So the Nacra comes apart this weekend after a great year. It likely has never been apart. Will PB Blaster affect the fiberglass? This is a non cored boat.
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John
Nacra 5.0
CT
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Boat disassembly - best oil to use on cross bar bolts
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Posted: Oct 11, 2019 - 05:37 AM
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Posted: Oct 11, 2019 - 08:12 AM
will not effect the fiberglass
https://www.thebeachcats.…ms/viewtopic/topic/15842
edit - took me a bit to find this data but check out the info in this thread:
https://www.catsailor.com…der-challenge#Post276469
Edited by MN3 on Oct 11, 2019 - 08:29 AM. -
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Posted: Oct 11, 2019 - 10:14 AM
Most of the advice in those links is sound; the only thing to be nervous about is heat (of course), though that's what usually helps most in the end.
There are as many favourite penetrants as there are guys working on boats (and cars). The homebrew of 50/50 acetone and diesel (or ATF) is one you hear a lot. Fwiw, the guy I trust the most for hardcore car questions (a Subaru specialist in Portland) swears by Chemsearch Yield (though I think they recently renamed it). It's (relatively) expensive and hard to get - you have to buy a case, and directly from Chemsearch, as they don't have any distribution. On his advice I'm planning on getting a case asap.
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Posted: Oct 11, 2019 - 10:30 AM
You can try letting them soak in PB blaster for a day or two. Disasembly is really going to depend on the level of prep the boat had originally; my bolts are coated in Tefgel which limits corrosion built up on the threads themselves, but many (most) boats didn't have this done originally.
Best bet is to use an impact wrench coupled with direct heat on the bolts themselves if you have an issue. Work the bolt back and forth to get it completely free. Worst case you'll damage the threads in the hulls and require helicoils.
Then there is getting the beams out of the hull sockets, I've found lifting the opposite hull generally releases the beams relatively gently. -
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Posted: Oct 11, 2019 - 12:26 PM
I would stick to penetrating lube and only use heat or impact as a last resort due to the potential for damage to be caused to the fiberglass. Stainless hardware shouldn’t be too difficult to disassemble as long as the threads haven’t galled and the bolts are not installed into aluminum compression sleeves.
Definitely use anti-seize grease when reassembling.
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Posted: Oct 11, 2019 - 12:47 PM
Use a good penetrating oil with lube. Something with moly is good. Go slow. When heat builds up stainless doesn't play well together. Don't use an impact, that makes heat. Once you heat a part up, when it cools it shrinks ever so slightly, so if you heat the nut or bolt up and don't get it removed, you may have caused more problems. Some of those stainless bolts are soft. Don't use too much force and twist one off. -
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Posted: Oct 11, 2019 - 03:22 PM
Use Tefgel or a good anti seize, NOT something with copper in it (you want nickel based). -
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Posted: Oct 11, 2019 - 05:57 PM
Tufgel and anti-size are great... Also, I believe the original assembly instructions mentioned using water proof grease when assembling the boat.. Page 6 paragraph 8
Hopefully when your boat was assembled they followed the instructions...
https://www.nacrasailing.com/wp-content/uploads/pdf/nacra-vintage-assembly-manual.pdf.
Edited by JohnES on Oct 11, 2019 - 03:58 PM.
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John Schwartz
Ventura, CA
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Posted: Oct 11, 2019 - 08:03 PM
The older Nacra will come apart easy, the hull sockets are not a tight fit, it will just lift out.
The assembly manual says to dip the bolts in the supplied grease cup before installing. If you are operating in fresh water, any marine grease will do.
Be very careful upon assembly, the inserts are not SS, (IIRC) they are brass. Easy to strip. If they are tight removing, run a tap or thread chaser through before assembly.
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Posted: Oct 14, 2019 - 10:18 AM
All good advice. I'd like to add one thing that was left out. Over the last several years, I've disassembled 4 different beach cats and the only one that came apart easily was the one where the cross tubes were bedded into their saddles with silicon sealer. I had to use a thin blade knife to cut through the silicon while at the same time prying up on the cross tube. If this was not done to your boat when it was assembled, you will see where sand and salt have been residing there for years. Don't use 5200! Good luck!
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Bill Townsend
G-Cat 5.0
Sarasota
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Posted: Oct 14, 2019 - 11:25 AM
A caveat on the silicone RTV, though: "Household bathtub sealant"-grade RTV is junk that doesn't adhere well enough to bother with, and most of it outgasses (corrosive) acetic acid as it cures. So if you're going to do this, it has to be something really made for the job, like Sikaflex.
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Southern Alberta and all over the damn place.
*
1981 SuperCat 20 "Roberts' Rockets"
1983 SuperCat 19
TriFoiler #23 "Unfair Advantage"
Mystere 17
Unicorn A-Class (probably made by Trowbridge) that I couldn't resist rescuing at auction.
H18 & Zygal (classic) Tornado - stolen and destroyed - very unpleasant story.
Invitation and Mistral and Sunflower and windsurfers w/ Harken hydrofoils and god knows what else...
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