Yanmar 4jh4-TE 75hp vs Volvo Penta D2-75 (or D2-60)

[yachtodyssey]

Originally Posted by carlwk3c

W have a Yanmar and love it. Solid, reliable, and parts readily available.

We met a couple on our way down the ICW in 2017 tgat had been stranded for over 6 months trying to get Volvo parts. After 3 months, they got the wing parts, and at 6 months they were still editing.

That’s the worst, but not the only, horror story we’ve heard. (And Volvo parts are reportedly much more expensive (if you can ever get them.)

Thank you!

[LongRange]

Originally Posted by wingssail

Just out of curiosity, why is that ability to maintain full speed motoring upwind in a squall so valuable to you?

Originally Posted by LongRange

To misquote a line from a favourite film ("Kelly's Heroes"), because we like to think we can get out of trouble quicker than we got into it

As an addendum, close to us in the boatyard is an awesome 58 footer that looks the business. Carbon mast, kevlar-reinforced hull, massive fittings... very high quality custom-built boat.

Upon closer inspection its rudder is missing, replaced by a jury-rigged plywood panel. The tips of its external lead ballast are upturned and mangled, and its massive prop shaft has been bent to port by at least 10 degrees.

It turns out this thing was caught somewhere in a Peloponnese bay during the medicane of September 2018. 35 tons and only 130 horses. It lacked the power to extricate itself from the bay under those conditions, and it was rolled into the beach surf. Apparently the hole in the hull where the rudder used to reside caused it to fill with water, and virtually everything inside is destroyed. Fortunately nobody was injured.

The insurance company wrote it off, and now it's being "reimagined" at the yard.

At the same power-to-weight ratio as them, our 45 footer would have a 39 HP engine, which intuitively feels too low. Had the boat matched our power-to-weight ratio, their engine would have been about 250 HP, and they might perhaps have been able to power out of that exposed bay.

[FAST FRED]

"Still, nice to have the extra oomph on tap when conditions deteriorate."

The concept of motoring off a lee shore in F 9 is fine , but the prop has as much to do with heavy weather powering as the engine does.

Even with 100HP extra , if the prop cantturn it into propulsion , its no help.

Try working backwards with prop diameter and blade area to see what you can put in the water , before over sizing an engine.

The old rule of thumb is 2HP per ton (2240lbs displacement) for normal cruise 3HP if you prefer bigger wakes and fuel bills.

Hull speed is fine with wind power , but a K under is quieter and about 1/2 the fuel bill.

5 hp/ton only for miss rated auto engine conversions.

The Beta line is non electric injection and seems rated fairly.

The key to me is an engine that produces the required cruising HP very near the engines torque peak.

Torque peak is usually a very efficient , and quiet operating choice.


If you know the current engines fuel burn at cruise , a gallon an hour is about 15HP , so 2 GPH is about 30HP a more modern engine might do a bit better , but a match of GPH at cruise RPM is a good guide.