Hey guys while finally putting my 5.7 together after some tlc i torqued the bolts to 17ft lbs however that appeared to be a bit to much for the old bolts and they pulled through. I''m thinking my best bet is to use a heli coil (5/16" -18) i was wondering if you guys had any ideas.
Thanks



Edited by mryella on Nov 25, 2012 - 07:00 PM.

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Nacra 5.7
Falcon Lake Manitoba
Canada
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Are you talking about the bolts in the beam straps? If so, I have been through this and have an easy solution. Under the boltholes is a 1/4"aluminum plate threaded for the 5/16" bolt. What I did was use a 5/16"drill bit and went right down the hole in the hull. Follow that with a 3/8" coarse tap. I used coarse to give a little more "bite". Then get a 3/8 stainless bolt the same length as the original and you are all set, Hope this helps.

Either method should work fine. If you are going the helicoil route make sure they are stainless (not sure they make a non-stainless version). Rule of thumb make they bolts are heavily greased, screw them down until they are tight using a medium ratchet, then go another full rotation. Not sure that the plate that is glassed into the hull is aluminum or stainless but replacing it is a real bitch.

D.

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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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I agree with Nacraman, it's less expansive to just retap with 3/8-16 tap. For the Heli coil you need special tool to thread it in. Also check what is the minimum wall thickness required for the Heli coil insert to properly work.

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Adam Bartos
Nacra 5.0
SolCat 18 (sold)
Lake Zurich, IL
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thanks for all the pointers guys, i already have the heli coils, so i'm probably going to go that route. Ill let you guys know how it goes.

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Nacra 5.7
Falcon Lake Manitoba
Canada
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Got it all done finally haha. Thanks guys. Now just have to finish gel coating the rudders. Hey wolfman I have about 500 ml of gelcoat left if you think you can use it before it goes bad.

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Nacra 5.7
Falcon Lake Manitoba
Canada
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late to this thread but i just wanted to add my 2 cents here.

i've had stripped threads in the hulls of a nacra5.8 and a nacra inter 20. in the 5.8, i drilled and tapped the insert for a larger bolt like Nacraman57, which worked fine in that strap system. but i just finished using a helicoil insert in the hull of the Inter 20 and i just want to say that it really worked well without a lot of trouble. took me about 15 min.

because of the unique (3/8"x 16 thread/inch) bolts thru the front beam of the Inter 20, which use an allen wrench to tighten them instead of a socket wrench, i didn't want to change bolts and try to find a larger one like it (good luck!) so i went to Advance Auto Parts and bought the kit which has 10 helicoils, a tap and a tool to insert the helicoils all for $23.

http://shop.advanceautopa…39-p?brandName=Heli-Coil

you have to enlarge the stripped out hole with a drill bit, then tap the hole, insert the helicoil, knock off a little tab on the helicoil and you're done. after i finished, when i tightened the bolt done, it really gripped tightly....tighter than the other factory bolts. i'm sold!

note: the kit did not tell me which size bit to use. for a 3/8" bolt, enlarge the hole with the next size drill bit, 13/32". be conservative and don't go too large in drilling the hole out.

watch some youtube videos on how to do this. they do a good job of explaining it!
j

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Aquacat 12 (sold)...'87 Nacra 5.8 (sold)...'03 Nacra Inter18 (sold)
Venture 15 (sold)....'89 Nacra 5.8 (sold)...'91 Nacra 5.8NA (sold)
'99 Nacra Inter20 (sold)
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Arch, I thought about the heicoils also, but going to the bigger bolt was recommended by the guys at Performance Catamaran in a phone conversation as a quick and easy fix. It's been eight years since that repair and it is still holding strong. As a result of that repair I got to thinking about adding beam straps to my '83 5.0. As you may know, a lot of those old NACRAS held the beams in place with just the half moon chocks inside the beam. After years of use the beam mounting holes would enlarge resulting in a "sloppy" boat no matter how hard you "cranked' on the bolts. I could lift one hull a foot and the other hull would still be on the ground. This results in a "hydraulic" action when trying to punch through waves. I resolved to fix this by ordering beam straps, bolts and wedges from Performance Catamaran Next, I cut an access hole through the deck behind the front beamI Roto-zipped an access hole through the front bulkhead to get to the front of the beam. I turned the hulls upside down on sawhorses and glassed 2"x2"x1/4" aluminum plate where the bolts would be placed. I used fiberglass resin instead of epoxy because of the faster cure time. Then it was a simple matter of drilling the holes Then tapping the threads Got the hulls lined up and squared, put the straps in place and bolted her down tight. Laid a layer of 8oz fiberglass over the deck, rolled a mixture of resin and blue pigment from US Composites and it looked like factory! What a difference it made! That boat was as solid as a rock...it would shrug off 4' waves in 20+ winds witout a whimper. Sailed like a raped ape! I was so impressed, I stripped down my Hobie 16 to the last piece and epoxied the frame back together this spring with the same results. Stiff is better than limp any day of the week...right?

nacraman57

. . .put the straps in place and bolted her down tight.
. . .solid as a rock...
. . .witout a whimper.
. . .raped ape!
. . .I stripped down . . .
. . .Stiff is better than limp any day of the week...right?

Wow.
Back on topic.
Every Nacra that I have ever owned was stiffer than a 16 year old slow dancing at the high school prom.



Edited by mummp on Aug 03, 2013 - 07:29 AM.

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Philip
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Quote

Every Nacra that I have ever owned was stiffer than a 16 year old slow dancing at the high school prom.

Love it! What a way with words! Actually, my 5.0 was the second 5.0 in the family. My brother-in-law also owned one back in the day. His boat also did not have the beam straps, just the chocks inside the beams. After a season of bobbing in 0-10 mph winds with "lake lice" and "stink boats" whizzing by and the mast banging in boat chop we resolved to become first class heavy weather sailors. From then on if we did not see whitecaps we wouldn't even bother putting up the sails. The learning curve was steep and expensive as the orders to Murray's Marine increased on Monday mornings! We did learn about sail shape, how to use the traveller,downhaul and mainsheet placement on the sail clew to depower. And how terrifying it is to be double trapped deep into a broad reach and have the sail suddenly gybe in 30+ winds!!! Good stuff!! After a few seasons we could no longer keep the beams tight to the hulls...finally the hulls became so cracked and delaminated we sawsalled them up and threw 'em in the dumpster and parted out the rest. Here you can see how the beam mounting holes are elongated. Today they are talking a 5-10 mph breeze so I'm not even going to try to compete for space with the jetskis, powerboats and the drunken fools on the pontoon boats. Is it just me or do others notice a decline of powerboat etiquette these days? I get cut off and buzzed all the time.

I've definitely noticed it, as it is a fact of life. Forget your ROW rights. You've got to assume that these idiots don't know the rules, so just stay clear. I've had my share of words with these morons and I'm convinced they just don't get it. How they get a vessel license beats me.

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Philip
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So I drilled out and retapped when I strippped my strap bolts years ago. My dealer said that the bolts are designed to rip out of the plates vs destroying the decks in event of an overtorque situation. Thus I did not use helicoils.

the hulls on a nacra inter don't have straps, just two bolts thru the crossbeams on each end. replacing these allen bolts with one size larger seemed like a real chore, plus, i needed to use the cat the next day. helicoils were the only solution in this situation.

here is a photo on an F18. the 20 is identical.

http://www.flickr.com/pho…in/set-72157626841276661

i can see how straps would distort a crossbeam if over-torqued.
j



Edited by arch on Aug 05, 2013 - 05:27 PM.

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Aquacat 12 (sold)...'87 Nacra 5.8 (sold)...'03 Nacra Inter18 (sold)
Venture 15 (sold)....'89 Nacra 5.8 (sold)...'91 Nacra 5.8NA (sold)
'99 Nacra Inter20 (sold)
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