I have a Hunter 31 (1984) with the Yanmar 2GMF engine and a 3 blade prop (not sure of size). What should be the max speed motoring
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7 Knots
1985 H-31 same engine as you with a 2 blade folding prop, at 3200 rpm I max out at just under 7 knots in calm water. (where is Stoney Point? Lake Ontario?)
1985 H-31 same engine as you with a 2 blade folding prop, at 3200 rpm I max out at just under 7 knots in calm water. (where is Stoney Point? Lake Ontario?)
About 6.5 knots with calm water and wind
I have a 1985 Hunter 31 with Yanmar 2GMF, standard two blade prop. I keep the RPM at 2800 or less.
I have a 1985 Hunter 31 with Yanmar 2GMF, standard two blade prop. I keep the RPM at 2800 or less.
2GM engine
The 2GM engine is rated at 3600 rpm Max rating. If you have the correct prop pitch/size you should be able to motor at approx 6.5 kts. This will be dependent on wind, current and sea conditions. Your bottom, prop and shaft should be relatively clean to get this speed too. You engine should be able to rev to approx. 3400-3600 at WOT (wide open throttle). You engine RPM's should be approx 70-80% of the max rating or 2500-3000 rpms while cruising.
The 2GM engine is rated at 3600 rpm Max rating. If you have the correct prop pitch/size you should be able to motor at approx 6.5 kts. This will be dependent on wind, current and sea conditions. Your bottom, prop and shaft should be relatively clean to get this speed too. You engine should be able to rev to approx. 3400-3600 at WOT (wide open throttle). You engine RPM's should be approx 70-80% of the max rating or 2500-3000 rpms while cruising.
My 29.5 with 2GM20F
Gives me around 5.5 @ 2400 rpm, 6knots at 2800/2900 rpm with relatively clean bottom and prop (3 blade), no wind or waves. I installed a temperature gauge for the freshwater cooliing circuit and it gets to about 170-175deg f at this point. Any higher rpms and she does get hotter but I can monitor it and keep it below 190. Neil
Gives me around 5.5 @ 2400 rpm, 6knots at 2800/2900 rpm with relatively clean bottom and prop (3 blade), no wind or waves. I installed a temperature gauge for the freshwater cooliing circuit and it gets to about 170-175deg f at this point. Any higher rpms and she does get hotter but I can monitor it and keep it below 190. Neil
Might Have a Problem
Thanks for all the information. I am only able to hit about 4.5 knots at about 3200 RPM. Could this be a transmission problem?
Thanks for all the information. I am only able to hit about 4.5 knots at about 3200 RPM. Could this be a transmission problem?
If......
...you are making rpm's then your problem is drag. When did you last clean the bottom? Have you inspected the prop and shaft for critters? Barnacle build up will dramatically affect the efficiency of the prop and hull. What kind of speed can you make under sail? If you're not making close to hull speed sailing you can bet your bottom is the problem. Hull speed for your boat is 6.87kts
...you are making rpm's then your problem is drag. When did you last clean the bottom? Have you inspected the prop and shaft for critters? Barnacle build up will dramatically affect the efficiency of the prop and hull. What kind of speed can you make under sail? If you're not making close to hull speed sailing you can bet your bottom is the problem. Hull speed for your boat is 6.87kts
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