CSC 30 Catamaran- the coastal passage

Discussion in 'Multihulls' started by peterchech, Nov 29, 2011.

  1. rob denney
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    rob denney Senior Member

    Almost all boats are built with polyester, without problems. Vinylester is better, particularly for thin laminates. I would not use either on ply, but with foam they are excellent.
    You said you were using WEST, so that is what I used. Generic epoxy will be around $13-14 per litre.
     
  2. Steve W
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    Steve W Senior Member

    As rob said the vast majority of production boats have been and still are built with polyester resin, absolutly nothing wrong with that. Higher quality builds are now done with VE and quite a few builders are now claiming the use of epoxy although I suspect they are more likely using VE and calling it epoxy which they can legitimatly claim as it is chemically related.
    Re the plywood choices BS 1088 Okoume is the gold standard mainly because of its realativly light weight and reasonably attractive color. All panels that are built to BS1088 are theoretically equal so you choose the wood species for appearance, weight or durability. There are many species that are more attractive and almost all are more durable than Okoume but when it comes to multihulls light weight rules and when properly protected with the epoxy of your choice it is quite adequate structurally. I wish someone would make a BS1088 panel out of paulownia, it would gain great acceptance in the marine industry I believe. I actually have a sample piece of 3/4" paulownia ply which is incredibly light but unfortunately the glue line is not waterproof as born out when I boiled some. It weighs 42.85 lbs for a 4x8 sheet. As a point of reference
    Okoume of the same thickness is 60lbs. This stuff has 6 equal paulownia veneers as a core and very thin face veneers of birch. The company claimed 46lbs sheet weight but when I weighed the sample on a very accurate triple beam gram scale and extrapolated I came up with 42.85lbs.
     
  3. Gus7119
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    Gus7119 Senior Member

    Rob and Steve Cheers. Now for the Question Rob was saying he wouldnt use poly or vinyl on ply. I was going to follow the theory of west system coating ply 3 layers glass hulls and under bridge deck. Well glass all outside if I can cost wise. But now Im confused if poly is used in most production boats and poly and vinyl are alot cheaper here then epoxy is there a legit reason not to use on ply. Westsytem resin seems really expensive and is it or is it not the same as other brands?

    Cheers Gus
     
  4. Gus7119
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    Gus7119 Senior Member

    Groper do you have pics internal of your boat? Whats the beam on the hulls? And do you know how much resin was used on your mates Easy and did he use epoxy or vinyl? As I have the expoxy and if viny is usex mainly I could sell the barrwls to buy heaps more vinyl but unsure of suitability.
    Cheers
    Gus
     
  5. Steve W
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    Steve W Senior Member

    Polyester is used for the fiberglass laminates on production boats where it is all laid up within a short timeframe and for this it does very well. In the early days when fiberglass boats were all stick built, as in fiberglass hull and deck moldings but plywood bulkheads, floors, engine beds etc all tabbed in to the hull, this was also done with poly with very mixed results. Polyester just does not do so well for secondary bonding. So, if you are going to commit to plywood construction also commit to epoxy throughout. I have seen 2 local Searunner 31 tris that were glassed with poly when built in the 70s get stripped and cut up and hauled to the landfill. This is not an area to go cheap.
    I don't know about the costs of epoxies in Aus but in the US there are many choices, I only use west brand epoxy where I work because that's what they buy, I would never buy it for my own projects, not because of price but there are many other epoxy formulations available for a lot less money with better properties such as higher tensile elongation, lower viscosity, sensible mix ratios and no blush formulations. I can buy epoxy for $35/ mixed gallon which is pretty reasonable but I still prefer ve for infusion work.
     
  6. catsketcher
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    catsketcher Senior Member

    If you are going timber Gus then you have to use epoxy. Epoxy is wonderful stuff that allows normal people to build lovely and strong wooden based boats. I would not use poly or vinyl anywhere near a wooden based boat.

    Except where you make your own fittings. I have seen glass steering wheels, have made glass deck hatches, and other fittings. You can use poly for some of these. I even made low load mast hardware using glass - gooseneck, mast base, mast crane, spreaders.

    Save money by doing smart things yourself - composite chainplates save hundreds, make your own bow roller assembly. Look on the web and at marinas and save money by finding ways to make your boat better and cheaper but don't use poly or vinyl on the hulls.
     
  7. groper
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    groper Senior Member

    i Wouldnt build a boat via wet layup in anything but epoxy at home - having a home or garage/shed near the house or other peoples homes constantly stinking with styrene fumes everyday is a bad idea- if your neighbors smell it theyll probably report you, if your wife constantly smells it youll be divorced, and for your own sanity id avoid it unless you like headaches or masking up with expensive charcoal filters everyday too... Rob denny advised the use of vinyl ester only under the premise that you were infusing with it - so its predominantly sealed up in a closed mold situation where the fumes are contained... Epoxy is the only resin to use with wood at its considered impervious to water, the other resins are not- and its the only resin to use for building at home or in suburbia...

    There should be photos of the interior in my build thread mate - but heres one showing the interior of the hull. My hulls are very narrow - only 660mm maximum beam at the waterline. As i live in sub 20degrees latitude tropics, we dont spend any time down below - its too hot and humid to be down there. The only time i go down below will be to use the head or goto bed...So this is why i designed it with galley up layout and i didnt mind reducing the volume of the hulls and with a bias towards lower resistance hulls more like that of a racing cat as i wanted the ability of cruise speeds in the +20kts range... a cruising sailing cat which spends more time around 8-12kts cruising speed doesnt really pay a big penalty to have more volume in the hulls, especially more beam...
    [​IMG]
     
  8. Gus7119
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    Gus7119 Senior Member

    Groper love the finish on your boat. Any reason you went for round port holes? I'll tet find your build posts as Im not to smart can you put a link up please. Thanks for info I have the expoy already so thats good just thought that if poly could be used I could buy a lot more if I sold the two barrels have.
    Do u also have a top down plan of your boat. If you dont feel like you want to share it its all good because I realise how much time and effort you put into your own design.
    As I said Im going to start 1st day of Feb and have organised my work so I have a week on the boat and a week at work. And have covered my rent for the next 6 months in advance and bills for same period so I cam make a real dent in the boat. Unfortunately it was the only way I could do it. It is a little crazy we can all admit. But Im so excited and know if I do it Itll be done right and Ill get the boat I want out of it without any need to make changes or being disappointed in the boat.
    So here we go...

    Cheers
    Gus
     
  9. Gus7119
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    Gus7119 Senior Member

    Steve and Cat thanks for the info. I already have two barrels of epoxy at a great price so got a little twisd thinking if I sold it I could almost by double the other two types. So will keep epoxy as planned.
    Australian prices for any brand epoxy are ridiculous. Hence groper suggestions that I try find a semi built project which would work out cheaper. But as explained I have to do it as money comes in And want certain things. And am pig headed :).
    Am looking forward to it more with you guys by my side itll make it fun. And if you see Im doing something stupid or going down the wrong path please dont hesitate to shout out as Ill need calm heads about.

    All the best for Australia day you Aussies.
    And cheers the rest
    Gus
     
  10. Gus7119
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    Gus7119 Senior Member

    Now for something out of left field.
    As the cat will have a huge amount of solar, a mate has been geting really excited as he has converted his entire house to off grid in the city. I have a thought. I can pick up a second hand prius electric engine for 500 bucks it can be rou from the solar batteries or a generator if need.
    My question is as these are really lite provide far more power then I will ever need and are efficient have I got my head in the clouds or does this sound like not only an interesting idea but a good one. I cqn even carry a couple of spares if the consensus is its a viable and good idea.

    Cheers
    Gus
     
  11. Steve W
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    Steve W Senior Member

    Gropers point regarding the smell of pe / ve annoying the neighbors is the only really valid reason to not use them when working with cored panels. I have not had any issues because I'm far enough away and use it infrequently enough. I am a big fan of VE for a number of reasons, it is very resistant to moisture and in fact is what the underground gasoline and diesel storage tanks at gas stations in the US are made with. Many repair yards here choose ve over epoxy for osmosis repair.
    Gus, I had forgotten that you already had your epoxy sorted out, good. Have you settled on what plywood you will use yet?
     
  12. Gus7119
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    Gus7119 Senior Member

    Groper foumd build disregard previous post.
    Cherrs
     
  13. groper
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    groper Senior Member

    Hi Gus - theres alot of info in that thread, hope you get something out of it...

    In the mean time re: your other question, heres 1 plan view that i drew a long time ago, but ive made some changes to it so its not built exactly as its drawn here, but it gives a pretty close depiction of it;

    [​IMG]
     
  14. DennisRB
    Joined: Sep 2004
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    DennisRB Senior Member

    Gday isladelobos. Love your model. You changed a lot on the design including making the beam wider. From what I have seen this comes with higher structural consequence than making the hulls longer. So I think you should not be worried about adding some length to the hulls in a minimalist fashion.

    Just keep the accommodation and rig etc the same, but give the hulls some more waterline without much weight or cost. This will help with the pitching motion, and it will make a big difference to speed. A cat this size when loaded will probably struggle to get passed the "hull speed" hump most of the time. With longer hulls the displacement to length ratio will be much improved and so will the length to beam ratio.

    There are plenty of threads on the forum on this subject which show the displacement to length ratio is the overriding factor when it comes to hull resistance.

    Also I vote for the cheapest foam and VE you can get.
     

  15. dialdan
    Joined: Jul 2008
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    dialdan Junior Member

    Problem with VE is it's shelf life .
     
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