screw mounting in cored deck

[dhays]

Guess I'm a bit confused. What is the bolt in there for? Typically, you would seal up the bottom of the hole with duct tape, or some other means and pot the hole up to the top, keep adding as needed until it gels. Then redrill as needed once it's cured. I wouldn't worry too much about amine blush for this sort of thing, it's just potting not a structural feature. If you are concerned about amine blush, switch to MAS epoxies which are amine free, they also have a low viscosity product that will wick well into any core material.

It is a long and old thread so your confusion is understandable.

No acceptable (to my wife) access to the underside of the deck. I wanted to be able to use bolts screwed into the deck to mount the hardware. I considered, and rejected, using a drill and tap method, in favor of the casting method I used. The drill and tap would work fine, but when testing I found that I was able to get more consistent results with the casting method. Likely just my poor technique.

 

[Northern Spy]

Hi Dave! I'd clean up the amine flush, or just mechanicaly agitate it with a Dremel or wire brush and top it off with more epoxy. I'm sure that your unthickened epoxy found voids. Not unusual.

 

[dhays]

Hi Dave! I'd clean up the amine flush, or just mechanicaly agitate it with a Dremel or wire brush and top it off with more epoxy. I'm sure that your unthickened epoxy found voids. Not unusual.

I was using thickened epoxy. I may have misspoke. I used 404 thickener. However, it wasn't super thick. I may have done better if I had used a bit more of the 404 to make it thicker. I ended up cleaning the amine as Commodave suggested and the result was good.

So far I have the two aft chocks mounted and they turned out very well. The biggest pain in the backside is trying to mark the location for the forward chocks. I don't have a helper so doing it solo is proving problematic. I'm slow at doing any project, but this is taking more time than most.

 

[Lepke]

A screw holds better in epoxy than in wood. Epoxy holds to wood better than a screw.
DavidM is exactly right. I've mounted dozens of screws in cored decks that way. Stanchions, etc. The first time I do any new technique, use a new glue or epoxy, I destructive test. Then I know.
Just like I know there is no such thing as a one part waterproof glue.

​

 

[dhays]

Quick update:
I have the two rear chocks mounted. It seems to have worked well. I started on the forward chocks today. I found a surprise. The Boat deck has a plywood sandwich. I was expecting this on the forward chocks as well. However, the first hole I drilled I ran into a honeycomb core material instead of plywood. I used thicker epoxy on this one what am waiting for it to setup. I drill another hole on for the corresponding starboard chock and hit the junction between plywood and honeycomb coring. Again, I used a thicker epoxy mix on that one and it is setting up. If they look good, I'll do the additional 2 bolts for each chock. I'll head back to the boat in a couple hours to check.

 

[dhays]

Ok, finally got it done.