PROPS, RPMS, KTS with YANMAR on 28's

[halfmoon]

My mechanic says the Yanmar 300 and 315 are the same engine so I need to know what speed I may achieve at cruise rpms and WOT. There are a variety of props in use, I apologize for bringing this subject up again, BUT the impossible dream of finding the perfect prop is tempting me. So, what do you have, and what are the numbers? You will, no doubt, comment on boat loading. Thank you for your help.

[Pitou]

Finding that top end efficiency is always a power boater's quest, so when doing comparisons don't forget to take into account what's in between the engine and the prop and it's ratio. Without knowing the vessels gear ratios that are being compared leaves a very important piece of the equation out. Different gears have been produced by ZF over the years during very short periods and one 28 only a couple of years apart may very well have a different gear ratio resulting in different pitch and different cup.

When doing your comparisons make sure that you have the information for the entire drive line before taking anything to the bank. Best in your quest.

[RobS]

All Yanmar 28's "should" have a 2.00 gear.

Boat loading aside, the same boat empty can have considerable weight variations, even going back to the day she left the factory. This is especially true with our Albins that were basically hand built in a somewhat less than hi-tech facility. And as we have noted MANY times here, no two Albins are alike.

My medium cup 19x18 L4 only gave me 3850 light to moderately loaded last season. Speed was ~22kts.

I have had her re-pitched to 17.5 to break the 3900 mark. Will splash around the 1st of May...

And don't forget to have the tach accuracy verified.