2700-2800 Wot rpm(39)s-gctid392159

[Guest]

Ok, last post. I've replaced fuel filters and added K&n's. Adjusted cables etc. I got 2800 today at 18.2 kts with empty water but full holding tank. Stock size/pitch props with recent pressure wash and shiny props.

Question, if my WOT is 2800 given my load is it safe to run WOT or should I limit my rpm's to ?

I don't want to overload the motor and damage it.

T

[Guest]

When ours is real clean and fuel was a lot cheaper we got 3000 rpm at WOT and Cruised at 2600 rpm for about 16+ kts. So, no, I wouldn't consider cruising at WOT but maybe at 2400 rpms if fuel cost is not important and your in a hurry to get somewhere. Other than that I would cruise at about 1800 to 2000 rpm and get about 10 kts.

Darby

[smitty477]

"Ok, last post. I've replaced fuel filters and added K&n's. Adjusted cables etc. I got 2800 today at 18.2 kts with empty water but full holding tank. Stock size/pitch props with recent pressure wash and shiny props."

Assuming the tachs are accurate , the motors are in tune, and the boat is not overloaded it would be highly suggested to adjust the props to achieve 3,000 rpm's plus 3-5% at WOT when doing brief tests.

You would then feel safe at cruising up to 2,700 or so as a fast cruise.

Hope this helps

[Guest]

smitty477 wrote:
"Ok, last post. I've replaced fuel filters and added K&n's. Adjusted cables etc. I got 2800 today at 18.2 kts with empty water but full holding tank. Stock size/pitch props with recent pressure wash and shiny props."

Assuming the tachs are accurate , the motors are in tune, and the boat is not overloaded it would be highly suggested to adjust the props to achieve 3,000 rpm's plus 3-5% at WOT when doing brief tests.

You would then feel safe at cruising up to 2,700 or so as a fast cruise.

Hope this helps

Boat is definitely loaded. I have 2 extra couches on the bridge, an extra couch in the salon, 430lb dingy, 3 kayaks, spare anchor/rode, 300ft of chain on primary anchor, memory foam over stock pads, full canvas, etc. I have used a photo tach and they are nearly accurate (within 50 rpm). The only other issue I can think of is the bottom paint has 25 years of layers and is a long way from smooth. I may pull it next spring and have it re-finished and I hate to drop pitch at $500 and then find out I'm under pitched once the bottom gets re-done.

So the question is, what is a safe max cruising rpm for me right now?

[mmichellich]

twiersum wrote:
Boat is definitely loaded. I have 2 extra couches on the bridge, an extra couch in the salon, 430lb dingy, 3 kayaks, spare anchor/rode, 300ft of chain on primary anchor, memory foam over stock pads, full canvas, etc. I have used a photo tach and they are nearly accurate (within 50 rpm). The only other issue I can think of is the bottom paint has 25 years of layers and is a long way from smooth. I may pull it next spring and have it re-finished and I hate to drop pitch at $500 and then find out I'm under pitched once the bottom gets re-done.

So the question is, what is a safe max cruising rpm for me right now?

I would never run a diesel engine that is a bit overloaded to over 80% of max RPM reached ( I think you said 2700) for any length of time. That would be about 2200. Some would push that to 90% of max RPM reached (2400 or so), but I would not. If you modify props and attain 3000 RPM, you should be able to run at 2400 to 2700 depending on your desires.