re power 1968 38 Hatteras with 440 HP yanmars

[silverback]

I have the opportunity to repower my 1968 38 ft Hatteras Convertible with 440 HP Yanmars.
Anybody go down this road before?

[Freeebird]

[Boatsb]

Not personally but they are nice engines. Are they new or did you get some rto's.

My guess is like the 41 and 42 repowers you'll want down angle transmission and may need to increase shaft size. 1.75 may work i c not 2 means new struts.lo

[saltshaker]

Not personally but they are nice engines. Are they new or did you get some rto's.

My guess is like the 41 and 42 repowers you'll want down angle transmission and may need to increase shaft size. 1.75 may work i c not 2 means new struts.lo

Aren't those high RPM engines? If so the 1.75" shafts should be fine depending on what gear he uses. Should be an interesting project. Don't see many repowers of the 38C I.

[q240z]

Oooo...sounds fun.
The only thing I've heard about Yanmars (aside from that they're great) is that they don't tolerate overloading at all. Make sure they can run all the way up to rated WOT when fully loaded.
And post pix!
Cheers,
Q

[REBrueckner]

A possible alternative is high strength Aquamet shafting instead of the standard.

[Boatsb]

A possible alternative is high strength Aquamet shafting instead of the standard.

The 38 has 1.5 shafts standard. Converting to 1.75 is possible with thin wall cutlass bearings and machining or changing out the shaft log. I think 1.5 will be far too small for 440 hp.

[saltshaker]

A possible alternative is high strength Aquamet shafting instead of the standard.

That's only available for 2 1/2" or larger shafting.

[saltshaker]

The 38 has 1.5 shafts standard. Converting to 1.75 is possible with thin wall cutlass bearings and machining or changing out the shaft log. I think 1.5 will be far too small for 440 hp.

I'd think that would be pushing it too far. What RPM does those engines max out at? I remember many of the Yanmars turning in the 3200-3400 range. Might be able to make it work with shallow gears if that's the case. Wouldn't make me too comfortable doing it that way but others have done that with many 36C repowers.

[silverback]

Thanks all for the REPLYS, WHAT I FOUND OUT TODAY IS, GEAR NEEDS TO GO FROM 1.4 WHICH IS WHAT THE ZF GEAR IS NOW TO 2.137, WHICH IS WHAT ZF CAN DO WITH SAME GEAR.
Shaft will go to 1.75 assuming struts are thick enough, will find out soon enough. if have to replace struts, project off. have to lift cockpit, pull tanks, not worth it for these engines; they have 3300 hours on them, are in great shape, new heads 500 hours ago, but I just do not fell it is worth that much effort for those engines. Am I wrong?