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Nacra 18 Square #288845
07/23/18 10:40 PM
07/23/18 10:40 PM
Joined: Jul 2018
Posts: 3
M
Minnesota Offline OP
stranger
Minnesota  Offline OP
stranger
M
Joined: Jul 2018
Posts: 3
Hi Everyone! I have a 1987 Nacra 18SQ that I was looking to do some modifications to and would appreciate some input.

I'm planning to add a jib for additional speed & to make this beast of a boat tack better. It'll require a new forestay at the minimum since the current one parts about 1 meter down form the mast attachment. Would it be a good idea to fabricate a bridal foil to better distribute the load onto the hulls? Has anyone here ever done this before?

I'd like to upgrade the hulls to something a little larger than the 5.5 hulls it currently has so it can better handle 2-3 people on it during a lazy afternoon. Is there any harm in using some 1986 foam core 5.8 or 6.0 hulls in its place?

Attached Files
IMG_9533.JPG (108 downloads)
smIMG_9555.JPG (105 downloads)
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Re: Nacra 18 Square [Re: Minnesota] #288846
07/25/18 12:37 AM
07/25/18 12:37 AM
Joined: May 2006
Posts: 1,353
Kingston SE South Australia
JeffS Offline
veteran
JeffS  Offline
veteran
Joined: May 2006
Posts: 1,353
Kingston SE South Australia
Gday there is a guy in Sweden putting 5.8 hulls on wider beams and putting a Tornado mast on with Tornado self tacking jib, which is sort of what your considering, if you want I will private message his facebook link to you, he's quite outgoing with his info, he currently has a widened 5.5. I'm guessing your looking at keeping your mast and maybe a F16 self tacking jib or Taipan 4.9 jib. Craig in Qld has put a new square top sail and infusion rudders on his 18 square and he says that has sorted the tacking issue. I haven't sailed my 18 square yet but hope to next month once I have the mast bits sorted, mines got a carbon 32ft mast and big square top sail and I'm hoping that will sort out the tacking. There is also a thread on catsailor.com which I revived a while ago and it has great info on spinnaker conversion etc. Good luck with your project as there are a couple more being revived at the moment and I have a mate looking for one to do up


Jeff Southall
Current boats
Nacra 5.8 1703 Cant have two Ram Raiders at the same time so not named yet
Nacra 5.8 1667 Ram Raider
Nacra 18 Square
Arrow 1576
Re: Nacra 18 Square [Re: Minnesota] #288851
07/28/18 09:51 AM
07/28/18 09:51 AM
Joined: Jul 2016
Posts: 16
SWEDEN
reVintage Offline
stranger
reVintage  Offline
stranger
Joined: Jul 2016
Posts: 16
SWEDEN
Hi,

The Swedish guy here ;-) . If you want to add a jib it will work with a self-tacking Infusion or another F18 ditto. I have done this to our 10" wide 5.5 . See image below where a Hobie Tiger mast is used.

As I see it, it would be easiest to share the forestay load with a third centered Dyneema forestay and a low Dyneema bridle(Liros Static 4 or 5mm) at ca 1´ 2" heigth. You might have to lengthen the side forestays and shorten the top snout, as the jib luff is 19´ 7". If you are lucky, it will fit without altering the side fore stays, as the 18SQ mast is almost 2´ higher than the F18 mast.

If we assume 220lbs total static forestay tension, let the center stay take max 80lbs and the side forestays split the rest. Tricky, but it will work, if you have a Loos to check tensions. Don´t know how much sag you will get in the jib luff, though.

For next years 5.8 Frankencat build, that Jeff refers to, I bought a pair of 18SQ beams, but had to return them as I found them all to weak to use for 2 persons. Designed and built new 10.5" inch wide ones. First opted for a pair of 6.0 hulls, but changed to the 5.8s from the same source, as they where in much better shape. Also bought a Tornado self tacking jib instead of the 49er mentioned in the link below.

https://www.catsailor.com/forum/ubbthreads.php/topics/288287/re-taipan#Post288287

Attached Files
infjib.jpg (57 downloads)
Last edited by reVintage; 07/29/18 04:12 AM.

Brgds
Lars

Frankencat 5.5
Frankencat 5.8
Frankenboat 49er
Re: Nacra 18 Square [Re: Minnesota] #288852
07/29/18 05:34 AM
07/29/18 05:34 AM
Joined: May 2006
Posts: 1,353
Kingston SE South Australia
JeffS Offline
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JeffS  Offline
veteran
Joined: May 2006
Posts: 1,353
Kingston SE South Australia
Thanks for jumping in Lars, I didn't want to just chuck your name out there, I'm just waiting on my new sidestays for my project


Jeff Southall
Current boats
Nacra 5.8 1703 Cant have two Ram Raiders at the same time so not named yet
Nacra 5.8 1667 Ram Raider
Nacra 18 Square
Arrow 1576
Re: Nacra 18 Square [Re: JeffS] #288853
07/29/18 09:19 AM
07/29/18 09:19 AM
Joined: Jul 2016
Posts: 16
SWEDEN
reVintage Offline
stranger
reVintage  Offline
stranger
Joined: Jul 2016
Posts: 16
SWEDEN
Hey Jeff,

Looking forward to more info about your new project.


Brgds
Lars

Frankencat 5.5
Frankencat 5.8
Frankenboat 49er
Re: Nacra 18 Square [Re: reVintage] #288855
07/30/18 06:57 AM
07/30/18 06:57 AM
Joined: Jul 2018
Posts: 3
M
Minnesota Offline OP
stranger
Minnesota  Offline OP
stranger
M
Joined: Jul 2018
Posts: 3
Jeff - Thank you for the pointers. I have a ~10-15 year old 5.8 jib I am planning to use for the first iteration. The mast I am using is a 32 ft aluminum mast, pretty sure it is the original that came with the boat - It is identical to the one from the 5.8 I have been sailing on.

Lars - Thanks for the pointers on the Jib attachment. I'll give that a shot when I set it up in the spring. Can you share more details on your concerns on the original 18 square beams being too weak? I was hoping I wouldn't have to fabricate new re-enforced ones. Did you just add the reinforcing at the hull attachment points or through the whole tube?

Re: Nacra 18 Square [Re: Minnesota] #288856
07/30/18 04:11 PM
07/30/18 04:11 PM
Joined: Jul 2016
Posts: 16
SWEDEN
reVintage Offline
stranger
reVintage  Offline
stranger
Joined: Jul 2016
Posts: 16
SWEDEN
First of all remove the striker band and rod and check for corrosion. Images of the rotten ones I got below.

The 18SQ beams I bought had no inserts what so ever. If so, try to find a pair of Australian 5.8 beam inserts. Think JeffS knows a guy who has a pair. Also add a 4" long 0.120" tube in the center.

My 5.5 front beam had tube inserts of something like 0.08". If you have them, change them for 16" inch long 0.120" and also add a 4" long center insert.


Attached Files
IMG_3042.jpg (36 downloads)
IMG_2998.jpg (31 downloads)
Last edited by reVintage; 07/30/18 04:13 PM.

Brgds
Lars

Frankencat 5.5
Frankencat 5.8
Frankenboat 49er
Re: Nacra 18 Square [Re: Minnesota] #288857
07/30/18 10:48 PM
07/30/18 10:48 PM
Joined: May 2006
Posts: 1,353
Kingston SE South Australia
JeffS Offline
veteran
JeffS  Offline
veteran
Joined: May 2006
Posts: 1,353
Kingston SE South Australia
wow that is corroded and would be a sloppy boat, the inserts for the beam ends are called I beams enable you to really tighten your beams without compressing the tube and are supplied by Brisbane Catamaran Centre. I'm assuming your welding a patch on those beams Lars or did you replace them? Definitely need the beam centre post. From what I hear the 18 square goes upwind brilliantly, outpointing most big cats but is slow off the wind, so I'm considering a spinnaker for mine but I do know they are a bit tender in the bows as far as pitchpoling so I'm reluctant to add the weight of a bowfoil up front.


Jeff Southall
Current boats
Nacra 5.8 1703 Cant have two Ram Raiders at the same time so not named yet
Nacra 5.8 1667 Ram Raider
Nacra 18 Square
Arrow 1576
Re: Nacra 18 Square [Re: Minnesota] #288858
07/31/18 02:39 AM
07/31/18 02:39 AM
Joined: Jul 2016
Posts: 16
SWEDEN
reVintage Offline
stranger
reVintage  Offline
stranger
Joined: Jul 2016
Posts: 16
SWEDEN
No worries Jeff, couldn´t accept that crap. The seller in the Netherlands didn´t mind and gave me the nice 5.8 hulls instead. Had to pay the shipping though. One of the guys in the 5.8 FB group said he had a pair of inserts. I made the new beam of 2x100mm tubing and the center and inserts of 3x100mm that I slotted 15mm for a tight fit. Then a M8 bolt through the beam end, like the new 5.8, with spacers from top to bottom. Used stainless 40x3mm for the beam strap and M16 for the striker rod.


Brgds
Lars

Frankencat 5.5
Frankencat 5.8
Frankenboat 49er
Re: Nacra 18 Square [Re: Minnesota] #288859
07/31/18 06:17 AM
07/31/18 06:17 AM
Joined: May 2006
Posts: 1,353
Kingston SE South Australia
JeffS Offline
veteran
JeffS  Offline
veteran
Joined: May 2006
Posts: 1,353
Kingston SE South Australia
Yep my mate Dazz has some I beams, are there many 5 8s over your way, I'm going off on a tangent here but I'm wondering about sending one of mine over for Texel so I can do it next year or wether I try and hire or buy one there but bring my sails and foils


Jeff Southall
Current boats
Nacra 5.8 1703 Cant have two Ram Raiders at the same time so not named yet
Nacra 5.8 1667 Ram Raider
Nacra 18 Square
Arrow 1576
Re: Nacra 18 Square [Re: JeffS] #288860
07/31/18 12:16 PM
07/31/18 12:16 PM
Joined: Jul 2016
Posts: 16
SWEDEN
reVintage Offline
stranger
reVintage  Offline
stranger
Joined: Jul 2016
Posts: 16
SWEDEN
I have no figures about how many 5.8s are left in Europe. For what I understand, the last 5.8 for the European market was produced in the US 1999. So no high hopes of finding a raceready boat over here. Anyway I guess, the Netherlands is where you have the best chance to find one.


Brgds
Lars

Frankencat 5.5
Frankencat 5.8
Frankenboat 49er

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