NACRA 5.0 chainplate repair :: Catamaran Sailboats at TheBeachcats.com

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NACRA 5.0 chainplate repair

bbaum

Rank: Lubber

Registered: Jun 09, 2012

Last visit: May 03, 2014

Posts: 6
Posted: Mar 07, 2014 - 12:10 PM

My 5.0 had some vandalism in my home driveway last night. The chainplates were levered back and forth where they exit the hull. Fatigue cracks in the steel are pronounced on one side, more slight on the other. Gellcoat is fractured around the strap on both hulls. There is other rigging damage on the boat I can deal with, but I'm concerned about the hull to chainplate bond, and of course a fatigue failure in the stainless steel chainplate itself. I would feel good about having new chainplates professionally installed. Can that be done?
bbaum

Rank: Lubber

Registered: Jun 09, 2012

Last visit: May 03, 2014

Posts: 6
Posted: Mar 08, 2014 - 08:57 AM

I wasn't going to offer the funny background story, thinking it would distract from technical input, but here it goes. About 3:00 AM Friday, I'm awakened by noise, like a possum or raccoon trying to climb a loose downspout. But I don't have gutters and downspouts. I get up, as the clanking starts again, and go to the front of the house. It occurs to me, the sound is halyards slapping a mast! In the driveway, I see a large bulge jumping up and down under the blue tarp covering the NACRA trampoline and mast. I call police dispatch, three officers are in my driveway in no time. After a few minutes peering under the tarp with flashlights, one officer comes to the front door. He says, "there's a naked girl on your boat". Her boyfriend split with all their clothes when he saw flashlights approach. My wife offered a blanked for the girl, it's about 50 outside, my neighbor and I are exchanging witty text messages. We all find it quite comical until after daybreak. Then I find that the Romeo needed my coiled rigging off the trampoline, and levered the shroud adjusters back and forth trying to break them before he comprehended how ring dings work. New trap bungies were cut, mast stay fitting was wrenched around, swage fittings twisted, a general mess. My homeowners insurance has $1000 deductible, I'm guessing I can fix it all just under that.
Really, its true, I couldn't make this stuff up.
Dogboy

Rank: Mate

Registered: Mar 19, 2004

Last visit: Nov 21, 2024

Posts: 964
Posted: Mar 08, 2014 - 03:31 PM

I'm pretty sure on the NACRAs, if you're careful, you can detach the deck from the hull. Then once you get the deck off, you should be able to un-bolt the chain plate and install a new one. Then you would epoxy the deck back on.

sm
Edchris177

Rank: Chief

Registered: Nov 26, 2009

Last visit: Aug 10, 2024

Posts: 2531
Posted: Mar 08, 2014 - 08:11 PM

Here is an album I made, showing what the inside of your hulls will look like. There are a couple of shots of the chainplate attachment.
I have never removed a Nacra deck, but several have...do a search, there were a couple of threads, mabe even an album in the Tech Help on just this subject.
People have used a stiff putty knife, or one of those oscillating hand held cutters to remove the deck.
http://www.thebeachcats.c…ictures/?g2_itemId=82844

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Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
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Dogboy

Rank: Mate

Registered: Mar 19, 2004

Last visit: Nov 21, 2024

Posts: 964
Posted: Mar 09, 2014 - 07:34 AM

Based on the pic Edghris177's album, it looks like there is likely a metal bar glassed inside the hull which has been tapped with threads (I don't see any nuts on the backside of the screws which leads me to think the bar must be tapped). I would just try unscrewing the anchor screws and see if they come out. You probably don't even need to pull the deck off. Not much to lose here. Sorry, I'm not a NACRA guy, but it looks like it's probably a pretty straight forward repair.

sm
bbaum

Rank: Lubber

Registered: Jun 09, 2012

Last visit: May 03, 2014

Posts: 6
Posted: Mar 09, 2014 - 01:38 PM

Thanks Guys, The image 2540 shows where the chainplate is attached inside the hull. That is a great album Edghris177, thanks for going to the effort. There are four blind rivets on the outside of the hull, that go through the chainplate, or the metal bar Dogboy refers to. The inside is heavily glassed over the chainplates. My boat has inspection ports near the chainplates fortunately, so the hulls may not need to be opened. I think I can reproduce the simple NACRA stainless steel strap chainplate easily. Getting it attached in place in the hull as securely as the factory did is my only real concern.
A great advantage to living in SoCal is THE racing Catamaran repair guy will stop by my house this afternoon, on his way home to Costa Mesa after taking care of some SD customers. I will try to get good process photos of my repair for an album.
Edchris177

Rank: Chief

Registered: Nov 26, 2009

Last visit: Aug 10, 2024

Posts: 2531
Posted: Mar 10, 2014 - 04:06 AM

With ports in the ruight place it is pretty easy. IIRC it is not a bar, but flat SS plate, shaped sort of like a "sword". There are no tapped holes, just drilled to accept the blind rivets. You should be able to get an angle grinder into the hull via the port.
Drill the rivets, grind the inside,remove old strap, bed new one in resin, then apply cloth tape/resin over strap.
The fellow you have coming to look at it will fix it pretty easy. If you have a problem with the strap, I think I have a couple of them in the junk bin.

--
Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
--
bbaum

Rank: Lubber

Registered: Jun 09, 2012

Last visit: May 03, 2014

Posts: 6
Posted: May 03, 2014 - 05:04 PM

Thanks everyone, thought it appropriate to provide a follow up report. The process Edchris177 describes above is exactly what my repair guy did. Exactly!
The SS strap from the factory was .100" flat stock, my local metal yard only had .125", I thought close enough. I cut to length, radius ground the end, drilled the shroud attachment hole and only the top rivet hole, while on the workbench.The repairman then drilled the remaining rivet holes with the part in place, by transfer drilling through my existing holes in the hull, as a drill template. The rest is what Edchris177 described. I will post an album with pictures.
JohnES

Rank: Mate

Registered: Sep 01, 2002

Last visit: Nov 30, 2024

Posts: 797
Posted: May 05, 2014 - 07:20 PM

bbaum He says, "there's a naked girl on your boat". Her boyfriend split with all their clothes when he saw flashlights approach.

Looks like Romeo is going to spending his summer working hard to pay you back...

Had a similar situation but it involved burn holes in my trampoline, caught the little bugger too!

Glad to see you're able to fix it...

Edited by JohnES on May 05, 2014 - 07:22 PM.

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John Schwartz
Ventura, CA
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