NACRA 5.5 uni - project boat, main beam damage

check out a local welding shop first, they may be able to cut out damage and put a patch in. if you make a new beam, i'd probably use 6061-t6 tube, 1/8" wall. i have a friend who made one piece beams for an sc20 and no problems with them.

I wouldn't bother trying to save it. That damage is too bad and they aren't hard to get. Measure it and Fire Pete begle and dan Berger on here a private message and see if they have one available. Someone else, like Chris Hilliard, may also have a spare.

It looks like New England catamarans also has some for sale.

Thanks Dave, I'll follow up those leads, much appreciated.

Wolfman wrote: I wouldn't bother trying to save it. That damage is too bad and they aren't hard to get. Measure it and Fire Pete begle and dan Berger on here a private message and see if they have one available. Someone else, like Chris Hilliard, may also have a spare.

I saw Wolfmans reply, I have a couple of beams, at least 1 V strap, & a couple of the pads that fit on the V strap.
Measure your beam length, DS rod length, & the distance between the holes that the V strap bolts to. Measure from the inside hole across the beam to the inside hole on the other side. Nacra used a bunch of different V straps.
You need a new DS rod, I only have 1 spare & am keeping for when disaster strikes. See my album in the Tech help section for building a new one for cheap. Make sure you install BOTH washers. The rod should be 9/16". You do not need that hole in the V strap, the square pad sits on the strap, held by something like Dow 5200, & the pressure from the DS rod. The rod sits in a hole in the pad. the last photo shows both washers, beam preload, & the pad.
http://www.thebeachcats.com/pictures?g2_itemId=73301

All the holes on the bottom of your rear beam are to give access to the nuts securing the traveller track, they are just big enough to slide a thin socket into. If you undo them, use nylock(aircraft lock nuts & or a drop of BLUE Loctite to re-assemble.
I'm in Canada, if you are in a hurry Dan Berger & Pete B would be able to ship cheaper. They are both trustworthy people. Otherwise I can send it next time I'm in the US.
I would get a used beam, they are not expensive.
One thing that looks different is the front beam tramp groove. It appears yours is riveted onto the beam?
All the beams I have seen have a groove integral with the extrusion. Looks like this; (Image from Bill)

If funds are scary tight, use the old rear beam, you're not racing in the Nationals. I sailed an N5.7 for two years with a definite "ripple" in the front beam. Drill bigger rivets,(IIRC 3/16" is about the biggest that the cheapo hand riveters will pull), or use an aluminum washer, as backing, with the same size rivets. If you use washers make a tool from a piece of tubing or broomstick, with a hole just smaller than the washer close to the end. Put a piece of masking tape over the hole, then stick the washer to it. Start with the rivet closest to the centre of the beam, if you start at an end, they will be in the way as you try to work inwards. Place a nail into a hole, have a helper push the broomstick in from one end til you hit the nail. Remove nail, & manoeuvre the last 1/4" to line the washer up with the hole. For the rivets in the centre, it will be easier to also slide a second wedge shaped stick in from the other end. This will serve to push the first stick upwards against the hull, & hold the washer snugly while you install the rivet. Push the rivet into the washer,through the masking tape, pull it...repeat til done.
The hulls look like they are Cal-I-forn-I-A registered, I assume you're close? Pete B is in Big Bear.
Post any other queries, there are a few 5.5 sailors here.

Edited by Edchris177 on Sep 22, 2014 - 06:54 PM.

Edchris177, thanks so much for your detailed reply - so much useful information there. How to I get in touch with Pete B and Dan Berger? If I can find replacement beam/s in good condition (I only want to do this once) at the same or significantly less cost than making my own new ones, I would consider grabbing them. After hearing all the advice, there is a certain appeal in making my own new beams from blank tube - but my wallet will decide ultimately. I promised my wife this project wouldn't get too expensive!

I think getting a machine shop to make me a DS rod is a good option. Your step by step albums are very helpful. With the v-strap, I will take the less expensive option between getting a shop to weld a little reinforcement on the underside of the centre hole, or buying a whole strap second hand. I'm curious to remove the pair of bolts on each side holding the strap to the beam, to see if there is as more bad corrosion hiding. That might make the decision for me.

Would you mind sending me a p.m. with how much you are asking for beam/s, ds support casting/pad, and v-strap? Thanks. I've been away from home a few weeks, but I'll try and measure things soon when I get back.

My tramp groove is indeed riveted to the beam, and not extruded as shown in your pic. Is this uncommon? Also perplexing, every Nacra thread I've read shows/describes the the anti-rotation in the beam coming from a bolt that threads through the internal beam casting 'half-moon' and into a hole in the hull. My boat has a threaded stud protruding FROM the hull, in each beam cradle. I assume I just need a lock nut on each stud, on the inside of the beam, for the same result, along with two of the internal beam casting 'half-moons' from Murrays. http://www.murrays.com/56-2511.html I can tell I'm going to spend a lot with them after I also get the mast ball and compression tube, and no doubt a few other bits and pieces.

I'm not far from Tahoe CA, a little north.

One last thing - how do I make a photo album? I wouldn't mind posting a whole bunch of pics of all the pieces I have for the boat, so anyone interested can comment on anything good/bad/weird that they notice. As I say, my understanding is the hulls do not belong with everything else I have, so there may be some mismatch.

Edited by sierracat on Sep 27, 2014 - 07:51 PM.

One last thing - how do I make a photo album?

Click on the tab at the top of page SITE FAQ, Damon has a tutorial there.
P Begle is usually on here, just look through some of the posts & PM him. I think you could also find Dan Berger by a search. I think if you go into your PM box, you can search out a member.
If trying to keep a shoestring budget, probably Pete or Dan can get you the beams cheaper, as shipping would be quite a bit less. If they are over 8', price goes up. I don't think I have any extra 1/2 moon chocks, try to get them used, some of those parts are pretty expensive new, & they don't really wear out.
Do you have the manuals for Nacra? Here is the link.
http://www.thebeachcats.com/pictures?g2_itemId=35212
I don't have personal experience with the 5.5, but I have never seen a Nacra with the tramp channel riveted to the front beam, nor have I seen "studs" in the hulls. What year is the boat?
Are all the bolts these studs, or is it possible they used to be bolts & the heads were twisted off?
I think I have an old mast ball, it's pretty worn, but I'll give it to you to get on the water.
PS don't buy the Parts Catalog, I can email you one, I don't think Damon has it cached here.

Edited by Edchris177 on Sep 27, 2014 - 08:42 PM.

Not sure what year it is. I've heard that the serial numbers are on the starboard transom, but I couldn't see one anywhere. There's just one bolt stud per side - to stop the beam twisting. It still has the normal holes for the beam straps (4 per hull).

This thread may help with finding an HIN #
www.thebeachcats.com/index.php?module=forums&func=viewtopic&topic=14494
It turns out a number of the Nacras did use the studs you show.
Do a search for Richard Obren,(maybe Obrian?) in members, I think you access it from your PM box. He used to post a fair bit & has a 5.5 Uni.

Thanks Edchris177, and I got your PM, I'll be in touch.

I'm starting to realize my current beams don't add up. I think perhaps they didn't come from/with these hulls, even if the intention was for them to fit when they were rebuilt. They are 8ft 5in long (is this spec for the 5.5?) and 4" OD, and appear to be 3/16 in thick. The front beam has the tramp track riveted on, as people have pointed out isn't normal. The studs coming out of the hull need corresponding holes in the beams. As I said, the rear beam has holes that don't line up in a way that makes sense, and the front beam it turns out doesn't have holes at all! The beams have a lot of weird holes and stains from previous fittings, as if they were set up on a different boat. The Nacra manual shows the traveller track running the full length of the rear beam. Mine has a stain in the beam where it looks like one used to run full length, but now finishes short, on the inside of each hull. I've learned earlier Nacras may have had these short bolt-on travelers, and later boats had a full length traveller that was extruded. More postings as I unravel the mysteries.

Edited by sierracat on Oct 01, 2014 - 09:12 AM.

I have a 5.5 Uni and can take as many pix as you need. It appears you have a hodge podge of parts. Call me if you want 816 436 161 zero.

Hey, thanks Ricard! I'll definitely be in touch once things start happening with putting it together or fabricating parts. Much appreciated. You could start by sending me a couple of snaps of your trailer, and the way the boat is supported on it? I picked up a light boat trailer I need to modify for my 5.5.

Thanks.

RicardOben wrote: I have a 5.5 Uni and can take as many pix as you need. It appears you have a hodge podge of parts. Call me if you want 816 436 161 zero.

Email me. Richard at Northracecars.com

Update: not a lot of used beams around. Looking at the blank tubing route. I can't measure wall thickness accurately, but it's a little more than 0.0625, and one source I have suggests 0.078 (5/64t) which apparently is an odd size. Thinking about going up to the common 0.125 (1/8in) and filing down the compression tube a hair to fit. Waiting on a quote for a stick of this stuff (4in OD) and I'm sure I'll almost fall over when I hear it.

Dolphin striker rod: trying to get around the $70 buying a new one, but custom making one mite be too expensive (I don't know any hobbyist machinists). Apparently 9/16th is an odd size for stainless rod, on top of the fine (18) thread. Damn sailboats!

V-strap: looking at either welding a brace over the corrosion at the centre of the V (isolating potential cracking and the mysterious drilled hole) while also acting as a dolphin striker rod casting. Or ordering the flat bar and bending a new one. Talking to a shop to figure out what alloy it is. He thinks 7 series (bendable, not very weld able) so may not be able to fix old one.

Oh, and to top of the weird sizing of all the materials (apparently this is deliberate by many manufacturers so that people have to buy original parts, not make them like I am) the trailer steel (channel) is an odd size, so I can't match it easily. Not that I care to much about that, since I'm not trying to fit anything to the old frame, just adding across the top of it.

I don't belive the 5.5 sl or uni ever had the bridle tangs on the outside of the hull. You may have an old 18 square that has been cut down in width. They had the tangs on the outside.

nacra55 wrote: I don't belive the 5.5 sl or uni ever had the bridle tangs on the outside of the hull. You may have an old 18 square that has been cut down in width. They had the tangs on the outside.

How do you mean? Without a jib, the uni doesn't have a single forestay and a bridle foil, it has twin front stays and then the aft pair (not sure if my terminology is correct). Are you saying the two chain plates on the outsides of each hull should be on the inside? That doesn't seem right. Thanks for your observations though, I'd like to understand better.

nacra55 wrote: I don't belive the 5.5 sl or uni ever had the bridle tangs on the outside of the hull. You may have an old 18 square that has been cut down in width. They had the tangs on the outside.

I think the uni rigged boats had tangs on the outside.

http://www.thebeachcats.com/index.php?module=forums&func=viewtopic&topic=11472

"for a uni rigged boat, like the 18m2, the best position for the bridal tang is on the outside of the hull, but for a jib equipped cat the bridal tangs need to be on the inside of the hull"

Album of the boat parts here: http://thebeachcats.com/pictures?g2_itemId=111519

Added some more pics to the album. More detail on tramp type/condition, traveller, wire rigging, trapeze, pivmatic, etc. http://www.thebeachcats.com/pictures?g2_itemId=111519

I looked through your album, & I know funds are tight;
Trap sheaves, don't worry about them. I have had several sheaves break, but the pin will stay. You can still use them, without the sheave til you change wires.
Same thing for the traveler sheave, if it breaks the pin will hold the line. It looks like an old Kenyon, I had the same thing on an old 5.2, it had "Kenyon" stamped on it. Don't put any lube on it. If you can find sheaves that fit, change them. Just be careful removing car from track. The wheels are sitting loose on short studs, they will fall off & spill TINY bearing everywhere.
Use a small block of closed cell foam,(something smooth...I stole a bit off the wifes yoga mat), make it wide enough so you have to squeeze it a bit to make it the width of track.
Squeeze & slide car onto foam block, then wrap some tape to keep it there, reverse to install. Do I need to remind you NOT to let those wheels fall off!
Use your traveler cleat,it looks serviceable, once the teeth get worn, they won't hold. They are easy to change, I have a bunch of them. You don't need the whole thing, just the jaws, they disassemble easy. Use blue Loctite to assemble, you don't want that small bolt coming loose.
The tramp looks pretty beat, but is probably serviceable, I would have it completely restitched with good UV thread.
The fitting on the front beam looks like a gudgeon for a rudder pin, same as on your transoms, don't know what they added it for.
When you rig your rudders, use the bolt holding tie bar to tiller to hole your bungee, it's easier than figuring out how much extra to stretch it to make up for the distance it slides back down the tube to the pivmatic pin.
Mast rotator- you might want to forget about it til you get used to the boat. It has to be released every tack, & if you forget, you can break the mast...there is a note somewhere in the manual about that. See my old Nacra 5.7 album for how to rig it.
DON'T leave your diamond wires as is. If those arms slide up or down on the wire, you lose the integrity of the truss, & all the strength. You can use rigging tape,(the bit of seizing wire the manual calls for is not great), but the cheap fix is a roll of electrical tape. Get coloured tape,(the black leaves icky residue) then tightly wrap it in a figure "8", above & below the spreader bar. That will prevent any movement of th e spreader on the diamond wire.
If you don't have those little plastic donuts on the diamonds, just above the spreader, add some. They keep the jib from wearing as it rubs on the bars. You can buy a set that clip on if they are missing, this is what I put on the 5.0.(I used the smaller size, for 3/32" wire IIRC...they were $18)
http://www.westmarine.com/buy/forespar--jib-rollers--111864

Use a small block of closed cell foam,(something smooth...I stole a bit off the wifes yoga mat),

I told my wife this, and she gave me a dirty look. 😉 I don't think I'll have to remove the car. I just duct taped it on to the track before I removed the track.

So the big news/update is: I took a deep breath and a fresh beer, and went to work drilling out all the old rivets to remove the fittings from the old beams. I was expecting to go slow, use lots of cutting oil, and probably wreck a few drill bits on the many stainless steel or Monel rivets. BUT, the first rivet drilled like butter… what the??? And I quickly realized EVERY SINGLE RIVET on the old beams were aluminum. Unbelievable. No wonder every fitting was loose and wobbly. But no matter, someone else's crappy work meant I was drilling out each rivet in 4 or 5 seconds. I am just hoping that the rivets on all the mast fittings are not aluminum too - this would be a disaster waiting to happen. Aluminum just isn't appropriate for high stress fittings on a boat. I shall investigate and replace them all if necessary.

Not only that, but I found things like the traveller cleat rotator plate was riveted with looooooong aluminum :-O rivets that didn't make it all the way through the casting so they could pull/mushroom properly. Essentially just a little friction from a very soft metal in the sidewalls of the hole. Oh dear. I can't believe half their fittings didn't rip off the boat.

The old beams are now stripped, and the new beam tube is cut to length and ready for assembly. I'm experimenting on a piece of beam tube off cut with x-fine grit wet/dry sandpaper. Since I'm not gutting anodizing done, the new beam tubing is quite shiny, and I want to dull it down a bit so it doesn't look odd, or show up scuffs and scratches too easily.

Questions: Should I through-bolt the traveller cleat on to the casting, rather than try to rivet? (It really looks to thick to rivet, as the previous owner must have found out).

Also, do I have any options attaching my old traveller track to my new beam, besides drilling a bunch of huge holes to fit a socket through to nuts on each screw?

What the hell were they thinking?!

Swiss cheese!

Like butter 😎

Edited by sierracat on Nov 29, 2014 - 11:50 PM.

If you don't have those little plastic donuts on the diamonds, just above the spreader, add some. They keep the jib from wearing as it rubs on the bars.

This is a uni rigged 5.5

Thanks for all the other tips. Will wait and see which sheaves/cleats decide to explode in the first big wind. Will install the rotator cleats but not use it unless needed one day.

I thought my tramp was serviceable, but went outside the other day for a proper look and the stitching is toast - it can all be ripped apart by hand. I think the fabric itself might hold up, so I'm taking it to a local upholstery place to get restitched (I'll ask if they have UV thread for UV resistant thread). In the meantime I'll be daydreaming about a brand new electric blue tramp from SLO sails some day…

Should I through-bolt the traveller cleat on to the casting, rather than try to rivet?

I've got several of them, from old 5.2's, I think they are all riveted. I think it was just aluminum rivets to hold the casting to the rear beam, I remember they drilled off easy. The bullseye used machine crews to secure it to the fitting. SS bolts would be easy, but you have to make sure the bolt heads don't interfere with the swivel mechanism, IIRC there is not much clearance. I', going up to the lakehouse tomorrow, I'll see what's in the bin, I might be able to send you an entire package.

the new beam tubing is quite shiny

It will loose much of that shine quickly, with exposure to the elements.

do I have any options attaching my old traveller track to my new beam,

Myself, I would suck it up & start drilling. Those old tracks are fairly high profile, the rivets would need to be close to 1" long. I think you also need countersunk heads that will end up flush with the track.
There is quite a bit of stress on the track, though it is spread out over a bunch of fittings. If you did go aluminum rivets, I think a backing washer would be in order. You will need to keep everything in alignment. I would fit the track, then wrap tape to keep it in place, then mark or drill pilot holes, from the track through to bottom of beam. Then drill out the bottom holes, that way everything will line up. The machine screws will be pretty small diameter, you can use a 1/4" drive, or even a nut driver handle with small socket, so the final holes won't be that large. Support the beam rightside up, so you can install nuts/lockwashers(or use blue Loctite) from the bottom, that way they won't fall off...it will be a 15 minute job. Just stick a bit of gum/plasticine etc into the socket so it holds the nut/washer just flush with socket edge.
You will probably need fasteners with countersunk heads, I can't remember how much clearance there is from track to car on those old setups.

so I'm taking it to a local upholstery place to get restitched

If they only do upholstery, it might not be a good choice. Someone who does awnings/biminis etc will understand what you are doing, the stresses on the tramp & have proper thread. A chap here who used to own a boat & awning business redid our entire 5.0 tramp for $40. Expect to pay more if they use Technora(sp?) thread.

I thought my tramp was serviceable, but went outside the other day for a proper look and the stitching is toast - it can all be ripped apart by hand. I think the fabric itself might hold up, so I'm taking it to a local upholstery place to get restitched (I'll ask if they have UV thread for UV resistant thread).

I had picked up a H16 a few years that had a tramp like yours with the stiching routed and the fabric still in good condition. I took mine to the local sail loft and they did a great job of restiching the whole thing and installing new hicking straps $60. it's still in great shape.

If they only do upholstery, it might not be a good choice. Someone who does awnings/biminis etc will understand what you are doing, the stresses on the tramp & have proper thread. A chap here who used to own a boat & awning business redid our entire 5.0 tramp for $40. Expect to pay more if they use Technora(sp?) thread.

took mine to the local sail loft and they did a great job of restiching the whole thing and installing new hicking straps $60.

No sail shops anywhere near me. I'm sure my local shop can handle it. They do boat covers and awnings etc.

I', going up to the lakehouse tomorrow, I'll see what's in the bin, I might be able to send you an entire package.

Thanks, very kind of you.

I think it was just aluminum rivets to hold the casting to the rear beam, I remember they drilled off easy

In my opinion, every rivet should be stainless or monel, unless through a very light duty fitting. Can't speak for what you've come across. I will be using all stainless 3/16 rivets on all my fittings. I've used aluminum for other non boat projects - they are very soft and weak.

Myself, I would suck it up & start drilling. Those old tracks are fairly high profile, the rivets would need to be close to 1" long. I think you also need countersunk heads that will end up flush with the track.

No issues with time spent drilling - the 6061 cuts like butter with a good bit, especially step drills for the large access holes needed for a socket head. (Step drill bits are AWESOME!) I just keep pondering the sag in the old beam, and the amount of material taken out from the underside of the rear beam with all those 1/2-3/4in access holes. Structurally, I don't like it. Swiss cheese. But if that's the standard way, so be it. My beam tube is 50% thicker (0.125") so I shouldn't be concerned. They probably had some sort of accident to put the bow in the old rear beam anyway. I keep hearing rumors of previous owner's run-in with heavy snow pack one year, so that could explain a lot of things.

I will be using all the old SS countersunk machine screws/nuts that came with the old traveller track. Loctite is a good idea - I'll pick some up.

BTW, I have a method of lining up through-holes on large diameter tube like a beam. Take a punch and make a dot. Get a flexible flat tape, and measure the circumference around and back to the dot. Divide that number by two, and measure that amount and make a another dot (e.g. 9in circumference, make a dot at 4.5). Drill each dot independently. Done - no need for a drill press. Did I mention how awesome step drill bits are? They also slightly
self-bevel the rough edges of the hole.

Edited by sierracat on Nov 30, 2014 - 10:40 AM.

and the amount of material taken out from the underside of the rear beam with all those 1/2-3/4in access holes. Structurally, I don't like it. Swiss cheese.

It isn't a problem, all the Nacra's were built that way,& I've never heard of beam failure. Think about aircraft construction, the webs in a wing are so full of holes there is more hole than material. It's all about where the holes are in relation to the load.
If the holes were in the side, it would weaken the beam. If the beam is subject to vertical bending loads, the bottom is either being compressed or pulled apart. Either way the remaining material is stronger than the rest of the boat.

Loctite is a good idea - I'll pick some up.

Be sure to use blue, red is for more permanent fittings, though it can be undone with the application of heat..

Tom,

It looks like your boat is going to be better than ever, glad you are able to get it all figured out.

DamonLinkous wrote: Tom,

It looks like your boat is going to be better than ever, glad you are able to get it all figured out.

Yes, it's coming along nicely, thanks! I appreciate your positivity. Almost done building the main beam from all raw materials, and then the rear should be even easier (less calculating anyway). I plan to start a new thread documenting the methods and tips for beam rebuilding, and generally compiling all the obscure information I've found out about early Nacras from different sources. Some of the info I've gained has been from these forums (I'll copy the links to my various threads with Q and A in the new rebuild documenting thread) but also there's some nifty facts I've found out that I couldn't find on the internet anywhere for the life of me. Hopefully the next person with an old Nacra project can get 90% of the information they need from one place.

One interesting fact I learned (from Nacra): Mast post/v-strap/beam assemblies are not mounted vertical relative to the top deck of the boat. They are angled a small amount aft (ball leaned aft, bottom of rod forward), perhaps 10º or less. Makes sense with mast rake.

OK, back to the shop for more tinkering.

Edited by sierracat on Dec 01, 2014 - 01:52 PM.