[PUP] Krogen 55 Expedition vs Dashew FPB64

[bob england]

Why do we automatically assume that twin engines use more fuel per mile than a
single. If it takes 50 hp to move the boat at a certain speed that's how much
diesel is used. If two small engines have less combined parasitic losses than
one bigger engine they will use less fuel to produce the required power. The
only remaining factor is drag. But, smaller shafts and props compared to a
larger single shaft and prop almost make up the difference. I would take the
Krogen over the Nordy simply because it has twins. If I'm not mistaken the new
Nordhavn motorsailer can be had with twin engines. Seems like all the big
players are going twin, go figure.> From: johnamar1101 at gmail.com> Date: Sat,
20 Oct 2007 14:12:34 -0700> To: passagemaking-under-power at lists.samurai.com>
Subject: Re: [PUP] Krogen 55 Expedition vs Dashew FPB64> > I'm not sure how to
parameterize fuel consumption between two small > twins and a single, larger
main, but I have to believe the twins eat > more fuel per mile, everything
else equal.> > That said, I have to assume a single-engine Nordhavn 55 with
2250 > gallons (N55 is a bit heavier, but gross hull dimensions are the same >
as KK) is going to have better range than a KK 55 with twins and 1800 >
gallons. Yet both have the same specified range at 8 knots.> > I don't see
how.> > John Marshall> N55-Serendipity> Sequim Bay, WA> > On Oct 20, 2007, at
1:18 PM, Dave Cooper wrote:> > > Weighing in on this one could generate a long
email!> >> > 1. Fuel tankage seems very light for a real long range> >
passagemaker...perhaps turning 2 or 300 gallons of that water > > capacity
into> > fuel capacity would help. One of the things we see is that having the>
> ability to purchase fuel where the price is "right" can save huge > >
amounts of> > money. If you can buy fuel at $2.50/gal vs. $6/gal then the
savings > > are> > large. If you can find some at the "International price" of
$1 to > > 1.50 /gal> > even better. If you can swing by Venezuela and fuel up
for the $.05/ > > gal or> > even the $.30/gal for unlimited amounts then even
better. We are > > working on> > increasing Swan Song's tankage for that
reason alone not range. I > > wouldn't> > consider anything under 3000 gals as
adequate today for a > > "passagemaker".> > Today, 10/20/07, buying 5000 gals
of fuel in Martinique would be > > $35,000.> > Whereas buying it in Isla
Margarita, VE would be $1250.00 and if > > you did> > some careful shopping
you could get 1000 gals of that at $.03/gal > > today so> > lets say $1030 vs.
$35,000 for one fuel up. Again if you are buying a> > passagemaker you aren't
staying in Kansas anymore and need to deal > > with fuel> > and fueling as a
highly variable commodity which it is. Big tanks > > help this> > process and
can lower your cost of operation dramatically.> > 2. The
beam/length/displacement ratios would seem to indicate that > > it will> >
take considerable power to over come head seas and wind. This of > > course
will> > have a large effect on fuel burn and range.> > 3. The 1/3 double deck
seems a bit out of place on an ocean going > > small> > vessel. As Seahorse
John said the A/B ration looks a bit off for > > this use.> > 4. The 18' beam
certainly gives interior volume but again at the > > expense of> > sea keeping
ability. IMHO.> > 5. The half load displacement of ~82,000 would yield a full
load > > with stores> > and gear of close to 95,000, IMO. This again takes
fuel to push thru a> > seaway. It is also on the heavy side for a 49'
waterline.> > 6. I would really wonder if the range is 3000 miles under
typical> > passagemaking conditions.> > 7. Not being a fan of active fins for
stabilization do to potential > > failure,> > I wonder how she'd handle 15-18
ft beam seas without them > > operating. More so> > how would the crew
stand-up to this for a few days or weeks on a > > passage?> > 8. Looks are a
matter of the eye of the beholder until they get in > > the way> > of
function. I'd be a bit leery of the ride up in that pilothouse > > if the> >
active stabilizers went out. Many feet above the roll center.> >> > Lots of
marketing speak in this one page release. Little in the way of> > showing real
thought to the real world in passagemaking today.> >> > The Krogen 55 is about
as far on the other end of the spectrum from > > the> > FPB64 design and
concept as one could get and still both be twin screw> > monohulls. Fat and
heavy vs. lean, long and light. KK focused on > > interior> > space and living
with more than a couple aboard. FPB64 is a > > couple's boat> > period no
pretense of more folks aboard for more that one laundry > > cycle.> >> > Swan
Song in its 58' X 13' has just enough space for Nancy and I. > > We have a> >
second stateroom for guests but tend to discourage anyone from a > > long
term> > stay. When full time cruising, which to us are passages interrupted >
> with> > longer stays at out of the way anchorages and some marinas, you do >
> need more> > space than what many consider adequate for shorter term living
> > aboard. You> > can get this space in one of three ways; increase beam,
height or > > length. Of> > these three two are detrimental to making a good
passagemaker, IMO. > > You only> > have length to work with as both beam and
height reduce the level of> > seaworthiness all other things being equal.> >>
> The Dashews took the long route to getting the interior volume they > >
felt> > they needed for their type of passagemaking. This won't work for > >
everyone> > and some might even consider the trade offs that they made over
the> > top....until of course you are a 1000 miles from the closest safe > >
harbor and> > the seas are 18 and building......The pucker factor goes up > >
remarkably fast> > then.> >> > Swan Song is by no means even close to the
Dashews in terms of being> > bulletproof but we are well ahead of what many
are selling today as> > "Passagemakers" to people who don't have the offshore
experience to > > realize> > what a bad day at sea can be like. If they did
they'd be beating a > > path to> > Steve's door if they're in the market for a
new all weather offshore> > passagemaker.> >> > As always YMMV.....> >> > Dave
& Nancy> > Swan Song> > Roughwater 58> >
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