A fundamental fact of yacht design is that if you want to move a given displacement—which is the only sensible way to compare boat sizes—through the water without planing, the most efficient hull form is long and thin, as demonstrated by Steve and Linda Dashew’s 83-foot motorboat, Wind Horse. A boat that can move her nearly 50 US tons (45 metric tons) at 13 knots using less than 200 hp. Drop the speed to 11 knots and she uses around 120 hp.
I got to take a ride on Wind Horse today and was very impressed. And if you think she is extreme, read on.
That’s the US battle ship Wisconsin. And both shots were taken with “normal” focal lengths—that’s not lens distortion you are looking at.
There is some distortion of Wind Horse in this wide angle shot.
Even the vintage motor sailor on the left in the photo above is pretty long and thin. So we used to understand that long and thin was the way to go, but somehow in recent years boat design has gone off the rails producing a lot of short fat inefficient boats. It’s a bit like the trend toward SUVs in automobile design and probably for the same reason: fuel that was, and probably still is, badly mispriced.
To me, the take away here is that trawler yachts make exactly no sense at all. If and when the day comes that Phyllis and I can no longer handle sails, why would we want a 40 to 45-foot trawler that would be about the same size (displacement) as Morgan’s Cloud but that would motor slower than we do, use way more fuel, be less comfortable in a seaway, and be a lot less safe due to stability issues?
Wind Horse may look military, industrial on deck, but she is all yacht below.
We are not ready for a motor boat yet, and may never be. But the thought of standing watch in a wheelhouse like that on Wind Horse in our shirt sleeves on the way to say Greenland does have its attractions after 20 years of open cockpit sailing in the high latitudes.
Phyllis and I won’t ever be able to afford a boat like Wind Horse, nor would we want a boat that big, even if we could afford it, but I do hope that the recreational motor boat industry comes to its senses and learns from Steve and Linda before the day comes that I’m too creaky to sail.
If you want to know more about the science behind positive effects of length, Matt Marsh’s excellent post on the subject is a great place to start.
So how many of you sailors are secretly thinking about the “motor boat years”? Please leave a comment.
Hi John
We saw ‘Wind Horse’ in Tobermory, Isle of Mull a few years ago, and she was very impressive indeed – a real voyaging machine.
And we weren’t the only ones who thought so – we did try and say hello, but the queue was too long – it’s a wonder they got any peace at all.
We hope we’re a long way from the motor boat years, but if we weren’t we’d love one.
Best wishes
Colin
What a great shot of the Wisconsin. I was on the Missouri – a sistership? – unforgettable. On deck her narrow beam relative to her enormous length was obvious.
Steve is what we often refer to as “one hell of an engineer”- the kind of designer who starts new trends and sets the gold standard for his field. I hope the motor yacht community will follow his lead on this one.
I’m fairly convinced that many of the key elements of the FPB concept could scale down to about 45-50 feet and 10 tonnes, if anyone wanted to do so. The hardest part is finding a way to sell a boat that has a 36-footer’s interior and a 50-footer’s dock fees. The market for powerboats that are good at being boats is much smaller than the market for powerboats that are good at being waterfront condos.
Hi Matt,
I love your last sentence, so true. But AAC is about boats that go to sea, not just up and down the ditch with an occasional venture offshore in settled conditions, so maybe we can encourage people to focus on the former, instead of the latter—that’s our goal, anyway.
Hello,
I own, live aboard and sail a Scott Kaufman sailboat, a 1977 aluminium built at Derektor Shipyard, 46′ (14m). It’s got similar lines as that of Wind Horse – long and pointy in front. AND indeed, what a difference in confort and speed in sailing/motoring with those “fat” more recent sailboats.
When motoring at 6.5knots, if we hit normal waves in the 3-4′ height, the recent sailboats hit hard and slow down to 5.5 even 5 knots. I stay above 6knots… and smoothly.
And everything else stays smooth on board… including sea sickness.
Fair winds,
Chris
Hi Chris,
Sounds like a great boat. “Morgan’s Cloud” is the same and we regularly motor past trawlers when punching into a chop. We pitch less and with our fine bow we are not stopped by the waves. And we have less than half the HP (87) of most 45 trawlers Now imagine that you took our boats and removed the drag of the keel and rig and added an efficient fixed blade propeller. Imagine how we would blow by the fat boats then.
Hello John,
Indeed, if ever I feel like motoring arond, like in the Europe Canals (some 8 000nm worth of), I thought of removing rig, install a low draft keel and rudder, and to 8-10knots I’am sure I’ll be cruising around.
Yes, Scott Kaufman’s sailboat are gems. Derektor himself co-designed and built the Boomerang LOA 65′ LWL 55′ which came in 2nd place in Fastnet 1979.
I crossed Atlantic W->E @35N latitude in november 2011, winds avging 35knots, high seas, got 24hrs of 40-45knots. We got very wet. But never! out of control or even the glimps of a fell of loosing control of sailboat, even on auto-pilot 80% of time.
And I slept in front berth! Of 11 nights, twice only I was awaken because of a good hit.
Chris
“why would we want a 40 to 45-foot trawler that would be about the same size (displacement) as Morgan’s Cloud but that would motor slower than we do, use way more fuel, be less comfortable in a seaway, and be a lot less safe due to stability issues?”
Your question tries to answer itself with incorrect assumptions. A well-built 40-45′ trawler will have more displacement than your current sailboat, will be significantly bigger and have more living space and be more comfortable especially while underway in bad weather, and be much more stable in all underway conditions if you have proper stabilization. Our 53′ trawler displaces about 80,000 lbs and has parts of three overlapping living spaces. Active stabilization means we’re stable in all sea conditions except head-on seas where no stabilization can stop the up and down motion. Sailing stabilization requires wind and doesn’t do very well against passing wakes inshore (if the sails are even up).
Fuel-wise, we burn 4 GPH at 8 kts. 2 MPG is quite common. Smaller, slower trawlers can inch up to as much as 4 MPG in some situations. We hold 1,000 gallons of fuel.
The moment you pass a sailboat in rainy, cold conditions where the skipper is all bundled up, getting wet outside, and looking uncomfortable, you realize right away how nice it is to be in slippers, sipping coffee, and sitting in a nice, warm pilothouse while moving along at a very predicable and stable speeds. What is Harley Davidson’s motto? If you have to ask the question, you wouldn’t understand the answer…
Hi Jeff,
Each to their own. Remember that I said “to me” trawlers make no sense. If one works for you, that’s fine too.
But keep in mind that a long boat can have a wheelhouse and stabilizers too, in fact all Steve’s boats have both. (I would never have active stabilizers, but that is a mission dependent decision.)
But one thing that is not up for debate is that a longer boat will always be more efficient than a shorter one assuming that both are displacement hull types and have the same displacement. And the difference will not be small either. Matt does a great job of explaining why in the link at the end of the post.
Also, perhaps I was not clear in the post, I was comparing boats of similar displacement. Of course your boat has more room than “Morgan’s Cloud” she is almost exactly twice the size. In fact your boat is the same size as “Wind Horse”
My wife and I saw Wind Horse on the hard in Lymington in May 2010. She was having some work done by Berthon’s, but I don’t know what. What really struck me about her was how shallow drafted she is. She’s an amazing piece of engineering, at 75,000lbs, and 65ft, she draws less than 1.4m… that’s what my 29ft, 8000lb boat draws!
I’ve been following the Dashew’s blog on setsail.com for a while, both their sailing boats and FPBs. I, too, would love an FPB when I can’t sail anymore, and until that time, will someone please by me a Beowulf?
I think your comments and to a certain extent John’s as well are having trouble comparing apples to apples. Given similar materials used in construction and similar levels of equipment, displacement is a more relevant predictor of build cost than overall length. Steve Dashew’s FRB 64′ at 75,000# is a reasonable basis for a performance comparison to your 53′ trawler, but not of build cost because materials and specifications are so different. For sure your boat will have more rooms, but I doubt it will be superior on other measures.
Fuel economy:
Nordhaven 52 @ 8.3 knots—–7 gph
Nordhaven 64@ 8.5 knots—–8.5 gph
Siegel 53@ 8 knots—————-4 gph
FRB 64 @ 8.3 knots————2.4 gph
Numbers are from the Nordhaven owners group and from Steve Dashew. From them I would conclude that your boat is a drastically different design than the normal trawler. Even then the FRB is nearly twice as efficient while carrying close to your displacement and not being substantially smaller inside.
Second point is the idea of “stability”. I think the definition you are using is “motion comfort in common sea states while the stabilizers are active”, rather than the righting moment factors that naval architects call stability. Dashew does a great job of explaining the factors that affect stability in the real world in this article: http://setsail.com/evaluating-stability-and-capsize-risks-for-yachts/
And for another take on stability in top-heavy vessels when they are not under active stabilization, go to my post on the above article and read about the capsize at dock of a newly coast guard certified vessel.
Finally, it you really want to feel what a smooth riding vessel can be like, take a ride on one of my friend Kurt Hughes tourist catamarans in Hawaii and stand on the fore deck, not holding on to anything, as it motors into a 6′ cross chop at 18 knots.
Hi Richard,
Thanks for the numbers and clarification on stability. I was, as you say, talking of resistance to, and recovery from, knock down or inversion.
To add to your numbers data base:
Morgan’s Cloud, McCurdy and Rhodes 56 Sailboat…….8 knots at 2.3 gph…..6.1 knots at 1gph and that dragging a rig through the air and a keel through the water being driven by a flat blade (max) prop.
My point in the post is that if I ever bought a motor boat I don’t want one that does not motor as well or as efficiently as my present sailboat motors—it would be a step backward.
So John, if you really want efficiency and stability your future motor boat would be a catamaran with 50′ long hulls, 28′ beam, and hull waterline beam(s) only 36″. Only problem is that you’d be be able to motor at 16 knots with the same fuel burn as your 8 knot monohull mini Wind Horse and you’d have far too big a salon living space! LOL
Hi Richard,
Interesting. I have certainly never been one of those mono-hull sailors that scorns multi-hulls. If I were serious about a motor boat, I would certainly look at all the options. I was under the impression that the problems with ocean crossing power cats included a very jerky motion in short seas (something my stomach is sensitive to), wave impact between the hulls, and lack or load carrying capacity.
But then the last time I had anything to do with multi-hulls was 40 years ago when I skippered a 50-foot day charter cat around Bermuda. The thing had all the problems listed above and also used to scare me witless whenever we were fully loaded with the 40 passengers that some idiot had licensed her for. Still I’m sure things have come a long way since then.
John, I think cats and tris are a bit better now than they used to be. Design features that solve all the problems you mentioned are now well understood and widely known.
Not all builders take advantage of this knowledge (if, for example, you know the boat will never see the ocean, you might draw her with less bridgedeck clearance and a larger deck saloon than engineering sense would ordinarily dictate), but it’s not a mysterious unknown field any more.
Power cats, alas, are still far less common than they ought to be- something about being charged for two slips at many marinas.
Hi John,
My 15 year old Sunchaser 58 catamaran design:
It is a true 20 knot boat under sail and under power— something that few 200′ megayachts can do. There are many things that could be improved with what we have learned in the ensuing years, but it is still a completely different animal than the condomarans that populate the Caribbean or day charter catamarans from the era before Roger Hatfield and Kurt Hughes introduced proper hull designs.
In particular, look at the entry angle of the bows in one of the later photos. With that bow shape you will not experience the jerky pitching you remember, because the impact with a cross sea is softened by a progressive build up of force as the hull partially penetrates the wave. (Just like you can observe in the heavy weather video of Wind Horse, except with a 25,000# displacement rather than a 90,000# boat.) And with a more optimum length/beam ratio than is possible in a monohull.
This particular boat (Aolani) was built from my molds by a quick and dirty boatbuilder using polyester resin and is about 3,500# over weight. It was never designed to carry 30 people on the foredeck. No problem in harbor cruises, but you certainly wouldn’t want to load 5,000# of anchor chain into the bows and go to sea with it! On the other hand, these hull forms don’t experience drastic increases in drag as they are immersed, so the load carrying capacity is probably as good as a monohull of the same displacement as long as you center it properly.
With a wing mast in this type of boat your heavy weather rig is already in place with no canvas up. The wing mast can produce enough power to sail at five or six knots in high winds, or be instantly stalled by rotating it out of trim with no sail handling involved.
Not to say that this type of boat doesn’t have its own set of disadvantages, not the least of which is build cost. And its no marina queen, unless you limit yourself to the one marina you’ve found that accommodates a 30′ beam.
Richard
not being substantially smaller? an n64 vs a fpb?….really?
the truth is for a lot of people trawlers fit what boating is about for them – day hops up the coast to explore nova scotia and perhaps down to the exumas if feeling adventurous …sailors say gentlemen dont go to weather …thats just a cute way of saying dont push the weather window. Coastal cruising …Dont forget thtat trawlers have a body of work too… dis em if u like but i think they r handsome, useful, salty and the guy that mentioned coffee in the pilothouse has a point. It’s nice…
ps – (i own a sailboat too so don’t get all up in my mug right off)
Hi Ray,
No one will “get all up in your mug”. We don’t behave that way here at AAC. Do be prepared for vigorous and logical debate though.
Harley Davidson’s Motto
Ridin on My Hog- Since I can’t maneuver or stop, I’ll just hit the sucker.
Speaking of long skinny hulls, the sweet spot for a displacement hull operating in pure displacement mode is with a length/beam ratio near 10-12/1 When you are in this range the hull can be driven above “hull speed” with little noticeable hump in the drag curve. That explains why a catamaran with narrow semi-wave piercing hulls can motor at twice the speed of a monohull with similar fuel consumption given similar waterline lengths and displacement. And of course displacement monohulls with LBL’s like that would have to be as long as a destroyer to have interior volume.
Very interesting discussion… i have a 45 feet steel sailboat (16 tons) with a deck salon and a swing keel (the ballast is on the bottom 3/8 plate of the boat). Doing 7.5 knots at 2 gph. When i’ll be to old to sail, i will just remove the rig, pull the swing keel in forever and add a heated cabin. With 125 degres of stability it is a great boat under motoring. I agree the FRB are great and truly innovatrive and Steve Dashew is a very bright and clever guy – but this is a top end product, not for the common man. Other trawler builders should notice and begin to design other kind of the boat than the floating appartement that we see by these days…
Hi Andre,
Now there is a smart answer to the transition to the “dark side”.
And my hope is exactly the same as yours, that a builder will take Steve’s lead and come up with a smaller and simpler boat at a price that more people can afford.
Hi John,
Actually (gasp,choke) a basic Adventure 50 motorboat with a 12′ beam, low profile cabin, pilothouse, and single 100 hp engine would be cheaper to build than the Adventure 40 sailboat. You’d just have to put watertight bulkheads with no access fore and aft to keep owners from filling those areas with boy toys.
Richard
Hi Richard,
I would certainly believe that.
When looking for boats to move aboard 15 years ago, our first choice was a Dashew Sundeer type, but the length was just too long, both for expense and for the places we wished to go. Amazingly (at least to me) in 5 years in the Med, we met 150-200 American flagged vessels and I believe only 3 were smaller than our 40 feet. We are now sailing waters (UK/Ireland) where we are often the larger boat and there have been numerous areas/harbors where being any larger would have curtailed our cruising options and in those areas where marinas are the only option, increased expenditure dramatically. It is impressive to me how few anchoring possibilities remain when “on” the beaten path rather than “off” and most of this area is on the beaten path. All comments about the sea sensibleness of length and narrowness seem warranted and wise, but practically, if your wish is to wander widely and keep your options open, there is a lot to argue for more modest length and more chunky midships to get living space. Dick Stevenson, s/v Alchemy (a Valiant 42), Dartmouth, England
Hi Dick,
A very good point. Although we have never found “Morgan’s Cloud’s” length of 56′ a problem, we have always cruised more out of the way places and therefore the speed, comfort, and safety conferred by a longer boat have paid off for us.
I can certainly see circumstances where a shorter and fatter hull would make sense. An example that relates to this post would be a couple that planned to cruise the US Intercoastal Waterway and who liked to spend a lot of time in mariners. For them the savings in dockage and ability to find plenty of berths to fit, resulting from the selection of a short, wide and heavy trawler type yacht might easily outweigh the benefits of a longer and thinner boat of the same displacement.
I guess you could even construct a spreadsheet that would come up with the break even point depending on the price of fuel, price of overnight dockage, nights in a marina, and miles to be traveled.
Horses for courses.
Hi all,
I love Steve’s designs and have looked at his websites lots. Two things that have struck me; Firstly – no paint on the outside – and yet they look fine. Secondly the piece where Steve recognises that owning windhorse costs, if my memory serves, a third less per mile than one of his previous sailboats… there’s one to ponder!
Paul
Hi Paul,
I have done the same calculation as Steve, albeit with less precision on the back of an envelope. The answer? A long thin unpainted power boat of the same displacement would cost us just over half as much to run and maintain as “Morgan’s Cloud”. Shocking I know, but true. Phyllis and I are still willing to pay the price to sail, but it does make you think.
I’m actually quite surprised by that, is it really cheaper per mile for a powerboat that is essentially a sailboat minus the sails? Does the cost of fuel not outweigh the cost of maintaining the mast rigging and sails?
Hi Richard,
Of course that depends on usage profile but I’m pretty sure it’s true in most cases. This is one of the many reasons I believe strongly that we should be charging ourselves (through taxation) a much higher and more realistic price for carbon: https://www.morganscloud.com/2010/07/12/the-real-price-of-oil/
Thinking back at the design of a safe, offshore boat, designed to take the oceans of the word; the primary safety factor is not necessarily thin versus fat but the height over water:
-Center of gravity issue
-Windage
-Protection of cabin windows from waves
Sailboats are of low height because of the necessity for sail to work properly and the result is a very seaworthy boat by design. I don’t know what it is to be in a trawler in a hard blow, but i doubt these boats have the same options has a sailboat. I think this is the lineage between the Sundeer series and the FRB, a flush deck, low windage, low center of gravity boat. Add to this a fine entry and you’re on to take some hard weather if needed.
les belles lignes fines, as we say in french, beautifull indeed,
there is so much to learn from Steve and Setsail, even if at top sizes and budgets, plenty of these concepts of steve’s long boats might be used in smaller sizes,
bare aluminiums and rugged design with warm interiors e.g.,…
about the length/width ratios, where is the right balance ?
what wide big boats owners regularly say, is that it is difficult to move or walk in them, as the hang on rails are too far from each other, another reason to keep a boat reasobably thin, no ?
the A40 shouldn’t be too wide …
Hi Bruno,
A really good point about the difficulty of moving around at sea in a short wide boat. It is also difficult to design a good interior because you simply run out of boat.
Don’t worry, the Adventure 40 will be of moderate beam, you can count on it. I have a post on her hull form coming in a weak or so.
Dashew’s Sundeers also were narrow, easily-driven hulls. Steve and Linda were gracious enough to give us a full tour of Wind Horse in Maine last year, a revelation to us. As with the Sundeers, Steve is not afraid to challenge conventional wisdom and gets fantastic results. Like to see a 50 ft Wind Horse.
agreed – a 50ftr of similar proportions and with a real emphasis on simplification
Hi Brian,
Having spoken at length to Steve about it, I don’t think the “Wind Horse” concept can be done at 50-feet. You need to think between 56 and 60 feet minimum. However, the boat could be a lot lighter and therefore smaller than the 64s that Steve is building in NZ. Think about 20-25 US tons.
The key thing that I have learned from Steve as that you never, ever, want to start with length when designing a boat. That is the road to disaster.
Rather start with a target weight (displacement) and then make the boat as long as it needs to be to do that weight right. In fact Steve has found that it can be cheaper to build a boat that is longer since it is easier and faster to install the equipment. Just don’t be tempted to fill the space, as RDE has pointed out earlier in the thread.
The boat has a brace of Rigid Industries Dually II LED lights mounted on an impressive pedestal on the bow. I’d be interested in hearing their progress report on those LED lights, and also the make of that bow mount.
i went on the 64s just after they were launched in whangarei – still plenty of room for two couples – scaling down to 50-odd foot wouldnt feel unduly cramped
http://www.artnautica.com/designs/long-range-cruiser-58
go to his facebook page to see it being built
in a nutshell, how is it that morgan’s cloud or any other sailing cruiser is more expensive to operate and maintain than a comparable power cruiser ? or did i misread the posts above ?
Hi Richard,
Well, of course there are a lot of variables here: how much you currently motor in your sailboat, how big the engine is in your sailboat as against the one in the motor boat you are comparing to, etc. In our case, the type of motor boat we might consider when and if the time comes would not have a much bigger engine than our present sailboat, so no big cost advantage to sailing there.
But the key thing to keep in mind is that most sailors dramatically underestimate what it is costing them a mile to sail. For example, a new set of sails for our boat is about US$20,000 and lasts about 25,000 miles. That’s eighty cents a mile, right there! And standing rigging should be replaced about every 10 years…you get the idea.
If one is realistic about the cost of sails and rigging, both capital and ongoing, the wind is anything but free. I say this not to encourage people to give up sailing, but just in the interest of dealing with the world as it is, not the way we want it to be. It’s really important to be realistic about this stuff when one is deciding how big a sailboat to buy.
interesting…my quick back-of-an-envelope figuring based on my hard-logged usage data on my bayliner discovery 246 usage since 3/08 when i purchased her new show she cost me $2.70/mi for operation and maint…cavu is history for me now that i have thankfully resumed the ranks of those under sail with my new dufour 433 lakota…a boat that makes cavu seem more like a toy than the stalwart power cruiser she really is having safely and comfortably taken me and my friends a total of right at 6,000 mi up and down the sw fl coast including twice to key west and beyond to boca grande key; however, cavu’s predecessor was my jeanneau sun odyssey 34…while my numbers for her are not at my finger tips as i write this now i feel sure her o&m costs were about half that including sail refurbishing costs and standing rigging replacement…sometime soon i will figure this more closely for sidra, but that is what my head tells me now, and i don’t think i am off by much on this…i am expecting my o&m costs for lakota will be somewhere between these two figures…lastly, let me clarify that i have excluded dockage from these costs as i count this essentially comparable between these three boats with lakota probably a bit more…take care…richard s. in tampa bay, s/v lakota’s skipper
John, Agree. It comes to pass that all 3 of our working sails are in need of replacement. Those sails have taken Alchemy about 25,000 plus sailing miles at a cost of about 46 cents (US) per mile not counting yearly repairs, renewal of UV shields, new lines etc. (We also have an asym which will last as long as we do not abuse it.) If the next set last 25,000 I will get about 60 cents to their mile. As you said rigging, occasional stepping and unstepping etc are all on top of that and the total would likely doubly the per mile cost. Dick Stevenson, s/v Alchemy, St. Peter Port, Guernsey, The Channel Islands
by comparison, just in fuel cost alone (equating this to sail o&m) my just-departed i/o sport cruiser (bayliner 246) at 2.5 mpg (good compared with most power cruisers) was about $2/mi (double if not in vicinity of the lower 48)…thankfully i am back under sail again as related above (dufour 433) where i expect my total o&m cost excluding dockage to be in this range ($2/mi) until abroad when this will doubtless go to half-again as much…richard in tampa bay, s/v lakota
While it might seem that sails cost $0.60 per mile or so, that’s not the only cost. Maybe it’s just me but certainly for most coastal cruising, I mainly see sailboats under power. I fully admit that for large passages, sailing is mostly done under wind power but if you’re looking at costs, you really need to consider the full movement cost.
There’s a well known trawler joke made by the countless sailors who now make up the trawler population…
What’s the difference between a sailboat and a trawler? A sailboat only motors 90% of the time.
We have cruised several sailing boats, the last one, with 3 kids, was a Chamberlin 13.5m sailing catamaran. We have since built and sold a 10m Power Cat also designed by Robin Chamberlin, and are now in the process of building the 12m version of this design for long term liveaboard cruising for ourselves. The 10m worked well, and 12m was chosen, as the “market” thought 10m was too short/small, and also at 11.9m for running cost (marinas and licencing). We are very encouraged by the above comments that it it much cheaper in the long term to run & maintain a power boat. We look forward to the much high cruising speeds (12-14 knots), and good fuel economy as documented by both the 10m and 14 m power cats designed by Chamberlin.
Catherine Hammond
Catherine could you post those fuel economy figures – i have been on the Chamberlin web site but couldn’t find them…
A trip just to determine the fuel economy of the 10m power cat was undertaken from Moreton Bay, Brisbane to Lady Musgrave Island, via the “outside”, and then back to Brisbane via the Sandy Straits and Wide Bay Bar, a total of 504 miles. The weather was benign and speed averaged was 12.5 knots up, and 13 knots back. The 10m has 2 x 50hp motors.
560 litres – 504 miles over 19 hours – 1.1 litres per nm.
The 14m Chamberlin power cat has 2 x 100hp motors, and went from Brisbane to Tasmania, in varying weather conditions, a total of 1050 miles, average speed 14 knots and recorded a fuel economy of 1.3 litres per nm.
Robin Chamberlin website – http://www.chamberlinmarine.com.au
Very impressive. I get about 1 liter per nm but at 6.5 knots. A good catamaran design provides great benefits, one of which is being able to flew away from bad weather easily – or stay shorter into it.
We rarely motor when coastal cruising. I don’t mean to be self-righteous about this: we’re fortunate in that we usually have a flexible itinerary, and we’re aided by the geography of Maine and the Canadian maritime. We usually start the day with a few destinations in mind, depending on the breeze. We often arrive (somewhere) in the early evening, having waited for the wind to fill. This has downsides: the most desirable anchorage is sometimes taken by a power boat (or a powering sailboat), and the mosquitoes drive us below decks soon after we set the hook. However, we’re happy with our approach. Back to John’s post, the great thing about an easily driven hull is that you can sail or power efficiently, your choice.
Hi John: I have an aluminun sailboat built in 1999. 55 ft with a 53 ft waterline and a 11 ft waterline beam. The engine is a yanmar 100 hp engine. At 8 knots it uses 1.5 gal. Per hr. top motoring speed is 9 k. Empty the weight is 32,000 lb. Last year I made a passage from Hampton Va. To St Marton in under 8 days using 20 gal. Most of the engine time was a small gen. Set for battery charging and refrigation. Draft is 10ft. With a lifting keel only raised when entering a shallow harbor. Lastly IMS measured 168 positive stability.
Hi George,
Sounds like a great long thin boat.
One suggestion: If you ever have to re-power, consider a smaller higher torque engine. “Morgan’s Cloud” is a considerably bigger boat at 48,000 LB empty and we have gained a lot of fuel economy by going down in HP from 115 to 87. And 87 HP is still more than enough for our easily driven hull.
Most modern sailboat are over engined and actually never use more than 50-70% of the power available, due to displacement constraints and sailing props that are inefficient at high tip speeds.
Berthing/ mooring costs are really high for this length. Otherwise great design.
Like every good thing it is possible to have too much. Do you think this goes too far or are we still in the relm of good things?
https://www.boatdesign.net/attachments/img_1321-jpg.29813/
John Spencer Infadel (later renamed Ragtime) aprox 73′ x 15’6″
Well, everything good needs to be taken in moderation. That particular boat appears to rely quite heavily on a deep and structurally complex keel to get its sail-carrying power. It would take a particularly unusual combination of requirements to push the yacht’s optimized proportions into that form.