Just do like Larry said with the Allen wrench, fill with thickened epoxy, and then just drill and tap your hole for whatever bolt size you need. Epoxy is tough as woodpecker lips and it can even be machined. I really like the 50/50 Clark Craft epoxy but there’s plenty of others out there.
Being superstitious is bad luck.
Time and tide wait for no man.
I got the new grab bar from Happy Bob (It’s beautiful! Thanks HB!) early last week, and I’ve been slowly working on getting it installed. I will be able to bed all the port side bolts in epoxy, but the starboard side bolts will all be over the wiring channel in the J16 so that I can run the wires through the grab bar. Not having many other options, I have drilled and tapped fiberglass deck in that section and plan to run 1/4 inch bolts into the thread and seal them with either thickened epoxy or 3M 5200. What advice to you guys have on which is best? See pics for the build:
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Perfect 
Capt. Larry Teuton
Cracker Built Custom Boats
“Ships are the nearest things to dreams that hands have ever made.” -Robert N. Rose
Larry,
Did you see my question about what to do on the starboard side?
Tom
quote:
but the starboard side bolts will all be over the wiring channel in the J16 so that I can run the wires through the grab bar. Not having many other options, I have drilled and tapped fiberglass deck in that section and plan to run 1/4 inch bolts into the thread and seal them with either thickened epoxy or 3M 5200. What advice to you guys have on which is best? See pics for the build:
Drill those out over sized too, just not as deep. Fill with thickened epoxy and drill and tap for machine screws. Machine screws are stronger than self tapping screws set in epoxy, they have more thread area. Put epoxy on the threads when you secure it and 5200 around the bases. With 4 mounting points, 4 bolts in each, it will be extremely solid, which is how we want it 
Capt. Larry Teuton
Cracker Built Custom Boats
“Ships are the nearest things to dreams that hands have ever made.” -Robert N. Rose
Larry,
I don’t see how I can drill those oversize and fill with epoxy, as there is nothing under the fiberglass but air–no way that I can see to fill with epoxy. I am using machine thread, but the fiberglass is the only thing I have at that point to thread into. Nothing underneath the hole to catch the epoxy.
Tom
quote:
I don't see how I can drill those oversize and fill with epoxy, as there is nothing under the fiberglass but air--no way that I can see to fill with epoxy. I am using machine thread, but the fiberglass is the only thing I have at that point to thread into. Nothing underneath the hole to catch the epoxy.
OK, no problem. It’s a 2 or 3 stage process without a 100% solid foam backing to start with, but it’s easy. This is one I did this weekend, it’s for a T-top base…
First you drill the bolt holes over size. For 1/4 bolts I usually drill 3/4 holes with a hole saw.
Then I pour a liquid 2 part expanding foam into the holes. This will fill any voids below the deck. About 2 ounces will fill a lot of space and expand out of the holes. No empty voids left under there.
After it cures a couple hours, cut the excess off flush.
Then re-drill them with the same 3/4 hole saw, as deep as you can without hitting important stuff. These are 4".
Now chuck a stout Allen wrench into your drill and use it like a router bit to cut the foam out from under the deck and create the cross section that I posted in the picture above. This one…
[img]http://gallery.bateau2.com/albums/userpics/13040/normal_Bolt_mounting_diagram.
Why not some SS nutserts and a bed of 5200?
“Banana Pants”
Indigo Bay 170
90 Johnson
Wilderness Ride 115
Not strong enough to suit me. Especially for a T-top or leaning post.
Capt. Larry Teuton
Cracker Built Custom Boats
“Ships are the nearest things to dreams that hands have ever made.” -Robert N. Rose
Hmmmm…I hadn’t thought about using the foam to make my own foam core. The only issue I see is that I’m still going to need to run my sonar wires down the channel and the foam will be in the way. Here’s an idea I had that I think would work, since I already have an access hole under one leg and can easily cut one for the other leg. It is complicated to explain, so I drew a picture:
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Just stick you a piece of pvc pipe with a pull string elbowed up in that hole you show. Then proceed with Larry’s process. The foam will fill around the pipe, and you will still have a chase tube for the wires.
“Banana Pants”
Indigo Bay 170
90 Johnson
Wilderness Ride 115
Yep, right after I posted the other method, I thought about the pipe, too. Getting it positioned might be a little tricky, but I think I can do it.
If you have that hole why not use SS fender washers and nuts glued to underside! No mess no fuss and done in no time!
I thought about that, but I don’t think I can glue the washer and nut in place securely enough that they won’t turn when I’m tightening the bolt.
Larry,
Can the expanding foam in a can be used for this application, or does it really need to be the two-part kind? I can easily get the can version, but will have to order the two-part, so I’m wondering if the can will do.
Tom
There are 2 types of that canned foam! One type expands so much that it will bend things, it exerts so much pressure! The other type will only expand until it fills the void! The first type will bow wood door frames! The other will fill and seal all the air spaces and stop. Ask me how I know:face_with_head_bandage: Home Depot or Lowes has both types, so read the can:wink: The type you need, should be the encapsulated closed cell marine foam and I’m not sure that’s the kind in the cans:question:
I’ve never seen any that works well, it’s too soft to effectively drill and mill. Almost like trying to drill a sponge. Too bad you aren’t closer, I’d give you some. You only need a few ounces. Maybe there is a boat builder near you who can spare a little.
Capt. Larry Teuton
Cracker Built Custom Boats
“Ships are the nearest things to dreams that hands have ever made.” -Robert N. Rose
Call Tim DePreist at Marine Pro. Their # is 803-407-6020. Tell him I told you to call. He might be able to help you out. If he has something for you, let me know & if you want, I’ll pick it up for you & we can meet somewhere. (I need an excuse to go over to their new shop anyway.)
Bob Van Gundy
Marine Designs,Inc.
Custom Aluminum Fabrication
803-727-4069
bob, thanks! If my alternate method doesn’t work I may just take you up on that.
The types of foam in the can are both open cell. They will absorb water like a sponge. DO NOT USE “GREAT STUFF”.
218WA Sailfish
200 Verado
The "Penn"sion Plan