The traveler on my G-Cat uses a standard cam cleat bolted to a bracket that is riveted with stainless rivets to the rear beam. The boat is 39 years old, and the rivets are finally getting loose. I don't have a rivet gun that will pull stainless rivets, but I could tap the holes and use quarter inch machine screws. I have the tap and the bolts; I could even go all the way through the beam and back it with nuts and washers, but I hate to add more holes. The cam cleat does not appear to be heavily loaded, after all I can easily adjust the traveler with the mainsheet heavily loaded. So, should I take the easy way out and do it with what I have or go find a rivet gun powerful enough to pull stainless rivets?
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Bill Townsend
G-Cat 5.0
Sarasota
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Bolts vs Rivets
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Posted: Jul 11, 2022 - 08:03 PM
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Posted: Jul 12, 2022 - 09:37 AM
My Gcat 5.7 traveler is attached with machine screws, not sure if that was done by previous owner or if they just did certain years like that. Either way it has held up with no problems, and I push her pretty hard. A rivet gun that pulls stainless isn't a huge investment and probably something a cat sailor should have so I think you could go either way. -
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Posted: Jul 12, 2022 - 12:41 PM
Here you go, only $20.
https://www.harborfreight…ection-bottle-58612.html
I've got one I bought to set 1/4" rivets. It does the common 3/16" stainless rivets we use with ease.
Edited by waiex191 on Jul 12, 2022 - 12:47 PM.
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Bryan in Poplar Grove, IL
Supercat 17, unknown year. Future project
Hobie 16, 1977 - died a spectacular death https://youtu.be/Y7O22bp2MVA
Hobie 16, 1978 - current boat
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Posted: Jul 12, 2022 - 12:43 PM
Problem is that your crossbar almost certainly doesn’t have enough wall thickness for 1/4-20 screws to get enough thread engagement before they strip out. I’ve tapped 10-24 threads into crossbars before and it seems to be right on the edge of stripping out if over-torqued. I would recommend just getting a heavy duty rivet gun from Harbor Freight (they’re like $25) and installing 1/4” stainless rivets. I’ve had one of these guns for over 10 years and it has held up and worked fine for my occasional use installing SS rivets.
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Posted: Jul 12, 2022 - 12:47 PM
Also if you are only doing 3/16" rivets, you can use the pneumatic riveter:
https://www.harborfreight…aulic-riveter-93458.html
$50 and you need an air compressor. It has a hard time with 1/4" rivets not due to power but due to the size of the mandrel.
I'm with Dogboy. Probably too thin for screws. Redo the rivets and worry about it again in 39 years.
Edited by waiex191 on Jul 12, 2022 - 12:48 PM.
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Bryan in Poplar Grove, IL
Supercat 17, unknown year. Future project
Hobie 16, 1977 - died a spectacular death https://youtu.be/Y7O22bp2MVA
Hobie 16, 1978 - current boat
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Posted: Jul 12, 2022 - 03:04 PM
do you guys have experience riveting through carbon (specifically mast). Is there anything different that needs to be done vs aluminum? -
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Posted: Jul 12, 2022 - 03:11 PM
If riveting into carbon/composite, you really want to have a metal washer or backing plate on the inside surface. Otherwise as the rivet expands, it can cause the composite to split at the rivet hole.
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Posted: Jul 12, 2022 - 06:07 PM
I have recommended exploding or tri-fold rivets to help distribute loads to a wider area and take the place of an internal washer, which is not feasible in enclosed structures. The tri-fold rivets work particularly well in holding trampoline tracks to older hulls that have had standard rivets pull-through. It could be a solution for any fastening that requires higher strength, load distribution and old-work.
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Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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Posted: Jul 12, 2022 - 06:41 PM
Jim if you are riveting the masthound on the Inter20, no worries, it's a beast. The carbon is thick and solid.
I prefer Stainless Steel over Monel. Just make sure you have the correct grip range and then seal it. Also dress the back side of the hound with silicone marine caulk before you set it.
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Philip
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Posted: Jul 12, 2022 - 08:13 PM
Try 10/32. -
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Posted: Jul 13, 2022 - 04:09 PM
10-32 screw would be slightly better than a 10-24, but recommended minimum thread engagement is still about 0.20” (and that assumes the screw and the threaded attachment are the same material). A beach cat crossbar is around 0.10” wall thickness so 10-32 is still pushing it and the OP was talking about 1/4” diameter screws, so even worse.
Another potential option would be to use sheet metal screws, but I think just bumping up to a larger rivet would be the best approach.
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Posted: Jul 13, 2022 - 09:29 PM
In cases like this- I install nutplates inside to replace rivets after tear-out. Have a look at floating click bond nutplates part number CB6009CR3-1P for 10-32 thread. Here are the steps: 1. Sand the inside of your beam, mast or boom with sandpaper on a broomstick for bond prep. 2. Acetone wipe the bond area and nutplate for bonding. 3. Then snake a piece of small diameter mig weld wire or safety wire through the hole you are looking to pull the nutplate up to. 4. Pierce the wire through the silicone end of the nutplate. 5. Cover the nutplate in Plexus MA 310 adhesive (or equivilent). 6. Pull the wire and nutplate silicone fixture end through the hole to seat the nutplate while the adhesive cures. 7. Pull out the silicone fixture after cure. 8. Grease your fastener upon screw installation to prevent fretting/friction welding during install, as clickbonds are agressive locknuts, and stainless can be problematic with small, tight screws. If your screw is too long, it may friction weld and snap. Electrician's wire strippers usually have 10-32 shears to help cut the screws down to the length you need.
Look up the click bond nutplate installation on youtube for a better description. Using MA 310 adhesive allows you to use a heat gun to break away the nutplate if you need to remove it or change it. This adhesive fails at a lower temperature than epoxy. These are standard, economical aircraft fastening methods that work well on boats too.
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David
Inter 20
Southern Maine
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Posted: Jul 15, 2022 - 09:22 AM
I have done the conversion from rivets to machine screws many times. If you can get a clean hole to tap into, you shouldn't have an issue. I would recommend red Loctite or bed the whole bracket with 3M 4000 or 5200. I prefer using 4000 for this application to give extra bonding. I rarely use 5200 for anything because it is so industrial, but it isn't good to lose a traveler cleat while sailing. With the thin wall, fine threads will not do well. Make sure you have a new sharp tap.
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Scott
Prindle Fleet 2
TCDYC
Prindle 18-2 Mod "FrankenKitty"
Tornado Classic "Fast Furniture"
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Nacra 5.8 "De ja vu"
Nacra 5.0
Nacra 5.8
Tornadoes (Reg White)
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