Marine Glues: Are we setting ourselves up for failure?

[Barnacle Jim]

I just finished reading an astounding section on glue failure (Appendix C of Larry Pardey's Details of Classic Boat Construction). Pardey argues against epoxy, citing a number of statistics and examples of epoxy failure.

Pardey also talks about plastic-resin glues (Weldwood and DAP) and failure rates, especially with oak.

I had thought epoxy was stronger than steel. Apparently, I was wrong.

Also, I did have problems with DAP and oak (in fact, the adhesive for my oak mooring bit was DAP; some of the joints have now opened, and I recently filled those joints with epoxy adhesive.)

I must tell you that I am troubled by what I read in Pardey. Can anyone counter his point of view on epoxy failures?

We may need to use a resorcinol adhesive such as Aerodux 500.

What do you think? and what has been your experience?

[BobSmalser]

Epoxy failures?

From my reading (we don't have much oak here for me to use) it's well known that White Oak seems to prefer resorcinol. Lotsa tannic acid that's fussy about glues, apparently.

But I've used epoxy in outdoor applications pretty regularly for 30 years and think it's the absolute cat's meow for applications requiring flexibility and/or weak clamping pressure.

Resin glue? Great stuff, I've done a whole lot of oak with over the decades for interior use. Lots cheaper than PVA glues, doesn't creap under load like PVA... and more working time combined with much easier repairs when the time comes. There isn't a single bottle of PVA glue in my shop, in fact. It's brittle compared to epoxy, though...and like all of them, will eventually fail in crossgrain applications.

I don't believe I've ever had a glue failure over the decades...and I've certainly had them...that I couldn't trace back to either improper clamping pressure, improper temperature (resorcinol needs 70+ degrees, period...use an electric blanket over it if your have to) or a crossgrain application like a round tenon joint that'll eventually fail at some point in its life anyway....in those situations, you want a glue that is easily repaired like hot hide glue for interior and epoxy for exterior use.

My epoxy failures have all been either an improper ratio mix or (usually) too much clamping pressure that starves the joint of glue. In fact, I've come to like poly for exterior edge joining, as poly likes a lot of clamping pressure that'll bring those sometime imperfect joints into tight alignment where that much pressure would starve out epoxy.

I haven't read Mr. Pardey...perhaps he was the first builder to discover that oak seems to like resorcinol better. But then again, I've heard arguments to the contrary of that, too. Otherwise, I'm not impressed. If I can trace back all my glue failures, so can other folks. Other peoples' glue failures? No telling. but dollars to donuts there is a mistake like one of mine in there somewhere.

[Frank Hagan]

You have to understand Larry Pardey's frame of reference ... the serious off-shore cruiser. Only the absolute best material will suffice, because your life literally depends on it.

When building a coastal cruiser or small boat like most of the day sailers we build here, there's not quite so much at stake. Pardey's comments in the book address some common misconceptions about epoxy, and then relate a few of his experiences (its been a while, but I think he mentions epoxy joint failure on steps, and on a working part ... perhaps a tiller mounting?) The experience of literally thousands of home boat builders counters his views, in boats going on some 15 years old now.

Epoxy should not be used to try and replace a mechanical fastener at something like a tiller mounting, or to be the only thing holding a step on. It is brittle, and its subject to UV degradation. But in a long glue seam with tons of contact surface area, epoxy works fine.

[BobSmalser]

Epoxy failures?

Other peoples' glue failures? No telling. but dollars to donuts there is a mistake like one of mine in there somewhere.

Epoxy should not be used to try and replace a mechanical fastener at something like a tiller mounting' date=' or to be the only thing holding a step on. It is brittle, and its subject to UV degradation. But in a long glue seam with tons of contact surface area, epoxy works fine.[/quote']

Not using proper joinery to begin with certainly qualifies as a mistake, IMO. :wink:

[MikeStevenson]

I don't think I'm going to lose one minute of sleep over the potential failure of epoxy or urea resin glues in our boats. The proof is in the pudding: they work, and have been working for quite a long time.

At some point everything can be found to fail; the Great Pyramids will weather down to the ground eventually. I don't think it benefits any of us to worry about this, but I suspect this Pardey fellow is benefiting quite handsomely by being an agent provocatuer.

As to failures of boatbuilding materials, I defer to our friends from the Northwest who have more big-boat experience than most of us and they seem satisfied. Through our family member who is deep in the higher-end fiberglass boat design world we've heard some interesting stories of failures of materials. Most are usually due to improper prep or some other mistake; seldom outright failure. Overstressing is a mistake in design, not necc. materials. (remember the Aussie Cup boat which folded off San Diego? I've sailed Peter's Weekender in precisely the same spot on a similar day and it was rough (and I was getting on the ill side from the chop...), but it certainly wasn't break-a-boat weather. That's pure design screw-up.)

On a sub-topic, does anyone still use end-grain balsa core or has that been phased out? I had heard that water got in the core and rotted the balsa fast on the decks. True, semi-true, are-you-already-in-the-rum-locker? Just curious, as I was chatting balsa boards (surf) with a guy the other day and we got discussing balsa core (boats.)

Mike

[Guest]

Oh yes, shaking in my boots Larry. :roll: Yes I am going to sink in my epoxy clunker, snot infiltrated floating hunk of pleaser from it coming apart. Yes this discussion comes up all the time. Conclusion, read the above concerning operator error and improper woods and materials. Improper satuation, too, is not a problem of the eopxy glue. Inexperience of the builder is not grounds for condemning epoxy glues. One must also realize that the actual building technigues are so different in designs slated for epoxy, or epoxy-glass construction, speced out by the designer themsleves. Glueing big hunks of wood together with no fasteners, and expect it not to move or work free, is not the fault of epoxy, either. Keep the PFDs close at hand. :wink:

[capt jake]

I had a rubrail glue joint fail. It was overclamping that did it! It wasn't the glue!!

I have a habit of making everything 'exact', which is a very good thing when building furniture. But I have had to loosen of my perfectionism when it comes to boat building and glue joints (totaly different animal from a dresser, etc).

[Dave Fleming]

Most all glue failures can be traced to a few errors on the part of the builder/s.

Resorcinol Resin ( the red stuff ) was used indiscrimantly early on and the failures were enough for it to get an undeserved bad reputation.

Plastic Resin had it's failures also.

***One MUST READ carefully the makers directions for all glues prior to even thinking of useing them.***

I willl make mention of one personal example of Plastic Resin ( Weldwood Brand ).

In the early 1970's I built two Redwood benches for the Sonoma Cheese Factory. I glued all parts with Weldwood and screwed the resulting laminations together. As of 2003 those benches were still outside the Sonoma Cheese Factory store on the square in Sonoma, California.

Now no argument that is not a marine environment but 7/24/365 over 25+ years in all seasons, rain, heat, cold, whatever, I was impressed to see them out there myself.

They received NO care all those years! The finish Flecto Plastic Resin and Sealer was worn just where you would expect it to be worn.

I have precious little experience with Epoxy Glues and what I have dates back to the time John Gardner was preaching Shell Epon Resin and another makers hardner ( circa 1975)bought by the 5 gallon pail and mixed according to the makers directions. I had good success with the formulation on TEAK, ASH and OAK.

When running the millwork shop at MARCO in Seattle, Washington State, we used Cold Cure Epoxies from British Columbia on TEAK and Mahogony and I liked them. To the best of my knowledge the line has been expanded and upgraded.

Lots of eary ***cold moulded*** homebuilt boats were built with Weldwood and some very long voyages made in those boats.

Keep in mind that any particular author/expert is using his or her own experiences as the basis for criticisms.

John Guzzwell's TREAKKA was built cold moulded and he sailed it round the world with time off to assist the SMEETON's on their leg around the Horn and subsequent pitchpoling. He rebuilt the damage in Chile and depended on Weldwood for many aspects of the repairs. He returned to Trekka and continued his voyage. The Smeetons suffered yet another pitchpoleing and had to get repairs done by local workers. If I recall correctly, Guzzwell's work stood the test just fine.

He built Treasure some time later and it was cold moulded. What adhesive he used, I cannot recall. And then Jay Benford asked him to assist in the construction of a big, as in 125+ feet cold moulded sailing vessel in Brazil.

All this is clearly documented in published works.

[Craig]

The only epoxy failures I have had is where I slapped it on and left it outside unppainted. The UV got to it finally and it let go. Todays epoxy mixes can withstand most any temperture range within reason and will last forever if the application and the workmanship is proper. For boats, it is all I am going to use from now on. It is wise to use a 200-250 degree mix however to make sure the laminations stays stable in the southern and western reagons where the sun's heat is a factor. Florin, not to worry.

[Florin {VACATIONER}]

I wish we had so much sun around here to worry about too much UV damage Craig. And as far as I know the poly resin in not quite as susceptible to UV damage. The epoxy we've used is "hidden" inside the keel, hopefully that is the part of the boat whe the sun don't shine hehehe.

I'm more concerned about water getting in somewhere and freeze up during our long cold season. That's the kind of damage I really don't care for fixing the next season. Like I think I've told you already, we're done fiberglassing a couple of weeks ago, now we're prepping for paint. We're hoping to have her ready to spray this coming weekend. Still got so many small things to do.

Cheers

Florin

[MikeStevenson]

I suspect everyone who's been building stuff for awhile will have similar failure and success stories (though the benches out for 25 years is a pretty exemplary one!)

For the most part, if you stick to using stuff as it's intended and follow the directions reasonably well, you'll not see parts going in different directions.

Mike