Just curious... What kind of rpms should I be pushing my YSE12 (single cylinder Yanmar Diesel)? I'm under the impression it should be around 2200 rpm...is this assumption correct? Thanks, Gary
I have the 2GM 15 2 cylinder, and I usually cruise at 2500RPM, with short bursts of 2900RPM. It does not seem to go beyond 3100 no matter what. I find that 2200RPM will not bring the boat close to hull speed (I have a 81' H30). I don't know if you can compare the two, but that is what I am running.
On H28.5 I have 2GMF 13hp and it it best at 2450rpm. I can go higher bit I suspect anything over 28-29 hundred is just boiling water. It varies slighly on the 2450 if the wind is with me, then I find I can notch it up to 2700-2800 w/o boiling water. In the thick manual for the "gmf"s there's a graph of the power out at various rpm. See if Mac Boring can fax it to you for your model. My book only has 1GM, 2
Thank you both for your input. I'm a little frustrated by the small amount of headway I make while under power. It'll barely get me out of my channel on a calm day. I have a service manual that should be arriving any day now, so I'm hoping some of my questions will be answered in there. Is it true that I can hook a tachometer up to an alternator? Does it take a specific kind of tachometer...or can I just buy one at West Marine? I don't have a way to test my rpms, but I'm 99.9% sure it's not even hitting 2000rpm. Again, thanks for your help and input! Gary
I put a 3 bladed Max prop on my '75 30 Hunter and need to verify if the suggested pitch is right. Torrenson Marine suggests getting the tach reading off the flywheel teeth or the alternator. I would prefer the flywheel, but unless I am lucky most YSE's do not have provision on the bell housing for a tach. I may have a diesel mechanic drill and tap a hole for the tach sensor. Bill S/V Gumption
Not sure of your theoretical limit of RPM for your engine, but 2200 may be a reasonable cruising RPM(75% of max.). I have a Volvo 10 hp and thats my cruising RPM. You did not say if you have a 2 or 3 blade prop and if you think the diameter and pitch are correct for this engine and boat. A prop that is too small will not put enough load on the engine that would allow it to give the rated hp at its maximum rpm. Too big a prop wont allow the engine to reach its maximum rpm and therefore its maximum power capability. Also a 3 blade prop will give more punch in a headwind than a 2 blade prop. Don
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