Found corrosion between the rear beam traveller support and the carbon beam on my A cat. Cleaned up the aluminium bracket and reriveted only to be told to drill out the rivets and put washers inside the beam crimped onto the rivets to spread the mainsheet load. How do you do it, especially solo. I bought a Usb cable camera which i shoved inside the beam then tried fixing washers to a plank and holding up to the rivet tips to clamp down when the rivet gun compresses the head. Lots of misses and retrys. In desperation used a string thru a thin straw screwed onto a bolt thread and successfully dragged the washer and bolt through the beam and out of the hole. Next problem, how to tighten the nyloc nut without stjffing the thread. Suggestions?

Dalai Lama levels of patience.

Can you please show a photo/pic of your problem. I don't understand your difficulty. Is it inside or outside the beam?

But with regard to this riveting thing. Why don't you glue first with epoxyfiller the washer inside the beam over the rivet which is completely stick in. Use a auxiliary piece of wood to do so.(be sure you not glue the wooden piece also). Tighten/compress the rivet first after hardening of the epoxy. Be sure you use a rivet with a long enough shaft; it will make things easier and gives a larger plug of alu before the hole.
Wax the rivets before.

Ofcourse all assuming that the shape of the beam is flat under the traveller.

I was going to say the same thing. Glue the washer to the inside of the beam before riveting. You can even use plain old silicone caulk. The glue just needs to hold the washer in position temporarily while you install the rivet. Also, if you can remove the beam from the boat and flip it so the holes are pointing downward, it will help a lot. Gravity will be your best friend or your worst enemy in this case.

sm

If you don't care about adding a little bit of weight, to replace the washers you may use a strip of aluminum or stainless the length of your beam and drill holes in it at the same spacing than the beam and you will be able to hold it from the ends. A lot easier than trying to align separate washers.

AB

with regards to the bolt method, I've had luck using electrical tape, a batten, and an open end wrench. I'll tape the wrench solidly to the end of the batten. Then I'll make one wrap of tape around the nut and jam that into the end of the open end wrench. You can also adjust the angle of the nut in the wrench to offset it slightly out of plane if you need to - the tape will hold it pretty much wherever you set it. I slide that batten in until I can see the nut from outside the hole and then carefully start to thread the screw into it. I've also used some liquid nails (a thick glue/sealant) to hold a washer onto the nut. I can get a nut on a screw in the middle of the beam relatively quickly this way.

A rivet washer, however, would be a completely different animal. It would have to be pressed up against the inside of the beam with some pressure in order for the rivet to take it up properly. I might try some hair-brained idea to glue a washer to a chunk of sponge and then tie that to a batten, push that into the beam with the batten and try to wedge it inside the beam to push the washer in place. Use a drill bit to clean out a bit of the sponge through the hole to allow the rivet to penetrate it without moving the washer, then rivet. I've never tried this but I've had crazier things work.

the guys that build "ships in a bottle" might have some neat tricks up their sleeves for this.

which makes your avatar that much more relevant!

To get the washers in place I would try a small line and contact cemment. Use a small artist brush to apply some glue through the hole in the beam. Dab a little on the washer. Tie a knot in the middle of a long enough piece of line to be able to tie the ends of the line together. This is done so you can pull the knot away from the washer. Let the glue dry and rivet. If the beam has some curve you need to match the washer to that curve.

Mistakes made, rivets not long enough to ensure plenty of take up to crimp the washer , i thought if they were much longer they may not have compressed and tightened up enough. washers not bent to match inner curve radius, should have glued washers in. Hindsight is a wonderful thing

I've bolted on full length travellers many times but you may need a helper for bolts right in the center of the beam.
Cordless screw driver, ring spanner, packing tape and a stiff batten. (Helper drives electric screw driver for the middle ones.)
Tape the ring spanner to the batten.
Packing tape over washer and down sides of nut.
Nut should just fit into the ring spanner with the packing tape. Not too hard as you have to wiggle the ring spanner off the nut when it is done up.
Stick hole in packing tape so bolt an go through washer.
Put center bolt in first and slide batten in until it hits the bolt. Then carefully move it around until you can feel the bolt go in the hole in the washer and drive the bolt with the electric screw driver. Then do the next one out from the center. Makes it way easier to do it in this order.
Whenever I do a task like this that requires a lot of care and patience I just keep reminding myself that
"This is a game of skill".
Good luck.

I've found the best way to glue the washers to a nut is spray on contact glue in a can, just a fine spray is enough, spray nuts and washers then press together after a minute, washers inside with a rivet worries me as any imperfection will stop the washer being pulled against the beam until the traveller is under load and then you have a loose rivet, bolting the traveller on is easy but if you want the rivets you could just spray the washers , stick them to the ring spanner and they pull of easily once riveted

That's why I suggested glueing the washer spacely with epoxy filler. It also compensates any imperfect prebend of the washer.

Thank you all for your comments. There is method to this madness called boat repairs. The epoxy glued washer idea is just brilliant have filed that away if there is ever a repeat performance. Half my problem has been doing this solo, another pair of hands would have helped massively. Put the usb camera inside today to have a final look and the rivets and washers were tight on the inner wall but one of the bolts hadn't pulled up tight enough so levered the top washer up and then tightened the nut down and something went right for a change and it bedded well.Test sail tomorrow so will see how we go

Wait, you are bolting aluminum to carbon with stainless steel and no one has a problem with that?
Jake has made it pretty clear that stainless and carbon react. In spite of that, it is a common way to add fittings to a carbon mast or whatever. Lightly rusted stainless seems to retain most of it's strength.
Adding aluminum to the equation makes a bomb of corrosion in my experience, and should be avoided. perhaps i have mis-read the OP.
Mainly, since i don't speak Australian, this post is to find out what a ring spanner is?
Also if you glue a washer down with epoxy it won't be stuck very well and it would be hard to keep the glue out of the hole in the washer. After it dries you won't be able to slide the rivet in. Trying to drill the dry glue out of the hole will prolly pop the washer loose.

Well...yeah..that goes without saying. Carbon is at one end of the galvanic scale so just about anything that is in contact with it will act as an anode and corrode (including stainless). Anything that connects to carbon (that isn't already carbon) should have an electrical isolator between them to help slow down corrosion.

If you have a carbon beam in good condition and you epoxy aluminium or Stainless to it there is no problem with corrosion as the epoxy doesn't promote corrosion, I regulary insert aluminium tube inside carbon tillers at the break to keep them straight when I put them back together and there is nil corrosion after a few years and a few repairs

Yes, you are correct Jeff. That's exactly the big misunderstandment.

Carbon laminate is a mixture of carbon fiber and resin. At the surface of carbon made part their will always be the last microns resin at the surface. Which electrically isolates. So you can let a aluminium traveller rest on a carbon laminate surface for a century and nothing will happen.
(Yes,I know saltwater surrounding will demand more isolation in order to prevent leaking-current, which may blow through)

But if you are drilling holes in the carbon laminate, then you indeed create vulnerable spots for galvanic corrosion. So, a responsable cat-manufacturer takes care for that before rivetting the traveller on the beam.

And after drilling a rivet out, you have to isolate the hole again with resin, or other isolator.

(Don't want to be the wise guy, but epoxy filler on the washer will do that trick too)

Ive found Duralac sorts out rivets and screws

Ok color me overly concerned about the ability to insulate the 3 materials from each other. Just keep going forward and juice the area regularly with oil or whatever in the future.
Maybe it's English that i don't speak. They are the ones that call a wrench, a spanner. Presumably a ring spanner is a box end wrench in american speak. inches, pounds, wrench; what's wrong with the rest of the world? ha ha

My hair brained solution would be to wet out a bundle of carbon tow about half a meter long on your plastic covered work table (you can un-weave cloth to get the strands if you don't have the tow). Squeegee it out with your hand by pulling through a fist. Make sure the bundle fits through your rivet holes. Once squeegeed out it holds shape pretty well.
Guide one end through the hole and clip off a section with scissors. Flair or fold over the top end so it doesn't fall through the hole and tape off. Figure out some way to fold or flair the bottom end, and a way to hold it like that until cured; like a plastic covered stick, tape, a bladder, etc.
I have never tried this exact procedure, but i like to use carbon and resin to replace as much of the metal components as possible.
If you had a carbon beam, bracket, and traveler track, it could all be glued together in theory.