fuel tank cleat attachment methods

[Grazer]

Thanks Sunbeam,
Your suggestions are appreciated and I did think of those. Like joe, the bonded threaded rod with a nyloc nut on the back would get better purchase with the vibrational stresses that may loosen machine bolts treaded into an epoxy plug. I like the idea of bonding fiberglass cleats to the sole, but may have to glass in wooden stringers as it is difficult to find premade fiberglass angle here. I would like to re-use the existing cleats and panel if I could.

[Grazer]

[Aurelia]

Ours looked a bit like the pic posted by Sunbeam when we bought it. I pulled everything out and slighly enlarged the holes in the floor strip, cleaned out and resealed the floor holes, re-padded the tanks, and re-drilled and connected the thin panels/aluminum angles for better alignment. I basically used the existing parts to improve the configuration and it turned out fine. Our cockpit will remain a dry space as we use it but if I were to keep it open and wet, I would have permanently mounted the strips to the floor and put in my own simple strap based hold-down system.

The way those tanks sit and the motions of the boat in normal use kept me from getting carried away with the strength of the mounts.

Heck, just the stiffness of that darn fill hose keeps them pretty well in place.

Greg

[Sunbeam]

[thataway]

Reading thru the posts from today: I believe that well cleaned rod, placed into the areas previously drilled out, and set with epoxy will be very difficult to remove. This should give a very strong bond. Using the washer and Nylox nut will work fine.

Epoxy to "glue" fiberglass angles, or square tubes etc will work fine. Just be sure that the glass on the angle and the bottom of the boat are well ground to fresh clean surface and clean of any wax or contaminate.

[T.R. Bauer]

Considering that the factory drilled then right into the floor during the 90s to expose the core to water on my boat, then anything you do will be better. I would agree that if you set something in epoxy like all-thread or a rod, it will be tough to get out if done right. If fact, I have some screws in a door at home I used epoxy on that will not come out, period. I guess I should have drilled and threaded them in instead of just sticking them into wet epoxy. Amazing stuff for sure......

[Grazer]

Thanks fellas for your advise and words of wisdom (read encouragement). I think I'll try the threaded rod technique, since I have some on hand. As far as doing it right, my thoughts are as follows: First to drill out a pilot hole in the previous epoxy plug, tap with threads, wet out holes, mix in some cabosil in the remaining epoxy mix, apply to threads, thread to bottom and cure in place. Reattach cleats.

[thataway]

The issue with using a tap in a fairly short hole, is that you may not be able to get the tap all of the way into the hole. You need to use what is called Blind hole taps: You start with a tap which as flat threads and a modest taper, then the second tap, is beginning to cut the threads--the final tap is almost square threads, and gives good threads all of the way to the bottom.



When using a blind hole tap you have to back it out more often than a thru tap, and best to use some compressed air to get debris and tailings out of the hole.

It is probably easier to over drill the hole, snug to the rid, and then put some epoxy into the hole, and also coat the threads with thickened epoxy,

The first way with blind hole, tap, you don't need much thickening.

[Grazer]

[Sunbeam]

A couple of ideas/thoughts:

1) If you have a fastener epoxied into a hole, and you later want to remove it, try heating the fastener. I've had good luck with that method as epoxy is quite vulnerable to high heat (it softens). You can exploit that weakness.

2) Another way to do it in the first place (although it's more similar to tapping in that the fastener is not bonded into the hole) is to wax a fastener, then epoxy it into the hole, and then after the epoxy cures remove the fastener and de-wax it (or use an identical fresh fastener), and then use the hole much like you would a tapped one.

I've known the type of tap that can reach to the (flat) bottom of a hole as a bottoming tap, so perhaps that's another name for it. That's what I used on the trim tab fastener holes, for example.

[thataway]

There is a different between a blind hole tap and bottoming tap. The Blind hole comes in a set, and is more satisfactory for hard materials. The Bottoming tap only has chamfering for the first 1 to 2 threads-and will not fully thread to the bottom of the hole, unless there is a little taper (easy to do) on the last two threads of the bolt. The bottoming tap will also be a bit harder to use.

[Sunbeam]

[thataway]

You have the correct set--use the Taper, then the plug and finally the bottoming. There is another way to do it and that is to use only one tap--which has chamfer on the first one or two and a half threads. Your final tap, assures that there are threads all of the way to the bottom of the hole. The single tap will not have complete threads to the bottom--although you may force or cut threads with the threaded rod or bolt (or booger up the last two threads)...

[Sunbeam]

Thanks for the confirmation. If I remember correctly, I went right from the taper to the bottoming tap and everything felt good; perhaps that worked because even "hard" epoxy is softer than, say, steel. (I did also sometimes use a drill one size down from what was recommended.)

Next time I'll try progressing through all three though - maybe it will work even better.