Cheers Proa scaled down

Discussion in 'Multihulls' started by valery gaulin, Dec 28, 2017.

  1. valery gaulin
    Joined: Jan 2017
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    valery gaulin Senior Member

    I have two complete laser rig laying around that are close to brand new. Looking at Cheers video the sail ratio look very similar to the one from a laser sailboat.

    Can someone tell me if Cheers could be scaled down in size to make use of my Laser rig? I was thinking of around half size, around 8 foot beam to fit on a trailer without disassembling it for transportaton.

    Would it still be a fun sailboat (proa) at around half the size?

    Are Cheers plan available?
     
  2. Russell Brown
    Joined: Jul 2012
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    Russell Brown Junior Member

    No Cheers plans available besides what is in the Cheers book, but check out what "Proa Sailor" has been doing on the SA multihull forum
     
  3. rwatson
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    Location: Tasmania,Australia

    rwatson Senior Member

    I think your project would be a worthwhile exercise.

    My personal opinion is that the only really functional and useful Proas are the ones be designed by Rob Denney (HarryProa), and his latest configuration for the large ones, is a schooner rig with two identical sails. eg. 30′ – Harryproa http://harryproa.com/?cat=40

    The concept, with the mast on a longer hull, and the accommodation on the windward hull for extra righting moment was the favorite layout of the famous Joseph Norwood,

    Norwood, Joseph
    21st Century Multihulls
    Norwood presents some good arguments for his "modified-Pacific
    Proas" in 21st Century Multihulls. You can *buy* the book from
    AYRS for 10 GB pounds. Well worth it, IMHO (and the fact that
    I "work" for the AYRS doesn't cloud my thinking one whit ;-)
    Joseph Norwood is an *outstanding* author, and knows his
    stuff. (Dave Culp) The Proa FAQ http://www.boat-links.com/proafaq.html

    Booklets https://www.ayrs.org/booklets/
    Publication No 120

    Between Rob Denney, the AYRS and Jo Norwood, you should get some useful design ideas.

    From my experience with amateur design and multi-hulls, your project should be quite doable. You may not want to got the exotic hull materials of Rob Denney with high density foam and glass, but a couple of plywood hulls can give excellent results.
     
  4. valery gaulin
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    valery gaulin Senior Member

    Thank you both for your reply.

    Are you really the Russel Brown that design Jzerro? Respect for this amazing design.

    Years ago I was following quite a bit the proa group on yahoo, and this Jzerro proa was my inspiration. I made a proa model but i eventually chicken out to instead built a trimaran.

    My trimaran was somewhat of a success because it was entirely built out of riveted aliminum. I learned quite a bit from this built. Wife and kids came to my life, therefore i needed a more conventional sailboat, I am now sailing my Grampian 26.

    Proa are still in my mind, I am aware of all the different style, Pacific, Atlantic, Harry, etc. I am just looking at my next project!!!
     
  5. Clarkey
    Joined: Aug 2010
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    Clarkey Junior Member

    Sounds like a charming idea. Half size would be 20' x 8' wouldn't it?

    I don't suppose there would be much load carrying potential but what a stylish and classy daysailer for one or maybe two (at a pinch).
     
  6. Russell Brown
    Joined: Jul 2012
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    Russell Brown Junior Member

    We re-published the book "Cheers" after years of getting the go-ahead and working in it. It's available in print at amazon for $12.95 or from us at http://ptwatercraft.com
    There are drawings of Cheers on the inside covers, lots of photos, and one hell of a story.

    If you use two Laser rigs, plan on lateral resistance aft, as the boat will want to round up. I built a proa with two laser rigs and it sailed great, but the aft rig was used more for trim than power.
     
  7. rwatson
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    rwatson Senior Member

    Sounds like a hull COE problem, not a schooner rig problem.
     
  8. ThomD
    Joined: Mar 2009
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    ThomD Senior Member

    Well you would have to know how to scantle a Newick design, but that is not overly complicated. The lines are easy to construct from the lines in his study packs or from the book, and he used a master mold system which is extremely easy to reverse engineer.

    As far as the rig: 1) Never take a shortcut like that to commit you to a large building project. The fact you have some rigs kicking around is not sufficient reason to start down a long path you would not otherwise have valued; 2) An Atlantic proa is very stiff there is no healing to spill the wind, be sure your rigs can work.

    If you respect Russ' Pacific proas so much why would you do an Atlantic? There could be any number of fine reasons, just curious.

    There wasn't much to Cheers in the first place, if you downsize her you will have possibly less than you want.

    It was incredibly inspiring what Cheers achieved, but the boat itself was a kludge. That wouldn't necessarily mean it shouldn't be copied for fun, but it could certainly be improved. I don't know what to make of the whole Atlantic proa thing for starters. Kinda a one hit wonder.
     
  9. rob denney
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    rob denney Senior Member

    Great idea, well worth doing from a 'fun' point of view. There are plenty of things you could improve if the sailing is more important than the scale model aspect. A linear scale will probably not work. The hulls will be too low at the bows (as were Cheers'), and at 6'6" wide, it will be too tippy. Cheers' rudders will not be much fun on a day sailer. Don't waste effort and weight on the pod and consider making both decks the same from a build time point of view.
    To maximise the fun, keep it light. If you want to keep the shape, 3mm tortured ply with external 120 gsm glass for the hulls, 3mm foam with 200 carbon each side for the decks , carbon tow rather than bulkheads to spread the loads, carbon rather than wood for the beams top and bottom.
    I doubt the laser rigs will last past 12-15 knots of breeze as the boat will be too stiff. Use bigger section alloy if you want to use the sails (I wouldn't, they are too full for fast sailing). Windsurfer rigs tied to stub masts work well and give options for rake, camber and different sail areas. The masts are easy to stiffen by adding carbon.
    I have had lots of schooner rigs, ELEMENTARRY – Harryproa http://harryproa.com/?p=1753 the trick is to treat them as a main and foresail. ie, don't oversheet the front one. Rounding up will be reduced if the long hull has the waterline carried all the way to the end and there is no daggerboard. With the Atlantic configuration, I suspect lee helm will be more of a problem, but rudders which can still steer when they are lifted will sort it out either way.
    Any specific questions, feel free to ask. Definitely get the book, it is a great read. Props to Russ and his wife for republishing it.

    Do you have any photos, specs, blog etc of the alloy tri?

    rwatson,
    Thanks.
     
  10. valery gaulin
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    valery gaulin Senior Member

    Any suggestion on what material to use? Plywwod epoxy or a little more exotic , foam- carbon fiber?

    Basically the original Cheers weight 2800kg scaled down to half size, the weight should be no more than 350 kg including 1-2 crew. This leaves a half scaled Cheers proa weighing around 200kg. Is this possible using plywood epoxy building method or foam carbon fiber is the way to go?
     
  11. Russell Brown
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    Russell Brown Junior Member

    Valery, Did you look at the hull designs that I was telling you about on the SA forum? Some beautiful hull shape choices and some would be easy to build in plywood. I'm pretty sure that if you asked, he would finish a hull design where full sized patterns could be printed for hull panels and bulkheads. It's pretty amazing how lightly one can build in plywood.
     
  12. valery gaulin
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    valery gaulin Senior Member

    @ Russel Brown, Thank you, I just check his website, Joseph Oster. Interesting, he wrote a script to generate proa hull form in a parametric drawing software, Rhino. Not familiar with Rhino, I use Autodesk Inventors or Autodesk Fusion 360.

    @ Rob Deney, did not do a blog for my aluminum trimaran but I did send couple pictures and updates to smalltrimarans. com. Here is a link: Aluminum Trimaran on the Water | Small Trimarans http://smalltrimarans.com/blog/aluminum-trimaran-on-the-water/

    Overall it sailed well but not the first time!!! LOL I did not get a chance to sail it in big windy condition. Being alone all the time to trailer, assemble, putting it in the water etc. got really difficult once the kids got in the pictures!!! I needed a normal sailboat and a marina!!! Therefore I refitted a 1973 Grampian 26 that I currently sail every summer!!! Love it.

    I will take some times in a next post to explain what work well, what did not work so well and what needs improvement in my trimaran if there is any interest!

    This trimaran is still sitting in my backyard...
     
  13. rob denney
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    rob denney Senior Member

    Pretty easy using ply. Elementarry, the 25'ter above weighed 140 kgs with it's 22 sq m unstayed schooner rig. Laminate is 300 carbon either side of 6mm foam, which is over built (we had the materials from another job). It is now 10+ years old and has had a hard life, including being airborne for about 10 metres and landing on the beach when we lost control of a big kite. No damage except to the outboard which smashed it's bracket. Elementarry is 4m wide. The beams telescope so we tried it at 2.4m and it capsized too easily to make it fun. This will be less of a problem with an Atlantic proa, but being caught aback is bound to happen at some stage, which will almost certainly lead to capsize the wrong way.

    3mm gaboon/okoume ply for a tortured ply build weighs about 1.5 kgs per sq m. 3 layers of epoxy each side and light glass will add about another kg. 2.5 kgs total.
    3mm H80 foam weighs 0.24 kgs per sq m, plus 200 gsm per side to fill it and 300 gsm of carbon cloth and resin each side, if you bag it. 1.24 kgs total. If not, add another 300 gsm. 1.54 kgs total. So about half the weight with foam and carbon.

    The ply one will have wooden stringers and frames and a bog keel, the foam one can include these in the laminate for almost zero added weight.

    Building a double or triple chine hull will be different to the original, require thicker ply than the tortured ply version, take a lot longer to build and require more fairing. Fusion 360 should handle the design or use the method in the Gougeon's book.

    I am definitely interested in the tri, which looks very nicely designed and built.
     
  14. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    Get that tri in the water!
     

  15. BlueBell
    Joined: May 2017
    Posts: 198
    Likes: 9, Points: 18
    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    Is it in?
     
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