Quick building strategies

Discussion in 'Multihulls' started by simon, Oct 17, 2007.

  1. waikikin
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    waikikin Senior Member

    Fanie, Pro Set is a brand for epoxy. Regards from Jeff.
     
  2. waikikin
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    waikikin Senior Member

    impregnator

    Fanie, if you google up proset epoxy & get to their site, look for process equipment & its in there. Regards from Jeff.
     
  3. rob denney
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    rob denney Senior Member

    G'day,

    Wet out machines are excellent value, but do not work very well with cut material, partly as knitted material tends to stretch and lose shape when wet and under tension, partly as the cut sides tend to fold over and the wet out is uneven. It is easier to use varying widths of unidirectional and trim the edges for the compound shapes of the hull.

    All the wet out machines I have used have had steel, not rubber rollers.
    Instead of sitting the bottom roller in resin, you get a better job with the resin sitting between dams on top of the rollers. Means less resin is mixed at any one time, so less chance of exotherm. If you are going to put it on a roller after wet out, you need a very slow resin system. We designed and built one for wetting out the tow when we build masts and other carbon components. Picture at http://www.harryproa.com/building_Vis/building_Vis_5.htm.

    Until I saw infusion, a motor driven wet out machine with automatic resin dispensing and mixing was the ultimate way to wet out bulk cloth.

    Alan, Great to see long, light boats beating short heavy expensive ones, and you are right about the floors.
    There have probably been as many boats with balsa core problems as with osmosis, which does not affect vinylester boats, or polyester boats built correctly. Doesn't stop people using balsa, and done properly, there are no problems.

    What rig are you putting on your boat? If it is unstayed, could you drop me a line off list (harryproa@gmail.com), please.

    regards,

    rob
     
  4. waikikin
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    waikikin Senior Member

    Rob, thats a neat looking wet out machine, I really like the rubber wheel drive part(wish we thunk of it), ours has a chain drive & some sneaky geometry to open & nip the rollers & an over centre mechanism to dunk an immersion roller into the resin bath, the bracketing for the resin dams on top look just the same as yours. Regards from Jeff.
     
  5. Andy
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    Andy Senior Member

    I think there are always better and faster ways of building boats. So here are my thoughts...

    If you want to do things reasonably quickly, you need to streamline as many of the building processes as possible. I reckon a stitch and glue cat, built in female mold frames and with all parts cnc cut would be an efficient way of building. The money you spend on the machining will probably be paid back partly through less time in the workshop (less heating and lighting bills, less epoxy etc through more accurate fits). Build your interior as a series of modules, to be worked on in comfort outside the boat and completed there too. Buy an HVLP spray gun for much faster finishing, and set up a production line for painting. Hire cheap labor for fairing, or figure out how to run a belt sander along rails which span any hollows in the hull. Plan all your joinery so that you can set up a production line and make it all in one session (e.g. enough stock cut and routed for all wood trim) and standardise as much as possible for the same reason. Create jigs for as many parts as possible, and avoid any fancy finishes (15 coats of varnish will take a lot longer than 3 coats of paint...). Basically, be utterly methodical and efficient in everything you do, and remember that a bit of cheap labour can pay for itself in certain situations by really helping the build along.
     
  6. Spiv
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    Spiv Ancient Mariner

    Of Vinyester v Epoxy and impregnators

    Rob is right, osmosis happened in some gelcoats of the past. Modern gelcoats do not have that problem, actually will last longer than two pack paints.
    My partner developed an epoxy sensitivity 6 to 8 months into the project: his skin was falling off him and developed asthma as soon as he came close to epoxy (especially curing) i.e everywhere - something I would not wish to anybody.
    Wet layup should, and will soon be, a thing of the past. Infusion, RTM, light RTM and a score of other up and coming technologies will eliminate almost all emissions.
    VE is my preferred resin, especially under the waterline as it is even more waterproof than epoxy. Secondary bond on VE is also excellent. Some of the concerns derive from old Polyester formulations and incorrect techniques. At half to a third the cost of epoxy, why waste money?

    I would discourage amateurs from strip planking, weather using cedar or durakore, just far too much time consuming, both to build and to fair.

    I will not use balsa again, call it duflex, duracore or else. Every hole you drill you must drill oversize, fill with epoxy bog, then drill it again: then one wanders where the time goes.... don't do it properly and the balsa will perish in time.
    The plumber or the electrician come on board and drill holes everywhere... a screw comes loose on deck: water finds it way in.. You are at your pen and you want to do some minor mods: get the scales out, weight the epoxy, wait till it sets. If you only knew how often I wished I did not use balsa...

    On a technical point, end grain balsa transfers any impact loads straight to the inner skin, delaminating. Foams absorb some of the impact and the inner skin stays put. Anybody not believing try it: laminate a 300x300 piece of foam with 600gsm double bi and do the same on a piece of balsa of the same thickness, put them across two bricks and hit them, gently at first, then a little harder with a hammer. You will see that the balsa will fail much quicker.
    If you do what the balsa advocates say and use thinner core, then the results are even worse.
    Someone mentioned Polycore, which is similar to Nidaplast; the stuff is even more impact resistant - and much cheaper - than PVC foams. Still, don't think that it is the best core as its flexural strength is less and you need a thicker core, but this is perhaps better discussed on another thread.

    One more point: if you want to build a quicker boat look closely at your furniture. Round lounges and seating might look pretty, but they require a LOT more work as well as being utterly impractical as you will not be able to take a nap on them weather you are at anchor in a beaut spot or on a long crossing.
    Build all your furniture on the shop floor, fair and prime it, then take it on board, trim the edges and stitch it in.
    If you can, buy cockpit and saloon seats, basins, chart table, cabinets even the cross beam from a builder that has molds. Yes it will cost you some money, but how many months of joy will you gain?
     
  7. Alan M.
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    Alan M. Senior Member

    You need to de-core and seal hull penetrations whether the core is balsa or foam though, so I can't see that being a valid complaint.

    I've tried hitting Duflex with a hammer, and apart from being amazed at just how tough the stuff is, I found that it was the side that I was hitting that got damaged - pretty much as you would expect, it eventually dented and then the laminate started to break up. It didn't transmit the impact through to the other laminate by enough to cause delamination or any other visible damage.
     
  8. DGreenwood
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    DGreenwood Senior Member

    A very interesting statement by Bob Oram from his site. I would love to know how he would pull that off. Anybody ever seen one of his cats like the one described?
     
  9. Alan M.
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    Alan M. Senior Member

    Bob is currently building a 46 foot podcat for himself. Only part-time, so it will take more than a year, but certainly if you took his approach, which is a minimalist fit-out, and don't try for a "showroom" finish, you could achieve exactly what he describes.
     
  10. Spiv
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    Spiv Ancient Mariner

    Alan,
    I know you need to decore both, but you don't need to be so particular with foams If you don't need to screw in the hole, you might just leave it as it is; this is a great advantage.

    I know that Duflex is tough, I uses $20,000+ in my boat!
    For the last 3y I have been consulting in the composite industry and carried out tests on many flat panels with cores such as Balsa, Divinycell , CoreCell, Rohacell, Soteco foams, Nomex, Polycore and more, as well as different reinforcements and resins.
    Every combination has pro and cons, but trust me, end brain balsa transmits impact loads to the other skin more than other cores.
    Do try same laminate, same resin, same thickness and see. Use 80kg foam (close to half the weight of Balsa) and note the difference.:)
     
  11. rob denney
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    rob denney Senior Member

    G'day,

    Any chance we can see any of those results?

    regards,

    Rob
     
  12. Fanie
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    Fanie Fanie

    I have a question please -

    Do one want the foam to be the structural strength, or the fiberglass - if you build using foam instead of wood ?

    If one uses a foam that is structurally not strong enough, but could assist in the initial hull forming, and if blocks of this foam can be removed after the hull is formed so it looks like a big 'honeycomb' that can be glassed over on the inside that should provide structural stiffness. The removed blocks can be trimmed and re-fitted and again fiber glassed over. Should make for a very strong and stiff ie hull, no wood.

    Has anyone considered using PCB fiberglass (without the copper of course) ?
     
  13. Alan M.
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    Alan M. Senior Member

    I'm not sure what you mean by this. But if you drill a hole in a foam core you need to de-core and seal it to keep water out - just the same as for balsa. And it really isn't that much of a hassle IMHO.

    For internal electrical and plumbing runs I am installing conduit where required. Where a conduit passes through an internal bulkhead I have simply glued it in to seal the core.

    A builder of a Schionning Wilderness 1230 told me that he got quotes for the standard balsa cored Duflex kit, and the same kit in foam cored Duflex. The foam cored kit was not only much more expensive, but it was heavier too. Apparently it required heavier laminates and in some places thicker cores to acheive the same result.

    Spiv, do you have a source for more information about vinylester being more waterproof than epoxy? I'm sure there are a lot of people applying epoxy barrier coats to vinylester boats who would like to see it.
     
  14. captainjsw
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    captainjsw Junior Member

    Hi Simon, I agree with almost all that is posted here. Its not possible to build a large boat singlehandedly quickly. You just need help, which can be difficult to get at the right price. I built a 12.8m Grainger and it took me 6 years and I had some paid help over the last couple of years.

    I'm currently building a new catamaran, upside down using DuFlex, one hull at a time, I hope to have the first hull turned by the start of Feb 08 - faired and primed, ready for top coat, and then we will be starting on the second hull. I will be able to give you an exact number of hours to get to this point when we are there - if you are in Perth WA you can come and see it :)
     

  15. AndrewK
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    AndrewK Senior Member

    Can time be saved by not having to tape all bulkheads and furniture panels?
    What size does the glue fillet have to be in order not to requre a glass tape? Has anyone seen any comparative test data for strenghth of glued only versus glued and taped joints?
     
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