easy, fast to build multihull with simple rig

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

  1. cavalier mk2
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    cavalier mk2 Senior Member

    I'll chime in with everyone here. While I don't think a round bottom hull is harder to build a sheet ply boat will be faster to build for most people. A stressform or cylinder moldhull can build quickly but adding the internal pieces will slow down people not used to getting out the shapes. For round hulls the defined shapes of a molded boat let you work interior structure into the set up and use lofting to get out parts but the skin builds slower.....All compromises.... A Woods or Wharram or similar would probably be the way to go for you. Conventional wood masts can be easily built from suitable local lumber. If you don't have plans you could size out the scantlings from the web or "Skene's elements of Yacht Design".
     
  2. guzzis3
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    guzzis3 Senior Member

    As well as Richard Woods designs consider Mick Wallers stuff:

    http://www.wallerdesign.com.au/cs35.html

    I've linked directly to what I would build given your criteria, or on of the similar RW cats.

    I know some people love Wharrams and I really couldn't care less about arguing the point. I don't hate them but unless you specifically want a Wharram the Waller and Woods boats will build as fast and cheap and give you more accomodations and probably better sailing on many points.

    The reality is if your trying to build a cruising cat cheaply none of that s**t matters, round bilge, building method, whizzo masts. What you want is some decent size hulls, sound connecting structure and some canvas up in the wind.

    Pick any good design, build to spec or consult the designer on changes and you'll have a good boat that will serve you well.

    The difference in total cost will be trivial. I realise that prices vary from place to place but using really top quality ply in aus nowdays is just about as dear as foam sandwich, and strip/epoxy has long been near as dear as foam polyester. More important the cost of your hull skins disapears into the dust as the total cost of the boat adds up, same with plans cost.

    If you want to minimise cost to build you have to be on top of EVERY cost, every dollar and cent you save on every component. Not just masts and winches, every cleat, every through hull because there are buckets of these little things that will add up.

    As Mr Woods says I'd probably go sheet ply if cost was my main driver. The sexy slim rounded hulls go faster on race boats but on a cruiser unless you build something awful they make stuff all difference. Think about what your going to be doing.

    In open water your either:

    Becalmed, in which case sexy hulls and rig might help (and this happens a bit at the equator) but an outboard soon sorts it.

    In big wind, in which case controlling your speed is the issue, not maximising it.

    In big water, in which case reserve bouyancy and easily handled rigs with low center of area are your priority, and of course structural integrity. It'll be now that your wondering of that lauan ply you saved so much money buying was such a great idea...

    Be aware a lot of the kite marked ply in south east asia is rubbish.

    Last point. I personally rate designers. There are, if you like, the A grade multihull designers, the also rans and the duds. I suppose everyone would have their own opinions on who makes which list. Unless you have a specific reason to deviate your really a lot better off going with an A grade designer. The cost won't be very different but the certainty of getting a good boat at the end of it is high. IMO Mr Woods and Mr Waller are on the A list, as are some others. Move away from this and what you get ranges from quirky to hopeless.

    So don't sweat over hull shapes, build methods and rig types. Just pick a nice design and be careful how you source stuff.

    2c.
     
  3. Silver Raven
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    Silver Raven Senior Member

    Design considerations

    Gooday 'Guzzi'. What a great & informative post. I do trust that 'sailor305' will pay attention to what you've wisely said. It seems that the cost of the hulls & crossbeams/bridgedeck is acknowledged by most - to be only 1/5 of the total cost of the whole project. As you've said - pay great attention to every little detail or you'll not have enough money to finish the project. Again - agree with you, hulls, mast(s), building method is all 'small potatoes' compared to the big picture - - make choice, keep simple (KISS), tight budget & get started. When finished - go sailing & smiling - you'll live longer.

    Thanks for your input cobber.
    Caio, james - just up the road from you.
     
  4. Silver Raven
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    Silver Raven Senior Member

    Why?

    Gooday Mick. Why would anyone choose Dudley Dix? Just who is he anyway? Are his designs in anyway offering any of what 'sailor305' was asking for/about in his first post.

    I've looked at D-D web-site presentation & can't see that the designs have anything special going for them that other designers are offering.

    What's the go here ??? Ciao, james
     
  5. guzzis3
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    guzzis3 Senior Member

    Seconded. The backpack 38 looks like a tiki 38 with slightly truncated v, so possibly a bit nicer but you'd go the waller 35 before that boat every time. Or flica in plywood ? if you want a bridgedeck

    http://sailingcatamarans.com/flica34.htm

    or meander for open deck

    http://sailingcatamarans.com/meander.htm

    Your really better off picking a designer with a LOT of multihull experience and a good reputation for backup during build.

    I should have mentioned before:

    For a given build method the material cost for the hulls etc will be proportional to the weight, so get an accurate empty weight and that'll give you a good idea what it'll cost.

    Epoxy and core materials are most of the cost per area. If you use two layers of ply your using a lot more epoxy and 2 thin sheets are usually dearer than 1 thick one. Glass is relatively cheap unless your using carbon/kevlar or some exotic weave obtainable only from suppliers in the foothills of the hymilayas.

    If you sit down with plans from various designers you will see some manage to bog you down in labor intensive details or are wasteful of materials (remember most cores come in 8x4) so the boat is a lot harder to build or more expensive on materials. This is another reason to go with someone who thinks the design through properly.

    Tri's are smaller and have less carrying capacity as you say. My rule of thumb for cruisers is 20% longer, so a 40' tri has similar carrying and accomodations as a 35' cat, obviously that can vary a lot but it's a starting point...

    If your building in SEA just remember while these boats are designed to be built by amateurs they are not designed to be built by idiots. There are some skilled workers in sea as with anywhere there are some imbeciles too. If your hiring off the street and managing your build every time your back's turned your cheap labour might be doing something stupid that may kill you later. I'm an engineer and I have to deal with suicidal labour all the time. Remember human stupidity is infinite, and your $5/hr labourer cares not at all if the boat falls apart 6 months after it's built.

    2c.
     
  6. mcm
    Joined: Sep 2006
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    mcm Senior Member


    Great directions !
    Do you know where we could find photos or drawings illustrating each step ?
     
  7. sailor305
    Joined: May 2012
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    sailor305 future cat builder

    Well, as far as I understand all your appreciated input hull shape, building method and type of rig are less important.
    But isn't this the basic structure of the future boat? It indicates displacement, hull speed, draft, payload, wave piercing and more. For me it should be well thought.
    I figured lout that all the designer mentioned in this thread are offering quite heavy displacement plans and I have some doubts if the advantages of a catamaran ability to sail away from bad weather are getting lost.
    Whenever sailing mono hulls I have been frustrated on their speed limitations by wide beam and undersized rigs. The only exception has been a McGregor 65 and some other boats at this size which are all out of my budget.
    So I'd really like to learn about light weight round bilge hulls with high payload proposed by Gary earlier.
    Thanks again to everybody.
     
  8. rob denney
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    rob denney Senior Member

    Me too.
    Hull shape is important, but the range of what works is enormous.
    Build method is critical to time taken and cost, also affects the weight.
    Type of rig will determine performance, ease of use and peace of mind.

    Check out the Visionarry design in http://www.youtube.com/watch?v=8chR6DAFjGA 15m/50' long, weighs 3 tonnes/tons and has payload of 1.7 tonnes/tons. It could carry appreciably more (the leeward hull is empty), but would sail slower.

    There is a "sports" version of this boat with a different saloon/cockpit layout. Weighs almost a ton/tonne less.

    Length is a poor parameter to save money on. Visionarry weighs about the same as Richard's Scylla 35 so would cost near enough the same to build. Visionnary has more waterline length so is faster and more comfortable to sail (compare the above video with the motion, speed and ease of sailing at http://www.sailingcatamarans.com/flica34.htm) Visionarry also has more space, payload and a much easier to handle rig.

    All the above are strip planked timber, which is great for curvy shapes, but is a slow, tedious and relatively costly way of building boats.

    Plywood was once the best way to build cruising cats quickly, but has been superceded by infused flat panels. Much less weight, labour, waste and maintenance. Also far less likely to be messed up by unskilled labour than plywood construction. See http://www.youtube.com/watch?v=j5idbIo19jA&feature=youtu.be This hull is for a pro built 15m daysailer. Cost $40,000 plus rig and is on target to weigh 500 kgs, ready to sail.

    A larger, but not longer or wider version of this boat would fit your parameters without taking forever to build, or breaking the bank.
    .........................................
    A free standing carbon mast is the lightest, cheapest, least maintenance option for a new mast. The mast tube on the 15m in the first video weighs 120 kgs: 50 kgs of carbon ($50 per kg), 18 kgs of glass ($10/kg) and 52 kgs of resin ($18/kg). Materials cost $3,700. About another $1,000 for the consumables, bearings and all the fittings. Less than 100 hours work for the tube, using techniques similar to those used to build the rest of the boat. It is also the easiest to sail with.
     
  9. Silver Raven
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    Silver Raven Senior Member

    Gooday Rob Denney - What a fabulous post. Thanks so much for sharing your vast knowledge. Greatly appreciated by all including 'sailor305 - I'm sure.

    A few questions here - if I may be so blod - sure hope so.

    1/ When cabon fiber(re) & high quality epoxy are so reasonably priced - which they are - especially for several rolls - etc, etc - why do people seem to feel/think it's out of the reach of the average yacht building person - as it's a excellent materials choice & quite obviously very good value for money & affordable ???

    2/ Why do some people choose - not to listen - to your - many years of experience with building masts & doing so at a very reasonable cost/value pricing ??

    I just don't understand. Everytime I raise the subject - someone - somewhere - wants to - shoot me down. That is by the way - not bothering me personally - it's just counter-productive to this 'forum' & in this place. They can find a 100 side issues to 'argue' about but don't seem to wish to focus on the facts. 1/ - ti can be done & by a competent amature ("not different nor more difficult than building the hulls, bridge-deck, cabin, c/b's & rudders) & 2/ it is affordable c/w many side benifits.

    I mentioned to 'sailor305' that he might be well advised to consider building his own mast as well as the boat itself. Several reasons for this not the least are; his awkward location & also the transport costs. Instead of that - people who should know better - saying - that might be a possible way to go - they chose to make a lot of negative comments. Someone said they got an alloy mast for a cat for $75 or something like that. WOW - what an intelligent comment - NOT. Not withstanding many other problems - the mast would cost $2000.00 USD to freight to the Philippines which is where 'sailor305' will be building his boat - if in fact it ever got there &/or in 1 undamaged piece - which I sincerely doubt. Next comment was something to the effect - that they could buy an Alloy 'wing-mast' cheaper than build one. Double NOT. I've been 'playing with boats' professionally for a few years now & I've never seen a - alloy - wing-mast - in the real terms of wing-mast & as far as building one as cost effective as a carbon mast - wing or
    otherwise - such as the ones that your so expertly build - well that suggestion is just preposterous.

    Why is it that - seemingly professional people - jump in - where they don't have any expertise - as if they knew all the answers - and mis-lead the very people we are trying to help & in so doing - make total fools of themselves & all of us as well ????

    Last but by no means least - your 1700 kgs of payload - is IMHO grossly inadequate. I've spent 4 years culling down the weights & costs of the safety & yachting gear - I need to keep me safe & sailing well - for 3 to 4 people for a period of 6 to 12 days & I can't get the total weight much under 3000 kgs & that's for a frugal minimalist type sailing adventure. So how big do I need to go to get that kind of payload. I'm sure that you - of all the experienced people in these forums - don't need a breakdown of my 'weights estimates' however I can assure you I didn't include the dinning room setting for 12 people, the lounge sofa nor the washing machine, drier, 2 freezers, fridges & ice-makers. Looking forward to learning much from your answer. Ciao, james
     
  10. sailor305
    Joined: May 2012
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    sailor305 future cat builder

    add on

    Hi Rob Denney,

    I like your Proa design a lot. Something different and simple but roomy and practical and not the floating 1 million dollar gin palace or the heavy plywood designs from yesterday. Although I like classic boats a lot but building a new one seems to me a step backwards

    The central location of the salon, helm and galley is wonderful due this is the most comfortable place with minimal motion. To shunt it can be learned for sure.
    Fascinating is the speed potential and we all know that more length means a faster boat.

    However, there are some questions I'd like to add to James ones

    1, No question asked, make the boat heavier means to make it slower.
    But where is the max. payload?
    2, What about seaworthiness, capsizing factor and hull speed?
    3, Do you have standing headroom for 6'4"?
    4, When I'm understanding you right the non accommoadation hull can be
    used for storage (workshop, emergency bunks?)
    5, Your rig seems to me also quite interesting and can be handled with ease.
    How many winches and what size are needed?

    Cheers,

    Mike
     
  11. gypsy28
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    gypsy28 Senior Member

    Hi Silver Raven, Could you explain whats included in the 3 tonnes for 4 people for 12 days:?: 750kg per person seems alot to me, but I spend up to 2 weeks on a camping on a Hobie 16 so I'm used to living light:D, sorry but just cant see where 750 kg could go?:rolleyes:

    Thanks,
    DAVE
     
  12. Richard Woods
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    Richard Woods Woods Designs

    Rob

    You cannot compare the Scylla with a Flica. They were both designed in the early 1980's and have similar hulls. But the similarities stop there

    The Scylla is an open deck fast cruiser with daggerboards and a big rig.

    The Flica is a heavy full bridgedeck cabinned boat with twin diesels and a small rig

    Apples to oranges

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  13. Silver Raven
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    Silver Raven Senior Member

    Gooday Dave. I'll PM you the 'weights estimates' as soon as I can remember how to do it.

    I'd be very interested to see you "spend up to 2 weeks on a camping on a Hobie 16 so I'm used to living light" - sailing throughout SE Asia with 3 or 4 people, food, safety gear, water, etc, etc for 6 to 12 days on your Hobie 16.

    Now I'm sure I did at least try to explain - that this was an ocean going tri & the trips were not in the harbour but out in the big oceans. Sorry if I left that out.

    I'll try to get the figures to you. I'd be interested to hear what you have to say especially - what I've got wrong & need to leave off the boat - oh - & still travel safely. Thanks, Ciao, james
     
  14. Richard Woods
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    Richard Woods Woods Designs

    The proof is in the sailing

    I attach two photos I took in the Bahamas when cruising on my 34ft sheet plywood Romany catamaran, built by a chiropractor in 2300 hours. The first is of Sunburst, a yellow hulled 36ft open bridgedeck, round bilge catamaran with a big rig and daggerboards. It was built using CM/tortured ply with a lot of help from J Watson of Gougeon fame. The owner told me "never again"

    The second photo shows it during a race. As I say, taken from our Romany. You can see which boat is ahead. We beat it to the windward mark, despite having a central cabin, keels, not daggerboards and a fixed second hand mast. And we pulled away from it offwind despite not using a screecher (as they did). We were both couples living on board and had both sailed down from the Chesapeake. Mind you, Sunburst wasn't that slow a boat, the PDQ36 and Fountaine Pajot 48 were way out of sight behind.

    I still think it is a big jump to go from a gaff rig and bamboo masts to a carbon rotating wing mast. I guess you have seen Kurt Hughes recent comments on infusion. Is Corecell, epoxy, glass, carbon fibre made in SE Asia? If not then it all has to be shipped in. And if you ship in hull building materials then why not a mast?

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     

    Attached Files:


  15. gypsy28
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    gypsy28 Senior Member

    Gday James, I simply misunderstood your statement theres no need for the tone of your PM, I understood we were talking about safety gear not the entire fitout of a cruising catamaran, engines-solar pales-cutlery!, and YES to answer your somewhat sarcastic question, your weights do add up.

    As I said I'm a small boat cruiser (Hobie 16) so some of your numbers seem extravagant to me, but thats my personal choice. Plus if theres not a little bit of risk then wheres the excitment :cool:

    DAVE
     
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