About the Drivetrain

This has to be the most critical item when docking and undocking the boat. Sailing up to the dock was fun in a small boat, sailing to the mooring was routine on my 40 foot boat, and doing either in this boat is simply silly. So, I need the engine to work perfectly. It is, more than ever, a critical system. Because of this, I reconditioned the prop, changed the cutlass bearing, replaced the bellows and rotor on the PYI dripless shaft seal in 2009. It all works marvelously, though the engine is showin some age at 3900 hours, it is in excellent shape, having been run a lot.

  • Yanmar 4JH2-HTE turbo diesel (I would prefer no turbo)
  • 35mm shaft
  • V drive transmission, the engine flywheel is towards the bow
  • PYI Dripless shaft seal
  • Three blade, 19inch PYI propeller
  • Attention metric boat owners: France-Helices carries a product line of cutlass bearings in metric sizes, so don't let your yard talk you into replacing, machining, or other expensive proposed work to retrofit a $70 euro cutlass bearing made in Italy.I have a pic of the bearing in the slide show as well as its label and this is confirmed to fit a Centurion 49

  • With the engine at 2400 RPM I estimate a fuel consumption of 1.75 to 2 gallons per hour at a speed of 6.5 knots to 7 knots. At 2000 rpm, depending on bottom growth, I estimate 1.5 to 1.7 gph at 5.5 to 6 knots. The boat reaches 8.5 kn under full throttle conditions, only temporarily tested.

    According to David Gerr, (the Propeller Handbook author) the propeller thrust shoudl approximate 2200 lbs force at full throttle.and a static bollard pull of approximately 1500 pounds of force. And, I think this drive capability allows me to keep forward motion in over 60 knots of wind with small chop. Above that, the wind force may exceed the engine thrust.