[PUP] Krogen 55 Expedition vs Dashew FPB64

Sun Oct 21 00:10:25 EDT 2007

Most of the bigger boats, including the Nordhavn 55, can be had with  
twins, but I know Nordhavn claims the most fuel efficient boats are  
still the singles. Until they get to the 68 footers, most of their  
boats go out the door with singles.

I've heard the same argument that Mike Maurice mentions, about  
various frictional (parasitic?) losses that increase with the number  
of engines for a given horsepower output (assuming same technology of  
engine), plus two shafts, props, etc. What I haven't seen is any hard  
data that compares miles per gallon on otherwise identical boats with  
twins or single.

Once the first N55 with twins is on the water (real soon now -- I  
heard that the first twin N55 is going on FUBAR as a support/sponsor  
boat), we might be able to get apples to apples fuel consumption  
data. The first 25 or so N55's delivered have been singles.

John

On Oct 20, 2007, at 7:20 PM, bob england wrote:

> 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> >
> _______________________________________________> >
> http://lists.samurai.com/mailman/listinfo/passagemaking-under- 
> power> >> > To
> unsubscribe send email to> >
> passagemaking-under-power-request at lists.samurai.com with the word> >
> UNSUBSCRIBE and nothing else in the subject or body of the  
> message.> >> >
> Passagemaking Under Power and PUP are trademarks of Water World > >
> Productions, formerly known as Trawler World Productions.>
> _______________________________________________>
> http://lists.samurai.com/mailman/listinfo/passagemaking-under- 
> power> > To
> unsubscribe send email to> passagemaking-under-power- 
> request at lists.samurai.com
> with the word> UNSUBSCRIBE and nothing else in the subject or body  
> of the
> message.> > Passagemaking Under Power and PUP are trademarks of  
> Water World
> Productions, formerly known as Trawler World Productions.>
> _________________________________________________________________
> Peek-a-boo FREE Tricks & Treats for You!
> http://www.reallivemoms.com?ocid=TXT_TAGHM&loc=us
> _______________________________________________
> http://lists.samurai.com/mailman/listinfo/passagemaking-under-power
>
> To unsubscribe send email to
> passagemaking-under-power-request at lists.samurai.com with the word
> UNSUBSCRIBE and nothing else in the subject or body of the message.
>
> Passagemaking Under Power and PUP are trademarks of Water World  
> Productions, formerly known as Trawler World Productions.