Nacra 5.0 Crossbeam Straps

Helping a friend who just bought a 5.0. It's a 1984 and has the strap arrangement for crossbeam to hull attachment. I'm unfamiliar with this arrangement as my 5.0 is a 1983 and uses the 3/8" stud up from the hull. Here's a pic of his strap/beam:

https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=130147&g2_serialNumber=4

The gap between the bottom of the strap and hull seems excessive and even with the chip, the bolt is being loaded sideways to an extreme.

Looking at the manual I see that the final geometry is much more square with virtually no gap.

https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=130154&g2_serialNumber=3

Then I see a note in the manual that specifies an 8-3/4" strap for all boardless boats.

https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=130158&g2_serialNumber=3

My conclusion is that this boat has the shorter, incorrect straps. Comments please.

--
Hobie 16 (3 formerly)
MacGregor 25 (formerly)
Chrysler Dagger 14 (formerly)
NACRA 5.0 (currently)
High Point, NC
--
leeboweffectMy conclusion is that this boat has the shorter, incorrect straps. Comments please.


That's possible.

On the 5.5, 5.8 and 6.0 there were front straps and rear straps, maybe they are the same on the 5.0 and the straps are reversed.

Beam bolts are torqued to 16 or 18 lbs, I can't remember, its in the old manual. I've seen lots of boats were the bolts did not pull the straps down tight to the hulls. Be careful with the beam bolts, it's easy to strip the threads inside the hulls.

--
Ron
Nacra F18
Reservoir Sailing Assn.
Brandon, Mississippi
--
so I have a 5.0 with a center beam front to back like the 5.2 my question is can I take it out
I don't have straps over the beams just the bolt through the beam to the hulls

thanks for your input on this

--
Jeff O
N5.0
solcat 18(sold),
N5.2,
H16
Camarillo CA
--
My old 5.0 was like that, one day one side of the rear beam came off while sailing. It wasn’t catasthrophic, everything came loose but the mast stayed up. I had a towing line with which I tied the beam around the hull, just to get back. The bolt ripped off with a block of epoxy, clearly a bad repair from the previous owner, which means it had failed before. I wasn’t freaked out but i sold the boat, it was about time anyway (to the guy that repaired it, so in good hands..). The buyer added straps, I would have done the same if I had kept it.
I didn’t have the front to rear beam, I think it’s not relevant in relation to the need of straps, I don’t think it serves any purpose on your boat, actually, except maybe support for your feet when flying a hull. On the 5.2 it’s function, as I understand, was to avoid rotation of the beam, because they were not bolted to the hull from inside.



Edited by Andinista on Jul 12, 2018 - 08:12 AM.
Regarding the original post, yes it doesn't look very good, I'd replace those straps if it was my boat.
The exposed corners of those straps look like the perfect place for a sheet to wedge itself into at the worst possible moment or for taking a nice chunk of flesh out of your leg in heavy conditions. I would definitely use a longer strap or at the very least put some type of spacer between the top of the deck and the bottom of the strap flange. It will also help distribute the load better and reduce the risk of the bolt shearing off.

sm
DogboyThe exposed corners of those straps look like the perfect place for a sheet to wedge itself into at the worst possible moment or for taking a nice chunk of flesh out of your leg in heavy conditions. I would definitely use a longer strap or at the very least put some type of spacer between the top of the deck and the bottom of the strap flange. It will also help distribute the load better and reduce the risk of the bolt shearing off.

sm


In addition to the structural issues I had the same thought on the "as is" being nothing more than a nuisance line catcher and/or meat hook. A spacer will fix these issues, but not the side loading of the bolts.

--
Hobie 16 (3 formerly)
MacGregor 25 (formerly)
Chrysler Dagger 14 (formerly)
NACRA 5.0 (currently)
High Point, NC
--
Actually, a spacer will help with the loading of the bolt because it will allow the flange of the strap and the head of the bolt to bear against a solid surface, so lateral load will be transferred to the flange of the bolt, through the spacer, and to the deck. The spacer would give the bolt and strap something solid to bear against which will improve the overall strength of the attachment. It will be a safer and more robust setup all around.

sm
QuoteThe gap between the bottom of the strap and hull seems excessive and even with the chip, the bolt is being loaded sideways to an extreme.

That does look excessive, however, the straps might be correct.
One thing to check is proper assembly, it is very easy to miss a small detail. I just put my 5.7 back together 2 weeks ago. When doing up one strap, I ran into the same problem, it looked to short.
Be sure to assemble on level ground The manual says to lift each bow & shake the boat, BEFORE you fully tighten the bolts down to 16-18ft lb.
I loosened the bolts, shook the bows, & bingo, it went together properly.
It appears you are missing the rubber piece that goes between the deck & the strap. This takes up some of the gap, & prevents the strap from marking the gelcote.
There are 3 different straps. As mentioned, the boarded boats use 2 different straps. The 5.0/5.7 use the same on front & rear, PART # 3510. The manual calls it 8 3/4". Dagger boats use an 8 1/2" strap for the rear, & an 8" strap at the front. Measure them up using a cloth tailors tape, or very thin steel tape. If they are wrong, Dan Berger, or Pete Begle can probably find you some.
I have the Parts Catalog in PDF. If you PM an email addy, I'll send it to you. I can't find it on the site here.
Quoteso I have a 5.0 with a center beam front to back like the 5.2 my question is can I take it out
I don't have straps over the beams just the bolt through the beam to the hulls

I don't think that's a good idea. The reason for the center beam is to prevent the mast from turning the front beam. Many hardcore racers would remove the center post, & the half moon chocks inside the beam. To prevent beam rotation they drilled 2 holes in each strap, & installed rivets.
Obviously you cannot do this if you don't have beam straps. On the older 5.0, the stud serves to hold the beam onto the hull, & prevent it from rotating when the mast takes loads.

--
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
--
So it sounds like the bolts alone are not strong enough to keep the beams connected to the hulls and the front beam from rotating ?
do all the later 5.0 have both straps and bolts?

thanks again for you input.

--
Jeff O
N5.0
solcat 18(sold),
N5.2,
H16
Camarillo CA
--
I don't have any personal experience with the pre '83 5.0 boats that just used the studs, I've only seen photos of them.
I assume it didn't hold up in rough conditions, so they changed it. My 5.7 has straps & the half moon chocks inside the hulls, so does the '88 5.0.
https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=80923&g2_serialNumber=6

--
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
--
Ed
on your 5.0 are the straps riveted to the beam or just strapped over the top

Thanks

--
Jeff O
N5.0
solcat 18(sold),
N5.2,
H16
Camarillo CA
--
No rivets, just wrap over the top, that is the factory way. Any that are riveted were done by previous owners.



Edited by Edchris177 on Jul 13, 2018 - 02:24 PM.

--
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
--
ohmsjSo it sounds like the bolts alone are not strong enough to keep the beams connected to the hulls and the front beam from rotating ?
do all the later 5.0 have both straps and bolts?

thanks again for you input.


Theres a tube that runs between the beams to keep them from rotating, otherwise yea they would rotate all over the place.

--
'82 NACRA 18 Square "Bangarang"
'85 Hobie 18 "Honey Badger Don't Care"
'86 Hobie 18 "The Rippin & The Tearin"
Jacksonville, FL
--
taumumpower1Theres a tube that runs between the beams to keep them from rotating, otherwise yea they would rotate all over the place.


My 1983 Nacra 5.0 only has the 3/8 studs from the hull for crossbeam attachment and no center beam. I've run the boat now for 3 seasons and so far so good. The front beam does not rotate because the correct front beam casting has a boss on it. Note that I added an extra smooth (no boss) casting on the inner stud just for peace of mind.

https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=119449&g2_serialNumber=4

https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=119499&g2_serialNumber=4

--
Hobie 16 (3 formerly)
MacGregor 25 (formerly)
Chrysler Dagger 14 (formerly)
NACRA 5.0 (currently)
High Point, NC
--
Anyone have any of the 8-3/4" straps available?

--
Hobie 16 (3 formerly)
MacGregor 25 (formerly)
Chrysler Dagger 14 (formerly)
NACRA 5.0 (currently)
High Point, NC
--
leeboweffectAnyone have any of the 8-3/4" straps available?

not sure of the size, but you could call and ask
Beam Strap All N5.0, 5.7
$18.00 each
https://www.murrays.com/wp-content/uploads/2016/11/56-3510.jpg
https://www.murrays.com/product/56-3510/



Edited by MN3 on Jul 14, 2018 - 12:45 PM.
`



Edited by MN3 on Jul 14, 2018 - 12:48 PM.
leeboweffect
Thanks for the info on your 5.0 I may look into the straps and see how hard it will be to add them.
I think the hard part will be getting the underside of the beam pocket to hold the nuts while you tighten the bolts. we will see how thing go.

thanks again

--
Jeff O
N5.0
solcat 18(sold),
N5.2,
H16
Camarillo CA
--
ohmsj

leeboweffect
Thanks for the info on your 5.0 I may look into the straps and see how hard it will be to add them.
I think the hard part will be getting the underside of the beam pocket to hold the nuts while you tighten the bolts. we will see how thing go.

thanks again


I suggest you try what I've been doing before going to all the effort/expense to add straps. If you have the arrangement with two 3/8" studs coming up from the hull and they're in good shape do the following. Clean the threads up thoroughly and do the same for the nuts (or just buy new SS nylock nuts). Install a beam casting with boss at the outer position and a smooth without boss beam casting at the inner position on all four corners of the boat. Apply plenty of anti-seize compound to the threads before assembly and tighten carefully and a little at the time, DO NOT overtighten. You will occasionally have to check and possibly retighten the nuts. I check mine whenever I start hearing my boat creak and/or after a good thrashing. My boat seems OK this way without the straps.

https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=130202&g2_serialNumber=3

This is the best anti-seize compound I've ever found. It is highly effective, but very messy.

https://www.walmart.com/i…be-Silver-Paste/19868891

--
Hobie 16 (3 formerly)
MacGregor 25 (formerly)
Chrysler Dagger 14 (formerly)
NACRA 5.0 (currently)
High Point, NC
--
That sounds like the way to go, I will let you know how it works out

thanks

--
Jeff O
N5.0
solcat 18(sold),
N5.2,
H16
Camarillo CA
--