New Engine Choice

[Celestialsailor]

Originally Posted by Marinheiro

Interestingly the installer (a Yanmar agent) said the JH series started off as a reverse engineered version of the Perkins 4.107, getting rid of the usual english oil leaks and other niggling problems - anyone confirm this?

Sounds like boat dealer folklore to me. They look nothing the same..

[Cheechako]

Look at the power curves and get the HP you need at a reasonable rpm, unless you like sounding like a biplane!

[olgy]

The Kubota oil pans were too deep to fit my boat when I repowered. I went with a Yanmar and have been very happy with it. measure the engine area a lot before you buy.

[boden36]

We replaced our Volvo (Green Death) with a Yanmar and are very happy with the choice. Get a 3:1 reduction of you can. Regards, Richard.

[redcobra]

Wouldn't a 3:1 ratio require more rpm's for a given boat speed? The Nanni is rated at 3000rpm for rated HP and the torque curve is at max at 1800prm. Idles at 800 rpm. I thought 2:1 would be recommended.

Thanks to all for your advice. Keep it coming as the decision is looming.

Alan

ps: I intend to get a Martek or MaxProp feathering prop.

pps: A friend of mine said that which ever one I choose, the engine will probably last at least 15 years with no problems and after that I probably won't care as I am very much over 39 now

[CAELESTIS]

I repowered from a M60 Perkins to a 4JH4-TE 75hp Yanmar last year. I couldn't be happier.

You should consider the 54hp Yanmar. It will work with your ZF trans.

Yanmar is like the Chevy small block--reliable, and anyone in the world can get parts and work on it.

[Mark424]

Originally Posted by CAELESTIS

You should consider the 54hp Yanmar. It will work with your ZF trans.

I like the concept of Yanmar's inline flywheel generator. YANMAR Diesel Power - Optional Equipment KMG65E

If you've got ~4" of space, it'd be a nice addition to the 39 or 54hp engine.

Now all we need is common rail tech to come to smaller engines. More complexity, but also lots less noise.

[boden36]

Alan, with 3:1 you get to swing a slightly larger, slightly coarser prop which spins slower and is more efficient. You play with the prop pitch and size so that at full throttle with a clean hull and prop, the engine can just attain full designed revs. You do not have to rev higher for a given hull speed, in fact your revs for a given speed may be marginally less. Also less wear on prop shaft, seal etc and a little less vibration. Regards, Richard.

[Marinheiro]

Rather than choosing the engine first you should verify what prop you can swing, then look at available engine/reduction gear combinations. You may find with a larger reduction gear you can come down a step in engine size with some saving in $$'s. On my yacht the biggest prop you could fit is about 22" - the ideal theoretical hp was about 70, but then you could only utilise a 2:1 box (& I did not want a turbo motor Yanmar/green mc which were the only options space wise),instead I have 54 hp with a 2.62:1 reduction - would have like slightly larger but was going to cost alot more. Calders Cruising Handbook has a section on how you can make the calculations, or a prop shop can do same

[Joli]

We swapped out our W108 with another W108, I figured it would fit. Pretty sure it's a Mitsu block. The one we pulled had 6k and still ran well but I had time, a couple bucks and a Skill Saw. Think there's a pic here somewhere. Good luck and have fun, it's not a bad project.

[redcobra]

Well it seems the decision is that it is to be the 37.5hp Nanni/Kubota.
The Yanmar was only about $800 more, but my boatyard is not a Yanmar dealer (they do represent Nanni and Vetus) and the service and warranty aspect came into play. Idles at 850rpm and cruises at 2800rpm. Am looking into the reduction ratio. Included the 100A Alternator. Scheduled for end of April.
Now the next question is, which 3 blade feathering prop? MaxProp or Martec.

Thanks for all the advice

[Marinheiro]

red cobra, have a look at the forum "FOF vs Kiwi Prop", props you should consider in my view are:
kiwiprop (will be the cheapest)
varifold
FOF
Variprofile
both the Max & Martec (actually Australian Autostream) are old feathering designs and not very efficient compared with the above (Kiwi prop probably about the same efficiency)

[redcobra]

After a lot of conversation with the US Nanni Distributor who have been very helpful, it has been determined that I can't swing a prop big enough for a 3:1 reduction ratio. The recommendation is for a 2:1 reduction and a 17x11 3 bladed fixed prop or a 16x11 3 bladed feathering prop.

[xxuxx]

YANMAR.....................FOR PARTS AVAILABILITY AND SERVICEABILITY ON THE EAST COAST

[Opie91]

I repowered 5 years ago with a beta and love it. Great price and all parts are easily available.

One other thing to consider is the British Pound has been getting beat up pretty bad lately, the Beta comes from England, and thus they are willing to make better deals on them. (Have seen this within the last month)