The frame that refused to be laminated

September 14th, 2007
Recently I faced a problem and since for once it had nothing to do with customers not paying, I think it's worth sharing with you.
A boat with laminated frames was brought back to my shop because four of the laminates had failed.
Indeed, at the turn of the bilge the glue joint had failed and even the stainless steel screws, used to fasten the frames to the battens (this was a batten seam boat), didn't keep the laminate together! What did this guy do with my baby?!
It turned out the boat was left uncovered for a week. Unfortunately, more rain fell that week than in an entire year, and the boat was filled with water, 20 centimeters high. After pumping the water out, the owner noticed the laminate failures. OK. Time to take my lazy brain to the gym for a serious workout. The oak frames had been under water, swelling for more than a week, and oak is known for twisting a lot when exposed to different levels of humidity. For these four frames, the swelling must have been too strong, causing complete glue failure. So did I use an inferior glue? But I used seawater-proof polymere glue that can handle forces of 50 kilo per square centimeter. Pretty OK, no? And what with the screws? They were literally torn out of the wood! And why did only these four frames, at different places in the boat, fell apart, while the other sixteen frames remained completely intact. The brain was boiling.
Suddenly old stories of other oak-glue failures came back to me. Like that heavy oak transom, made up from several thick planks glued with epoxy, that broke under the force of an outboard engine. Or that guy who spent six hours of circling, trying to get back in the harbor with a broken oak rudder...
An idea started to bubble up! Not the glue was the villain but the tannin, a substance which gives oak its resistance to rot. Maybe my four oak frames didn't spend as much time in the steamer as their siblings, and therefore contained more moisture - read tannic acid. The acid made the oak less receptive to gluing and this could be thE reason for glue failure.
Now, since more woodworkers, not only boatbuilders, but carpenters and cabinetmakers will start using epoxies, polymeres and other 'modern' glues, the more information will come to our ears concerning the oakgluing business.
Anyway, this whole thing is highly hypothetical, and I promise some testing and updates on the results!

ps. How did I fix the problem:
I resteamed the four frames in the boat, using a tarpaulin cover and a tube, and refastened them with stainless screws. Simple as pancakes...
(with the same glue)