Low Displacement/length ratio boat designs

Discussion in 'Boat Design' started by Theotilus, Feb 27, 2015.

  1. Richard Woods
    Joined: Jun 2006
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    Location: UK, USA and Canada

    Richard Woods Woods Designs

    Have you considered a power catamaran? Maybe something like our Skoota 28 which does everything you are asking for.

    Lots of space, good speed (12 knot cruise) economic (6mpg with twin 20hp outboards). Designed for cruising places like the Salish Sea

    Check here

    http://www.sailingcatamarans.com/index.php/designs/6-powercats/264-skoota-28

    here

    https://www.youtube.com/watch?v=UGW3qWib0RQ

    and here

    http://woodsdesigns.blogspot.ca/2014/07/cruising-broughtons.html?view=magazine

    Currently our own boat is ashore in Port Townsend. We will be coming back to it next week and then be living on board full time until September. You are welcome to visit any time once we are back on board. There is also a larger 36 ft version being built in Steveston

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  2. Theotilus
    Joined: Dec 2014
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    Location: Bellingham, Washington

    Theotilus Junior Member

    I have looked at your designs several times. The Skoota 28 "fits the bill" really well.
    I would like it to be more easily transportable and the build would in my humble opinion be more complicated than a monohull. The Skoota 28 does offer very spacious accomodations for a boat of its size which my wife would definitely like. It is very likely that we will get over to Port Townsend at some point this summer so I will pay you a visit if you are in port. Since I am an experienced aluminum boatbuilder, what would you think of building the 28 out of aluminum - pros and cons. Not sure I would attempt the build in aluminum, but I consider that option with every design I look at.

    I really appreciate all of the thoughtful and informative answers to my thread. I am finding that there are quite a number of options out there. It is a matter of choosing the
    one that bests suits our needs.
     
  3. Tad
    Joined: Mar 2002
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    Tad Boat Designer

  4. Rurudyne
    Joined: Mar 2014
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    Location: North Texas

    Rurudyne Senior Member

    The Ned looketh good to ... scene of moths escaping wallet ... dang!
     
  5. AlexMorozov
    Joined: Jul 2004
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    Location: Spain

    AlexMorozov Custom yachts

    LDL is right way for boats which is designed for running, others just confirm Alik's opinion, have alook at Slovenian OverBlue44 :confused:
     

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  6. WestVanHan
    Joined: Aug 2009
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    Location: Vancouver

    WestVanHan Not a Senior Member

    Salish Sea..you mean the Strait of Georgia


    Anyways if you use Yachtworld's advanced, and plug in parameters you'll get ideas:

    http://www.yachtworld.com/core/listing/advancedSearch.jsp

    You may also look at Bill Garden's designs,he has lots of long and skinny boats of which the most extreme was Tlingit at 65' by 7'.
     
  7. Richard Woods
    Joined: Jun 2006
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    Location: UK, USA and Canada

    Richard Woods Woods Designs

    The Salish Sea includes the whole PNW from Tacoma to (I think) Seymour Narrows. So includes not only the St of Georgia but also Desolation Sound, Juan de Fuca and Puget Sound which are now all in the "Salish Sea". Which is just a recent PC name for the area and presumably cost Wa and BC tax payers thousands of dollars to so name.

    The Skoota 28 is fuel efficient in part because it has lightweight multihull scantlings (6 and 9mm ply) rather than fishing monohull scantlings, as many powercats have.

    An aluminium boat will be built with roughly the same number of stringers and frames as a wood boat, but will use 3mm plating. So clearly will be very much heavier than wood. Furthermore, people generally don't like a metal interior but want a wood one. That's already "built in" when you build a wood boat, but is extra non structural weight on a metal one.

    So I am afraid you cannot build a Skoota 28 in metal. Sorry

    Every boat is a compromise. Yes it would be nice to have it easier to transport. But there are not many live aboard 28ft x 14ft cruising powercats that can be assembled by man/woman power (been there done that) nor transported by road without permits (again been there done that - our Skoota was built in Sequim and went 40 miles by road to Port Townsend to be launched).

    If the cabin is transported on the aft bulkhead then the total load is 40ft long and 7ft wide. And, at under 4000lbs towed weight (1.8T), it can be towed behind a regular pickup truck

    Look at the photos of the Skoota in the water, can you see the joins? I chose this photo because , again, there are not many live aboard powerboats that can beach like this

    Because of the lighter scantlings and engine size, material cost is lower than a more conventional build. Build time is around 2000 hours and you can have one built in Wa for USD125,000 including engines ready to cruise. Or, as the builder has quoted "without engines, accessories and final painting a grand total of $84,867.00"

    Obviously long narrow monohulls have very limited room inside (check out the British "narrow boats") but you tend pay for moorings, marinas, licenses, insurance etc by length, not volume. So not good value for money. Interestingly, more "Narrow Boats" capsize each year in the canals of England than cruising catamarans in the English Channel

    And narrow boats tend to roll more and are generally unseaworthy in a cross sea. I talked to the owner of Winifred

    http://pacificmotorboat.com/dreamboats2

    (scroll down) a couple of years ago and he said he was quite concerned crossing the Juan de Fuca in a F6 and beam sea.

    Finally, I think I have said this before, but worth repeating.

    The power catamaran is not a new idea. In fact the second boat ever to be driven by a motor was a power catamaran, back in 1788. Check this page for more

    http://en.wikipedia.org/wiki/Patrick_Miller_of_Dalswinton

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     

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  8. Theotilus
    Joined: Dec 2014
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    Location: Bellingham, Washington

    Theotilus Junior Member

    Tad, thanks for the links. Especially like the "Eagle". By the way, I helped Bill Childs with the majority of the aluminum fabrication on the Timbercoast 23 he built a couple of years ago. It was a fun project and was a great looking boat. Really admire your designs.

    Richard, I kind of figured that an aluminum Skoota would be heavier. It is just something I consider when looking at a design. I wish I could say that I have picked out a design. Half the fun for me at least, is exploring all of the different designs and how they would meet my requirements. Frankly, I never get tired of looking at boats. I clearly at this point have no idea where my searching will take me.

    Again, I really appreciate all of the information and comments that have been contributed to this thread. This has all been invaluable to me.
     
  9. Hoppoz
    Joined: Apr 2011
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    Location: Australia

    Hoppoz New Member

    Has anyone found any follow up on the article about Nigel Irens Design that was referred to in the Woodboat Article? Apparently he is looking to start an online community?
     
  10. nemier
    Joined: Jan 2004
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    Location: North Vancouver, Canada

    nemier Specialist in long-range Expedition Yachts



    I hear you brother. Your thoughts echo mine. :)
     

  11. popobowa
    Joined: Apr 2012
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    Location: Tanzania

    popobowa New Member

    I am studying the market for fuel efficient power boats. Obviously one will have to resort to a multihull when choosing a short LWL....Supercat (South Africa) make an interesting 38'..mostly as fishing boat , but seemingly very "customisable".
    Tennant Catamarans were built with fast long range in mind.
    Then there's the Dashew's designs (FPB's)...very costly though
    I further found this (a bit similar to FPB): http://www.elburgyachting.com/sp/s5043en.htm?b=NED70 Alu Long Range MY&t=ix&st=13579&f=ixen.htm&h=0

    All of those mentioned should be able tu give you app. 2nm/gal @ 8knt

    I am getting ready for a few years of cruising and considering such a vessel compared to a sail Yacht...the overall costs are not more on the powerboat.
    Then one can consider a good motorsailer...but there are not many around and they tend to hold their price well.
    I would be happy for ideas.
    rgds
     
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