Trampoline track loose
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Posted: Feb 05, 2022 - 02:12 PM
It had been repaired a couple years ago, because there were leaks throughout some of the rivets. I didn’t do the repair, now some of the rivets are cut and the track is loose on the rear part. They are aluminum rivets and many of them are cut on the upper part, the head is just gone. Should I replace with SS rivets? I’m afraid they may brake the fiber when pressing them. I couldn’t upload pictures from the cell, will do in a couple days. -
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Posted: Feb 05, 2022 - 04:00 PM
On my 5.5 it is either SS or Monel, not aluminium. Anyway the jib sheet track was fitted that way, when I removed them, when I rebuilt to self tacking. Same on my 5.8 hulls in the workshop.
By the way do you know, how the reinforcements are inside the hull under the track, some kind of aluminium strips? Thought of removing the tracks and replace with lace bolts.
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Brgds
Lars
Frankentri 5.8/5.5/Inter20
Aerow trimaran foiler
https://www.facebook.com/groups/1192604934176635
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Posted: Feb 05, 2022 - 05:16 PM
Thanks Lars. I removed the track and a few holes on the hull were too big, I’ guess it started from there. Just a bad job on the previous repair.
I don’t think there’s a strip of any kind inside, just thicker fiberglass. Part of the length is accessible from the access port behind the front beam, you can check there. Unless there is something inside the fiberglass, l’ve no idea. -
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Posted: Feb 06, 2022 - 10:18 AM
My trampoline was pulling free from the hull and standard blind pop rivets would not hold in the fiberglass. My solution was to drill out and replace with "exploding head, tri-fold rivets in a 5/16 length. These rivets have a mandrel that shears the body of the rivet and pulls it against the hull of the boat. This is a very strong attachment that distributes weight to a much larger area, almost like if you were able to put a washer on the back-side. The mandrel hole needs to be sealed. You may have to search for exactly what you want, but here is a typical link. https://www.walmart.com/i…Rivets-25-pack/933821125
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Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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Posted: Feb 06, 2022 - 03:20 PM
Sorry, no access ports on the 5.5. Neither on the 5.8 hulls seen to the left of the foiler center hull, I am working on now. Will anyway remove a rivet from the 5.8 hull tracks and check down the hole, how it is bullt up.
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Brgds
Lars
Frankentri 5.8/5.5/Inter20
Aerow trimaran foiler
https://www.facebook.com/groups/1192604934176635
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Posted: Feb 06, 2022 - 05:54 PM
I stand corrected, there is an aluminum strip. It is covered by a fiber layer which was a bit loose. It is missing from the port forwards, easy to repair. Also missing on the last 40 cm aft or so, exactly where the holes in the fiber were bigger. So that explains things… I couldn’t open the hull top, used a putty knife but I’m just breaking it. I’ll try Tom’s idea. Thanks! -
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Posted: Feb 06, 2022 - 09:02 PM
I have a bunch of them leftover. If you have time to wait until I'm at the lake, let me know how many you need and pay shipping and I'll send them along. Winter here, so it could be a few weeks.
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Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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Posted: Feb 07, 2022 - 03:19 AM
Thanks for the info Andinista! They might have added the reinforcing alu strip, where the jib sheet track is attached. Might add brass inserts, if the fiberglass is thick enough, where the alu reinforcement is missing, if I remove the complete track if I go for lace bolts. Tominpa´s offer should do the trick for you.
Edited by revintage on Feb 07, 2022 - 04:11 AM.
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Brgds
Lars
Frankentri 5.8/5.5/Inter20
Aerow trimaran foiler
https://www.facebook.com/groups/1192604934176635
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Posted: Feb 07, 2022 - 02:45 PM
Thanks! I just placed an order, they should be here soon. -
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Posted: Feb 08, 2022 - 09:15 AM
The exploding head rivets work great and you will never have a problem of the track pulling. I was always more worried when raising the mast and putting all that weight and pressure on the back of the tramp. I'm an extra-large, so that might have something to do with it.
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Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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Posted: Feb 09, 2022 - 04:46 PM
:)
Good to hear! This time it could have been bad, because I saw the loose track AFTER sailing and lowering the mast. But I step and lower the mast assisted with lines, to the front and sides, so the mast weight is supported by those lines more than my feet. When I start stepping the mast I put my weight on the rear beam rather than the tramp. That first pull, until just before i put it on my shoulder, is done before having the mast secured with the assisting lines. There’s people and kids circulating around so I want to control the risks.. and without any assistance it’s quite scary anyway. -
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Posted: Feb 10, 2022 - 11:02 AM
Nice that it went well! Without assistance, the mainsheet will make things easier. With the 5.5 a gin pole is needed on other cats the boom works fine. Tried this as I have gone to old to do it on my own standing on the trampoline. I used a hand winch the first time I did it.
Edited by revintage on Feb 10, 2022 - 11:10 AM.
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Brgds
Lars
Frankentri 5.8/5.5/Inter20
Aerow trimaran foiler
https://www.facebook.com/groups/1192604934176635
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Posted: Feb 11, 2022 - 11:33 AM
I like the exploding rivet. When I had my 5.8, I had similar issue. I ended up just using stainless rivets, but I had flipped the boat over and dabbed epoxy on the inside through the rivet hole before placing rivet. This allowed the epoxy to fill any voids the previous rivets caused. It had worked well.
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Scott
Prindle Fleet 2
TCDYC
Prindle 18-2 Mod "FrankenKitty"
Tornado Classic "Fast Furniture"
Prindle 19 "Mr. Wiggly"
Nacra 5.8 "De ja vu"
Nacra 5.0
Nacra 5.8
Tornadoes (Reg White)
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Posted: Feb 12, 2022 - 10:22 AM
I repaired it yesterday, the rivets didn’t arrive before we came to the beach, and my plan was using aluminum rivets temporarily, just to be able to sail now and change them later. That was plan C, but plan B worked: I passed thin cords through the first and last hole for the aluminum strip segment near the rear beam and “fished the cords with a hook to bring them out through the inspection port near the front beam. Once out i secured each end of the strip passing the cord through the hole and tying a washer on the other side. Then pulled the cords to have the strip in position and riveted it. The hook was a longer aluminum strip, with the end curved 180 deg. It worked great :) -
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Posted: Feb 16, 2022 - 06:54 PM
Hello. Apologies for the length of this post. I have just joined this forum and am in the process of replacing both the tramp rails on my 2000 /1 NACRA 5.0. It appears one of the tramp rails had been replaced by the previous owner who used rivets all along the rail - including in the middle section of the rail where the jib block track is placed on top of the tramp rail. Having now removed all the rivets on this hull, it has revealed the poor repair the previous owner did along this middle section of the tramp rail by using pop rivets. This middle section of the hull is made of thicker fiberglass with a short aluminium/SS plate embedded in it (it appears about 20 inches long). Clearly the rivets used in the previous repair were not long/strong enough as the jib block rail "exploded" off the tramp rail while out on the boat! I can't believe that there would be a pop rivet big enough or strong enough to go through the jib block rail, the tramp rail and then through the thicker section of the hull including the embedded SS/aluminium plate. I think this is proven by what appears to be the original tramp rail on the other hull. This rail is badly corroded and likely to fail and therefore needs replacing. The middle section of the tramp rail where the jib block rail is attached is secured by a number of flat-head SS screws along the approx 20 inches long length of the embedded reinforcing SS/aluminium plate . Having had to grind out a few of the failed rivets from the middle section of the other hull - which revealed the embedded SS/aluminium plate - it looks as if there are drilled holes in the plate for the SS self-tapping screws to go into. I have a couple of problems that I would be grateful for anybody's help with. First, I can't undo the flat head screws to remove the original tramp rail! Its possible they have rusted into the SS/aluminium plate over time. Has anyone had experience of having to remove these screws and the best way to do so? Secondly, before fitting the new tramp rails, I was going to fill all the existing rivet holes along each hull with epoxy and then re-drill them before putting new "dome head" or "exploding" rivets in (as suggested above). Does this sound like the right thing to do? If anyone has any experience of how best to refit the new tracks and whether to fill the existing rivet holes first, I would be very grateful for any advice. Thank you and apologies again for the length of this post! -
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Posted: Feb 16, 2022 - 08:00 PM
From your description there may be a couple things going on. It sounds like there was galvanic corrosion, which may have happened if stainless steel screws were driven through aluminum. The difference between a pop-rivet and an exploding head rivet is the pop rivet is held in place by a swelling in the end of the rivet barely larger than the hole, but an exploding head creates a large bloom of retention that acts like a washer up to 1/2" diameter. The exploding head rivet is in tension, pulling the pieces together, and if it pulls through, the hull is coming apart. My jib track is connected parallel to the trampoline track but is on a separate track and rivets. I know the track has a lot of pull, but to have it yanked out of the hull is way beyond my expectations. I have not modified the jib track rivets. I included an image of my jib track while on a beam reach at 20 Knots last summer. How does that rip loose?
Edited by tominpa on Feb 16, 2022 - 09:01 PM.
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Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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Posted: Feb 17, 2022 - 05:07 AM
Hi Lecrin2022,
No need to massacre your hull with a grinder
. Cut the screw heads and fill all open old holes. Don´t redrill them or remove the remains of the screws! Instead move the track and move the tramp rails something like 1/2" rear or forward and drill fresh holes. When replacing them use something like Sika 292 between rail and track to hinder salt water to reach the joints. When I removed my tracks on both 5.5 and 5.8 to go selftacking, the rails didn´t look nice due to severe corrosion in the anodized rail. When redoing, be sure to find long enough Monel rivets. Tominpas exploding rivets is also a good choice.
Edited by revintage on Feb 17, 2022 - 01:15 PM.
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Brgds
Lars
Frankentri 5.8/5.5/Inter20
Aerow trimaran foiler
https://www.facebook.com/groups/1192604934176635
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Posted: Feb 17, 2022 - 10:52 AM
Anyone got a good source for monel rivets, besides buying them by the each from retail re-sellers?
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Chuck C
NACRA 500 Mk2
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Posted: Feb 17, 2022 - 03:55 PM
Many thanks Lars - that's great advice. Will have to check the correct length for the rivets - especially the ones for the middle of the tramp rail that also have to secure the jib track on top. I reckon they will have to be at least 25 mm. Also I think Monel rivets for this section and "exploding" rivets for the rest of the tram rail.
Also, thank you Tom for your suggestion on the exploding/trifold rivets. I can tell you it was a hell of surprise to me when the track suddenly detached itself from on top of the jib track!! Thankfully I was able to attach the jib block to the lacing eye on the outside of the hull to keep going!
Does anyone know if you can get "exploding" or trifold Monel rivets? Thanks again for your great advice.
Brgds Rob. -
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Posted: Jun 01, 2022 - 07:54 PM
Tominpa THANKS SO MUCH! I installed the rivets you specified on the rear half of one tramp rail and it seems to have totally fixed the problem. The rail had lifted almost an eighth of an inch and these rivets were able to pull it down FLUSH! You may have saved my ancient boat ('83 5.0) for a few more years.
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Mark Hirte
Nacra 5.0 1983 - (1st cat)
Deerfield, Il
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