What is it, do I need one, or is my boat meant to have one? Nacra 5.5 uni.

Thanks as always.





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Tom
Hobie Getaway, Nacra 5.5, Hobie Tiger
Wish list: A-cat classic, F16 Viper!
Northern California
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If you can easily move between those three holes, you need it a little bit less..
A hook like this one may help (just got the picture from google, it happened to be from this site, of course)

Most of the boomless nacras just hook the mainsheet block into one of the holes in the clew plate. A few had a little boomlet. You should just be able to hook in I think.

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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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Wolfman

Most of the boomless nacras just hook the mainsheet block into one of the holes in the clew plate. A few had a little boomlet. You should just be able to hook in I think.

Ok. But what is the purpose of being able to sheet from a different position? What does it affect?

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Tom
Hobie Getaway, Nacra 5.5, Hobie Tiger
Wish list: A-cat classic, F16 Viper!
Northern California
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In fact, while we are on the topic, why are there boomless cats at all? Seems like mostly a Nacra thing. What's the advantage, when most every other modern sailboat has a boom. And why doesn't the clew of the sail flop around if you were sheeting from the most forward hole?



Edited by sierracat on Nov 24, 2014 - 06:24 PM.

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Tom
Hobie Getaway, Nacra 5.5, Hobie Tiger
Wish list: A-cat classic, F16 Viper!
Northern California
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Andinista

If you can easily move between those three holes, you need it a little bit less..
A hook like this one may help (just got the picture from google, it happened to be from this site, of course)

I do believe I have the very same hook on the sail end of my main sheet blocks.

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Tom
Hobie Getaway, Nacra 5.5, Hobie Tiger
Wish list: A-cat classic, F16 Viper!
Northern California
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Now, if you were ever thrown 20 ft off your boat after an unexpected jibe caused you to get a boom to the head you wouldn't ask that question. Seriously got a concussion a few years ago because of that.

Just simplicity and safety more than anything.

Its one less thing to worry about and you won't smash a beginner when you are sailing if they are in the wrong spot at the wrong time. Boomless rigs are mostly on the more recreational cats than the racing ones. The hobie wave and getaway are both boomless. I'm also pretty sure that some of the gcats and darts didn't have booms. The need for the boom is partially removed by the tension an extra triangle of fabric in tha sail that goes to the bottom of the mast provides. This tension pretty much keeps everything from flopping around. That being said depending on how much mainsheet tension you have, some of the leech of the sail will tend twist off.

Having a boom helps you keep the sail shape better and distribute the tension throughout the sail better. Helps you control sail twist and allows better control over mast rotation. This all means you can point a little higher and get a little more efficiency and speed out of the sail. I sail both a boomed boat 5.2 and a non-boomed boat 5.7 and I honestly love not having to worry about the boom and since I dont race I havent really noticed any huge performance differences.

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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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Interesting. I was under the impression that most of the nacras were considered performance boats, especially running daggerboards etc. And FYI, I have most definitely been hit in the head by a boom! I've also been thrown off/jumped from capsizing 18ft cats and landed body between traamp and boom but arm between boom and sale. Ouch.

So, any pointers on which of the three holes to hook my main into for different conditions or situations?



Edited by sierracat on Nov 24, 2014 - 07:45 PM.

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Tom
Hobie Getaway, Nacra 5.5, Hobie Tiger
Wish list: A-cat classic, F16 Viper!
Northern California
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Quote

Ok. But what is the purpose of being able to sheet from a different position? What does it affect?

Have you downloaded the 2 Nacra manuals from this site, under Tech Help?
Read them, read them carefully, as if you were a lawyer preparing for trial. They are not as good as a modern manual, but if you read every sentence, there is a great amount of knowledge there.
http://www.thebeachcats.c…pictures?g2_itemId=35212
I use an "S" hook on both boomless Nacras. It cannot be made simpler. Drop the "S" into the clew, & sail away. My record on the 5.7 is 7 minutes, & that includes going to the garage to get the mainsail.
On boomless boats the traveler track faces a bit forward. This means sheet tension pulls the clew rearwards. Changing the "S" hook to a forward hole stretches the sail (flattens) & depowers the rig. In conjunction with more downhaul,(Flattens sail) this is a powerfull combination to de power the rig.

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Interesting. I was under the impression that most of the nacras were considered performance boats

Do not get any ideas into your head about this NOT being a performance boat. When the wind gets to 20mph you wil be shi**ting your pants & wishing you had less power.
Read the manual, light air use the rear hole, the more wind the more you move forward.

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And why doesn't the clew of the sail flop around if you were sheeting from the most forward hole?

It can't...think about it, the clew plate is solid & holds the leech. Just go sailing, it will be very evident.
Booms obviously win, otherwise they wouldn't exist. You are overthinking things. My boomless Nacra's go 21mph. They won't win against more modern designs, but they are simple, to sail & rig, & 30 year old sails (the 5.7 is an '84) still go 20mph.
Lets be honest, most of us are not racing around cans, we head out & reach. If you can come back here in 6 months & tell me that 5.5 doesn't give you some shivers when the wind gets up, I'll buy you an F18
Here's how it looks.


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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
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The ARC 22 is a boomless rig as well, although it has a significant tubular aluminum lower batten. We hook the mainsheet to the aft hole in the clew plate in light air, and move it progressively forward as the wind picks up, mostly to reduce mast rotation, which reduces the sail's draft. Works well on this boat.

Dave

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Have you downloaded the 2 Nacra manuals from this site, under Tech Help?

I have read every word in the one manual with the photo on the front, of the boat from above. I went over it again today. Never is there the words 'clew traveller' and the only thing related to that setup is very vague (and the pictures are almost unrecognizable in those scanned manuals). I had overlooked the second manual, with older typeface, until now. I study up on that one too, it actually looks a little better.

From the newer manual: "Instal upper block to traveller car [are they talking about a clew traveller?] with 1/4" shackle or 'S' hook. Instal lower block to traveller with 1/4" shackle. Adjusting fore and aft will affect sail shape." Hmmm...

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Changing the "S" hook to a forward hole stretches the sail (flattens) & depowers the rig. In conjunction with more downhaul,(Flattens sail) this is a powerfull combination to de power the rig.

Good to know.

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Do not get any ideas into your head about this NOT being a performance boat.

I certainly don't have that idea - quite the opposite! That's why I'm asking questions, so I have the best experience that first sail and onwards, with the rig set up appropriately. I have all winter to play around and get familiar with the rigging.

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Booms obviously win, otherwise they wouldn't exist. You are overthinking things. My boomless Nacra's go 21mph. They won't win against more modern designs, but they are simple, to sail & rig, & 30 year old sails (the 5.7 is an '84) still go 20mph.
Lets be honest, most of us are not racing around cans, we head out & reach. If you can come back here in 6 months & tell me that 5.5 doesn't give you some shivers when the wind gets up, I'll buy you an F18

Ha ha! Careful what you offer I don't believe I'm over thinking things, but I may be getting ahead of myself. I'm sure many things will be more evident once I can a) rig the boat, and b) look at it in the flesh. Unfortunately the boat isn't in a rigging state yet, but I'm rapidly changing that. I've stockpiled almost everything I need now for the rebuild, I'm just waiting on a few more orders to arrive and then of course the time and weather to spend on the build. I had decent sailing experience nearly 20 years ago, but always with boom rigged monohulls and cats. This is a new concept for me, even if it is a simpler one, and seems a no brainer to others. I'm embarrassed to say I wasn't even aware there was such a thing as boomless rig before I was given this boat

Thanks for the lesson!

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Tom
Hobie Getaway, Nacra 5.5, Hobie Tiger
Wish list: A-cat classic, F16 Viper!
Northern California
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You will love the boomless rig! Next you will want to get rid of the boards. :)

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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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Quote

Have you downloaded the 2 Nacra manuals from this site, under Tech Help?

Wow, I just had a quick look through the really old 1985 manual which I hadn't seen before. That entire section on tuning was omitted in the later manual! Great info, I have some reading to do... like a lawyer preparing for trial

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Tom
Hobie Getaway, Nacra 5.5, Hobie Tiger
Wish list: A-cat classic, F16 Viper!
Northern California
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Being an 18^2, I'm thinking your boat had a clew traveler fitted at one time. the clew plate looks a littler weird IMO compared to the boomless Nacra clew plates that I have sailed.



Edited by bacho on Nov 25, 2014 - 05:45 AM.

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Greenville SC

Offering sails and other go fast parts for A-class catamarans
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Pre 1990 (or so) Nacras had clew plates, after that they went to a clew traveler. This was a piece of Harken track with a traveler car and cleat. The traveler would allow for adjustment on the fly. As the wind picks up you want the sheeting point further forward to help flatten the sail. Downwind in light/medium air we used to release the clew traveler completely to give the sail some more shape.

Boomless rigs are not "lower performance". Nacra used them on all their boats until the Inter18 came out. The overall adjustment of the sail shape is more limited. The main disadvantage is the adjustment of the mast rotation. Upwind it is difficult to adjust to anything other than where it naturally wants to be. Also, moving the traveler has a more significant effect on the overall shape of the sail than on a boomed rig. For recreational sailing there is nothing better than not having a boom in the way and for racing its not an issue either.

bacho

Being an 18^2, I'm thinking your boat had a clew traveler fitted at one time. the clew plate looks a littler weird IMO compared to the boomless Nacra clew plates that I have sailed.Edited by bacho on Nov 25, 2014 - 05:45 AM.

You are probably right. Seems like I should be able to hook in OK anyway and manage just fine.

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Tom
Hobie Getaway, Nacra 5.5, Hobie Tiger
Wish list: A-cat classic, F16 Viper!
Northern California
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tiger2216

Pre 1990 (or so) Nacras had clew plates, after that they went to a clew traveler. This was a piece of Harken track with a traveler car and cleat. The traveler would allow for adjustment on the fly. As the wind picks up you want the sheeting point further forward to help flatten the sail. Downwind in light/medium air we used to release the clew traveler completely to give the sail some more shape.
G
Boomless rigs are not "lower performance". Nacra used them on all their boats until the Inter18 came out. The overall adjustment of the sail shape is more limited. The main disadvantage is the adjustment of the mast rotation. Upwind it is difficult to adjust to anything other than where it naturally wants to be. Also, moving the traveler has a more significant effect on the overall shape of the sail than on a boomed rig. For recreational sailing there is nothing better than not having a boom in the way and for racing its not an issue either.

Thanks for specifics as to what was fitted on which era of boat. The hulls are late 70s I think, but I can't speak for mast and sail - they seem more modern. Not suggesting boomless is lower performance per se , someone else threw that out there, but I think they were just generalizing to help explain. Sail shape adjustment are something I haven't had to think about for a long time, thanks for the tips! Looking forward to a simpler rig and not hitting my head!



Edited by sierracat on Nov 25, 2014 - 10:47 AM.

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Tom
Hobie Getaway, Nacra 5.5, Hobie Tiger
Wish list: A-cat classic, F16 Viper!
Northern California
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Hi Tom,

After we were talking about adding a boom to your cat I think I would try it as a boomless first. After looking at your sail set up and your pictures of the original beams I can see that this is one of the early squares that had the boom attach to the front beam. The sail in the picture looks like a modified sail with the added clew plate to eliminate the boom. I think I would stick with this setup for a while and not add a boom and see how it works.

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David
Nacra 5.5SL
Nacra 5.2 (sold)
San Diego, CA
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