Design proposal - help needed

Discussion in 'Boat Design' started by Jon E, Feb 13, 2017.

  1. UpOnStands
    Joined: Nov 2015
    Posts: 334
    Likes: 1, Points: 18, Legacy Rep: 16
    Location: Sydney

    UpOnStands Senior Member

    interior height over keel in the cockpit is what? 1.26m? minus thickness of roof and floor etc.
    so internal height available for engine is 40 cm? what type of engine?
    Canoes work only if the paddler is active in controlling stability and of course are much slower.
    Your flat keel, high bow, and fine sections suggest that the boat will be impossible to hold to a line in wind or cross waves.

    For OP, which part of Skagerak? Seems as if you are looking at travel times of 6-10 hours depending on weather. Very few of us can sit in a constrained cocoon for that length of time -- for a race, maybe.
     
  2. fallguy
    Joined: Dec 2016
    Posts: 59
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: usa

    fallguy Junior Member

    What about smaller Wood's Skoota? Some more cost in an extra hull(inside humor aside Richard), but lots of margin of safety. Richard might not like me suggesting it, but the instant I saw the picture of the boat crossing Juan de Fuca, I thought about his Skoota 20. If nothing else, well worth checking out if you like boats.
     
  3. HJS
    Joined: Nov 2008
    Posts: 251
    Likes: 15, Points: 0, Legacy Rep: 288
    Location: 59 45 51 N 019 02 15 E

    HJS Member

    Internal height available for engine is 70 cm
    Interior height in the cockpit is 150 cm

    Calculate and test, no guesswork, please.

    js
     

    Attached Files:

  4. Jon E
    Joined: Jan 2005
    Posts: 51
    Likes: 3, Points: 0, Legacy Rep: 22
    Location: Norway

    Jon E Junior Member

    Proa sounds very interesting, Stumble. I don't know how much it will attenuate rough weather either. Anyone having experience?
     
  5. Jon E
    Joined: Jan 2005
    Posts: 51
    Likes: 3, Points: 0, Legacy Rep: 22
    Location: Norway

    Jon E Junior Member

    Very interesting HJS. What about stabilicing your suggested hull with a proa? Easy construction in aluminium is important, so the shapes must not be too complicated.
     
  6. UpOnStands
    Joined: Nov 2015
    Posts: 334
    Likes: 1, Points: 18, Legacy Rep: 16
    Location: Sydney

    UpOnStands Senior Member

    my understanding is that proas are not great if the wind/wave direction is variable.
    Constant tradewinds are its specialty.
     
  7. Mr Efficiency
    Joined: Oct 2010
    Posts: 5,485
    Likes: 67, Points: 48, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Gawd, I wish those cooling trade winds had been blowing a bit more in the Australian summer.
     
  8. UpOnStands
    Joined: Nov 2015
    Posts: 334
    Likes: 1, Points: 18, Legacy Rep: 16
    Location: Sydney

    UpOnStands Senior Member

    bet the foam cored hulls got soft, real soft.
     
  9. HJS
    Joined: Nov 2008
    Posts: 251
    Likes: 15, Points: 0, Legacy Rep: 288
    Location: 59 45 51 N 019 02 15 E

    HJS Member

    Check email, private message
    js
     
  10. Stumble
    Joined: Oct 2008
    Posts: 1,884
    Likes: 67, Points: 0, Legacy Rep: 739
    Location: New Orleans

    Stumble Senior Member

    In an absolute sense I don't know, but a friend owns Jzzero, a pretty famous ~37' sailing Proa he soloed/duoed to New Orleans from Seattle. With an average speed from Panama to New Orleans of about 14kn. But this has a lot more liveaboard capability than you would need.
     
  11. peterAustralia
    Joined: Mar 2006
    Posts: 339
    Likes: 21, Points: 0, Legacy Rep: 233
    Location: Melbourne Australia

    peterAustralia Senior Member

    My handle on the concept is this. A low power long thin displacement Hull.

    A starting point may be the 21 feet long boat that Seiko namajira crossed the Atlantic with. Power was a, 2.5 hp tohatsu outboard. Beam was 5 feet and draft was 2 feet. Just scale up his boat by thirty percent or so. I think 15 knots is too high. I think 9 or 10 to be much more realistic

    Just Google tohatsu outboard Atlantic Ocean crossing for the website
     
  12. Turnpoint
    Joined: Jun 2011
    Posts: 45
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Port Townsend

    Turnpoint Junior Member

    I would definately recomend a power catamaran or stabilized mono for this type of craft. You will need a very fine hull shape to meet your power requirements and if you go with a monohull you will create a vomit rocket unless you add some form of active stabilizing system such us stabilizer foils and or a gyro stabilizer system.

    I would much rather have a boat like Richard Woods Skoota that you can walk around in, carry some people and overnight on if you needed.

    I have made two boats that are applicable (im not trying to sell these designs but hope my experience is usefull). The first was a 24 foot trimaran with a 20 hp outboard and 20 knot cruise speed. The customer uses it often to cross the straight of juan de fuca which can have some terrible conditions for small boats ... open ocean swells stacked up by large currents and usually on the beam. Teh tri is safe in these conditions but can develope an uncormortable motion and wants to broach if surfing a big swell. It also leans outboard in the turns which feels really weird. We have since added hydrofoil assist and the speed is now up to 24 knots but the biggest gain is its stability... it now has a comfortable ride and stays flat in turns.
    The second boat we made was a 24 foot cat with twin 20 hp outboards. This is my own boat that I use to get accross the Straight of Juan de fuca. The ride is a lot more comfortable and you can take more people and gear, take the kids inner tubing, knee boarding, sleep overnight, and walk around. The trimaran feels like a motorcycle and the catamaran feels like a comfortable mini van. On a long trip I would definately want to be on the catamaran. We also added foils to this one and top speed went from 20 to 24 knots... but the biggest improvements were in ride comfort in a seaway, and load carrying ability. Without the foils the boat would start to get bogged down with more than 3 people and now we can have 6 people onboard and still maintain 20 knots.
    Hope some of that helps your search.
     

  13. philSweet
    Joined: May 2008
    Posts: 1,989
    Likes: 91, Points: 48, Legacy Rep: 1082
    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    An appropriate length for an efficient 1 ton craft would be about 24 feet or 7.3 meters. Additional length won't help in rough conditions. For cheap, you want an outboard motor. That also limits your options for hullform. The good news is that this was exactly the challenge faced by boat designers during the 50s and 60s when outboards were just coming into their own. Johnson introduced the V4 50hp outboard around '58. Look at the '60s commuter and utility designs for inspiration. There are a few modern interpretations.

    http://yachtfocus.co.uk/new-boat/nieuwbouw/75777/statement-marine-pts-26/

    note, they seem to be listing the speed as 15km/h, not in kts, which is a bit cheeky, or a typo. And this one happens to be 2.5 tons. Keep the design, drop the amenities, maybe shave a couple inches off the beam, swap the diesel for an outboard, and I think you are getting close.

    more eye candy

    http://www.prinsvanoranje.nl/en/yachts-for-sale/yacht/yacht/1/88190/Rapsody_R29_Classic_-_New.html
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.