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itsme1414 01-22-2013 02:57 PM

Bayliner Bucaneer Cruise Speed Under Power
 
I have a 275 bayliner bucaneer with volvo penta diesel that max revs is 2500 rpm. At cruise I run 1800 rpm and get 4.7 mph under power measured by GPS. Does this seem, slow? Wondering if changing props would really be worth it. Just had bottom done and new paint put on. Max hull speed is suppose to be 7.29 mph. Would a new prop be worth it and if so how much would I pick up speed wise at cruise?

kellysails 01-22-2013 05:10 PM

Re: Bayliner Bucaneer Cruise Speed Under Power
 
What is the Max RPM you can reach with Wide Open Throttle while under load?

What is the Max RPM you can reach with Wide Open Throttle while in neutral?

If both are the same you might be under propped which at that point I would check with the boat yard to validate.

chuck53 01-22-2013 05:55 PM

Re: Bayliner Bucaneer Cruise Speed Under Power
 
What is the mfg's rated WOT RPM? If more than 2500, you are over propped. Even if 2500 is the rated RPM, you should be able to run comfortably 2000 RPM's all day long.
So before doing anything, prop wise, find out the rated RPM for your engine.

Faster 01-22-2013 05:58 PM

Re: Bayliner Bucaneer Cruise Speed Under Power
 
Time to 'get nautical' and set your GPS for knots! ;)

If you can't achieve rated RPM it's likely you're 'overpropped' and repitching may get you back up the the max revs. It may not give you any more speed.

Using GPS for speed can be deceiving, esp if any current is a possibility. Around here if you time things wrong you could be doing hullspeed through the water and a GPS will show close to zero.

mad_machine 01-22-2013 07:05 PM

Re: Bayliner Bucaneer Cruise Speed Under Power
 
yes.. diesels can run close to Redline for hours on end without issue. I used to drive a truck for a living and running at Redline or even slightly above for 250,000 miles certainly did not hurt the engine of the truck I drove in the slightest

itsme1414 01-22-2013 09:06 PM

Re: Bayliner Bucaneer Cruise Speed Under Power
 
What I was wondering is would changing props increase my speed at 1800 RPM cruise speed from 4.7 mph to like 6 mph or is it even worth the money to increase or if I would notice any difference in 1800 rpm cruise speed?

chuck53 01-22-2013 10:04 PM

Re: Bayliner Bucaneer Cruise Speed Under Power
 
You need to match your prop to the engine. if the mfg has rated your engine to run 2500 RPM's then you have the right prop. So if 2500 is correct, you can easily cruise at 2000-2100 to get more speed and not damage the engine.
Yes, you can put on a larger prop that will give you more speed at 1800, but you will be overloading your engine and only have a WOT of 22-2300. Overloading an engine is NOT a good thing. if you wanted you could put an even larger prop on that will bring your WOT down to 1800, but then you would be running at WOT.
Again, the main question is, what is the mfg's rated WOT for your engine. Until you know the answer to that question, don't do a thing.

itsme1414 01-22-2013 10:22 PM

Re: Bayliner Bucaneer Cruise Speed Under Power
 
This is what I found in the manual. Max. engine speed: MD7A 43.4 rev/sec (2600 rpm).

chuck53 01-22-2013 10:50 PM

Re: Bayliner Bucaneer Cruise Speed Under Power
 
Assuming a nice clean bottom and running gear and that your motor is running at peak, you are slightly over propped but not enough to be concerned with or to make a change. Bump up your cruise RPM another 2-300 RPM's and you will be fine with a little more speed.

mad_machine 01-23-2013 09:10 AM

Re: Bayliner Bucaneer Cruise Speed Under Power
 
yes, this is not a gas engine. Diesels thrive on running at WOT fully loaded. It is what they are meant to do


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