 1300 hours on it, in a Catalina 320. I think the engine was fairly well maintained by the former owner, and I have tried to be good about changing oil, filters, etc.
The question is, how many RPMs would you push this engine at cruise or for short periods when trying to clear other traffic, etc.? I usually cruise between 2000 and 2500 RPM, but wonder if I am being too cautious. I have a service manual for the engine, but it doesn't address this question. Any advice?
While I am not familiar with your particular engine, I am with Perkins in general and of those I have been acquainted with, Perkins rates their horsepower based upon a maximum RPM which can be maintained for a short period, a few minutes, but a maximum continuous service RPM that is typically in the range of 75% of rated horsepower RPM.
For example, our 4-108 is rated at 50hp at 4,000 RPM but that rate can only be maintained for a few minutes. Our maximum continuous service RPM is 3000 which, on our yacht with our prop gives us about 7.5 knots is moderate seas. We typically run the yacht at about 2500 RPM which gives us a good trade-off between speed and fuel consumption.
"It is not so much for its beauty that the sea makes a claim upon men's hearts, as for that subtle something, that quality of air, that emanation from the waves, that so wonderfully renews a weary spirit."