CARAVELINA - New JR scow minicruiser

  • 23 Dec 2020 11:39
    Reply # 9447928 on 7917477

    The hull construction is going on. Central cockpit basically enclosed. Floor, side walls, benches, back supports and side decks on place. Now starting play with complicated curved planes of over-structures - fore-cabin and main astern cabin side walls and decks.

    However, in case of frost  (Winter in Poland  :( ) I have ready other job prepared - sail sewing. I came thru about all possibilities how to make cambered sails, and chose flat sails with hinged battens. About to order alu pipes, and just realized - I do not know whether the boom should be also hinged, or straight, and the lowest panel is to be cut differently???

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  • 27 Sep 2020 16:29
    Reply # 9267987 on 7917477

    You may want to look at Collano Semparoc 60 as an alternative to epoxy for wood. It's a gap-filling foaming urethane glue. SV Tapatya (a JR Benford Dory) is being built using it. The builder discusses it in this video.

    (I'm also interested in these scow bows.)

    Last modified: 27 Sep 2020 16:30 | Anonymous member
  • 10 Sep 2020 11:34
    Reply # 9224984 on 7917477

    Many thanks all of you for so many informative advices. Lot to read, think of and check the availability, prices etc. Surly I may reduce the usage of epoxy resin, however not exclude with the technology of building my boat chosen. It is gluing plywood to plywood, where strong filleting is essential.  Luckily, most of it is done. I must check on the acrylic resin, it looks promising. My first dingy I build back in early 70ies I laminated with linen fabric for window curtains and two pot floor polyurethane paint. 

  • 07 Sep 2020 06:53
    Reply # 9216703 on 7917477
    Anonymous member (Administrator)

    Titebond 3 is an aliphatic resin glue and it is available in New Zealand. I have not used it, but I got this useful email from Dave Z (triloboatsWayward) and  I am sure he won't mind me posting it here. I believe it is a very good glue, but Dave has used it for a deck covering in conjunction with acrylic cloth reinforcement, as a way of avoiding the use of epoxy.

    "Our TBIII / Acrylic decks are now in their third year, and are looking great. I'm starting to hear of more successful probes from the internets. So the method seems solid.

    Our TBIII source was Home Depot. Ordering online in 2x1gallon packages (postal delivery) came to about US$26/g plus shipping. Deliveries to any of their stores for pick-up was free shipping.

    That's going to be a little more difficult in NZ... maybe via Amazon? Amazon Prime shipping is 'free' (after monthly membership), and Alaskans rely heavily on it. Maybe they have some arrangement to you?

    Our 2oz (?) woven acrylic was purchased from Jamestown Distributers (they have an online store), for about US$22/yard x 56in. It was called Dynel although that is no longer in production. Personally, I think any lightweight woven or knit acrylic would be optimal (acrylic is very wear resistant and is used over fiberglass - in kayaks for example - to protect it from abrasion). I wouldn't hesitate to use any synthetic cloth.

    The method is a descendant of using a latex lagging compound to saturate just about any cloth. Burlap was popular (!) since it was so cheap, but I lean to synthetic (on the advice that if water does penetrate, it's immune to rot). Lagging is the fabric wrapped around hot water pipes to insulate and protect people from contact burns. The compound is cheap and waterproof when dry, and sets up to a relatively soft, but easily repairable deck.

    This may be a more available choice for you. Better yet, it's cheap and easily removed/replaced (just peels off). Burlap was good for about 15 years, I've heard. Our LUNA's deck (lagging compound on fiberglass cloth) looked very good at 21 years (I'd go for cloth, rather than fiberglass, these days, as cheaper, easier to handle, more pleasant to work with). "

    While on the subject of deck coverings here are another two possible alternatives to epoxy, for consideration:

    1. Thickened acrylic resin with glass chop strand mat. I did that on a domestic deck 20 years ago, with just a coat of alkyd undercoat as a prep, on cheap plywood. It was a proprietary product (Deck Tread), not cheap but very user-friendly (wash hands and rollers with water etc).  It is slightly flexible and wrinkled at the unglued plywood butt joins (rather than cracking). Never heard of it being used on a boat, but I can't see why not. The membrane is still intact and as good as new after 20 years under our harsh sun, having had just one re-coat of acrylic about 5 years ago. Non-skid surface. Possibly not able to withstand rupturing (hobnail boots etc) or too much abrasion. MUCH easier than using epoxy. The idea is food for thought anyway.

    2. I'm currently trying a few things with water-borne epoxy resin which I have used in a number of ways over the years, including thickening with portland cement and fine sand. Had very good results over 50 years as a surfacing for cementitious surfaces in marine applications. Again, hands and tools can be washed with water - sort of - and it doesn't have the heavy solvent smell of conventional epoxy so possibly might be more user-friendly for someone who has become epoxified. Possibly not suitable for structural purposes but proven as a surface coat (water-borne epoxy resin is the basis of coppercote antifouling). I'm fooling around with it again on a current project. Just bouncing ideas here. I think it would be easy to use with either glass or acrylic reinforcing and will be trialing some ideas this coming summer.

    3. I shredded a sheet of plywood once, tryinh with great difficulty to remove a recently-bedded-down cockpit floor fastened down on a polyurethane rubber sealant (which I had mistaken for silicone rubber). In some particular applications polyurethane rubber would be a better glue than epoxy, but perhaps not for the work you are doing at present. There will be others who can advise better on this class of glue - and other alternatives I am sure.

    Prior to epoxy resins we used wood preservatives such as copper napthate ("metalex") and for glues we used urea formaldehyde glue, and resorcinal glue (with the lovely smell). In my view epoxy is the best, but not the only solution - and not worth it if it is poisoning you.

    Last modified: 07 Sep 2020 07:18 | Anonymous member (Administrator)
  • 07 Sep 2020 05:25
    Reply # 9216568 on 7917477

    On the subject of glues I have used waterproof PVA many times in non structural boat work, even the exterior, and so far have never had any problems. A friend of mine has built dinghies using this glue and they have stood the test of time. The Titebond 3 looks to be similar to the PVA products, but may not be. The polyurethane glues which are the expanding joint filling type can also used and they have the advantage of expanding into the joint. The big advantages of epoxy is that it is completely waterproof, and is gap filling. Also the one resin base can be used for gluing, filling, and sealing.

    I did do some research into this when looking at glue types for my catamaran build and was most interested in strength properties. If epoxy is rated at 100 %, PVA glues come out at 120 % plus, and the polyurethane glues were down around the 30 - 40%. At least that is what I seem to remember from a couple of years ago.

    The other very big advantage is that in composite boatbuilding epoxy creates a homogeneous structure where the wood is just a part of the combined wood, epoxy, and fiber reinforcing. This is offset though by the health risks of using epoxy based products along with the various additives. 

  • 06 Sep 2020 23:34
    Reply # 9216082 on 7917477

    I have been looking at this recently and was recommended a product called titebond 3 which many claim to be waterproof.  

  • 06 Sep 2020 20:55
    Reply # 9215854 on 7917477

    Sorry to hear of your epoxy allergy, bad news for a boat builder.  
    I would never consider PVA waterproof, and would never use on a boat.  Even inside the high humidity would affect it.  As you say, there other options besides epoxy.  Polyurethanes that moisture cure seem ideal.  
    Regarding epoxy, I understand that they are not all the same, some being for worse for allergies.

    For sealing the interior, a good vapour resistance is very desirable, which is where epoxy wins.  That said for a cheap n cheerful project, I have used acrylic paints on the house to good effect and would try those.  Acrylic roof paint is magic, Thomson’s Roofseal. The beauty of acrylic is they tolerate a slightly damp surface.

    Last modified: 06 Sep 2020 20:56 | Anonymous member
  • 05 Sep 2020 21:32
    Reply # 9214366 on 9213739
    Kris wrote:

    In my work I am slowed down by an allergy to epoxy - even grinding dry glass-epoxy after a few hours result in itching pain in my palms. Using doubled medical gloves helps to control this issue.  

    There was a time, not really that long ago, when boats were built with glues and sealers other than epoxy. And they have held together for a very long time. So are there other alternatives, even at this stage of construction? Waterproof PVA glue is stronger than epoxy and can be used for a lot of areas on the boat. I understand that it may not be compatible with epoxy over coating. And there are still the Urea Formaldehyde glues. Polyester resin can be used for sheathing. I once owned a boat that had been fiberglass sheathed using polyester resin and it was very successful. For interior sealing I have been using a very low viscosity epoxy sealer which is quick and easy to apply which might be helpful. And of course the interior can be sealed the old way with suitable paint primers.
  • 05 Sep 2020 14:47
    Reply # 9213739 on 7917477

    Building CARAVELINA  slowly goes on. After gluing on side panels - boards, it is time to fix horizontal planes - bunks. Some have a storage spaces underneath, some form flotation compartments, that I stuff with a foam to make my boat truly unsinkable. These compartments are closed and sealed except a 6mm hole to allow equalize pressure.  In my work I am slowed down by an allergy to epoxy - even grinding dry glass-epoxy after a few hours result in itching pain in my palms. Using doubled medical gloves helps to control this issue.  

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  • 17 May 2020 02:08
    Reply # 8974018 on 7917477
    Anonymous member (Administrator)

    That's not a tank.

    THIS is a tank!

    Seriously though - your planking looks lovely, both inside and out.

    You are on the way to a unique and interesting boat. Good luck and keep up the progress reports.

    Last modified: 17 May 2020 02:09 | Anonymous member (Administrator)
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