rub rail from epoxy w/ graphite

[Charly]

I haven't seen this anywhere... maybe for good reason anyway, last night I had a brainstorm and would like some response from others.

The idea is a cast rub rail strip from epoxy with graphite mix.

This piece could be fabricated in a half round shell... say, the inside of a ripped down piece of pvc pipe, screeded flat and peel plyed. then when set up, it could be glued directly to the sheer, or deck near a cleat, or wherever needed for chafe. No fasteners.

The strip would keep its uniform color regardless of wear, and could be taped off when the hull is painted.

Would the graphite leech out onto the paint job over time? Would the graphite discolor the line? Has anyone tried this or anything similar? Is there any other negative? Thanks for all input.

 

[gonzo]

It will be very brittle which is the opposite a rubrail needs.

 

[michael pierzga]

UV will eat it , chafe will eat it and it has no impact resistance. Use either a bumpered energy absorbing rail or a stainless chafe rail.

 

[MoePorter]

I agree with the negatives but

UV will eat it

isn't one of them - West suggests graphite/epoxy mix in between the strips on teak decks (3/16 - 4.5mm thick strips). I've got 20 years on some decks & so far so good. It's a good additive if the epoxy will be UV exposed.

UHMWPE is my choice 1st choice for rub rails - although you have to plan for some thermal expansion/contraction. Moe

 

[PAR]

The idea is a good one, though you don't need the peel ply. Graphite is one of the filler materials I'd use, but I'd also use a fair percentage of milled fibers and other fibrous materials (silica, cotton flock, etc.) to stiffen and add interlocking stiffness. In fact I wouldn't bother with the graphite and would just use a standard heavy structural fillet mixture, but with pigmented resin. Graphite/epoxy caulk lines on a deck work, because these not much surface area exposed, but this isn't true on a rub rail, so some UV protection will be necessary. You can clear coat or use a paint. Naturally it's a good idea to use the same color as the pigment, do dings and scratches don't show as much. Lastly, don't bond the rub rail. These are sacrificial in nature and have to be replaced/repaired from time to time, so screw or bolt it down over a good bedding compound.

 

[michael pierzga]

Since Charly is building a lightweight Cat, it may be difficult to conceive an aesthetic, functional chafe rail. Fastenings wont work well and will damage the core. Perhaps nothing is the best choice. To disguise chafe at the sheer clamp a contrasting paint scheme that can be easily touched up each season might work. Perhaps Graphite epoxy for its lubricity, covered by black paint, then just be careful with impacts by using fenders.

On a typical small boat, A teak chafe rail capped by ss oval is a beautiful thing...easy to clean, easy to replace and it crushes and deforms on impact... before you damage your topsides. Teak is easy to work with...scarph to length, cut a rolling bevel. This is why god invented teak.



UHMWPE is burnt by the sun and has no abilty to absorb shock. Plastic is very difficult to shape and join. I have UHMWPE as RIB dingy skid pads on my transom. When the dingy whacks the plastic at the wrong angle during launch or load, it tears the SS fasteners out of the deck. Not good on a light weight cored cat.

 

[PAR]

If weight is a concern, a solid epoxy casting isn't the logical route. An extruded PVC or aluminum rail would make a lot more sense in this application. It could be set in a stiff bedding and permitted to cure good, before the tape holding it place was removed.

 

[Charly]

Since Charly is building a lightweight Cat, it may be difficult to conceive an aesthetic, functional chafe rail. Fastenings wont work well and will damage the core. Perhaps nothing is the best choice. To disguise chafe at the sheer clamp a contrasting paint scheme that can be easily touched up each season might work. Perhaps Graphite epoxy for its lubricity, covered by black paint, then just be careful with impacts by using fenders.

.

This indeed may be the best route for the rub rail, in my case. I may just add an extra layer of 6oz tape along the exposed area and be done with it.

PAR -For chafe guards at the cleats etc, I could still form up something and lay it down on the deck. What would you suggest as a bedding compound that would be strong yet not permanent? I want to avoid penetrating the (balsa) deck.

Thanks

 

[PAR]

Well 3M-5200 is out, but 3M-101 is an option with a much less aggressive adhesive. There are others as well.

 

[JSL]

Not an issue in this case but don't use this on an aluminum boat