Long - Skinny Power Boats

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

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  1. I am a member of the Antique Boat Museum in Clayton, N Y and our volunteers love to help any walkin to the library. What kind of goofball management does Mystic have to allow that. Have you notified the Director or the Chief Curator?----------If that fails. There are hundreds of other museums.
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    FAST FRED Senior Member

    Would the table of offsets be enough , or do you need the entire plan set?

  3. announcer
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    announcer Junior Member

    Thank You Fast Fred

    Fast Fred,

    I do have a table of offsets that were in one of Garden's design books. What transpired since that was printed is when the owner of the boat died Garden bought back the boat and added in new design features like a get home sail plan and a new keel that made the bow not slap the flat bottom anymore. According to someone close to Garden he also made offsets for an 80’ and 100’ boat in the same paperwork.. This might be pure speculation except it came from close source to Garden and with Garden’s attention to detail there could very well be a new set for both new sizes.

    Since he did remodel the boat after buying it from the estate I think this is the only way to see the way he wanted the boat to look after and for all new copies that people would be compelled to build. He was quoted in his book as saying with the vee drives and longer hull with sleeping quarters added it would be the closest thing to the sound of sailing in a motor boat anyone could get With a new turbo small diesel combined with vee drives and very wet exhaust sitting behind the pilot station forty feet you could sneek around anywhere. I think it would be a great canal cruiser in Europe and also be able to make the coastal hops to the next set of canales much better than the long boats of Europe that sit so high.

    With an even longer water line the hull speed would be very high and probably could be pushed there by a small diesel just barley above idle to give it some turbo boost and good oil pressure but most of all very miserly fuel use. With enough tankage and a clear hole in the weather it could give people on fixed incomes the ability to cross an ocean without renting space on a freighter and the ensuing insurance costs with the terrible fees for boats over forty feet..

    An amusing side note to this is, I was the manager of an Algae harvest company and I built a 110 foot Algae harvest boat. Since both owners of the company were felons ( yes I did not work there long after watching the drug use) I registered the boat in my name and myself as the builder, a very true statement since none of them had ever built any boats at all.. Very soon I had motor yacht magazines subscriptions coming in almost every day and tickets to a big yacht show on the French Riviera where they wanted me to take my creations and show them to the beautiful people of the world. I guess registering a boat over one hundred feet puts you in some kind of club I knew nothing about.

    How I wish I could have taken my twin hulled Algae harvester over there complete with a crew streamline travel trailer for sleeping bolted ten feet off the deck and the 12-71 gen set roaring at full throttle with the forty by thirty Algae screen sitting out over the bows. What an entrance, they would have had to get the French navy to sink it before it bumped any of the precious French floating cream puffs could be damaged..

    To bad all the big boats I have built so far where for fishing and work. BTW I did also design the algae harvester. It is still working out on Klamath lake and selling pond scum to people that don’t have enough sense not to pay $600.00 an once to eat the stuff.
  4. Skippy
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    Skippy Senior Member

    To the Riviera, that's hilarious..... Please post pix if you're ever able to. :)
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    FAST FRED Senior Member

    OEM status is precious if you are planning on building another boat.

    Discounts from list of 50%+10% are NOT to be sneezed at!

    Wish engine mfg were as generous as hardware hawkers .

  6. Packeteer
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    Packeteer Junior Member

    good to see that somebody has already mentioned the Dashew boat

    nice boat and very efficient!
  7. safewalrus
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    safewalrus Ancient Marriner

    Welllllll, I've waded through all the stuff in this thread for some reason I can't figure - the question was I believe about the viability of a l-o-n-g slim motor boat! As the man at the start said 'depends what you want it for?'

    From experience - back in the 60's we (the lot I was with at the time) had occasion to come across several vessels of that type - long slim canoes with ginormous great outboards on the back, used I believe for smuggling cigarettes (light payload!) around the Malay and Indonesian islands. When we first saw them we chased 'em they just opened up the throttle and were gone like **** of a shovel - the only thing we could catch 'em with was that stuff which comes out of the front of a gun! and with the speed aiming was pretty awkward! So yeah they do work! (we wern't really interested in that particular commodity at the time so didn't push it to much).

    Interesting to note that certain UK Special Forces now have a couple of the same style of vessels (only more sophisticated build) which have the same style of movement - bloody fast in calm water - depends what you want it for?!? As a yacht? to get you there and back in time for tea, OK but for comfort? Try a hotel - or sleeping bag in the bilge?

    well that's my pennyworth! of use?
  8. yacht371
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    yacht371 Yacht Designer

    Economy in cruising yachts

    I'm a late comer to this thread, but I have read through all of the posts. I think that we could come up with the true cost of yacht ownership in a formula. Don't ever tell your spouse!

    Recently I bought a new car. I didn't lease but I did evaluate lease rates. Interestingly, the best lease rate offered was on a BMW 3 series, cheaper than on several other makes that cost less to buy. Why? Extraordinarily high resale value!

    A major part of boat ownership costs is what you can sell it for when you are done. I know from bitter experience that even the finest custom yacht drops about half its value on launch day. Home builts are even worse. Popular production boats with inboard diesel power depreciate the least.

    So the true cost of the boat equals:

    B is the cost of buying or building the boat including taxes (don't forget to value your time properly if you build her)
    S is the net selling price after brokerage etc.
    F is the money spent on fuel during the time of ownership
    M is maintenance costs during that time
    P is port charges, moorage, shore power and other such charges
    y is the number of years owned if you would like to put costs on anannual basis

    Now plug in some real numbers. I happen to have owned a lot of boats and I have those figures handy, but I'm reluctant to publish them in case my wife reads this...:D

    These are based on real world numbers, the first a benehuntalina 35 and the second a custom built wood/epoxy boat of the same general size. This was done much earlier so the actual dollars look similar in purchase, but in reality bought at the same time the custom boat would cost about double. I used sailboats because that is what I have numbers for.

    Benehuntalina 35
    ((152000-122000)+600+12000+15000))/3=19200 P.A.

    Custom Wood/epoxy 35
    ((120000-39000)+950+36000+18000)/6=22658 P.A.

    The better resale value of the production boat, and possibly lower maintenance more than makes up for the longer ownership time of the custom boat. All figures rounded for clarity, but it makes very little difference.

    I make a good bit of my living designing custom boats but I always tell the clients what they are getting into. If they are rich enough, or plan to keep the boat so long depreciation is not a factor, they may still go ahead. Many say "thanks for the info" and go buy a production boat.

    You will note that changing fuel prices would have little influence on the above equations. With a power boat the fuel numbers will be bigger, but depreciation will still be the major factor.

    That said, a well made fuel efficient production power boat will have low depreciation. Price out used Nordhavns...might as well buy a new one!

    For a fuel efficient production boat see the MC27 at www.aviadesign.com
    This has twin hulls of B/L ratio 14:1 and overall beam of 8'-6" so trailerable. It isn't designed as an ocean voyager but as an economical coastal cruiser but we are in the planning stages of a trans-atlantic voyage in a diesel version.
  9. flipper08
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    flipper08 New Member

    some other considerations

    When we discuss the design of long and slim hulls it might be worthy to consider a couple of very important considerations. First; weight always plays a big part in the overall picture because weight equals displacement, and more displacement always costs something; speed or fuel. Within the hull of any boat, space is always a major consideration but there can always be a balance between space and structural strength. "Space frames" have not been widely used in boats but they should be considered because of the tremendous advantages in terms of their weight to strength ratio.
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    FAST FRED Senior Member

    ""Space frames" have not been widely used in boats but they should be considered because of the tremendous advantages in terms of their weight to strength ratio.'

    With modern cored construction a very strong hull can easily be done almost as a tea cup, no framing at all inside.

    For speed a looong hull and a D/L of under 100 seems to be the best answer.

    How cheaply the vessel can be constructed very light is a different consideration.

  11. moTthediesel
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    moTthediesel Junior Member

    Very glad to see this thread revived, it's one of my all time favorites!

    Interesting to see what changes have come about since it was started. Four years ago we were fretting about oil prices of $54/bl. Who would have guessed then that it would double in that time? Makes you wonder what things will be like in 2012 doesn't it :?:

    Last edited: Apr 10, 2008
  12. Tad
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    Tad Boat Designer

    My latest "long and skinny" is 39' by 7'. Construction is plywood. Weight is less than 5000 pounds, power is a 50 or 60 Hp outboard in a well. D/L is about 52 thus she will eaily run up to S/L of 2.4, a little less than 15 knots. At 12 knots her S/L is 2, reqired power is 22HP and around 1.8 gph for 6.5 mpg.

    Of course the accomodation is that of a boat 10-15' shorter, but the speed and motion in a sea will be far superior to shorter boats.

    The form is based on Garden's Tlingit, I call it a Motor Canoe.



  13. Chris Ostlind

    Chris Ostlind Previous Member

    Slender Trimaran

    I really like that boat, Tad.

    My take on this genre is a bit different.

    Four person utility transport with style.
    30' LOA
    3' BWL
    2800 lbs. displacement
    Beam in passenger compartment 4.5'

    Folding amas for dry storage and trailering.

    30 hp four stroke gives 16.5 knots with a 12 knot cruise at half throttle. It coulda been optimally skinnier, but I wanted the trailer length to be something manageable on a regular basis.

    Attached Files:

  14. charmc
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    charmc Senior Member


    I like the concept, but 3' BWL doesn't seem enough for side by side seating, unless there is a lot of flare that I didn't see. I'm neither a giant nor a body builder, but my shoulder width is a good bit more than 18". I think 4' would be a minimum for comfortable seating.

    The look is neat, very original for a power launch.

  15. charmc
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    charmc Senior Member

    Very nice, Tad. That bow is a work of art.
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