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NACRA 5.5 uni - project boat - damaged main beam

Posted By: sierracat

NACRA 5.5 uni - project boat - damaged main beam - 09/21/14 05:50 AM

Hi all, hoping I can draw from your collective experience. I'm stoked to join the forum.

I was recently given a Nacra 5.5 Uni by a kind neighbour. I used to sail a similar sized cat in Australia as a teenager, called a Stingray,. It's been a long time though, and I've never had anything to do with a Nacra.

The Nacra was given to me disassembled. The story I got was that a local guy had his 5.5 crushed in the snowpack one year, so he acquired two new hulls. We think everything else other than the bare hulls came from his old boat. My neighbor was given it all, he stored it in a barn for 6 years, and now he gave it to me. Hopefully the beams and everything else fit the replacement hulls without a catch. *Hopefully*.

[Linked Image]
[Linked Image]

Everything was really dirty - mostly heavy dust. Once I gave everything a scrub, it turns out the hulls are in excellent condition. The sail is also in excellent condition, along with the mast and all its components. The rudder blades (x4) and daggerboards (x3) are also in exceptional condition. The tramp is questionable but might hold up, we shall see. The only items that need attention are main/front beam and dolphin striker - which have had some serious damage - and possibly the rear beam is showing its age. I will have many questions eventually regarding the subtleties of setting up the boat properly and the various NACRA tricks and mod's, but first I wanted to get advice on the main beam issue (since this is the essence of the boat really) and get the hulls back together.

The main beam has a deep depression and jagged, torn hole on the underside where the dolphin striker rod passes through it.

[Linked Image]
[Linked Image]

From studying the damage, and doing some research on various forums, I have hypothesised: the holes through the centre of the main beam for the dolphin striker rod have corroded; the compression fitting inside the beam has ripped through the beam with the weight of the mast - possibly aided by the support rod jumping out of V-bar (or the pad was missing). The mast probably fell down, further denting the beam and also cosmetically denting the sidewall of the mast a few inches up from the base. It seems that some other folk have also suffered beam damage through some of the mechanics I just mentioned, like here and also here. I don't understand why the torn hole is dented inwards around it, from the underside of the beam, but something bad happened that's for sure. Maybe the beam had a severe downward load (eg. snowpack) that forced it down on the rod enough the force the washer on the rod through the corroded hole of the beam?

The dolphin striker rod is pretty badly bent.

[Linked Image]

The nylon ball that the mast rotates on is missing. The dolphin striker casting/support pad between the dolphin striker rod and the V-bar is missing. The aluminum V-bar appears undamaged, but has some corrosion around the centre hole. I'm not sure if it's enough to be concerned about - but I want the boat to be safe.

Corrosion on V-bar strap at dolphin striker rod hole
[img]http://s25.postimg.org/kvoonm1r3/IMG_5528.jpg[/img]

[img]http://s25.postimg.org/pyalw50f3/IMG_5529.jpg[/img]

So my key questions are:

Main beam - repair, replace, or make another one from blank tube? Welding some sort of curved patch around the torn hole (after stop-drilling the rips) seems possible, such as they planned to do here but I have many questions regarding the alloy of the patch material, the affect of the heat from the welds on the undamaged areas of beam, the extra height of the patch affecting the mast/rigging, and the cost of the welding. A replacement beam could be very difficult to find, and likely outrageously expensive. Did I mention my budget for this project is almost nothing? I understand they didn't make all that many of these boats. Finally, I've begun researching blank tubular marine aluminum , but this also seems very expensive and I would need 4.5" tubing from memory. The main beam looks to be a very simple thing, so maybe I could buy 8.5ft of blank and swap all the hardware across.

Rear beam - Is it meant to have a slight downward curve along the length of it? It is very symmetrical and seems deliberate, not just the consequence of prior overstressing. Can anyone confirm this is part of the design? I wouldn't be able to replicate this curve in a blank tubular section.

What's with the enormous number of holes in the underside of the rear beam?
[img]http://s25.postimg.org/4fpevd7bz/IMG_5461.jpg[/img]

The rear beam is intact otherwise, but some of the tramp eyelets are missing where the rivets have dissolved and pulled out of fairly badly corroded holes. Some others are loose. I could probably drill all these rivets out, and also drill out the holes larger to clean up the corosion, and redo them with bigger rivets? I don't think the corrosion is bad enough the warrant replacing anyway, since it's not as load bearing as the front beam.

Thanks for taking the time to read this, if you've gotten this far. I really appreciate any advice so I can work on this over the winter!

Cheers,
Tom

Posted By: JeffS

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/21/14 07:50 AM

Welcome to the forum Tom, my first two cats were Stingrays a great boat! The rear beam would have started straight, the holes in the rear beam could have been to lighten it or might be access holes to nuts inside the beam can you see the bolts for the traveller track through the holes? You really need a new main beam and new strap for the dolphin striker there is no short cut your up for a length of pipe for the front and rear beam, Nacra will have the parts or specs for everything you need. The bad news is you are up for a few dollars but the good news is you'll have a great boat for not much
Posted By: peterk

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/21/14 09:33 AM

gp to TheBeachcats.com and look in the classified section under boat parts. I bet someone has some beams for a couple hundred bucks each. Do a little research, I bet the beams cross over to some of the other nacras, like the 5.2. Pete
Posted By: Hullflyer1

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/21/14 12:27 PM

I believe the 5.5 has a beam of 8 feet 6 inches, if so it would take a nacra 6.0 beam. The 5.2 or 5.8 will not work
Posted By: Hullflyer1

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/21/14 12:28 PM

I believe the 5.5 has a beam of 8 feet 6 inches, if so it would take a nacre 5.5 or 6.0 beam. The 5.2 or 5.8 will not work
Posted By: srm

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/21/14 08:53 PM

I'd first check for used beams. thebeachcats.com is a good place to start as mentioned above.

If that doesn't work out, I would either try an internal or external sleeve or source out a blank tube. There is nothing special about "marine aluminum". It is typically 6061-t6 alloy and anodized. Pretty standard stuff. Check out onlinemetals.com.

sm
Posted By: bacho

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/21/14 08:55 PM

You can make your own beam pretty easy and cheap. You need 4" tubing, no need IMO to pay extra for marine anything. I made new front and rear beams for a super cat in a few hours.
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/22/14 05:18 AM

Originally Posted by JeffS
Welcome to the forum Tom, my first two cats were Stingrays a great boat! The rear beam would have started straight, the holes in the rear beam could have been to lighten it or might be access holes to nuts inside the beam can you see the bolts for the traveller track through the holes? You really need a new main beam and new strap for the dolphin striker there is no short cut your up for a length of pipe for the front and rear beam, Nacra will have the parts or specs for everything you need. The bad news is you are up for a few dollars but the good news is you'll have a great boat for not much


Hi Jeff, that's amazing you sailed Stingrays too.

I'm disappointed to hear that the rear beam shouldn't have the curve that it does. I wonder if it would affect anything? Theoretically it would bring the hulls slightly closer together in the rear, but it's probably barely measurable. At least now it is something I could make myself from (non bowed) aluminum tube.

I wondered if the holes were to lighten the beam - but unlikely given that much aluminum couldn't possibly weigh more than an ounce or three. You may be right that they are for the traveler. I'll take a closer look.

I am also wondering if I can make a new dolphin striker strap by ordering that dimension in aluminum or even stainless from this place and carefully bending it myself. It seems like a pretty simple hunk of metal. The strap I Have would also be a pretty good/cheap candidate for welding strengthening layer at the centre hole and a few inches up each side.

Money money money! I know I got a great free boat, but my budget is extremely tight, and I need to be as creative as I can be while fixing it properly. I don't have plans to race the boat, so I have some flexibility with all this.

Thanks again Jeff for your input, much appreciated!
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/22/14 05:22 AM

Originally Posted by peterk
gp to TheBeachcats.com and look in the classified section under boat parts. I bet someone has some beams for a couple hundred bucks each. Do a little research, I bet the beams cross over to some of the other nacras, like the 5.2. Pete


Good idea Pete, I'll duck over there and put up a note and see what's around. It seems second hand beams could be almost as expensive as making my own new ones from blank tube. At least the latter would be new, and not come with it's own history and wear and tear.
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/22/14 05:22 AM

Originally Posted by Hullflyer1
I believe the 5.5 has a beam of 8 feet 6 inches, if so it would take a nacra 6.0 beam. The 5.2 or 5.8 will not work


Good to know, thanks!
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/22/14 05:32 AM

Originally Posted by srm
I'd first check for used beams. thebeachcats.com is a good place to start as mentioned above.

If that doesn't work out, I would either try an internal or external sleeve or source out a blank tube. There is nothing special about "marine aluminum". It is typically 6061-t6 alloy and anodized. Pretty standard stuff. Check out onlinemetals.com.

sm


I just spent some time browsing http://www.onlinemetals.com/ , what a great site! Man, I can use them for all sorts of projects I have in mind coming up (wood fired pizza oven on a trailer anyone?). I cant believe how expensive blank aluminum tubing is! I'd be looking at US$160 per beam for 4" OD, although I thought I measured it at 4.5" the other day, which jumps up to US$195 each. I doub't I will ever take this boat to salt water, so should I even worry about the anodizing aspect?

I'm leaning towards this blank tubing idea though, or a second hand beam, rather than trying to fix the old one. The damage is pretty bad.
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/22/14 05:34 AM

Originally Posted by bacho
You can make your own beam pretty easy and cheap. You need 4" tubing, no need IMO to pay extra for marine anything. I made new front and rear beams for a super cat in a few hours.


Good to know it can be done.
Posted By: bacho

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/22/14 10:17 AM

Your local metal supplier should be able to get you better prices than you can find online.

IF you should used beams locally, they would probably be about the same price as new tube.
Posted By: JeffS

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/22/14 11:17 AM

If you beam the boat up with a new beam front beam and the old rear beam, the front will bolt up square and the rear will bolt up splayed outwards so there will be twist in the load on the hulls. If anodising will break your budget don't worry about it but make sure you use duralac or similar on all rivets and bolts to impede corrosion. A cheap place to look for this type of pipe is a Centre Pivot manufacturer or similar for agriculture, you would just buy a length and cut it up
Posted By: JeffS

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/22/14 01:20 PM

The rear beam doesn't carry much load if you need to save money you could weld patches on the front beam and use it as the rear beam, you could even use the existing tramp arrangement and lace to the new front beam
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/22/14 03:41 PM

Originally Posted by JeffS
...make sure you use duralac or similar on all rivets and bolts to impede corrosion.


Awesome, I was wondering about this. It seems like all the corrosion problems on the existing beams are galvanic, wherever there was/is a stainless rivet. I'll be sure to grab some of this stuff.
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/22/14 03:42 PM

Originally Posted by JeffS
The rear beam doesn't carry much load if you need to save money you could weld patches on the front beam and use it as the rear beam, you could even use the existing tramp arrangement and lace to the new front beam


Great idea!
Posted By: Ventucky Red

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/27/14 12:34 AM

Did you reach out to Pete Beagle who is up in Big Bear? I seem to remember him having some 5.5 or maybe 18 Square beams laying around....
Posted By: A. Bourgault

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/27/14 11:25 AM

Originally Posted by JeffS
The rear beam doesn't carry much load if you need to save money you could weld patches on the front beam and use it as the rear beam, you could even use the existing tramp arrangement and lace to the new front beam


With all the holes in the rear beam it's load carrying abilities may be not sufficient.
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/28/14 12:04 AM

How do I get in touch with him? I tried searching his name with no luck.
Originally Posted by Ventucky Red
Did you reach out to Pete Beagle who is up in Big Bear? I seem to remember him having some 5.5 or maybe 18 Square beams laying around....
Posted By: JeffS

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/28/14 08:25 AM

Originally Posted by A. Bourgault
Originally Posted by JeffS
The rear beam doesn't carry much load if you need to save money you could weld patches on the front beam and use it as the rear beam, you could even use the existing tramp arrangement and lace to the new front beam


With all the holes in the rear beam it's load carrying abilities may be not sufficient.


Yep I hope that's how my post reads throw away the old rear beam, weld some patches on the front beam if it's straight then use that as the new rear beam and buy a new front beam. I wouldn't drill the holes under the old beam I would put the bolts through the traveller then put a spanner on a long thin pole to tighten the nuts inside the beam
Posted By: rehmbo

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/28/14 11:27 AM

Pete still frequents the "thebeachcats.com" forum under the username pbegel

I purchased some battens from him earlier this year. Nice guy - easy to work with.

I have his email address if you have trouble making contact.

Edit - I see you're already engaged with those guys on that forum. I'm sure you can make contact with him.
Posted By: Ventucky Red

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/28/14 03:14 PM

Originally Posted by sierracat
How do I get in touch with him? I tried searching his name with no luck.
Originally Posted by Ventucky Red
Did you reach out to Pete Beagle who is up in Big Bear? I seem to remember him having some 5.5 or maybe 18 Square beams laying around....


Check your privet messages.... I just sent you his email
Posted By: carlbohannon

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/29/14 02:46 PM

First, if you have a way to get it to you, I think I have have a rear 5.5 crossbeam with a dent in it. It is in Houston. I may have some other cross beams that you can have. There are probably people like me near you. We held onto damaged hardware first, thinking we might need it and later because the snakes living in it had gotten BIG.

A couple of comments:

The front beam does not look like the one on my 5.5 uni. The tramp track on your is separate, mine was internal to the beam, like the 6.0. It may be a homebuilt replacement. I would not order anything based on the dimensions of that beam. Also, I do not remember factory beams corroding like that

I have replaced at least 3 NACRA crossbeams. Online companies normally only stock 8 foot beams and shipping an 8.5 foot tube is over half the cost. Your best bet is to find one locally.

A used 6.0 beam with no corrosion would be ideal. Check other catamarans for beams that have the same dimensions, F18's for example.

Did the Inter 20 use the same extrusion?

If you buy a tube from a metal dealer, tell them this is is for structural use. No reputable supplier will sell you anything they have questions about. I had an industrial supplier search the stack for a tube that had 6061-T6 printed on it and the paperwork taped to it. Try to avoid surplus companies, they do not always know what they have or you may be buying a reject.

Good luck
Posted By: Jake

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/29/14 03:17 PM

Originally Posted by carlbohannon
First, if you have a way to get it to you, I think I have have a rear 5.5 crossbeam with a dent in it. It is in Houston. I may have some other cross beams that you can have. There are probably people like me near you. We held onto damaged hardware first, thinking we might need it and later because the snakes living in it had gotten BIG.

A couple of comments:

The front beam does not look like the one on my 5.5 uni. The tramp track on your is separate, mine was internal to the beam, like the 6.0. It may be a homebuilt replacement. I would not order anything based on the dimensions of that beam. Also, I do not remember factory beams corroding like that

I have replaced at least 3 NACRA crossbeams. Online companies normally only stock 8 foot beams and shipping an 8.5 foot tube is over half the cost. Your best bet is to find one locally.

A used 6.0 beam with no corrosion would be ideal. Check other catamarans for beams that have the same dimensions, F18's for example.

Did the Inter 20 use the same extrusion?

If you buy a tube from a metal dealer, tell them this is is for structural use. No reputable supplier will sell you anything they have questions about. I had an industrial supplier search the stack for a tube that had 6061-T6 printed on it and the paperwork taped to it. Try to avoid surplus companies, they do not always know what they have or you may be buying a reject.

Good luck


All F18 and "Inter" (20, 18, 17, etc) beams are not round - they're all sqround and wouldn't work on these hulls (without significant modification, anyway).
Posted By: waterbug_wpb

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/29/14 04:02 PM

Originally Posted by Jake
"sqround"


that's a new one...
Posted By: catandahalf

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/29/14 06:45 PM

Jake is referring to the beam mounts for beam tubes (old style) versus the flat - sided design currently employed. Modernization via the newer beams will require hull mods to the attachment molding/laminating.

Too bad Jim Bauman has retreated to the CA mountainside...that used to be an F 18 HT debacle for awhile... maybe A cats, as well. Jim did a bunch of beam mods for the F 18 HT guys and the Tybee teams back in the day.
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/30/14 03:58 PM

Originally Posted by carlbohannon
The front beam does not look like the one on my 5.5 uni. The tramp track on your is separate, mine was internal to the beam, like the 6.0. It may be a homebuilt replacement. I would not order anything based on the dimensions of that beam. Also, I do not remember factory beams corroding like that


Interesting, I'm starting to wonder what crazy combination I have here. When we dry fitted the front beam on the hulls, the couple of holes to choose from to go over the stud in the beam moulding in the hull (my boat has a threaded stud coming out of the hull, not a threaded hole like most nacras) didn't make much sense. Either the beam seemed to extend slightly out over the edge of the hull, or sit inboard slightly so that the outside strap barely grabs the end of the beam. I hope that made sense.

[Linked Image]

Can anyone with a 5.5 in one piece and original parts give me some exact measurements for their beams (length, OD, ID, and distance inboard from each end for the anti-rotation bolt? Or point me to a document on the inter webs with such info.

Posted By: Jake

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/30/14 06:49 PM

Originally Posted by sierracat
Originally Posted by carlbohannon
The front beam does not look like the one on my 5.5 uni. The tramp track on your is separate, mine was internal to the beam, like the 6.0. It may be a homebuilt replacement. I would not order anything based on the dimensions of that beam. Also, I do not remember factory beams corroding like that


Interesting, I'm starting to wonder what crazy combination I have here. When we dry fitted the front beam on the hulls, the couple of holes to choose from to go over the stud in the beam moulding in the hull (my boat has a threaded stud coming out of the hull, not a threaded hole like most nacras) didn't make much sense. Either the beam seemed to extend slightly out over the edge of the hull, or sit inboard slightly so that the outside strap barely grabs the end of the beam. I hope that made sense.

[Linked Image]

Can anyone with a 5.5 in one piece and original parts give me some exact measurements for their beams (length, OD, ID, and distance inboard from each end for the anti-rotation bolt? Or point me to a document on the inter webs with such info.



Huh...that's not supposed to be a stud if I remember correctly...and, is that black material carbon fiber in the beam socket? I don't remember any 5.5's having carbon either (did the Uni version have some perhaps?). I'm pretty sure my 5.2 had a bolt that went down through a has spherical spacer through the beam into the hull. It was necessary to loosen that up and move the hull inward to get a new trampoline on. I can't imagine how you would do that with a stud there.
Posted By: Jake

Re: NACRA 5.5 uni - project boat - damaged main beam - 09/30/14 06:53 PM

You might find these links useful to 5.5 manulas over at thebeachcats.com. I see that it had a side laced trampoline which would have meant that you could use a stud in that position on the beam...but they still show a bolt.

Nacra 5.5 assembly manual

More nacra assembly manuals.
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 10/01/14 06:05 AM

OK, so 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?). 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, add if they were set 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. The plot thickens.
Posted By: JeffS

Re: NACRA 5.5 uni - project boat - damaged main beam - 10/01/14 08:20 AM

My 5.8 has a bolt through the top of the beam and beam strap about where that stud is. I highly recommend you contact the closest Nacra dealer to you and get the original specs of the beam. Don't be shy about contacting them even though you don't want a beam from them now they know that if they look after you properly now you will buy something from them one day. Sometimes the beam isn't the widest part of the boat when you are beaming up a boat to it's maximum width you need to find the widest part on the sides of the boat and measure from there. You may not have a standard tramp so will need to be conscious of installing the tramp you have the way it is installed now or you will be up for money to modify the tramp. An original Nacra 5.8 front beam will have a track built into it to slide the tramp into don't know about your boat
Posted By: P.M.

Re: NACRA 5.5 uni - project boat - damaged main beam - 10/01/14 11:44 AM

Originally Posted by sierracat
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. The plot thickens.


Nacra made two versions of the legacy rear beams. The earlier version used a bolt-on traveler track that ended short (inside of each hull). The newer rear beam included the traveler as part of the extrusion, so naturally it would be the full length. There was a slot machined into the track to allow the beam straps to pass through. Sounds like you have the earlier version.
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 10/25/14 05:13 PM

So I have some new information! Apparently the beams I have now came from a Nacra 18sq, originally 11ft wide (?) and were cut down to 8'5" or 101in. I don't believe they have been installed with these hulls before, which explains why some things weren't adding up (hole locations for anti-rotation hull bolt, and stains where a full length traveller track used to be, along with a myriad of other old holes and stains). Not that this changes things much - I still need a replacement front beam, and ideally a rear one too. Would be nice to get original equipment, but if I do fabricate them myself, I'll be asking y'all for some hard numbers on the dimensions of various aspects of the factory beams.

I'm still open to purchasing some used beams, and a few of you have sent me contacts that I've replied to. Thanks for that.
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 11/12/14 09:26 PM

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 off 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.
Posted By: bacho

Re: NACRA 5.5 uni - project boat - damaged main beam - 11/12/14 11:27 PM

That blank tubing shouldn't be too bad. I would guess about $140 for a 24' stick. The thinner material is actually more expensive....

If your going all home brew anyways, there is no reason you can use material sizes that are more available. Step the DS up to .625"
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 11/13/14 05:40 AM

Originally Posted by bacho
That blank tubing shouldn't be too bad. I would guess about $140 for a 24' stick. The thinner material is actually more expensive....

If your going all home brew anyways, there is no reason you can use material sizes that are more available. Step the DS up to .625"


If I don't keep the ds rod to spec, the nylon ball won't fit atop the threads. Also I won't be able to reuse the compression tube, which appears undamaged.

Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 12/29/14 08:58 AM

Update: I've been busy! I built my new beams, and assembled the hulls, along with finishing the trailer. No tramp installed yet, and need to overhaul the rudder assemblies. First test today putting the mast and sail up, checking the stays were the right length and all my calculations add up (they did!). Very exciting to see it come this far!

One concern - with the sail up I noticed the old adhesive outline of a removed sail marking that reads '18s' (as in 18 square). You may be able to just make it out in the photo, below the Nacra logo and the red 5.5 numbers. So my 5.5 uni, made up of 18sq hulls, with previously chopped down 18sq beams, may now also have an 18sq sail?! I guess I don't really care what we should be calling it, but I would like to know if it truly is an 18sq sail, and if so, how that might affect the boat on the water. Bigger sail area comes to mind, with added power, but not sure if this will change the handling adversely (besides the extra healing moment). The mast is 29'6" long (excluding casting) and the sail seems to fit it well. I know early 18sq had a boom, then they went to boomless. This sail almost looks like it was made for a boom. Perhaps the silver colored clew plate could have been added later?. Even hooking my mainsheet to the most inboard hole of the clew plate, sheet tension isn't pulling outboard enough, and the foot of the sail won't tension properly. On the most outboard hole it looks just ridiculous - the foot of the sail has a giant flapping belly in it. I know the rear beam/traveller is meant to angle slightly forward on boom less, and slightly aft on boom rigs, but I don't think that will fix sail tension the way things stand. Any thoughts appreciated. Is it a 5.5 uni boomless sail, or 18sq boom/boomless sail? Issues?

[img]http://www.thebeachcats.com/gallery...p;g2_itemId=112746&g2_serialNumber=4[/img]

[img]http://www.thebeachcats.com/gallery...p;g2_itemId=112749&g2_serialNumber=4[/img]

Posted By: Jake

Re: NACRA 5.5 uni - project boat - damaged main beam - 12/29/14 12:16 PM

You are correct in that this is not nearly enough angle on the mainsheet for a boomless rig to function properly.
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 12/29/14 03:33 PM

Originally Posted by Jake
You are correct in that this is not nearly enough angle on the mainsheet for a boomless rig to function properly.


Hmmmm. That's what I am thinking. *sigh*. So, does this frankenstein of a boat need a boom added to it now? The sail is quite nice. Do you think the mast is also from an 18sq, or were they the same as the 5.5 uni? (this mast is 29'6"). If I recall correctly, the 5.5SL mast is a little shorter than the Uni, but don't know the specs on the 18sq masts.
Posted By: Jake

Re: NACRA 5.5 uni - project boat - damaged main beam - 12/29/14 04:01 PM

Originally Posted by sierracat
Originally Posted by Jake
You are correct in that this is not nearly enough angle on the mainsheet for a boomless rig to function properly.


Hmmmm. That's what I am thinking. *sigh*. So, does this frankenstein of a boat need a boom added to it now? The sail is quite nice. Do you think the mast is also from an 18sq, or were they the same as the 5.5 uni? (this mast is 29'6"). If I recall correctly, the 5.5SL mast is a little shorter than the Uni, but don't know the specs on the 18sq masts.


I'm pretty sure that Nacra once marketed a widened 5.5 as a factory available 18 square if I remember that correctly. You may have some sort of combination of the two.

But, yes, if you intend to use that sail, you are definitely going to need a boom. Note that if you can put a strop around the boom to the mainsail so that the mainsheet loads are directly transferred to the sail, and only use the boom to support an outhaul adjustment, you can go with a much smaller (and cheaper) material for a boom (like most of the catamarans available today do).
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 12/29/14 04:21 PM

Originally Posted by Jake
I'm pretty sure that Nacra once marketed a widened 5.5 as a factory available 18 square if I remember that correctly. You may have some sort of combination of the two.

But, yes, if you intend to use that sail, you are definitely going to need a boom. Note that if you can put a strop around the boom to the mainsail so that the mainsheet loads are directly transferred to the sail, and only use the boom to support an outhaul adjustment, you can go with a much smaller (and cheaper) material for a boom (like most of the catamarans available today do).


Thanks Jake,

Hoping some others chime in on this, but what were you thinking regarding boom specs? Build my own (like the beams) rather than try and source a nacra original? Perhaps 2" 6061 Aluminum tube, maybe 0.0625 wall thickness? How about a gooseneck assembly? The old main beam had a rudder gudgen fitting attached facing aft, I suspect this was how the boom was attached when this was an 18sq. My sail doesn't come all the way down to the tramp at the tack, so I would need something a little higher on the mast. Maybe getting ahead of myself here, but throwing some ideas around.
Posted By: Jake

Re: NACRA 5.5 uni - project boat - damaged main beam - 12/29/14 05:44 PM

Originally Posted by sierracat
Originally Posted by Jake
I'm pretty sure that Nacra once marketed a widened 5.5 as a factory available 18 square if I remember that correctly. You may have some sort of combination of the two.

But, yes, if you intend to use that sail, you are definitely going to need a boom. Note that if you can put a strop around the boom to the mainsail so that the mainsheet loads are directly transferred to the sail, and only use the boom to support an outhaul adjustment, you can go with a much smaller (and cheaper) material for a boom (like most of the catamarans available today do).


Thanks Jake,

Hoping some others chime in on this, but what were you thinking regarding boom specs? Build my own (like the beams) rather than try and source a nacra original? Perhaps 2" 6061 Aluminum tube, maybe 0.0625 wall thickness? How about a gooseneck assembly? The old main beam had a rudder gudgen fitting attached facing aft, I suspect this was how the boom was attached when this was an 18sq. My sail doesn't come all the way down to the tramp at the tack, so I would need something a little higher on the mast. Maybe getting ahead of myself here, but throwing some ideas around.


Nothing says that the sail has to meet the boom at the goosneck...they could be three feet away and the boom angled upward if need-be...but, that takes up a good bit of real estate to get across the boat and having the boom up higher on the mast is definitely desirable.

BTW, sunfish masts will make an operable boom (or spin pole) and they're typically cheaper from a sunfish dealer than you can get the same extrusion from a metal wholesaler.
Posted By: bacho

Re: NACRA 5.5 uni - project boat - damaged main beam - 12/30/14 04:53 AM

2" .0625 is plenty stout, that's what my i20 had.

Some downhaul will probably pull that sail close to the bottom on the track.
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 12/30/14 05:11 PM

Originally Posted by bacho
2" .0625 is plenty stout, that's what my i20 had.

Some downhaul will probably pull that sail close to the bottom on the track.


yeah, I figured that will help a bit. Didn't have the downhaul rigged up for the test.
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 12/31/14 06:37 AM

What sort of gooseneck fitting do the older boom Nacras e.g. 5.2 use. I believe they were rectangular booms, so what could I make work? I've google searched and pulled up some pics of hardware (not installed, just the item) and I can't visualize the connection.

Originally Posted by Jake
Note that if you can put a strop around the boom to the mainsail so that the mainsheet loads are directly transferred to the sail, and only use the boom to support an outhaul adjustment


I like this idea a lot. Would I have just one loop/strop and pick one of the 3 holes in the clew plate, or have multiplier strops, one in each hole, to maintain the option of pull point? Or will the outhaul take the place of a clew traveller type arrangement, by adjusting foot tension and sail shape ?
Posted By: Jake

Re: NACRA 5.5 uni - project boat - damaged main beam - 12/31/14 12:12 PM

I remember that the 5.2 used a short piece of 3/4" (roughly) square stainless tubing as a trunion. It had a pin through the top and a pin through the side that attached to stainless yoke fittings in the boom and the mast.

The boom fitting was a "U" shaped bent piece of stainless (15 gauge?) that had a large hole in the middle with a bolt (5/16"? maybe 1/4"?) that went through a plastic end cap in the end of the boom. That "U" shaped yoke could swivel on the bolt and swivel on the pin.

The mast had a fitting that riveted to it and made a yoke with the pin oriented in the vertical axis.

Really, though, gooseneck fittings are a dime a dozen...you could probably adapt just about anything from any sailboat.
Posted By: dave mosley

Re: NACRA 5.5 uni - project boat - damaged main beam - 12/31/14 04:04 PM

The boom fitting attachment and the tiller crossbar arm fittings were the same from what I remember from my 5.2
Posted By: JACKFLASH

Re: NACRA 5.5 uni - project boat - damaged main beam - 12/31/14 11:19 PM

Just one strop. The out haul will determine the foot tension. It is important to note that the mainsheet should either pull straight down, or preferable slightly forward to induce rotation and to not pull the foot of the main flat.
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 01/01/15 05:45 PM

Originally Posted by JACKFLASH
It is important to note that the mainsheet should either pull straight down, or preferable slightly forward to induce rotation and to not pull the foot of the main flat.


As in, my strop will probably go through the furthest aft of the three holes on the clew plate, pulling the boom towards the mast somewhat?
Posted By: JACKFLASH

Re: NACRA 5.5 uni - project boat - damaged main beam - 01/02/15 09:02 AM

Yes a slight inducing of forward pull to help promote mast rotation is a good thing. Too much however will bend a boom, even a two inch diameter one. If the bottom attachment point of the main sheet is between 1-2 inches forward of the hole in the main that should be about right. I know from experience that three inches will bend the boom.. When I say bend I don't mean catastrophic destruction, but rather a permanent bow.
Posted By: Jake

Re: NACRA 5.5 uni - project boat - damaged main beam - 01/02/15 06:09 PM

Originally Posted by JACKFLASH
Yes a slight inducing of forward pull to help promote mast rotation is a good thing. Too much however will bend a boom, even a two inch diameter one. If the bottom attachment point of the main sheet is between 1-2 inches forward of the hole in the main that should be about right. I know from experience that three inches will bend the boom.. When I say bend I don't mean catastrophic destruction, but rather a permanent bow.


Are you talking about a sail that is pinned to the boom at the clew separately from the mainsheet? If you put a strop around the boom and use that connect the mainsheet directly to the sail and only use the boom for outhaul, you shouldn't be able to bend the boom (I wouldn't think).

On the Nacra 20s I've owned, it was amazing how much we could bend that rectangular boom when sheeted hard (because the sail and the sheets were pinned at different places).
Posted By: JACKFLASH

Re: NACRA 5.5 uni - project boat - damaged main beam - 01/05/15 09:30 PM

I am talking the main attached to a strop which is attached to the clew. The boom simply runs through the strop. The out haul however does attach the boom to the sail and that connection is what allows forced rotation and bent/bowed booms.
One could argue the out haul needs to be eased a bit but I would disagree. When I noticed the first boom I assumed one of us had landed on it during a capsize. The second one had not been in a capsize before I noticed it was bowed.
In both cases the boom was/is still serviceable, it just bothered me that it wasn't straight.
Posted By: catman

Re: NACRA 5.5 uni - project boat - damaged main beam - 01/05/15 09:37 PM

Originally Posted by Jake
Originally Posted by sierracat
Originally Posted by Jake
I'm pretty sure that Nacra once marketed a widened 5.5 as a factory available 18 square if I remember that correctly. You may have some sort of combination of the two.

But, yes, if you intend to use that sail, you are definitely going to need a boom. Note that if you can put a strop around the boom to the mainsail so that the mainsheet loads are directly transferred to the sail, and only use the boom to support an outhaul adjustment, you can go with a much smaller (and cheaper) material for a boom (like most of the catamarans available today do).


Thanks Jake,

Hoping some others chime in on this, but what were you thinking regarding boom specs? Build my own (like the beams) rather than try and source a nacra original? Perhaps 2" 6061 Aluminum tube, maybe 0.0625 wall thickness? How about a gooseneck assembly? The old main beam had a rudder gudgen fitting attached facing aft, I suspect this was how the boom was attached when this was an 18sq. My sail doesn't come all the way down to the tramp at the tack, so I would need something a little higher on the mast. Maybe getting ahead of myself here, but throwing some ideas around.


Nothing says that the sail has to meet the boom at the goosneck...they could be three feet away and the boom angled upward if need-be...but, that takes up a good bit of real estate to get across the boat and having the boom up higher on the mast is definitely desirable.

BTW, sunfish masts will make an operable boom (or spin pole) and they're typically cheaper from a sunfish dealer than you can get the same extrusion from a metal wholesaler.


A Sunfish mast is a 2 1/4" section. Fairly heavy section. The booms are 1 1/2" and are used for spin poles and booms.

I made a boom using a 2" section. I found a aluminum cap that fit. It might have been from a Holder 14 boom. If you have access to a lathe you can make one easy enough. I got a shroud anchor bolt from a Hobie 18 or 16 and installed that in the cap. I had what is called a super goose which was for a Hobie 18 boom. This is an aluminum fitting that the eye of the shroud anchor bolt will fit perfectly. This same fitting attaches to the goose neck fitting on the mast. Simple and strong. I believe that fitting is still available from Murray's. Google "Hobie super goose" I will try to post a couple pic's if you like.
Posted By: NL_Expatriate

Re: NACRA 5.5 uni - project boat - damaged main beam - 02/08/15 08:57 AM

Hello while I am a newbie cat sailor. I do own an 18sq I think you are right in your assuming that you have a chopped down 18sq.

Mine was pretty much stock when I got her. Rectangular boom attached to bottom of 30' mast. Three pulleys attached inline on boom. Two torsion tubes running ontop of trampoline on either side.

I am curious if your booklets sail works though?

Also will you be adding a jib as the 18sq were unI'm because I would like to add one.

If you have any questions about the 18sq feel free to ask me.
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 02/23/15 08:01 AM

Hiya all,

If you have been following this, then the latest is that the tramp has been restitched (fingers crossed) and installed on the boat. The trailer is finished, except for lights, and the front upright for the mast (the rear upright is finished, and pivots down for boat unloading). Still need to paint my welds. Also need to remove what's left of the ancient hiking straps and install new ones (line through eyelets, with pipe insulation foam wrapped around them). Also had the upholstery guy make a simple pocket on the front of the tramp (the white thing in the pic) with a velcro closure, for stashing the main halyard and the righting line.

[img:left]http://www.thebeachcats.com/gallery...p;g2_itemId=112991&g2_serialNumber=3[/img]

[img:left]http://www.thebeachcats.com/gallery...p;g2_itemId=113033&g2_serialNumber=3[/img]

[img:left]http://www.thebeachcats.com/gallery...p;g2_itemId=113034&g2_serialNumber=3[/img]
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 02/23/15 08:04 AM

Next step is working on the rudders. Rudder thread is here
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 02/23/15 08:09 AM

Hi there,

I plan to add a boom, and have committed to it now because of the able I chose rear beam/traveller and where the eyelets for the tramp lacing have been attached.

I will not be adding jib. I wish it had a jib, but the more I've read and learned, it seems it's a lot of modification to do it properly and it can put a lot of pressure on the bows (especially older boats like mine with the chainplates on the outside of the hull). Better off just finding a 5.5SL or another type of boat.

Have fun with your 18sq. Pics?
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 05/29/15 09:59 PM

Finished! Maiden voyage last weekend was in very light winds, but enough to test everything out, and it went very well. Rigged quickly and without issue on the beach, and away we went. So happy to be done and looking forward to a great summer of sailing and exploring local lakes. Thanks everyone for you helpful input as I navigated this project.

Before: Dirty, damaged boat in pieces, as retrieved from a barn after sitting many years
[Linked Image]

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After:
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[Linked Image]
Posted By: Redtwin

Re: NACRA 5.5 uni - project boat - damaged main beam - 05/29/15 11:05 PM

Nice!
Posted By: Jeff Peterson

Re: NACRA 5.5 uni - project boat - damaged main beam - 06/03/15 06:12 AM

Yes, very nice!

What was the final cost to refurbish the boat? How many hours of actual labor? (Free isn't always free, but it still can be a good deal.) I bet it feels good to have rescued an abandoned orphan.

Posted By: Todd_Sails

Re: NACRA 5.5 uni - project boat - damaged main beam - 06/03/15 06:29 PM

Awesome work, nice thread, nice boat
Posted By: sierracat

Re: NACRA 5.5 uni - project boat - damaged main beam - 06/23/15 05:57 AM

Jeff,

I was on an incredible budget, and also got lucky that the key things were in good condition (hulls, sail, boards, rudders etc). I'd say I spent about $750, and half of that went to building up a trailer. I couldn't even guess the labor! Lots.
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