CSC 30 Catamaran- the coastal passage

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

  1. redreuben
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    redreuben redreuben

    shelf life

    VE's shelf life is massively enhanced if you bubble dry air through it at least weekly.
     
  2. dialdan
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    dialdan Junior Member

    Didn't know that, lost about a third of a drum too shy to use it again , Iso poly and foam are great.
     
  3. redreuben
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    redreuben redreuben

    VE loves a temperature boosted post cure too. I even like the smell, I think it's sweet ! Although it's been awhile, might have worn off.
     
  4. Gus7119
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    Gus7119 Senior Member

    Havent settled on ply yet but know that Id be silly not to use best stuff for bulkheads and chimes and keel. Honestly Ive been doing alot of reading and some purists may have a heart attack but theres been alot of old ply boats that are doing just fine using ply thats got no voids and Agrade glue which is sometimes sold as marine grade flue, or is marine grade not sure on that one. But Groper mentioned a mate building with BB grade ply that has a tolerance for cavities only very small with a over all allowance that I would think would be acceptable bue to the fact Im going to be doing it properly and not cut corners with coating the thing.
    My main desire is that the waterline be as tuff as nails and bullet proof. Next s that with the usual maintenance that it lasts till the very least Im dead. There is no concern for retail or resail value as Im building for my wife and I. I want something I can live on after my son finishes school. Rents here in Australia well Sydney Anyway are more then a mortgage by qlmost double in some parts. And as Ive lived on boats a feq times and my mrs and I have been together since she was 15 we are used to close quarters.
    I am goimg to be doing the boiling test on thw wood as Steve I think said he had done just to test consistance. All that said though if I cant find a supplier of decent ply of a decent quality I wont waste my time but I dont rwally wat to pay 120-180 a sheet of A grade marine ply. If I did I might as well go foam as groaper stated itd work out cheaper.
    So the Answer is NO but I have a mate whos returning on Thursday whos a boat builder. Interestingly hes made the comment that neither he nor most builders he knows has not built a boat in over 15yr so why thry call them boat builders makes him chuckle. Here Oz you can buy a 200000 old mono for 15k or less and put 20k in qnd shes good as new so unless your in some parts of Queensland or Western Australia theres not to many boats built.

    Now heres a qustion Ive always heard of people sandwiching foam between layers of ply to make cabintops and bridge decks like the bad diagram below. Does anyone have any thoughts on this? I have sailed on a cat many many years ago that was entirely constructed this way hulls and all and it was nice. Apparently very lite and really solid and a mate saw it sailing in Pittwater today so its gota be at least 20 years if not morw old.
    Love your thoughts on use of this idea for coach house and bridgedeck floor.

    Cheers
     

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  5. Gus7119
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    Gus7119 Senior Member

    catsketcher really interested in what you built. Ive built hatches before to save moey out of plexyglass with a tinted film on it and they worked great they also cost 1/20 of the cost of buying them. Plus there still out there as I did a toe rail repair on the boat 2months ago and they looed almost as good as new 4 years later.
    Any online planes or video of hardware design and builds really intrested in as not only have a very limited budget but really want to make the boat mine hence going fo a very eclectic own design grabing a bit from here a bit from there and lots from the great advice Ive had here. Mate if everyone who was going to build a boat had this much support more boats might actually get finished.

    Cheers
    Gus
     
  6. Gus7119
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    Gus7119 Senior Member

    Diffrent Hull shapes

    Sorry for the many qoestions. But the only stupid question is the one not asked Ive always been told..

    Now below is a diagram, again a poor one, with three shapes. Lest csc30 is 1 CKD 2 and Others 3. the cs 30 has chimes which combined with keels the idea is to help stop slide. Although that said many cats have been built with none and keels. And then Wharram like bulkheads with triangle base.
    Now obviously 2 would be easiest to build then 3 then 1. But is there a major major difference in performance between the 3 designs when talking a cruising cat not a race cat. Looking for comfort while sailing and while sitting at mooring. (Very crude and obviously not to scale or with angles set)

    Cheers
     

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    Last edited: Jan 26, 2016
  7. Steve W
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    Steve W Senior Member

    When you infuse flat panels on a table you are able to take advantage of the cost savings of bulk buying your resin and you also use it up fairly quickly so shelf life is not an issue.
    Re the ply /foam sandwich I have done quite a bit this way for decks, cabin tops, cockpit soles etc. Sometimes I have used ply on the inside, foam core and glass top skin, I dry fit the panels, mark the bulkheads etc on the under side, then remove it and mask off the gluing surfaces then epoxy seal and pre finish before installing. Again use good quality materials.
     
  8. Steve W
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    Steve W Senior Member

    Don't know what happened there. Mask off the glue area and the epoxy and pre finish the panels before installing. Again, use quality materials. Cored panels are always going to be stiffer.
     
  9. catsketcher
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    catsketcher Senior Member

    As to hatches - they are easy - make a flat mould out of MDF and pine surrounds. Cove the edges and seal. Coat with wax and you have a mould for hatches. Personally I don't like perspex hatches in the deck as they let too much heat in and are slippery.

    You can put ply on foam. Lightest I have done is 6mm as people's heels have a lot of pressure. One great reason NOT to do it is that you should vacuum bag the thing, or you may get some serious air voids. A large gluing area should a runnier glue mix than say a cove (say runny hiney rather than smooth peanut butter) but still the pressure needed for a large expanse is really only suited for vac bagging. It isn't that hard at all - a compressor venturi will hold the vac after the vacuum cleaner has pulled the air out.

    As to hulls - don't worry. I will say it again because it seems so counter intuitive but the hulls don't matter too much. All of those hulls shown will take about the same time to build. YOU are by far the biggest factor in this.

    I met Peter Snell last holidays - he can build a pair of 40ft Easy hulls in about 4-6 weeks (IIRC). The whole boat takes him about 10 months and it is top quality throughout. I have an acquaintance who has taken about 4 years to make two smaller Easy hulls. Hulls are not what is going to slow you down. Hulls are fun to build but they are about 20% of the build. Saving 5-10% on 20% is not worth it. So get the right design, not the easiest to whip up as a set of hulls.

    The best way to save time and money is to get a really good set of plans so that you never have to think or redo something - Farrier, Woods and Easy's have a great reputation here. Just plod out to the shed and continue rather than have to work out what has gone wrong.
     
  10. DennisRB
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    DennisRB Senior Member

    Guys talking about balsa infusion. Isn't it scary to use anything other than epoxy, or maybe VE because water may get into it? Does the endgrain and gaps soak up a lot of resin making it heavy? Seems like decent and more water resistant way to go than the pressed version ATL uses which is riddled with pin holes.
     
  11. DennisRB
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    DennisRB Senior Member

    Talking hull shapes. The multichine shape like the CSC30 is a good approximation of the ideal low wetted surface area shape which is a semi circle. Also it may allow you to walk on the bottom so you don't need floor boards. I think the whole setup needs to be taken into consideration. If your chosen shape requires floor boards, the hulls sides will need to be higher, that will mean more weight and windange, so in the end the hull resistance may be higher even if the underwater shape is better in theory.

    The numbers respond to wetted surface area.

    [​IMG]
     
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  12. Steve W
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    Steve W Senior Member

    Dennis,
    In the past I would always choose foam with hand layup but for me infusion has made balsa truly a viable core. No one has ever doubted the structural qualities but in hand layup balsa is problematic but with infusion every single block is surrounded by a wall of resin so if a incompetent boat owner were to install a piece of deck hardware poorly any subsequent water damage is contained in that particular block. Yes the end grain and gaps do take up quite a bit of resin but so does any other core with infusion, contour balsa is knife cut after being glued into a sheet and scrimmed so the gaps are only those that are opened up when pushed into a compound curve in a mold but when used on a flat table they are very small. The extra resin uptake in balsa or foam are going to be similar but it is somewhat offset by an easy to achieve 60-65% or higher fiber fraction . I would expect that ATL would be using 4x8 sheets of non contour balsa so all the blocks would already be glued together since they are pressing flat sheets so they should be lighter but with infusion you need a way for resin to get through so contour balsa works well and I am happy to pay a small weight penalty for what I consider a superior panel. I can see no advantage in using epoxy over ve or even pe for an infused panel.
     
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  13. Gus7119
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    Gus7119 Senior Member

    Dam questions on some replies

    Steve great info yet again. Providing some invaluable information.

    Catsketcher Ive become a little pig headed regarding plans and am going to go with the outline of ths csc30 except add an extra 2400mm sheet to the hulls instead of 4 sheets she'll be 5 giving me extra length for stern stsps and full coach house instead of cuddy. Using info from previous builds and tweaks from other designs. I will have full plans drawn up before I start so az not to be left sctratch my head half way through. But thanks for the concern Ivs explainded my reasoning in previous posts.
    And if he likes it or not as I dont think it was his intention Groper has given me a huge boost to back myself with his own design build. And reading where people have gone wrong has given me ideas of what to and not to do. But dead keen on anything you feel you can build yourself to help save some cash

    .DennisRB it seems that the multi and single chime are a good compromise. As the CKD is not in your diagram list I take it its not so crash hot? I have seen a number of hulls built this way with total flat bottom but no experiance of how they sail although the CKD would give you no requirement for floor boards. Although I am leaning towards the multi chi.e but if I am told the CDK waz az good Id change to it in a heart beat. But I must say it dods seem that there are alot of boats with this design.

    Now az for foam core ply. Cool it seems most agree its a good lite product for bridge deck and cabin with the bonus of insallation for sound anx heat. Please chime in if you have bad experiance or know of bad exper5with this idea. This is the one thing I will vacuum bag as the large area to try and weight down and get a good bond would be near impossible.
    Now I have heard in the past that epoxy eithed doesnt bond to foam or eats if if applied directly to it. And that a way around this is to cover the foam in a layer of wood glue and let that set prior to using epoxy on it. Is this true or not.

    Cheers
     
  14. DennisRB
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    DennisRB Senior Member

    Gday. I don't think the CDK shape was omitted because its not crash hot. I guess they just forgot or couldn't put everything in. But there is enough info there on similar shapes. It appears almost square, but the shape is also kind of like the multichine but without the bottom corners missing. So I would guess the wetted surface area will be between the box and the multi chine. Maybe about 108% of the the semi circle. But there are also other factors here other than WSA.
     

  15. rob denney
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    rob denney Senior Member

    20+ years ago we produced balsa cored, ply faced panels using epoxied 1.5mm ply under vacuum, 20 sheets at a time; and individually in a heated press using phenolic. They were both pretty good for their time, but heavier than glass faces for the same stiffness and the ply needed the usual 3 coats of epoxy applied by roller to stop it rotting. The demand for them now is near zero.

    The ply was more expensive than glass, the sheets needed joining to make long panels and as with all 8 x 4 sheets for small jobs, there was a lot of wastage and a lot of edge routing, bogging and rounding or glued on edges required. Table infused glass faced panels are better in all these respects.

    Unless you have fat ladies wearing stillettos walking over your boat, a layer of 600 db over 80 kg foam will be plenty strong enough.

    If you vacuum your own ply faced panels, resin coat the foam and apply the glue to the ply as the vacuum will not suck the air from the foam surface. Ensure there is a way for the air to get out. If the edges are pressed down first, there will be a 6' x 3' air bubble in your panel.

    In as much as YOU are choosing the method, I agree. But all the usual build methods are hard, dusty, sticky and time consuming compared to intelligent infusion which has no fairing, no wet laminating and no cutting or grinding cured laminate.

    Don't be shy about designing your own boat. It is where everybody starts and looking at the variety of shapes actually sailing, they mostly work well enough. But there have been some increases in build efficiency in the last few years, so carefully weigh your cheap/free materials and plans against the extra time and effort they require.

    Re hull shapes: Harryproas have flat bottoms with large, variable radius chines and gunwhales. Flat bottom saves the lousy job of building floors and means less freeboard to get headroom. They look better and have less wetted surface and windage than a ply box and are far less work than a double chine. If the boat is kept light enough, they plane.

    The hull and deck are built in a simple mdf mould (2 jigsaw cuts along a bent batten and some screws) which don't need polishing and are inherently fair. Remove the hull half from the mould, pull off the peel ply and it is ready for high build (or paving paint if you don't need a showroom finish).

    On these non compound surfaces the foam does not need to be carefully tailored and the laminate and the core can be infused in one shot. The dry materials stack includes: slots for the bulkheads and furniture, rebates for windows and hatches, the hatches themselves (no need to build a separate mould), reinforcing for fittings, all the edge treatments and the male/female join for the two halves. Post infusion, remove the peel ply and glue in the components.

    Apart from needing 4 cuts instead of 2 for the mould, all this applies to cat hulls/decks as well as proas.

    Read any decent build blog (Bob N's is one of the most honest) and remove the sticky, dusty, sweaty work. Replace it with cutting dry foam and glass, placing it in a cheap mould you built in a couple of days and covering it with an air tight bag into which exactly the right amount of resin is sucked. Almost no personal contact with toxic materials or dust, a better quality, lighter job and shorter build time.
     
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