Looking for suggestions from those that have been there. The starboard trampoline track on my N-5.7 is pulling rivets from the aft tract for the first 5 rivets. My thought is to drill out the rivets that have pulled and reinforce the fiberglass Options I have thought of, from easiest to hardest:
1. stuff epoxy putty (JB Weld Steelstick) into the holes and re-drill
2. use liquid JB-weld epoxy, and drill
3. West system epoxy with microfibers
4. Install a rear port (need location fore or aft of crossbar) and laminate glass or kevlar from inside.
5. remove aft top-deck and use West Epoxy to re-laminate, then reinforce with rivet washers.
Anyone have ideas. There is a long winter ahead, and I don't want to rip out the track in the spring.
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Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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Trampoline Track Repair
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Posted: Oct 27, 2016 - 09:22 PM
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Posted: Oct 27, 2016 - 10:52 PM
Toss #5 in the garbage, way to much work.
I had the exact same thing on my '84 N5.7. & contemplated a hatch & adding AL washers to the inside. Unless the fibrglass is breaking down, I wouldn't bother.
I simply drilled out the bad rivets, picked up a handful of 3/16" diametre x 1/4" shaft, & pulled them. That was 4 years ago, & we drive the sh*t out of these boats on windy days. So far it has held up. You could get those "sleeves" that make them sightly oversize, ( and watertight), I only had rivets so I just used a dab of silicone seal.
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Posted: Oct 28, 2016 - 12:02 AM
I used 3/16 x 1/4 rivets this summer, and they are pulling through. So the simple solution isn't working. There are stress fractures around the rivet holes, and I need to reinforce or fill them.
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Tom
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Posted: Oct 28, 2016 - 12:03 AM
Well, another option is, I might lose weight. LOL easier said than done.
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Tom
NACRA 5.7 (1984 Sail 181)
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Posted: Oct 28, 2016 - 08:51 AM
In that case, separate the hulls, lay them across a couple of saw horses so that the rivet holes are on the bottom, & parallel with the ground.
Mix up a few CC's of epoxy & inject with a syringe, then put a piece of tape over the rivet hole. Gravity is your friend, will level the epoxy, & allow it to penetrate into the cracks. It is important that the holes are "level", otherwise the expoxy will run elsewhere. Use additive carefully, you don't want the mixture to thick, it needs to be able to creep into the cracks.
Redrill & rivet.
You cannot reach the tramp track ,(to install washers, or an AL strip) from behind the rear beam. There is a bulkhead on the 5.0 & 5.7 under the rear beam.
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Posted: Oct 28, 2016 - 09:21 PM
Another option occurs to me and that is to drill out the rivets on the entire rail, silicone in the old holes and move the rail 1" forward or back whichever is easier and redrill the holes using the rail as the template. You are not going to see the old holes and the new holes will be in sound glass. If you can get to any of the rivets near the hatch do put a reinforcing washer on any rivets you can reach.
It might also be possible bail on the rivets, or at least some of them and go to screws and nuts.
dg
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dg
NACRA 5.2 #400
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Posted: Nov 02, 2016 - 01:30 PM
I take it there is no metal reinforcing strip inside the hull. What, if any, bedding adhesive did Nacra use under the tramp rail. A nice bead of 3M 5200 might help to spread out the load.
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Posted: Nov 02, 2016 - 06:33 PM
The hulls are fully broke-down and stored upside down for the winter as you described. I'm going to use your suggestions. The question now is whether to use something like JB-Weld, or West Systems epoxy, and possibly reinforcing with kevlar fluff, microfiber or other filler. I will probably go ahead and treat the entire rail, then re-rivet using the 3/16x1/4 aluminum rivets. I may also take doug's idea and move the rail enough to offset the old holes. I guess, I could remove the rail, fill the holes, and I still have enough Perfection epoxy paint to coat this repair. It' a bit more work, but with the hull already disassembled, it won't be too bad.
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Tom
NACRA 5.7 (1984 Sail 181)
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Posted: Nov 02, 2016 - 06:33 PM
i will eventually need to address this issue too.
my plan is: to wait until it explodes and then....
drill out and remove ALL rivets
fill all holes with west system + appropriate filler, and some glass-cloth (at a minimum)
I will also consider cutting a VERY small access hole in the decklid somewhere so I can slide in a little backing plate. I would figure out how to do it with just a little slit that i will then fill with west system, glass and a little gel coat to match the decklids -
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Posted: Nov 02, 2016 - 06:39 PM
I think waiting until the it explodes could mean replacing the aluminum trampoline track. If it fails on the water you will not only have a difficult time limping into shore, but the track will be trashed. I will likely fail partially resulting in an unrepairable bend. It may also be hard to retrieve your trampoline from the bent track.
As best I can tell the hull was not reinforced in any way where the tramp track is riveted, and no backing is used for the rivets. I kind of like the idea of filling with filled epoxy while inverted and covering with tape until cured.
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Tom
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Posted: Nov 02, 2016 - 08:14 PM
The boat survived 30 odd years with only the hull wall, you won't be sailing it another 30 from now. Use West epoxy, it will bond well to the inside of the hull. Add a bit of microfibres, but not so much that it won't self level. Dril, rivet & sail the crap out of it til you are to old!
I sailed my 5.7 an entire season with 5 rivets pulled partially out. I wouldn't bother moving the track, with some epoxy it will be as strong as new.
Not to big a deal. Maybe more if you are in hurricane conditions. I tore the tramp on my 20' x 10" Mystere, from stem to stern, 20 miles from home. Sailed it back with no noticeable difference, other than you had to watch where you stepped when changing sides!
Old Nacra tramp tracks are readily available, I think Pete, & Dan Berger have them pretty cheap.
Correct, here is the interior construction of a 5.2, same as your 5.7
http://www.thebeachcats.c…pictures?g2_itemId=82844
Of particular interest for your problem is this photo,
http://www.thebeachcats.c…pictures?g2_itemId=82865
Edited by Edchris177 on Nov 02, 2016 - 08:29 PM.
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Posted: Nov 02, 2016 - 09:31 PM
Need a LIKE button for this ^^
I had already seen the images you posted, so was aware there is nothing inside the hull. And yes, at 63, I am not likely to outlast any repair I make.
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Tom
NACRA 5.7 (1984 Sail 181)
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Posted: Nov 03, 2016 - 12:03 AM
Definitely need a like button.
I think ed was more referring to not expecting a boat to last more than about 50 years as opposed to you not outlasting the boat. ;)
Suggest moving to a foiling cat when you hit 70 or so.
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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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Posted: Nov 03, 2016 - 01:12 AM
I'm having a hard time with injected epoxy repair that Ed is suggesting. A rivet acts like a wedge when it is being pulled up tight. These rivets are under both shear and tensile forces. If there is no glass structure or a significant amount of filaments in the epoxy resin to resist the wedging effect of the rivet, the epoxy will crack up just like the polyester resin did and the rivet will pull through again. This repair might work for a while, but will likely have to be revisited again before you are tired of sailing the boat.
The rivet needs to pull against sound structural glass material, hardened epoxy resin alone will not long resist the expansion forces of a rivet being pulled into place and the tensile force of the rail pulling up on the rivet. Find a way to drill new holes in sound glass, or back the rivets up by adding the inspection hatch to gain access.
Drilling additional holes in the rail to get more rivets into new sound glass structure seems to me like an easy way to make the repair last far longer. Or similarly go to 1/4" rivets in the same positions because the enlarged hole will be into sound glass structure, not to mention the dramatically increased area of the rivet and the much larger bulge this sized rivet creates is going to be really hard to pull out.
The boat is worth the effort of a sound fix.
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dg
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Posted: Nov 03, 2016 - 01:59 AM
I'm having a hard time with injected epoxy repair that Ed is suggesting. A rivet acts like a wedge when it is being pulled up tight. These rivets are under both shear and tensile forces. If there is no glass structure or a significant amount of filaments in the epoxy resin to resist the wedging effect of the rivet, the epoxy will crack up just like the polyester resin did and the rivet will pull through again. This repair might work for a while, but will likely have to be revisited again before you are tired of sailing the boat.
The rivet needs to pull against sound structural glass material, hardened epoxy resin alone will not long resist the expansion forces of a rivet being pulled into place and the tensile force of the rail pulling up on the rivet. Find a way to drill new holes in sound glass, or back the rivets up by adding the inspection hatch to gain access.
Drilling additional holes in the rail to get more rivets into new sound glass structure seems to me like an easy way to make the repair last far longer. Or similarly go to 1/4" rivets in the same positions because the enlarged hole will be into sound glass structure, not to mention the dramatically increased area of the rivet and the much larger bulge this sized rivet creates is going to be really hard to pull out.
The boat is worth the effort of a sound fix.
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dg
NACRA 5.2 #400
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Posted: Nov 03, 2016 - 09:59 AM
+1
My track has tripped the amount of original rivets - worked for the past decade but it's not getting any better. my track is pretty deformed. -
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Posted: Nov 03, 2016 - 01:08 PM
I have lusted for a Windrider Rave more than once :)
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Tom
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Posted: Nov 03, 2016 - 01:39 PM
If there is a bulkhead at the rear beam, then the very best solution is to add the inspection hatch in front of it. This hatch also lets you inspect the front side of that bulkhead for cracks and probably just as important more of the inside of your skeg allowing you to beef up and repair from the inside of the hull. Getting access to the rear part of the tramp rail rivets then is just bonus. Far and away the best way to reinforce the rivets from pulling out is with the washers. I added hatches in front of my main beam so that I could inspect that bulkhead as well as see the area forward of the beam. It was a pretty simple job to do.
Or just consider drilling some of those holes out to the larger diameter 1/4" and see if that improves the holding. I think the only challenge to the larger rivets is pulling them with a standard tool.
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dg
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Posted: Nov 03, 2016 - 07:17 PM
I think the rivets are already 1/4 dia by 3/16 length. The next size up would be 3/16 x 3/16.
I'm not sure how the old 5.7 is constructed with regard to bulkheads. I suspect there is one just in front of the rear crossbeam. Anyone know? How far in front of that do I need to stay? What I don't want to do is place a port where I would sit.
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Tom
NACRA 5.7 (1984 Sail 181)
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Posted: Nov 04, 2016 - 03:19 AM
Not likely that the rivets currently installed are 1/4" diameter. This diameter is a big step up and I would be surprised if you had any of this diameter on your boat now. Pulling these larger diameter rivets takes a much more powerful tool like this:
and even if you did have a pneumatic tool the cycle time would be pretty high.
This tool is also very useful for pulling the Monel or SS rivets that require dramatically more force than the aluminum ones. It is not good at close quarters like pulling the rivets on clam cleats because the nose is too large.
dg
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dg
NACRA 5.2 #400
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