cold molding, maybe?

[Todd Bradshaw]

Re: cold molding, maybe?

I disagree strongly with the assertion that fiberglass adds little strength to a stripper.

You can disagree all you want and try to bury everybody in mumbo-jumbo, but that doesn't change reality. The guideboat isn't designed for rocky streams and they have basically just replaced the internal glass strength and stiffness with ribs, the same way a fiberglassed Old Town wooden canoe gets its strength from the ribs and planking, not the glass. If you hit something or flex it enough, the outside fiberglass won't do squat. It has about as much stiffness as a plastic milk jug and under pressure, it will just bend until the wood breaks, so providing impact strength is going to have to be done by the wood. We see this when rookie strip builders try to get clever and use really light glass cloth on the insides of their boats to cut "excess" weight, figuring that the outside glass is where the strength is. Wrong. Their later posts generally start with "My boat's core and inner glass layers split down a glue line or weak grain line. How do I fix it?" The outer glass may prevent a break that goes all the way through and leaks, but the boat will have a big soft spot where the core broke and fractured the inner glass. This is not from some book, it is from actual real-life experience over 45 years using and building strippers.

As for $16,000 strippers of any sort, there's a sucker born every minute. They're very nice boats, but get real. For less than that, you can buy a real Adirondack Guideboat.

In the case of this boat, the fact that the strips aren't glued together is really unfortunate. If they're just screwed to the ribs, I might even consider pulling every other one, applying epoxy or other glue to its edges and then sticking it back in there.

[master of nun]

Re: cold molding, maybe?

Thank you all so much! I think the consensus is cold mold and then epoxy the inside. I closed the hull today. What a kick!

Well done and congratulations!

Mark Bowdidge marine here in Australia uses a technique where the hull is stripped dry, no bonding, and later squidgies epoxy between the planks. Although a larger gap between planks is used. Check it out.

http://www.bowdidgemarinedesigns.com/STRIP_PLANK_CONSTRUCTION.html

[Rumars]

Re: cold molding, maybe?

Prime the seams with epoxy (a stiff brush works), then follow with some thickened epoxy. Use a putty knife to press the mass in the seams. You may have to experiment to find the best consistency to get it into the sems. Then fair and glass. If you cold mold fair first, than as above using more thickened epoxy. Read the gougeon book for cold molding procedure.

[cejenkinsjr]

Re: cold molding, maybe?

I am seeing some different opinions, which I appreciate and expected. I am considering all of your thoughts and expertise. There seems to be concern for the hull’s stiffness. I have built previously a strip canoe, no ribs, glassed inside and out. It was floppy until I installed gunwale and thwarts. It appears unfortunate that I haven’t edge glued all of the strips and so I understand the idea of the planks working apart with boat movement and stresses. I am, honestly not worried about time or money. I am in year two of this project now. I had very seriously gone back and forth between strip and traditional planking and went with strip because she will live on a trailer, not moored or otherwise more constantly in the water. It concerned me deeply that she might have to take up and then dry out repeatedly and I feared that this would be harder on her and make occasional day sailing, maybe frustrating.
So, after considering all of your opinions let me present my proposed course of action. I am buying and will read the cold molding book. As mentioned above, I believe that with the frames and deck stringers, knees and sheer clamp etc, she will be stiff enough, and so it is stabilizing the wood hull moisture contend as well as securing or minimizing the strips working against each other that is my major objective. I am coming to the conclusion that I should be able to achieve these goals by cold molding however it would seem to me that I should be able to seal and secure the strips with one perpendicular layer and then heavily interior coat with epoxy. I may consider a thickened epoxy fillet along the frames on the inside, similar to what would be used in a stitch and glue type application. I said previously that time and money aren’t big concerns but I’m not crazy either. At this point I’m wondering where to buy veneer, or if I might be able to cut my own. I milled out my strips and use a thin kerf blade. Thoughts please and thanks.!

[Brian Palmer]

Re: cold molding, maybe?

I would definitely not do kevlar on the outside because if it is sanded it will produce surface "fuzz" that is very hard to fix.

This is not a high performance boat that will benefit from the use of the lighter composites.

A lot of boats have been built with diagonal veneers and then glass on the outside.

[debenriver]

Re: cold molding, maybe?

I think you will find it substantially more difficult to lay perpendicular strips than diagonal ones. Diagonals lay more naturally around the curvature of the hull without too much edge fitting and with the edges laying down more easily – many many thousands of boats of all sizes have been very successfully built this way.

Sliced veneers are very common in Europe, and easily available in many varieties of timber (khaya being the most common) - but seem more difficult to find in the USA for some reason. Cutting your own veneers is reasonably straightforward if you set yourself up right to do it, though a bit wasteful. You need to aim for something like 2.5mm thick x 100mm wide. Done properly, they will be OK to use right off the saw.

Though rather less satisfactory in some ways, builders have used good quality 3mm ply in place of veneers, ripped to strips 100mm or thereabouts in width. The only problem with this (apart from finding decent quality ply) is that the outer veneers on 3mm ply tend to be very thin, so any amount of fairing on the final layer cuts through the outer veneer.

The thickened epoxy will work its way into the seams between the strips to a certain extent - really depends on how much gap there is – so you will get some adhesion strip-to-strip. It would pay, I think, to sand the stripped hull and apply a coat of un-thickened resin, working it into the seams wherever possible – then prepare for bonding the diagonals on (scrub/wash/wet sand etc.).

Epoxy coating on the inside will also work its way into the seams. But what you don't want to end up with is some areas fully coated and moisture proof, while others have little gaps etc that will allow water to seep in – that's really the worst of all worlds. Same under the frames - there is going to be an uncoated area of hull skin with a doubtful seal between it and the frames. I suppose filleting will do the job of sealing this up but it seems a somewhat tedious way to build a boat!

Cheers -- George

[the_gr8t_waldo]

Re: cold molding, maybe?

I would avoid adding more material than required. veneers with the added epoxy to glue 'em, will turn a delightful vessel into a bit of a dog. I'd start by carefully injecting unthickened epoxy into the seams. inject with a syringe with the point ground down to be a delivery pipe /and as big a barrel as reasonable. once that's started to harden up work some thickened epoxy into the inevitable gaps. the drips can be sanded off later. at that point, I'd step back and reassess.... you can then decide if fiberglass/veneers will add anything worthwhile...I'm reminded of the adage..If you find yourself in a hole, the first thing you should do is stop digging

[DeniseO30]

I would avoid adding more material than required. veneers with the added epoxy to glue 'em, will turn a delightful vessel into a bit of a dog. I'd start by carefully injecting unthickened epoxy into the seams. inject with a syringe with the point ground down to be a delivery pipe /and as big a barrel as reasonable. once that's started to harden up work some thickened epoxy into the inevitable gaps. the drips can be sanded off later. at that point, I'd step back and reassess.... you can then decide if fiberglass/veneers will add anything worthwhile...I'm reminded of the adage..If you find yourself in a hole, the first thing you should do is stop digging

The right thickness of epoxy will fill between the strips and they'll be bonded almost as well as if they were edge glued. With frames installed already it's going to be a rather strong boat. It does not appear to be a design that would be running rocks and white water. The strips are actually horizontal frames, glass or veneer. finish the boat and go sailing rowing!

When threads like this get carried to extremes in discussion it's no wonder that builders get discouraged.

Sent from my LG-M430 using Tapatalk

[the_gr8t_waldo]

Re: cold molding, maybe?

we both seem to be advocating addressing the edge gluing. and I wrote the above saying "I would". this is a big forum and can accommodate different opinions. and assuming cenjen is an adult, he/she can evaluate the quality of opinions expressed here, and if it should be followed-or not

[Ted Hoppe]

Re: cold molding, maybe?

Cold molding makes sense in one area never talked about. Insurance. Insurance companies like progressive will cover and pay for a boat that is made out of composite materials rather than traditional wooden boats. Something to think about and will save you thousands over the lifetime of the boat if the boat is cold molded.

[debenriver]

Re: cold molding, maybe?

I would avoid adding more material than required. veneers with the added epoxy to glue 'em, will turn a delightful vessel into a bit of a dog. I'd start by carefully injecting unthickened epoxy into the seams. inject with a syringe with the point ground down to be a delivery pipe /and as big a barrel as reasonable. once that's started to harden up work some thickened epoxy into the inevitable gaps. the drips can be sanded off later. at that point, I'd step back and reassess.... you can then decide if fiberglass/veneers will add anything worthwhile...I'm reminded of the adage..If you find yourself in a hole, the first thing you should do is stop digging

I don't know ... she was designed for ½" planking – she has ⅜" strips. Adding two 2.5mm veneers will only make her about 9/16" hull skin - hardly enough extra weight to make her a dog!

Cheers -- George

[MN Dave]

Re: cold molding, maybe?

As for $16,000 strippers of any sort, there's a sucker born every minute. They're very nice boats, but get real. For less than that, you can buy a real Adirondack Guideboat.

On this we can agree. The point was that they have stayed in business for a long time selling boats that are more than adequately constructed. If the gold plated boats fell apart, you would never have heard of them. They have been successful without interior glass. I have talked to them, they aren't stupid, just pricey. I was eating dinner in an over

In the case of this boat, the fact that the strips aren't glued together is really unfortunate. If they're just screwed to the ribs, I might even consider pulling every other one, applying epoxy or other glue to its edges and then sticking it back in there.

Yes, it would have been better to have applied glue between the strips, but I would not consider dismantling it. I think that the epoxy will wick into the gaps well enough, especially if it is applied to both sides. Some gaps along the centerline of the seams will not make much difference.

You can disagree all you want and try to bury everybody in mumbo-jumbo, but that doesn't change reality. The guideboat isn't designed for rocky streams and they have basically just replaced the internal glass strength and stiffness with ribs, the same way a fiberglassed Old Town wooden canoe gets its strength from the ribs and planking, not the glass.

Relax, the Haven 12 1/2 isn't doing white water either. All the blethers about canoe construction boils down to the fact that you need strength in more than one direction. So ribs, glass, canvass, they all do the same thing. If you don't understand the mumbo-jumbo, that doesn't make it wrong.

It is very simple, wood is weak across the grain. The glass layers balance the properties. Bending a flat panel puts the outside of the bend in tension. So you are absolutely right, when you try to bend the panel in one direction, the glass needs to be on the outside of the bend. You don't always load every surface in the same direction. That little bugaboo is why you need to support both sides. Most of the nasty hard pointy things are outside, so a hard shell is going to help there. The ribs can do the job on the inside.

Without the wood core, the thin fiberglass skins have some tensile strength, but don't resist bending. There is a difference between the stiffness of a material and the flexibility of a thin sheet. Aluminum is five times as stiff as any wood. Comparing a thin FRP sheet or Al foil to a board is not a valid argument.