Alternative to epoxy

[Erik le Rouge]

Hi,
I am new to boatbuilding. In fact I have just build a sea kayak using the stitch and glue with epoxy method.
I have plans for a Footloose skiff (plywood on frame) and want to use more traditionnal method to assemble, glue and seal the hull.
So I need info on good glues for assembling, wood sealers and paint, and alternatives to epoxy to protect hull and inside of boat against salt, rot, bumps etc.
PS : Boat will not stay permanently in water...
PS 2 : Any experience with Weldbond, "the universal space age adhesive"

[Dave Hadfield]

For glueing the ply to the chines and the gunwales, cheap, simple Bulldog adhesive (sold in the caulking gun cartridges everywhere) is fine. It's a polyurethane adhesive.

I'd tape and epoxy the outside of the chines.

Then paint the plywood with any good-quality primer and paint. For trailer use, it'll work fine.

[RodB]

Is there anything better than epoxy to do what you want...I would think any other product will not be as tough...

Whats wrong with epoxy?

RB

[ 11-30-2005, 08:42 PM: Message edited by: RodB ]

[Rick Clark]

Well I make my own glue bonding with wood flower and fiberglass resin. Make it about like soft butter don't mix it too hot the longer the cure the strong the bond.
Built a row boat with this and clamped it, but not so tight you squeeze it all out. It sands real nice.
OK try making up some and put a joint together and test it yourself, it is waterproof.
I also use it as a filler instead of buying bondo you can spread it with a trowel, I use a 12" for leveling a rippled hull on customers beat up boats

[Cuyahoga Chuck]

There is a lot of discussions about "new" glues (polyurethanes)that are as good or better than epoxy. Old glues (resourcinol) that doesn't cause allergic reactions. But no glue has the all-around provenence of epoxy. It does it all and has for many decades. If you want glue, fillet material, resin for bonding glass, tinted filler to repair a gouge or a good coating to waterproof plywood epoxy can do it.
Straight polyurethane glue (Gorilla for example) costs as much or more than an equal amount of epoxy. The reason that that poly adhesives in tubes (also called construction adhesive)are so much cheaper is there is a lot of filler in each tube and the polyurethane content is correspondingly small.
If you insist on avoiding epoxy you had better research any substitute thoroughly. Anecdotal evidence from me or anyone else is just that.
If epoxy didn't work for boatbuilding the Gudgeon brothers would have had their brains sued out by now.
Charlie

[Thorne]

There has been a very similar question asked on the duckworks forum Yahoo group, and for exterior coating several builders have recommended cotton or artificial cloth and good paint as an alternative to epoxy with or without glass cloth.

For gluing up the plywood, not sure what to suggest. There was another thread on this forum that posted a link to a site where a guy had tested PL Premium adhesive against epoxy -- the epoxy tested out best, but the PL Premium poly goo did well when backed with a batten/block.

It looked to me that using these more flexible adhesives for designs where the materials provide the stiffness and form -- like a lapstrake ply hull -- would work much better than designs that rely on the strength and flexibility of epoxy and glass tape to hold hull sections together.

But I'm a relative newbie and certainly no NA, so there are probably much more experienced opinions out there...

;- )

[ 12-01-2005, 01:03 AM: Message edited by: Thorne ]

[Bruce Hooke]

I'm not familiar with the design you have in mind but if I read your question right, it is designed for "traditional plywood construction" where there is a wood frame member backing up every joint in the plywood. If that is the case then:

If you don't mind using lots of screws to hold the plywood to the frame then whatever gooey material you put in the joints does not really need to act as a glue, it can largely just act as a sealer to keep water from migrating through the joints. In that case there are plenty of "products in tubes" that will do the trick. If you don't mind making the joints as permenant as the would be if you used epoxy then 3M 5200 would certainly work. Other less tenacious products would also work just fine. It might even be possible to just use good old marine bedding compound, but I think I'd prefer something with a little bit more ability to stick to the wood.

In the old days plywood boats were simply painted with good quality marine paints and they did just fine. You do need to be more careful with your maintenance if you take this route. Few things can kill a small boat faster than rotting sheets of plywood because it is generally a major hassle to get such sheets off the boat so that you can replace them. However, it is pretty hard for rot to get started in a boat that is only in the water when it is in use, as long as you have a good place to store the boat when it is not in use.

If you can stand using just a bit of epoxy one place where it has no good "traditional" substitute that I know of is as a chafe guard along the seams in the plywood. Plywood edges are pretty vulnerable to damage and subsequent rot, so a stip of glass cloth and epoxy to protect such edges is a VERY GOOD THING. You could probably get away with using polyester resin for this, but the ONLY good thing about polyester in this context is the price, and given how little resin we are talking about I just can't see any good reason for messing with polyester resin unless money is VERY tight. Polyester resin smells horrible, does not stick to wood as well as epoxy, is harder to apply smoothly, and so on. I use the *&^@! stuff only when I absolutely have to.

[Thorne]

It appears that Footloose has frames so the older 'screw & glue' approach might work well, but why not contact the designer and see what he suggests as an alternative?

http://www.jordanwoodboats.com/images/sp3.gif

[ 12-01-2005, 12:57 AM: Message edited by: Thorne ]

[pipefitter]

When combined with fasteners,any construction adhesive would exceed it's intended duty. Below waterline it seems to just go with the proven epoxy. Has anyone here ever tried to pull up decking or roof decking that has been liquid nailed and stapled? Any of these would be strong enough above waterline if they were under paint on atleast dry sailed boats.Most adhesives and even epoxy is going to fail if the wood gets wet between it and any glue bond. Does anyone really build boats without any fasteners at all other than the glass covered strippers? Seems the advantages of epoxy is it's ability to seal or provide it's own scratch coat as it is being applied.In other words,you can preprime the joint with the same material or a thinner variation of before you do the actual glue up.Would be nice if one could thin the urethane adhesives to wet out the wood first instead of just laying a bead on dry wood.Just like with contact cement we would always put a sealer/flash coat on dry/porous materials before putting the adhesive coat on.After it is all said and done,there seems there would be about the same amount of work involved and cost getting an ideal bond from any adhesives used.

Also,thickened epoxy works quite nicely out of a caulking gun.

[ 12-01-2005, 02:18 AM: Message edited by: pipefitter ]

[Lewisboats]

From what I can tell the plans call for a chine (log) and calls for epoxy glue in the construction (Glue and Screw). As you are only using the epoxy as a glue and not as a sealer, you are still building the boat in a 'traditional' manner. Other than resorcinal (sp?) epoxy is the strongest thing going, so why discount it as a glue? The designer also likes to tape the chines with FG tape an Epoxy.

Steve

[WayGray]

The first boat I built (1976) was entirely bonded with resorcinol glue. I used well-fitting joints, decent clamping pressure, and enjoyed that it was simple to mix in batches just size I needed. Also relatively easy to clean up. Less allergy potential too. I used that boat alot and had no joint failures.

Just got through using a couple gallons of epoxy, but resorcinol would be a decent second choice for me. Titebond III is also proving to be a good adhesive, although I haven't yet trusted it for below the waterline, constant emersion uses.

[jimendel]

Originally posted by pipefitter:

Also,thickened epoxy works quite nicely out of a caulking gun.How do you get the epoxy into the caulking gun without severely cutting into the time you have to work the stuff?

[Dave Hadfield]

For the last 2 summers I've been running the rapids in my local river with a sharpie canoe I designed and built. It's traditional plywood. The wood sides and bottoms are screwed and glued to the chine logs with Bulldog adhesive and brass screws. Then the outside chines are taped and that tape is epoxied. The rest of the boat is simply painted.

This is using 1/4" underlayment from a home depot (virula, or some brazilian wood like that).

The only epoxy I used was for scarfing the plywood together to make a pair of 4 x 16 sheets.

Worked fine, for non-continuous immersion.

[pipefitter]

I cram it in there with a paint stick. You save so much time doing fillets in this way that it cancels out the fill time substantially.Only sanding I had to do on fillets was the lap marks where I would change directions. I used medium and slow cure with a mixture of microballoons and crushed fibreglass. Took me 20 mins to do all of the interior fillets around the deck of my boat.I had cut the tip of the tube just the right size to fit the amount needed for a clean wipe with the rounded spatula I had made of wood.No excess ran outside the spatula profile.If it did it was a hair line that was seperate of the fillet and could be cleaned out with a 6" drywall taping knife.
When I glued my laps,I started to put it on the lap with a putty knife and switched to the caulk tube.I was able to run a zig zag line and wipe it with the knife afterwards to coat the whole lap evenly without it getting messy. The goop that squeezed out when putting in the screws, I filled the same screwholes with at the same time.

[ 12-02-2005, 12:08 AM: Message edited by: pipefitter ]

[jimendel]

Thanks pipefitter, I'll give it a try.

[pipefitter]

When you are done you can push the plunger back out and clean it with vinegar or alcohol soaked rag and use them many times.You'll never go back to the wipe and cram method. Also to say that the epoxy should be about the same consistency as latex caulk.The surfaces should also be primed with resin to keep the dry wood from drying out your glue.

[Tom W.]

Pipefitter:
Do you use empty caulk tubes? Where do you get those, save empty ones from actual caulk?

[pipefitter]

There was tubes here of some cheap stuff in plastic caulking tubes that had been here forever. So I emptied those into some empty paint cans I was throwing away and rinsed them out with water and let them dry. I didnt know where else to buy them locally and didnt want to wait to order online. They were more expensive to buy empty than they are full.
Ok,maybe not.Here is a site that sells them.
http://www.freundcontainer.com

[ 12-02-2005, 10:01 PM: Message edited by: pipefitter ]

[Thorne]

I have seen empty tubes (regular and jumbo size) for sale at good hardware stores and chandleries -- worth calling around for if you prefer to shop locally.

Great ideas, guys!