easy, fast to build multihull with simple rig

Discussion in 'Multihulls' started by sailor305, May 15, 2012.

  1. redreuben
    Joined: Jan 2009
    Posts: 1,680
    Likes: 73, Points: 48, Legacy Rep: 349
    Location: Beaconsfield Western Australia

    redreuben redreuben

    Silver,
    The whole point with tricolour lights is they don't work on a rotating mast !
     
  2. Corley
    Joined: Oct 2009
    Posts: 3,741
    Likes: 175, Points: 63, Legacy Rep: 826
    Location: Melbourne, Australia

    Corley epoxy coated

    I've often wondered whether there would be a simple way of aligning the masthead tricolour lights on a rotating mast it does not seem an insurmountable problem all things considered a lightweight servo would be all thats required and a simple control module.
     
  3. redreuben
    Joined: Jan 2009
    Posts: 1,680
    Likes: 73, Points: 48, Legacy Rep: 349
    Location: Beaconsfield Western Australia

    redreuben redreuben

    I would have thought a fixed lightweight carbon tube straight up the axis would be a KISS solution ?
     
  4. Silver Raven
    Joined: Oct 2011
    Posts: 437
    Likes: 11, Points: 0, Legacy Rep: 67
    Location: Far North Queensland, Australia

    Silver Raven Senior Member

    Gooday 'Happy-daddy' How's bub?? Now re tri colour.

    Hey there 'Redrue' - give me a break will-ya-please. Been sailing boats for just a few days now. Few 'Hobarts', few 'Bris', few 'Cairns to PNG', few Trans-pacs.

    Fix/fit the tri colour to the forestay - what's the biggy here ???? Ciao, james
     
  5. Silver Raven
    Joined: Oct 2011
    Posts: 437
    Likes: 11, Points: 0, Legacy Rep: 67
    Location: Far North Queensland, Australia

    Silver Raven Senior Member


    Yes - fitted to the very top of the forestay - say in the last 70mm to 85mm above the top of the sail. You got it, it's easy-peasy. Ciao james

    OH Corley - HELP please - I tried to follow your instructions but can't get the 'weights' thingy out of the PM to send it to Michael & Gary - DAMN - very stupid older man - I is. What the heck can I do next, Please. james
     
  6. redreuben
    Joined: Jan 2009
    Posts: 1,680
    Likes: 73, Points: 48, Legacy Rep: 349
    Location: Beaconsfield Western Australia

    redreuben redreuben

    On a fractional ? Main will blanket at least 2/3 of it if viewed from aft which is it's function.
    Wont work on a roller furler.
    And is no solution for wind instruments either.
     
  7. Gary Baigent
    Joined: Jul 2005
    Posts: 2,959
    Likes: 102, Points: 63, Legacy Rep: 509
    Location: auckland nz

    Gary Baigent Senior Member

    Here are some directions for 9 - 10 metre wing mast build. For a taller mast you'd need to increase the thickness, 150 - 160 mm otherwise it would be the same process and materials. For column stiffness you'll need ud carbon laminates laid at the thickest outside section, also lowers and running backstays, imo, for a 12-15 m rig are required:

    Try this wing mast out Akaroa. You could add a couple of sections to make it a metre (or whatever) taller.
    If you want to go ahead I'd suggest you use 4mm ply, cut into 140mm wide strips, then scarph and glue them together to make your 9-10 metre mast length I beam, coat both sides with epoxy (lay out some plastic strips to lay the wet side on if you're in a hurry, otherwise do one side at a time) then cut out the frames, also in 4mm. Remember they need slots cut for the thin timber leading and trailing edge stringers plus elongated holes cut into them to carry your halyards. When they are shaped and epoxy coated, cut them in half where the I beam goes through, then glue and cove the front frames vertically to the I beam, along with the leading edge stringer. When that cures, flip the mast (lie it against a wall) and do the same with the trailing edge frames and stringer. There's your skeleton. Then with 3mm ply cut and scarph into strips, say 450mm, enough to bend around the frames to the trailing edge stringer, glue and staple both lengths to the leading edge stringer, let it cure overnight then next day epoxy coat the inside of the 3mm skin, epoxy glue the edge of the frames and trailing edge (make sure you've got your false halyards in, fishing line is good) then bend the skins over and staple them to the trailing edge.
    You don't want the inside coating to harden, otherwise you'll never be able to
    bend the stiffened skin. You can do this on your own but another pair of hands or two makes it easier. You want the frames to have a good layer of glue on the edges and if you tap along the skin, you'll be able to find the frames and staple them too, if necessary, but usually, if you tension both sides together and staple them to the trailing stringer, the frame glue will make contact with the skin. There's your mast.
    The mast spanner needs to be strong, but light and you have to cut holes for the halyards and sheave blocks and positions for your cam cleats, also cleats for the spanner rotation sheets - but they can also be placed on your main beam if you want to. There are no rules, whatever you like. The trailing edge of the spanner where your mast control sheets go through needs to be reinforced with carbon fibre - there are quite savage, fast loads there when you gybe.
    The main halyard sheave at mast top can to be set in afterward or before you bend the skins around - it is easier to just use a simple sheave, make a small plywood box to contain halyard from jumping sheave, then reinforce the outer mast skin, slide through your axle, then glue and glass coat the area. Needs to be solid, don't want it grinding lower from halyard loads. For the headsail (also offwind sails) I just use a delrin/stainless eye. Mast rotation makes normal headsail halyards fray against the sheave box sides - the eye works perfectly though. You can live with the little friction of an eye.
    The mast base bearings are male/female and the position can be either at the
    leading edge or in line with the I beam. This area also needs beefing up with
    carbon to handle compression loads.
    All this sounds complicated and a lot of verbiage but it is pretty simple and
    straight forward really. I forgot to say that from the hounds to masthead, the wing tapers not only fore and aft, but sideways too - so the I beam and frames will narrow in this area.
    For the hounds you make a rounded edge sort of beak shape out of wood or a
    couple of layers of 4mm ply glued face to face and then glue the beak to the
    leading edge of the mast and cove the connection edges with glue so you can run the uni directional carbon in a curve, no sharp or hard corners. You run the carbon tows, like in the drawing, so you spread them round the beak and up the front and the side of the mast over a distance of say, a couple of hand spans.
    When you have built up half a dozen layers, let it cure then drill out a larger
    hole for your shackle pin fitting near the end of the beak. Remember all the
    rigging loads will be concentrated at the bottom and front of that hole so make sure you have a good buildup of carbon there. Then fill that hole with epoxy glue - put some tape each side to stop the glue running out. When that cures, re drill the same size as your shackle pin. The stainless pin is now protected from contact with the carbon so there will be no electrolysis problems. When finished spread some lightweight filler over the carbon tows and when hard, lightly sand - there will be slight bulging there but once smoothed it will look fine. Far better, lighter and stronger than a whole lot of metallic junk up there. You can build your rigging "chainplates" in the same manner. I've done this for decades and never had any problems.
     
  8. gypsy28
    Joined: Mar 2010
    Posts: 218
    Likes: 25, Points: 28, Legacy Rep: 120
    Location: NSW Australia

    gypsy28 Senior Member

    Thanks Gary, great informative post

    DAVE
     
  9. Richard Woods
    Joined: Jun 2006
    Posts: 2,179
    Likes: 145, Points: 63, Legacy Rep: 1244
    Location: UK, USA and Canada

    Richard Woods Woods Designs

    To Silver Raven:

    I will try to keep this brief. When I answer a post I do so by saying what I know. Not what I have read, nor what I think/hope might be true. I also try to answer the real question the poster has asked. So if someone says they want a KISS style boat, and talks about gaff rigs and bamboo masts I try to see things from his perspective, not from my own.

    I am a designer and a sailor, not a boatbuilder. Having said that I have built many boats for my own use over the years. Which means building at home, not in a boatyard. I have built in sheet ply, tortured ply, double diagonal ply, strip plank cedar, foam sandwich and solid glass.

    By far the quickest and cheapest has been sheet ply.

    I note you agree we are talking about "flat panel" hulls, ie ones with straight sides. So not tortured ply, not round bilge, not even constant camber or CM.

    A typical hull will have a 10:1 L/B ratio. So a 10m hull is roughly 1m wide at the WL. So the most a panel will need to bend longitudinally will be 500mm. That is assuming a canoe stern. A transom stern hull will have less bend over its length. That is a MAXIMUM of 5% curvature, probably it will be nearer 3%.
    Suppose a flat panel 9mm ply hull is strong enough for a 10m long cruising catamaran, which evidence over the last 50 years indicates is a true statement.

    You claim a panel made your prestressed way " is 100's of times stiffer for the same weight as would be a single thicker piece of ply & it's already partly water-proof."

    If that were the case then there is no need to make it 9mm thick, so it would be thinner than that to be worth doing. So say 6mm thick, (for the sake of argument).

    You say make it from three layers. Ie 2mm each layer, assuming zero thickness for the epoxy (impossible of course). So where do you buy 2mm or less marine plywood? And at what cost?? The thinnest I can get in the UK, Canada or USA is 3mm and even that isn't "marine plywood"

    But even if it were available how do you actually make a boat your way? I can see how you make a test panel in a laboratory but how do you do it on a boat?

    I just cannot see how it can be done. But then unlike you I am not a boatbuilder. Please explain so that I know how to draw a boat for home builders that uses your technique

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
    1 person likes this.
  10. Richard Woods
    Joined: Jun 2006
    Posts: 2,179
    Likes: 145, Points: 63, Legacy Rep: 1244
    Location: UK, USA and Canada

    Richard Woods Woods Designs

    To Gary

    You are right. I am not experienced for I have never sailed a boat with a wing mast. I did think back though. Over the last 40 years I have owned 18 boats with rotating masts and 9 boats with fixed masts. I didn't reply until now as I was away sailing on my trimaran, fitted with a rotating mast. Next weekend I am racing a 35ft catamaran in the Swiftsure race, also with a rotating mast.

    I have also never sailed in Australia or New Zealand. You are obviously very lucky that you don't need to worry about being seen at night. I don't think anyone crosses the English Channel at night without a good working tricolour light. Way too dangerous

    When I home build a boat I want to go sailing in it. As I just said I am not a boatbuilder, it is just a means to an end. So the last thing I want to do is spend a few more hundred hours building my own mast. And I don't think a wing mast will be any cheaper by the time you add in a one-off mast step, hounds, gooseneck, mast spanner and buy a sail track.

    So when I built my Gypsy catamaran I bought a used mast. It cost me GBP50 (USD75). The original builder of my Romany bought a used mast, as did the builder of my Merlin, the last two boats I have owned.

    I had a quick look on Craigslist and saw this

    http://seattle.craigslist.org/kit/boa/3029816713.html

    advertised today. Probably would be fine for a 35ft cruising catamaran.

    You can buy a new alumimium wingmast of course, but there are only a few sections available. The one you would use on a 35ft catamaran is much heavier than a fixed mast. The only wood wing masts I have seen are the Gougeon ones and they are VERY heavy. Maybe yours are lighter.

    Bottom line is. Does the OP now want to build a stressed ply boat and fit a wing mast? or build a sheet ply boat and a fixed mast?

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  11. Silver Raven
    Joined: Oct 2011
    Posts: 437
    Likes: 11, Points: 0, Legacy Rep: 67
    Location: Far North Queensland, Australia

    Silver Raven Senior Member

    Gooday bloke. How are you proceeding in you effort to find 'what way to go'.
    It's always a difficult time - the original decission making process. Would you please answer Richards question - about which way you want to go - in your own words - so I'm not guiding anyone in the wrong direction, thanks.

    I thought that you were looking for;
    easy to follow plans
    not to expensive to buy the plans
    reasonable time-frame to complete building the vessel
    KISS principle to build & not to expensive at the stage of launching
    35' plus long c/w headroom for a 6'4" person to more around in with comfort
    able to be built - economically - in SE Asia
    powered by 1 or 2 moderate size o/b motors
    KISS rig - not to complicated & not to expensive & easily controlled
    Safe cruising multihull
    Comfortable long-term live aboard

    * I seem to know - you may wish for other assets ie;

    shallow draft due to cruising in the shallow waters of SE Asia
    efficient sailing vessel to reduce danger, increase safety, reduce cost
    be handled by 2 people with ease & safety

    May I suggest that you pay serious attention to an in depth look at Richard Woods designs of;
    38' Transit
    36' Mirage

    These may well - fall within your required;

    time frame
    plans cost
    building time allowance
    payload carring capacity, which is substantially above other designers figures
    & essential for your cruising desires.

    I think that Richard's 40' Rhea - open-plan - tropical living, plans are 'super' but may cost to much to build & take to long to build before launching which will eat-up valuable cruising time - that we are running out of. As Richard says - BIG boat & it is. 2 for sale in NZ - 1 @ 158,00 - 1 @ 115,00 sterling

    Regardless of Richards seeming desire to - argue with what Gary & I have put forward, as our opinions - which is his right (but totally wasted) - You - 'sailor305' would be wise to look into the value of Richards designs to get your boat under your feet & in the water promptly & within budget. Your value achieved will then to be - go sailing. Do it soon Mike & I'll come & join you. Ciao & good fortune in you hunt, james
     
  12. Gary Baigent
    Joined: Jul 2005
    Posts: 2,959
    Likes: 102, Points: 63, Legacy Rep: 509
    Location: auckland nz

    Gary Baigent Senior Member

    Well, those are excellent prices for alloy masts, Richard, and would be difficult/impossible to duplicate with a home built wing version ... but having said that, the expense in self building one is not high (compared to new alloy or carbon rigs which are out of sight); the six to eight or so sheets of ply and the epoxy being the most expensive components (not counting time) - and the 6mm luff track is just alloy curtain tubes, in 5 metre sections, very cheap, around 40 dollars NZ a length if I remember correctly. You roughen the alloy back section and glue it to the trailing edge wooden stringer, fill edges and glass tape the sides.
    Most people are leery of wing masts but to those who want to build, enjoy building, it is an alternative.
    The two 6.5 meter wing masts on the black dinghy weigh around 10 kgs each.
     

    Attached Files:

  13. gypsy28
    Joined: Mar 2010
    Posts: 218
    Likes: 25, Points: 28, Legacy Rep: 120
    Location: NSW Australia

    gypsy28 Senior Member

    In Richards defence, I dont think he's argueing James, He's just expressing his opinion same as everyone else:)

    DAVE
     
  14. sailor305
    Joined: May 2012
    Posts: 23
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Miami Beach FL

    sailor305 future cat builder

    Thanks to all for the sometimes a bit heated up discussion.

    Regarding Richards statement of a used mast. Yes they are cheap and as Gary said you can't build one for $500, but have you ever thought about shipping costs of a 42' mast.
    We are living in a containerized world and shipping lines are thinking in container and pallets only. So the bargain used mast may cost probably $ 3000 on arrival in SE Asia.
    And I guess, that we are then not too far away of building a new one.

    Boat design of multihull moved on together with new materials within the last decade. The main advantage seems to me that we can get light weight catamaran hulls with streamlined profiles which provide more hull speed and more payload.

    Sometimes I think, that the advantage of a catamaran to achieve about 50% more miles a day than a monohull seems to be forgotten due they become heavy gin palaces with a draft of a long keel mono, overloaded, averaging similar logs like comparable keel boats.

    In short, I'm looking for a light, fast but safe catamaran which can carry myself in safety
    wherever I'll go.
    Easy and fast to build, to maintain and go cruising asap instead of building four years or so.
     

  15. Mick@itc
    Joined: Jan 2011
    Posts: 98
    Likes: 4, Points: 0, Legacy Rep: 49
    Location: Melbourne

    Mick@itc Junior Member

    Try Dudley Dix designs!!
     
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.