Boat is a 1977 Flying Dutchman FD-12 by Tayana. 50' with a 12m waterline, hence the FD-12 name. Apparently them came with a 63 Hp Peugeot
engine that was reportedly underpowered, and mine has the 80.
I am thinking of replacing the old
Lehman 80 with a modern
engine as it is leaking again, and I am getting tired of the constant niggling problems and
parts availability
"Transmission" is hydraulic with the
pump mounted on the engine and the
motor remotely mounted on the shaft. Presumably this costs some
power compared to a conventional
gearbox. Both
motor and
pump are new.
This makes
installation easy as there is no alignment issue, but a plate would need to be made to mount the pump on the engine
Part of the re-power decision is whether to keep this drive system or go to a conventional
gear
I am in
Asia and leaning toward
Yanmar simply due to the availability of (expensive)
parts.
I suspect that I am over propped as the
Lehman will not pull full
RPM. Prop is adjustable
pitch and feathering so this can be changed
Questions:
How much
power is required? I would rather have too much, than not enough, to allow for some reserve or to push into a
current.
Yanmar offers 75, 80, and 110 HP
I understand the Yanmar likes to run at 80%. Is that 80%
RPM or 80% load?
How does that fit with over propping to achieve
hull speed at 80%?
Is over propping a bad idea, and should I prop it to pull
hull speed at 100% RPM
Keep the hydraulic drive to change to a conventional box?
I need to move from thinking to doing and would appreciate input form those in the know