Pardey says that epoxy should not be used as structural glue for wood.

[davidpm]

West System et al. would disagree I’m sure.

This is the short story
http://www.landlpardey.com/Tips/2007/April.html
This is the whole story
http://www.cpadhesives.com/media/Cla...atAppendix.pdf

Where do the sailnet experts fall on this question?

[Blue Eagle]

I might be way off-line here, but I don't seem to recall, from reading their book "The Gougeon Brothers on Boatbuilding" that they advocate using traditional boatbuilding methods in conjunction with West System epoxy. The spend quite a long time talking about alternative methods - such as laminating and cold-moulding where the bearing surfaces are significantly larger, and the structure much more monocoque in nature than in traditional boatbuilding.

I'm not sure how many people have access to resorcinol glues nowadays, or have the skills or knowledge to use them efficiently. I certainly wouldn't know where to get it from, but if you're restoring a traditionally-built vessel, or building one new, perhaps West System isn't the best stuff to use.

BE

[Sailormann]

Certainly not an "expert" but I won't let that stop me...

The Pardeys make valid points and if you're going to spend a lot of time in a warm climate on a boat with epoxy that is exposed, well, maybe not the best idea...

However. Nothing that is currently used in the construction of watercraft is actually "waterproof". Steel rusts, fibreglass and epoxy absorb water, wood rots, aluminum oxidizes, ferro-cement wears away....

There is no such thing as an absolute in the world of boats except that the wind will always come back and the sun will continue to rise. Everything else is subject to change and interpretation.

You do your studies and you make your choices. Epoxy is stronger at moderate temperatures than pretty well anything else out there. While not "waterproof" it is incredibly water-resistant.

Polyester resins are a bit more stable at higher temperatures. They are not as water-resistant or as strong as epoxy, but they are cheaper.

Steel is pretty good up to about 700 degrees, but it rusts fairly quickly, particularly in warm salt water.

Aluminum doesn't rust but it pits and corrodes and costs a lot and is hard to weld.

Wood is warm and beautiful but it's not as strong as epoxy or at all water-resistant and hence rots quite easily. Takes a lot of time to work with it too.

Make your choice. No boat will last forever. All of them can last longer than you will.

[Lion35]

Resorcinol is water proof and West is not. In my opinion on a traditional wood boat West is fine above the waterline, but if wood is to see a lot of water resorcinol is the ticket. Resorcinol requires a very tight glue line, unlike epoxy being easily starved if the glue line is too thin. I've sailed a few and been aboard many West built cold molded boats and I believe it's a great way to build, specially for one offs. The key is in cold molding to use a barrier coat, conversely on traditional (Carvel) boats it's Key to allow the boat to swell and to keep the wood wet. This is a long debated subject in wood boat circles.

[sailingdog]

From what I've seen of cold-molded epoxy-wood laminate boats, I don't see any real problem with using epoxy for a properly constructed boat. For the majority of amateur boatbuilders, epoxy is probably a far better adhesive than resorcinol, primarily due to the more forgiving nature of epoxy as an adhesive. As Lion35 has pointed out, Resorcinol requires much more precise building, cutting and clamping techniques, which are generally not the forte of most amateur boat builders.

The problems with heat are well known and that is why epoxy constructed boats should never be painted dark colors. I was recently on a twenty plus year old cold-molded wood-epoxy boat, and didn't see any signs of water penetration into the wooden core, even though its been in the water most of that time.

[USCGRET1990]

Epoxies, such as the West boys, are designed to completely incase wood that never gets wet for the most part. It is also painted for UV protection.
Any wood that may absorb water, actually shouldn't even be painted. Doing so, only traps the water in the wood. If that water is salty, not so bad, as it's a preservative. Topside, at least one side should be kept bare and treated with a preservative. If you are familier with old wood boats, you have certainly seen how the cabins rot badly vs. the hull that sits in the salt water.
This is because the topside wood gets wet with fresh water and is painted on both sides.

[Jeff_H]

When this issue first surfaced in the late 1990's I wrote to Gougeon and asked about the issue. They mailed me a series of articles on this topic which included destructive testing of actual panels from older boats that had been exposed to real use, tests on cycling of panels with heat and moisture, and so on. There was also a set of destructive tests of epoxy adherred panels at elevated temperatures.

As I recall the findings, while it is true that all adhesives (including resorcinol) will allow some migration of water, in the case of epoxy and vinylester the amounts of moisture are at a molecular level and so extremely small that it does not promote expansion or contractions.

My recollection of the tests was that epoxy did lose some strength at elevated temperatures but that even at fairly high elevated temperatures the panels behaved within the normal design strength range for epoxy which already has a reduced design strength for this very reason. (i.e. in essense the published design strength for epoxy that is used for engineering purposes is the strength of epoxy at an already elevated temperature.)

As much as I admire the Pardeys, his views or materials and methods are really dated, and tend to be a little hypebolic when it comes to newer materials.

Respectfully,
Jeff

[chucklesR]

I built my 10.5 foot sailing dinghy out of okume, mahogany and West products, including the wood flour fillets and the 3 encapsulating cover coats. It also has two coats of white LPE paint over the non-bright parts and varnish on the bright bits (elbows, seats, no structural portions are bright). I've beat the crap out of that boat for 5 years without a problem.

Losing 30% of it's strength in high temp's is only an issue if 70% isn't good enough and you are in high temps. Last time I saw 125 degrees on a thermo it was inside an oven (granted decks in the tropics can get that hot).

I can't imagine using resorcinal - for one thing where do you get it?

[ReverendMike]

Woodenboat forum beat this to death, with people who know a lot more about both sides of the issue than most of us here:

http://www.woodenboatvb.com/vbulleti...ad.php?t=71972

Not really trying to kill the thread, just seems that way, sorry.

[sailboy21]

My local hardware on an Island, in Alaska has Resorcinol on the shelve... Now if it has been there since 1972 is another question

Originally Posted by Blue Eagle

I'm not sure how many people have access to resorcinol glues nowadays, or have the skills or knowledge to use them efficiently. I certainly wouldn't know where to get it from, but if you're restoring a traditionally-built vessel, or building one new, perhaps West System isn't the best stuff to use.

BE