I would like to have some advice for the best hp my C36Mk2.
Currently is using Universal Diesel 30hp Model 35. The fact is most of other boat if running engine they are faster then my boat can overtake me!
My GPS ground speed MAX is around 7.5knts in flat water at 3500rpm. Usually running on little wave @3000rpm around 5.6knots GPS ground speed.
Any advice are welcome
Cheers
Boat hull is 1773
located in Hong Kong since first hand in 1999
Yes using sail is faster top speed i do acheived around 5.8knots upwind at 40degree @ 20knots ture wind.
why i asking is as when no wind got to use the engine to go back to home port it some kind of slow as other boat around 32ft was faster then me.
Cheers
Jason
5.6 kt at 3000 RPM is a little slow. First, your tachometer is probably off and sounds like it may be registering higher than the engine is actually turning.
The two main things that might be holding you back would be a dirty or fouled bottom or a propeller which is not optimal for your boat. What kind of prop do you have and what is its size and pitch?
Gene Foraker
Sandusky Yacht Club
Sandusky, OH
1999 C36 #1786
Gypsy Wagon
Jason, as mentioned above, it may be that your tachometer is out of adjustment. Our C36IA Technical - Maintenance library has an article on how to do the calibration of the tach. You must be a paid-up Member (capital M) of C36IA to access this valuable library.
Other factors that can affect motoring speed include: wind and waves, condition of bottom (growth, barnacles, weed, etc), condition of prop (weed, barnacles, etc), whether or not the prop is correctly sized (your 1999 boat is most likely factory-original, and thus correctly sized), calibration of the knotmeter (that's the measurement standard and it must be calibrated properly to make any discussion productive), and weight of the boat (heavier is slower, but this is the least likely to very much affect a 19,000 lb boat).
GPS-derived speed is irrelevant for RPM/speed comparisons, except in absolute No Current conditions [and where in HK waters is there an absence of current???]. Only knotmeter speed counts in this analysis.
I cruise my 35hp Mk II at 2500 RPM and typically get a hair over 5 kts. If I were in a hurry I would own a power boat, or so I say to my wife. Although I can get more speed from the boat above 2500 RPM, it comes at the cost of greater fuel consumption and more noise. I have also discovered that after a lifetime in the aviation business 5 knots is now my "personal best", my "natural", speed for watching the world go by.
[Where in HK do you keep your boat? What marina? When my office was there back in the late '70s the HK Yacht Club was in Causeway Bay, I think. Still there?]
Larry Brandt
S/V High Flight #2109
Pacific Northwest, PDX-based
2002 C-36 mkII SR/FK M35B
We finally got out on the weekend after being stuck doing more last minute projects and then really crappy weather. At 2150 RPM the GPS is showing 6 knots, that was while motoring into about 6 knots of wind and minor waves, no current. The engine seems to like that speed, it just down and runs smoothly there so I am thinking for this particular boat that's the sweet spot. As always, YMMV.