Scarab 16

Discussion in 'Multihulls' started by Brorsan, Feb 6, 2011.

  1. Brorsan
    Joined: Nov 2007
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    Brorsan Junior Member

    Think hydro lake is a lake made to generate electric power out of the water. Washboard.. um that should be where you wash your clothes, but dont think that is what Megwyn mean. My guess is that it is a small piece of wood that stop water from the cockpit to enter the cabin. Like the ones that can be found on regular doors (the thing you slam your foot into when you are to tired to lift your feet high enough)

    :)
     
  2. Eric17
    Joined: Apr 2011
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    Location: Marennes France

    Eric17 Junior Member

    Hi Brorsan & everybody !

    Well, I still don’t know what a washboard could be on a boat (something to do with the whirl following a boat I suppose), but I posted the translation of Merran’s commentaries on our french site http://www.nauticaltrek.com/12516-scarab-16-le-retour-d-experience-de-megwyn-et-trevor, and the questions/answers during the boat’s auction http://www.trademe.co.nz/nz/auction-248435145.htm as well (what does "GOP" on the first line mean ??)

    But after this testimony, I changed my design three times, to have enough buoyancy under the cockpit, with a slim and good looking mainhull : not easy :-(

    If you look at some pictures on Ray’s website, you see than with just the engine and Trevor in the cockpit, the boat is already sitting very heavily on her stern… (~ idkfa's submerged transom :)). Makes me think of an electric drive like this one : http://www.duckworksmagazine.com/11/howto/trolling/index.htm

    Cheers
    Eric
     
  3. Eric17
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    Eric17 Junior Member

    I forgot something !!

    yes, @Merran : do you still have the pictures you posted during this auction ?
    or other ones ?
    If yes, could you post some of these here ? I think everybody would be very interested :)

    thank you...
    Eric
     
  4. jamez
    Joined: Feb 2007
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    jamez Senior Member


    In a boat without cabin doors the washboard(s) drop into a groove either side of the companionway to close the cabin off.

    GOP = Glass Over Ply
     
  5. Eric17
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    Eric17 Junior Member

    Thank you Jamez !
     
  6. idkfa
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    idkfa Senior Member

  7. oldsailor7
    Joined: May 2008
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    oldsailor7 Senior Member

    Thom D said:- "There is a ton to be said for small cats, particularly the Jarcat".
    and I agree with him".

    I was languishing "between boats" when my wife and #2 son clubbed together and bought me a used Jarcat as my 65th birthday present.
    When my younger children saw it, they said "Why it's just a little shoebox".
    The name stuck and it became "Shoebox".
    It was a great little sailer and came with trailer.
    It had one double and two single berths, a folding table, chemical toilet, radio, compass, speedo, anchor and chain in the forward stowage locker, outboard motor, metho two burner stove and cutlery drawer complete four place sets, curtains on the windows. It had a full set of sails and at no time did it ever feel as though it was unstable. The self bailing cockpit made it an ideal base when the younger kids wanted to go swimming at anchor off a beach.
    It was by no means a racer, but a really great all round fun boat.
    There is a guy on Pittwater who I have seen zipping around in one with a huge assymetric spinnaker, and hiking racks. So it's no slouch and like the Buc 24, it is light and simple to build.
     
  8. luckystrike
    Joined: Feb 2010
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    luckystrike Power Kraut

    You are not wrong! No need to loose volume with TP!

    Take a look at this F 16 building blog, done with TP. Please note that the hull has a very full underwater body from the midle of the boat to aft. The trick is in the third (middle) panel at the keel line to give a lot of extra volume there.

    http://www.thebeachcats.com/pictures/?g2_itemId=11955

    Greetings from the North Sea Coast, Michel
     
  9. Eric17
    Joined: Apr 2011
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    Eric17 Junior Member

    critical speed

    thank you Idkfa, very good links.

    Using the formulas given, and for a Froude number of 0.5 (maximum resistance), the critical speed for a ~5m boat would be 7 kts... Couldn't be worst, I fear, as there is no 'gas handle' on our boats to increase the power and go over this limit.

    I notice D. Newick never used submerged transoms, and his boats have nearly no wash nor whirl following them. Maybe we should upgrade our project, Brorsan, and build a Tremolino :-D :-D
     
  10. Samnz
    Joined: Nov 2008
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    Samnz Senior Member

    problem with TP is that to get full sections you need to flatten the body line. A tri centre hull needs lots of boyancy aft so the shape is all wrong. TP would be ideal for the floats, but just wont work well for the main hull
     
  11. luckystrike
    Joined: Feb 2010
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    luckystrike Power Kraut

    Samnz,
    we are talking about amas in TP building method, nothing else.

    This is what is said above and this is what I mean too. For todays amas you need a lot of volume. Its a good thing to have a trick to increase volume and still build with the fast, light, simple and cheap TP. The Blade F16 has very round and full aft sections as you can see on photos in the mentioned building blog.


    Grreetings from the North Sea Coast, Michel
     
  12. idkfa
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    idkfa Senior Member

    Eric17 not sure if I understand, we are talking multi not mono?

    If done right, one can increase the apparent hull length, especially on a multi, granted there is more drag at low Fn when a double ender would be best.

    Gas handle? It's called a spinnaker and many monos break Fn0.5 with it. A lot of the change in multi shapes we see now, are an optimization for top-speed downwind, at the expense of upwind, not that I'm agreeing with them for small tris
     
  13. Eric17
    Joined: Apr 2011
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    Eric17 Junior Member

    You are right, "critical speed" was not the good word. I was thinking of the huge increase of resistance at a Fn = 0.5 speed, (that seems to be = 7 knots on a 5 m boat...)

    And yes we are speaking of a tiny trimaran, wich for me would be mostly singlehanded : I will need long time and experience before I launch the kite !! A reacher maybe...
     
  14. oldsailor7
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    oldsailor7 Senior Member

    Not if you use a launch/retriever tube, as in dinghy racing. :D
     

  15. Corley
    Joined: Oct 2009
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    Corley epoxy coated

    Bob Forster has designed an interesting boat in the Wavelength 780 it folds and is built in vertical strip ply built in a half female mould it's much bigger than what you are proposing but may be an option to help with achieving the shape you want in your mainhull.

    http://smalltrimarans.com/blog/?p=3211
     
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