From reading up it looks as if the 5.5uni uses the same hulls as the 18sq, it just has a narrower 8'6" beam and less sail area?

Edited for emphasis

Just looked it up 172sq feet vs 194sq feet on the 18sq.

Storz, you are correct that the hulls are the same. Sail area has been optimized to each boat (beam and righting moment differences).

Uni's are a ball. I setup and sail mine comfortably in most any wind at 185lbs. Standard size trailer too.

Flexibility wise, you can sloop rig a Uni or Uni rig a sloop without a lot of fuss as riggings are readily available. Certainly gives you options should you later pick up a crew. No need to change boats. All depends on where you see yourself going in the future.

Check with Mark at the Cathouse (located in Michigan). Last time I looked he had a couple of 5.5's on his website.

Sail fast, Tom G

Can the 18sq accept a jib/spini should the need for a two person boat ever some up...

Don't know, suspect you'd need to find or develop your own design...foil, bridles, blocks, routings and sails.

There is a sometimes active group of 18sq sailors that frequent this site. I would suggest searching for previous 18sq strings and contact some of them direct. You'd be receiving advice from those who regularly sail the boat.

Sail fast, Tom G

Hey, I just became the owner of an old square 18 and had the same ques. I am currently trying to find a good deal on a new sail. Mine came with a large and small jib so someone had it rigged. Keep in touch. Maybe we can help each other out.

If you stay in Cary, chances are there will be a rule against keeping it at your new house. I have this problem and just keep it at crosswinds with the mast up. The convenience of not having to trailer/completely unrig is worth it.

i sail my nacra 5.2 solo95% of the time, it has 15.5m2 main and 4.12m2 jib

that's 19.62m2 total

i know the center of effort is lower than the 18sq's but then the boat is a whole lot narrower too...

wouldn't be so happy to do so on the ocean, but on an inland lake it doesn't seem too over-powered

in fact once you get used to it having crew just seems to kill the performance

That,s the problem with a wife...they think that houses should come first! ??

Everyone knows it's boat first THEN....another boat.

From an actual NACRA 18sq sailor:

Yeah, you can rig whatever headsail you want, but then you'll have to take knocks for it. "18 Square" stands for 18 square meters, which is the maximum legal sail area. The reason for the unirig has to do with maximum efficiency for limited sailarea.

When you install a jib, you'll lose pointing ability and won't have enough sail area to make it worth it for downwind. And you'll take a knock for it. If you just have to do something like that, at least install a chute which will help you downwind, and go away so you can point to weather.

But for DAMME sure if you have a stock NACRA Sq with the old-style "bendy" mast with loose diamond wires, DO NOT RIG HEADSAILS, and DO NOT TAKE ALONG CREW unless they're very light weight (kids, for example.)

The old-style (1980s, early 90s) NACRA masts will break, they are optimised for the boat and expected crew weight, and NOT designed AT ALL to carry headsails NOR extra crew.

All 18sq are NOT equal and you cannot generalise... keepup's is some sort of aftermarket or custom boat. newbie may have a NACRA Sq. I have a NACRA Sq with a newer 5.5u mast which has been lengthened. Husband has a Cat 1 Sq homebuilt with a carbon mast. Do you even really know what you have?

Squares are box-rule boats and usually are not alike so generalisations tend to be incorrect.