Long - Skinny Power Boats

Discussion in 'Boat Design' started by SAQuestor, Sep 24, 2004.

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  1. fcfc

    fcfc Guest

    long and skinny

    Look at http://www.setsail.com/dashew/do_PARADIGM.html

    This is an interesting technical thread, but I fear you forget the economic/psychologic side.

    There was an article by Tom Fexas, designer of the "midnight lace" series, narrow and light boats. He was explaining why the new series are heavier and wider and yes less efficient.

    Look at GB classical series. They now have 2*400 up to 2*800 hp for semi disp hull because the owner of a 1 M$ boat want some speed and does not give a **** to the fuel bill, be it 1000 or 5000 $. And putting 2*115 hp as the initial design have no meaning, because you will reduce the cost only from 1M$ to 900K $, but you will cut the speed more than half.
    You are at price level where this is unacceptable.
    And with a heavy use of a leisure craft at 300 hours / year, in both cases, the fuel bill will be insignificant for the owner. (marina fees, insurance, electronic maintenace etc ...)

    Even on nordhavn site, they explained why they switched from canoe transom for the first series (46 -62) to wide transom for all the newer. They simply said that the owner of such a boat does not care if the boat burn 1.5 or 2 gph, provided he has enough range with bigger tanks, and more importantly, sligthly higher cruise speed and more interior space.
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    FAST FRED Senior Member

    "Anyway, I thought we were discussing monohulls. The hull resistance calculator is based on the equations and formulae in chapter 3 of "21st Century Multihulls" by Joseph Norwood Jr. "

    Thje AYRS (site owner for the computer) is mostly a speed under sail group.
    They hope eventually to hit 50 K under sail , with 80K as untimate goal.(46K now)

    Their work is either for the main hull of a Tri or twin hulls of a Cat.

    The minimum drag form of the hull from them would seem ideal for a single hull cruiser.

    Stability could come from Form alone , Tri configuration ,Flopper Stoppers or powered gyro from Mitsubishi.

    A semi circular hull form would be really rolly , but should have a better softer motion than a chined boat.
    The numbers generated seem good enough for comparing LB ratios and weight changes on the same hull.And assesing the ability of a hull to get 5 to 10 mpg at speed.

    We head south in a week , I will attempt to post the Numbers for different weight sets previously generated ,after the US election.

  3. SAQuestor
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    SAQuestor Senior Member

    Not a Millionaire

    Ok. But you're referring to folks that have made a zillion bucks someplace/how and don't care a whit what their total costs are - at least as long as they can afford the total bill. I fear that those sorts of folks - except for the Dashew's and others of similar thought - care more about looks and 'how many she sleep' sorts of concerns than being efficient. And there is enough anecdotal evidence (and perhaps some surveys or studies?) that support the idea that the guy wants the boat to show off his "manliness" and his mate wants a floating apartment.

    I started this thread because I'm not one of those zillion buck guys and I want a boat that can be safe and efficient while providing more than a modicum of comfort and still be affordable, both to build and run on slightly more than a Social Security budget.

    Agree completely. But again you are speaking of $1 million boats. Not something that 'average Joe's' can afford to purchase or run.

    Again, I agree completely. But that sort of boat purchaser isn't going to be here reading about what criteria makes a boat efficient. That person is going to go buy a boat that compensates for any masculine lack and he's going to look real good with that drink in hand having his dock tied to the boat.

    It's my opinion that this discussion is not about how much space one can get in a mega-horsepower semi-planning boat where the owner doesn't have a need to consider efficiency.

    Rather this discussion started out - and still should be focused - on how to achieve reasonable safety and comfort in an efficient hull package. And though those of us that have participated in this discussion may disagree on the particulars, I think we all agree that a long - skinny boat is way more efficient (in terms of movement and usage of dwindling resources) than the plastic fantastic million dollar dock warmers that are the current rage for those folks that don't care about design, but rather buy and have a boat to show off their wealth.

    Your opinion may of course vary.


  4. fcfc

    fcfc Guest


    I just simply was saying that recipe for fuel efficient boats are know for decades, if not centuries.
    And such boats does not exists, it is that fuel efficiency is not on top priority for boats owners.

    Look at http://www.andrewsyacht.com/andrws52.htm Remove the ballast and rig and you will get a 52 ft 8000 lbs boat fully equiped with curent engine. Strong enough to cross ocean (and to resist to ballast rigthing moment). You can even narrow it a bit. say 11/12 ft beam.

    Remove the auxiliry prop system. Put a new aluminum euro diesel 3 cyl 70-80 cid, with 24000 psi electronic injection pump and 28 psi turbo. This will give you about 50 -60 hp sipping a misery. Drive a 40" prop with a 5:1 or 6:1 redrive.

    And you will get at end a very fuel efficient boat with today technology. (All is available for at least 5 years). Nothing fancy.

    But there is not a single boat like this on earth.
    There must be some strong reasons. That s all what I wanted to show you.
  5. SAQuestor
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    SAQuestor Senior Member

    Let's be real clear - RICH boat owners don't (may not) care if it is a priority or not. The folks that I chat with constantly talk about and bemoan the cost of fuel, especially at marinas.

    Long - skinny efficient boats don't current exist because we are just at the end of an era where exploiting the oil riches of the earth made energy extremely inexpensive. There hasn't been any demand because energy has been very cheap. These next few years may show us to be at the beginning of a major paradigm shift. Since we don't have crystal balls to tell the future, we'll see in 10, 15 or 20 years. Maybe by then boats will truly be the exclusive playtoys of the ultra-rich.

    And why on earth would anyone want a power boat (a converted racing sail boat no less) with a 10.5 ft (3.2m) draft? They'd have to be daft!

    Thanks be to your diety of choice!

    And all this thread is about is thinking outside the current short and fat, dock tied to the boat, drinkmobile that you see in every marina all over the world. There are indeed many strong reasons. Several of which I enumerated in my previous post.

    But let's be realistic here. The price of crude is over $54/bbl. Do you really think that the price will go down anytime in the next decade - and I don't mean downward fluxuations of up to $10/bbl?

    Not likely, IMO. So if I or anyone that IS NOT a millionaire wants to have a efficient power boat that means that we need to think outside the box.

    Portager has a great concept in being able to transport his boat from sea to shining sea and get the best of the various cruising grounds.

    So what if 99% of the boats aren't like this? The time for a long - skinny fuel efficient boat may soon be upon us, especially if it's one that doesn't have to sit in a marina sucking up $10-$15 per foot per month. If that long - skinny boat can be cruised efficiently and then trailered off to the next cruising grounds or even just hauled onto the hard until the next cruise, there very well may be a market that develops for a commercially produced boat. A long- skinny efficient boat that has the required systems to avoid marinas and be able to anchor out 95% of the time and safely go from 1) the Baltic to Med via the canals or 2)from the NE to Florida and the Bahamas via the intercoastal or 3) from the Puget Sound to Alaska and then on a trailer to Baja may well fit into the retirement plans of lots of folks that can't afford to have that 600hp diesel sucking masculinity compensating $1 million dollar yacht.

    That's all I wanted to show you.
  6. Tad
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    Tad Boat Designer


    You are correct, fuel consumption is not a factor to the average Joe buying a boat, he will probably only run at cruising speed for 15-20 hours per year. While lots of folks think they want to cross an ocean in their "PassageMaker", very, very few people do so. Yes, I know some will do it if gathered together and run across under close supervision. That was the lesson PAE learned, they have also learned that people who do live aboard (which is their customer base) want to carry every toy imaginable. Thus bigger butts.

    But yacht designers can learn lessons about what could be from what is. Right now the buying public are being offered various versions of fuel hogs. This cannot last. So where do we go from here?

    Your comments about a converted TP52 are great, but I think you forgot a couple of things. I don't know what the fuel capacity of a TP might be, perhaps 20 gallons? Certainly not enough to get very far. Taking a TP across an ocean is busy and hard work, no time to get bored. But a powered version would offer none of that sailing distraction, so the power voyager carries along a bunch of diversions. Books, movies, toys to play with, a decent dinghy. These all drive the weight up.

    I think powered versions of high-performance sailing types have been around for a long time. LF Herreshoff's Marco Polo was designed around the end of WWII. She is 55' by 10', she has a short sailing rig and weighs about 42,000 pounds ready for sea, with 15,000 pound in ballast. She was designed to travel at 10 knots around the clock, at the time an unheard of level of performance while ocean cruising. She carried 1000 gallons of fuel and her behavior in a sea is, in the words of Phil Bolger, "Like that of a hooked Swordfish".

    The next long skinny powerboat I would draw your attention to is Jim Hawkins. She was designed and built in 1969 by two racing sailors, Avard Fuller and Bob Derecktor. She is aluminum, 61' by 13', weighing about 47,000 pounds and twin 64 HP engines would drive her at 9.5 knots. Her range at 210 miles per day, burning 100 gallons of fuel per day, is 1500 miles.

    Why didn't these types become popular? First off because they were never built and offered to the public at a reasonable price. By all acounts there is considerable interest in Phil Bolgers Tennessee design. She is a long skinny flat bottomed plywood skiff, well suited to flat water cruising. Length is 30' and beam 6'2". With a 15 HP outboard she will cruise at 10 MPH. The problem for the marketing people is that there is no room for windfall profit in building such a cheap looking boat.

    I do think that the next 10 years will see a real market develop for boats that use less everything, and are of reasonable cost. It will take some vision to get there.

    All the best, Tad

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  7. 8knots
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    8knots A little on the slow side

    My Opinion on the long skinny is this! You have two real groups of buyers
    1) The guy who is loaded and can afford to feed 3412 cats and go fast
    2) the majority of us who have a good job and can afford a moderate sized production boat and afford reasonable sized fuel bills for the 6 weekends a season we use it.
    most folk in group 2 only have one boat and probably work up to and top out at 40 or so feet. He has 2 kids and a wife. he more than likely has the 9-5 job so he has the week end to get his boating in. to him differance between a $40 dollar or $200 fuel bill is of little consequence.
    You would have a hard time trying to sell "long skinny" to group 2. $160 bucks is not worth all the sacrifices you have to make to get a good family cruiser. We all know people want and buy the "condo on jon-boat" style. ads in any mag prove this.

    Ina nutshell we are group 2.5 the weirdo's who know just enough about boat design to push for true performance and buck the cookie cutter production boat mold.
    Gotta run Wifes working on kid number two... another 2.5 :p
    enjoy your weekend 8
  8. fcfc

    fcfc Guest

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    FAST FRED Senior Member

    I'm not sure that the box boats are built with no concern for fuel , there more concerned with overall cost.

    AS the boats usually sit in a marina , where LOA is the $$$ detirminant , the choice of a box boat 3 or 4 stories high maximizes the cottages room and allows some privacy, at the lowest cost.
    If the box takes 30GPh its of no concern with only a few hundred hours (if that ) per year.
    Even the "trawlers" sold by folks that claim passagemaking ability , are usually top heavy and vastly overpowered for distance cruising.

    So far , ONLY the "Long Skinney boat" seems to have the ability to do any distance , at a good speed 10K+.

    This leaves us with the need for a custom designed (or early design , modified )to seaworthy scantlings and with 24/7 engineering for engine & equippment.

    My experience camping in a Greyhound Bus conversion 35 X 8 is very posative , it is enough room for 2 , but crossing an ocean is far easier with 4 total.

    3 hours on 6 off , skipper on call 24/7 , and filling in with the cooking and dishwashing has worked fine on a couple of sail trips to the Carribean for the winter in a 33ft sail boat.

    I'm with Portager in the concept of a trailerably hull , but the cost of an extra long tow does not get as expensive as an oversized hight or extra wide haul.

    I think a very fine & comfortable design could be 12ft beam and 65 ft long.

    The Air draft would be limited to under 9ft for the Euro canals , and to get her down to 13.5 on the trailer.

    Using the Computer on the AYRS site allows me to think that 5MPG should be possable at 12 to 15K .This I think is within the realm of a normal persons pocketbook.

    With Aluminum construction , the use of a marinized truck engine & tranny (to obtain efficency at low RPM), I believe such a boat could be built (to work boat interior specs) for under 100K.

  10. fcfc

    fcfc Guest

    Can you give a weigth estimate (empty/loaded)for your 65*12 proposal ?

  11. fcfc

    fcfc Guest

  12. Tad
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    Tad Boat Designer

    There are at least two threads going here, an economy coastal/inland cruiser, and an economy ocean cruiser. The two should really be split as the original question concerned an economy coastal/inland cruiser.


    An aluminum boat 65' by 12' might be about 37,000 pounds light ship. The raw aluminum might be about 11,000 pounds * $2.00. Nesting, cutting, shipping, and welding materials will be another $1 /pound minimum. So material cost for the shell will be 1/3 of your budget, paying nothing for labour perhaps you could do it.

    A professionally built aluminum boat, 54' by 11', bare bones (mostly empty) with minimum birch ply interior, no paint, and 65 HP Kubota engine is currently & locally about $350k CAD.

    A complete Kasten Coaster 40' in aluminum with no exterior paint, generator, stabilizers, bow thruster, or autopilot is currently $572k CAD. These are real numbers, not hopeful quotes.


    At 31000 pounds the Kasten boat will just manage 8 knots with 65 HP. At 10 knots she will stand on her tail and you will see nothing but foredeck from the wheelhouse. It will also require twice the 65 HP.

  13. tspeer
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    tspeer Senior Member

    Steve Dashew has taken the sail-boat-hull-as-powerboat idea and developed it into his FPB: http://www.setsail.com/dashew/FPB_Milestone.html

    On a smaller scale, right next to my trimaran in the dry storage lot is a boat belonging to Seattle NA Paul Bieker. This is a powerboat conversion of an Ultimate 30 sailboat hull. At the stern you can still see where the hiking racks mounted. But he's added a cuddy cabin, cockpit seats, and raised the aft skin (I find it hard to call it a deck since it's not flat) to hold the fuel tanks, etc. It's a fast, efficient powerboat for Puget Sound. I'm sure he picked up the hull for a song, so it's a cheap solution, too.

    He's told me it's the way he thinks powerboat design is going to go in the future - light and fuel efficient. I think he's right.
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  14. fcfc

    fcfc Guest

    The only problem of the FPB (other than the guessed 4M$ price) is that the concept is not really downsizeable.
    If you divide all by 2, you get a 41 ft LOA, 9 Beam, 6.5 BWL and 12500 lbs displacement.
    The closest I have found is this :
    Nigel Irens design, 3.5 nautical per gallon at 12 kts.
    Although a bit wider than pure scale (11 ft beam), the stability, loading capacity and space only allow this design to be a picnic / day boat.

    Or this : http://www.motorboating.com/motorboat/seatrials/article/0,12696,553628,00.html
    . A bit less efficient, (2 nmpg), but cruise 15 kts with twin engines.

    Just for info, these slender boats are only at a slighly lower (15-30%) price range of a great harbour 37. http://www.mirage-mfg.com/html/body_gh37.html who can go about the same efficiency if you don't want to go beyond 6-7 knots. (range 1475 nm with 500 gals incl 10%reserve at 6.6 kts).
    The living space is in another world.

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    FAST FRED Senior Member

    The concept of the hull/deck in aluminum at 1/3 the budget ($100,000US) cost would work just fine.

    If commercial assembly brought it to 50% that would work very well.

    Welding aluminum is a very straight foward process , with the correct gear.

    So budget wise that would work just fine.
    Here in CT with welders being released from Electric Boat , that come with their weight in certification , 2 @ $20.00 per hour EACH should make short work of a few thousand feet of welding.

    I had estimated the all up weight at 25,000 lbs , about doubble the hull weight.

    With fairly inexpensive interior construction (work boat not Yachty) the overall weight CAN be held down .This I would prefer to do, not contract.

    The "need for speed " at least 12K+ ocean cruise cuts down on the required supplies and crew .
    If you can transit in 10 days rather than 20 -25 , the ability of the weather guessers to allow a good weather window increases too.

    The detirminant of suitability for offshore is the hull & deck integraty ,and suitable machinery instalation not mere internal volume.

    As many circumnavigations have been made with 30ft sailboats , the volume and lifestyle from a 65X 12 (-8BWL)should be grand .AS would be the living conditions while at anchor.

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