[PUP] Krogen 55 Expedition vs Dashew FPB64

[Ken Williams]

Bob E said: "...I would take the Krogen over the Nordy simply because it has
twins..."

As a Nordhavn owner, who has twin engines, it's tough to understand the
above comment. My boat is an N68, but I believe that several N57s were made
with twin engine configuration. I've heard the N55 is available with twin
engines. I don't know about other models.

Prior to purchasing, I convinced myself that the fuel consumption running
single or twins was roughly the same. There is some lost efficiency because
of the extra friction of the dual props, but there is also some increased
efficiency from running the engines at lower rpms. Presently all N68s are
twins. I'm sure there'll be a single engine N68 within a year or two, and it
will be interesting to compare fuel stats.

Our prior boat was a single engine N62. I once lost the main engine crossing
the Bay of Lyon and had to run for 24 hours on the wing engine at 3.5 knots.
It was knot fun. On the other hand, we recently had to briefly run without
the starboard engine on the N68, and it was impressive that we only lost
about 1/2 knot of speed (we still made over 9 knots), and fuel consumption
appeared to be the same.

We plan to cross the Pacific next year, and I really want to understand the
differences in fuel efficiency running single engine or twins, so that I can
maximize range across the Pacific. Although I've tried, the data is so close
between running a single or a twin, that I still don't know which is more
efficient. 

The bottom line presently is that fuel economy seems to be roughly the same
twin versus single (or, at least it appears to be within 5%). However,
should I lose an engine, I'd rather be moving at 9 knots than 3.5 knots.
And, it's certainly preferable having two engines that use the same spare
parts.

Another side benefit of the twins is that I am able to run at lower RPMs.
Generally we cruise at 1,300 or 1,350rpm. In a single engine boat I'd be
running 1,600-1,700 rpm to maintain the same speed. I prefer less vibration.
It seems to be easier on the engine. 

-Ken Williams
Sans Souci, Nordhavn68.com