I'm to design a canal cruiser that can handle high seas...

Discussion in 'Boat Design' started by solitaire, Aug 17, 2012.

  1. tunnels

    tunnels Previous Member

    Yeah same here used to ski behind my 24 foot trailersailer as well the big power boat guys used to get pissed after they had ploughed past pushing a mountain of water with a big smile so just a tug on the cord and a twist of the handle winch up the keel and we'd pass them and head off up a shallow stream they couldnt get within a mile of .:D:p
     
  2. Emerson White
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    Emerson White Junior Member

    After looking at the maps it occurs to me that everyone who uses them must be in the same boat, figuratively. To get from one stretch of canal to the next you need to cross lakes, and if those lakes are rough you need some kind of sea keeping capacity.
     
  3. solitaire
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    solitaire Junior Member

    Why couldn't the moderators have kept my thread in the multi-hull section, I wonder... You know DCockey is quite correct on his assumptions, to hats off to you mate. And that's from somebody basically conceived on a boat, so I hope that will put most overly concerned peoples fears at rest I'm sure.
     
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  4. solitaire
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    solitaire Junior Member

    You are quite correct on that David. The height limiting factor here is the ability to passing bridges without having them opened. Strömsholm Canal I believe runs on a timetable with one assisted lock and bridge operation in either direction a day, the intervals set to correspond to an estimate cruise speed. If you can't make the clearance, should you chose not to keep to that timetable you might get stuck until the next day if late or having to stay afloat and with no chance of mooring if early.

    Most other canals, let you either run the lock and bridge operations yourself should the canal not be one of the busier ones, or have very frequent or nearly instant assistance you're serviced immediately or each 10 mins or so. So most restrictions - and in essence what sets the SOR (you choose the meaning ;) ) - is that one canal unfortunately.
     
  5. Boat Design Net Moderator
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    Boat Design Net Moderator Moderator

    Currently there is the main Boat Design forum (where this thread is located now) which is the most appropriate place for discussing whole "boat design concepts, projects...", there is the powerboat forum which covers motorboats of all types, there is the (monohull) sailboat forum, and the multihull (sailboat) forum for discussion of "multi-hull sailboats, catamarans and trimarans..." Since the first post mentions "it's for motor propulsion" and the canal + lake requirement makes for a unique SOR, the main design forum should hopefully be a good place for a thread like this to develop.
     
  6. solitaire
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    solitaire Junior Member

    Thank you for filling me in on that. I suppose it's my not so precise wording that somehow seems to haunt this thread. From the onset the idea was having more hulls than one, so the thread was placed there to avoid singular hull suggestions. But I can see your reasoning on that more clearly than that of some.

    Should I want to make a post about a multi-hull motor vessel, then where do I post? In naval nomenclature I'm possitive a motorboat is said to be sailing when in motion.
     
  7. Boat Design Net Moderator
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    Boat Design Net Moderator Moderator

    For a thread about designing a new motor vessel, the Boat Design forum is the best place; the powerboats forum would be the second best place and a good place for discussing an existing motorboat or adapting an existing vessel; it includes any powerboat (motor-powered vs. powered by sails) from small speedboats to motoryachts at present.
     
  8. SamSam
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    SamSam Senior Member

    Go with the semi-displacement type catamaran...
    http://www.powercatgroup.com/cat-hull-types
     
  9. Frosty

    Frosty Previous Member

    This is one of those situations where it is better to please the teacher than answer correctly.

    It sounds like your teacher is a boat enthusiast,---probably a canal admirer with a little tub called 'sally', wears a blue blazer and a peaked cap and talks of storms and battoning down the hatches as he rolls on the canal waving his fist at the ducks.

    'Sally' has an anchor for those bad summer nights at the wide bit.
     
  10. erik818
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    erik818 Senior Member

    Solitaire,
    In my opinion you are going in the right direction with a cat. Also a displacement cat can be pushed beyond "hull speed" with reasonable power because the hulls are long and thin.

    For a cat to work properly, the hulls need to be narrow and the separation of the hulls should not be too small because of wave interference between the hulls. Also, the length to displacement ratio shouldn't be too small. On this forum there are numerous references to overloaded cats behaving like pigs.

    Start by making the cat as wide as possible. With my lack of skill as skipper I would need a beam less than 3 m or so to avoid touching canal walls that are 4.5 m apart, which would mean a monohull. Whether a cat is 3.5 m or 4 m wide wouldn't matter much; I would tuch the walls more seldom with a 3.5 m cat. In any case I would have to design the cat with sufficient rub rails to allow it to touch the canal walls without being damaged. I would probably go for a max beam of 4 m.

    The hulls should be longer than a monohull with the same load capacity. I'd set the length to just below 10 m. The advantage with a boat shorter than 10 m and slower than 15 knots is obvious to all Swedes.

    The least complicated propulsion would be two outboards with a power of 10 - 25 hp each (select them small enought so 15 kn is not exceeded.)

    Make a weight budget.My guess is that you land at 2 - 3 tonnes.

    Assuming that the BWL of each hull is 0.5 m and LWL is 9.5 m, the draft will be approximately 0.5 m for 3 tonnes displacement.

    The need for compromises arise when trying to meet the max 2.5 m height requirement. It would be nice to have full standing height inside (1.9 m) and also have a tunnel height that is enought to avoid waves slapping at the bottom. Assume that 0.2 m height (guess) is needed for hull connection beams plus roof beams, 0.4 m is left for tunnel height. Make masts, lanterns, antennas etc. on the roof easily detachable for that one bridge passage that restricts the height.

    Depending on your boat designer skills, the best route might be to start looking for plans for a hull that is close enough in the material you prefer and then modify it to get the exact size.

    Good luck with your project. Your SOR is not too far away from my own, except that I have fuel efficiency high in the list and prefer a monohull, so I'm interested in how you go forward.

    Erik
     
  11. peter radclyffe
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    peter radclyffe Senior Member

    your better off aiming for an overloaded pig behaving like a cat
     
  12. brian eiland
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    brian eiland Senior Member

    Attached Files:

  13. DCockey
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    DCockey Senior Member

    Brian, if you had the time to read through this thread before replying you'd find that there is wide variation in canals, and the Swedish canals Solitaire is interested in have limitations different than the Dutch canals your photos and links are relevant for. Also the boat Solitaire is designing will be used to cross open lakes, not just in the canals, and is a smaller and different boat than the ones in your links. The differences are appropriate given the differences in requirements.
     
  14. brian eiland
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    brian eiland Senior Member

    Sorry didn't have time to read thru it throughly. Butif I rmember correctly there are some discussions in that other subject thread about folks that wanted to be able to take their European canal boats across the English Channel, etc....and were not looking at multihull craft.
     

  15. Emerson White
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    Emerson White Junior Member

    The OP does not seem to want to do that.
     
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