Epoxy and Fastenings

[Foster Price]

Hello All

I'm building a new hatch, the frame is done and I'm about to "plank" it using 1/2" (12mm) shiplap planking fitted in a 1/2" wide rebate.

Now I know traditionally such a thing would be fastened with screws and bunged, but I'm glueing the stakes with epoxy.

I'm am thinking of leaving the screws out to save a lot of work with bungs, any thoughts on wether this is a good bet or not ??

Timber is Kwila, a Malaysian hardwood that glues pretty well, the hatch is 20"x32" so it has quite a span and has to be able to stand being "stood" on.

Thanks & Cheers - Foster

[bjornar]

Epoxy seems to be todays answer to virtually anything. Sure - it is useful stuff, but I don't think it replaces screws. I know I wouldn't feel comfortable stepping on a hatch held together only by epoxy under a direct sun. Bunges and screws are not that much job. Besides from that, someone once told me that anything on a boat should be possible to take apart.
bjornar

[Ross Faneuf]

I always epoxy everything; then screw and bung it. It's more work - and you can't have too much of that ;) . The phrase 'Faneuf-built' really means something in our family.

[Bruce Hooke]

If you trust your epoxying skills I would just epoxy it. My thinking is that the screws are irrelevant once the epoxy cures, unless you really mess up with the epoxy, so why mess around with screws. Also, I'm not sure why it happens now that I think of it, but I have seen cases where the finish seemed particularly inclined to fail around the bungs, so why add that possible issue to the mix. I know some people don't quite trust the idea of just using epoxy but many critical joints in boat hulls are commonly made solely with epoxy, for example in stitch-and-glue hulls and laminated keels, and the consequences of having a boat hull fail in mid-ocean are clearly much worse than having a hatch fail.

Also, I would assume that when someone stands on the hatch they will be pressing the boards down against the glue joints rather than trying to pull them apart, so the ability to support someone has more to do with the strength of the wood, and possibly the hatch hardware, than it does with these joints.

[JimConlin]

I've built similar hatches where the panel was 1/2" plywood with a 1/4" teak overlay set in epoxy. Secure the slats with screws and fender washers BETWEEN the slats and remove them when the googe has set. The screws serve to establish the spacing between the slats. Clean the squeeze-out pretty carefully. Backfill the grooves with either black polusulfide or blackened epoxy.
This looks right, is bulletproof and lightweight and uses a minimum of the treasured teak.

[Leon Steyns]

Foster,

Please beware that the epoxy is several times stronger than the wood you're glueing! If something will fail, it is going to be the wood which will go first. Any forces applied are more evenly distributed by using epoxy, than by using screws. Besides that, epoxy doesn't corrode (but make sure to use paint that includes UV-inhibitors).

Greets, Leon Steyns.

[Victorious]

I built several wooden Wayfarers in the 80's while working for Porter Bros.
Ian Porter was for many years national champion racing three classes of boat and wayfarers built by us were considered very quick.
Everything was epoxied together and where screws were used they were removed when the epoxy had cured and the hole epoxy/microballon filled.
To be honest temp and huumidity were not very well controlled in the workshop so i can only conclude that Epoxys are not as fussy as people seem to think.
20 years later there are several of these boats still racing locally and none are showing any significant signs of coming apart.
Epoxy does soften when its very hot and I have sometimes wondered if such a boat might one day get left on the beach somwhere realy hot and the owner returning a few hours later to a boat in Kit form! :D (here in the UK there is little danger of that happening......)

[Dan McCosh]

I've used epoxy to edge-glue the tops of two varnished hatches, with the frames, etc, screw-fastened, and the top planks screwed and bunged. Both had the glue joints fail on a hot (100-plus) day, when the horizontal surface soaked up the heat.