What's the deal with old NACRA masts
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Posted: May 15, 2017 - 04:31 PM
if you read the post he tells exactly where he got the struts
he told them the size and weight of his rig and they told him which struts to order
Rocco made a tilt trailer a few years ago - similar idea but no where's as nice an execution
his was built too high off the ground it it was a bear to load and unload - and his struts were not quite enough ... so in the end it was not great - a large part of why he stopped sailing his mystere 6.0 xl -
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Posted: May 15, 2017 - 04:34 PM
That is a good looking boat. With a modern square top, it would be killer.
Tilt trailers are all a pain in the rear. Need to counterweight the trailer which makes them heavy.
I'd be hesitant to do much to that boat, she looks in fine shape. If you just lift the bows up onto the beach there shouldn't be much wear. Maybe carry a par of throwable PFD's, these make good padding. Kevlar is very abrasion resistant but there are a lot of other issues, a big one is that paint doesn't want to stick to it. -
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Posted: May 15, 2017 - 04:37 PM
Not sure who you emailed within Nacra, but I didn't hear from you.
I'm guessing that what you heard about being one mast on those boats is right. However, over 40 years some things are bound to change in production.
Also you have to remember the company was purchased in 2007 and we no longer have anyone that was involved with the company prior to 10 years ago. A lot of our information was lost in the great minds of some of our predecessors.
We have a handful of extrusions in our U.S. inventory that we're not even sure what they are.
We're doing our best to support the older boats but it's really quite difficult! There was no internet databases back then that we can still access and most of the paper has been lost. -
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Posted: May 15, 2017 - 04:56 PM
could be buried under a few layers of gelcoat - correct? -
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Posted: May 15, 2017 - 04:56 PM
Yea I'm with you. I think I'm going to take the easy route for now and just re blast paint on it as needed before getting into exotic materials. I'm pretty good about knowing the shallows here locally and I doubt the hulls will ever get sanded too much. I've already stripped the gelcoat off the boards and rudders and filled them back to new and put a few extra layers of sacrificial glass on the tips for when they eventually carve a little sand.
Ah, that would explain the crap shoot on the reliability of old information. I'm not sure who emailed me, I might have saved it, not sure. My only reason for the whole thing was that I for sure have a floppy noodle mast and had hopes of putting my 18' sized spin setup over on it but with the mast the way it is it's mega questionable. To get a stiffer mast I'll probably have to retrofit over something from a modern boat instead of looking for a stiff older era mast and then having to lengthen it for the square. The spin idea is on hold for now. Not really in the mood of doubling the cost of the boat just for a newish mast anyway. -
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Posted: May 15, 2017 - 05:22 PM
Back during the aluminum Tornado mast days, because of the variance inherit in the extrusions, teams would buy multiple masts (like 10) just to get one that they liked. Even though they all came from the same place, some were stiffer or more flexible than others; they even needed to attach corrector weights to the tip if they came out too light. Granted, those masts were made for a higher performance boat, and likely to a smaller safety margin than a typical consumer boat; therefore the extrusion is probably thinner than what Nacra or Hobie would sell and variations is the extrusion thickness and grain structure of the metal would be more noticeable. I don't have any data to support this, just a hunch.
Also, don't forget that different alloys have different properties and the base metal could have slight variations from job to job. Additionally, as aluminum ages, it's structure and properties change; assuming I remember correctly, it will get harder, but more brittle over time. Another guess would also be variations in the extrusions produced as the tooling ages and wears. -
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Posted: May 15, 2017 - 05:44 PM
When the tornado design was implemented and people were backyard building them who was the official mast supplier since there wasn't a single OEM making the actual boats? I could put a tornado mast on this boat it would just be a few inches short. Most of the squares ended up with 31-33 footers instead of the stock 30' one. If I was gonna put a different one I'd probably go even taller in case I make a new higher aspect main to play with. Kinda hilarious I can put a different design main/mast etc and not take any score penalty. I'm sure people would love it if I show up with a wing mast that's still 18 square meters to a mixed fleet race haha -
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Posted: May 16, 2017 - 10:23 AM
Both Marstrom and Sailspar built masts for the Tornado in Aluminum (http://www.aita.asn.au/index.php/tornado-info/tornado-classic/tornado-classic-tuning-guides/15-the-classic-tornado-guide)
If you are series about this, call Matt McDonald @ Falcon Marine, he may still have some blank wing mast extrusions available. Nacra may also be able to sell you an Infusion mast in the 32' range, as they use that extrusion (or something very similar, may be different alloy or internal reinforcements) for refitting Nacra Inter 20's and some of their cruising range. There are some other F18 rigs available (AHPC, Exploder, Cirrus) that would also fit your boat but they are a tiny bit shy of 30'. Then you move into carbon rigs, which are nice, but even a fully kitted aluminum wing mast is going to be $2-$3k, which is the base price of a blank carbon wing mast tube.
Edited by samc99us on May 16, 2017 - 10:57 AM. -
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Posted: May 16, 2017 - 10:50 AM
I bought the struts from bansbach.com. I told them how much I needed to lift and sent them a diagram of the platform. They spec'd out the struts, and told me exactly where to mount them. I could tilt the F20c with one hand.
I think I paid around $200 for the pair of struts. -
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Posted: May 16, 2017 - 12:31 PM
Nice link to the Australian site. This one guy on there is my hero with the boat name. I might have to copy that haha.
I guess I'll look out for some wrecked or parted out boats and see if I can get a stick on the cheap. I don't really need it, or at least know I need it yet, until I sail the boat and get a feel for how it handles. I can slap my spin on it since its a little bit smaller than the F18 spins and see how the mast looks in light air and just baby it. Might be ok. I know a guy that won a few national events back in the 80s with the noodle mast and he played around with a spin on it and said it was fine for medium air so we'll see. I'm going to convert it to swept spreaders and prebend so that should help the noodle flop at least a bit.
Thanks, when I get it built up I'll see what I want to do with it. I might end up using the mast support as a crane arm since I have an extra crank winch and just manually lift the frame up. The shock idea is cooler though. -
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Posted: May 16, 2017 - 12:41 PM
These guys have pretty "bendy" masts and spins up - besides all the capsizes, collisions, and running into tankers, they do pretty well
https://www.youtube.com/watch?v=fFYGJ6ox6DI -
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Posted: May 16, 2017 - 01:54 PM
MN3, totally different load cases and rigs. Those 18' skiffs mostly have carbon rigs in the air which can take enormous deflections before failure. In either case, keep the mainsheet on and you should be OKAY, the stiffer rigs I mentioned would probably work fine with 100% masthead spinnakers and enough mainsheet. -
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Posted: May 16, 2017 - 03:04 PM
Oh i know - i was just being cheeky.
i actually have RonStan Skiff race VHF (where i think this video is from)
pretty wild watching those masts curl and flex -
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Posted: May 17, 2017 - 10:43 AM
Yes, there are differences. It comes down to different ways of depowering the rig.
If you have a 'bendy' mast, you over rotate the mast in order to induce camber on the minor axis, and also creates drag/turbulence in the forward part of the sail.
Stiffer masts use prebend tuning, which combines with extra downhaul purchase and bends the mast on the major axis, with less drag.
The sails are cut different for each approach
IIRC, wither White or Fragale discuss the different modes in their books.
I can state from personal experience that older NACRA Squares had bendy masts with little, perpendicular spreaders and the upgrade was to either install swept spreaders or get the stiffer mast which usually had swept spreaders installed.
Jay
Ex-1981, -82 and custom Squares
Now cruising in my old Catana -
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Posted: May 17, 2017 - 11:56 AM
Yea so the previous owner who got second at nationals in 87 with the boat says he always ran the stock perpendicular spreaders and pretty loose diamonds. Can touch them to the mast about 18" up.
Then I talk to the guy who won nationals most of the time in the late 80s and he says to go prebend for sure on the bendy mast. I'm gonna try it both ways and check the sail shape. The diamonds attach to the front of the mast up top so there is essentially some spreader rake built in to the setup already and since the previous owner has a 12:1 downhaul on the thing he's already depowering the rig just like a prebend setup anyway. I think with the downhaul I should easily get the mast to bend on the primary axis enough to work given the flexibility of it.
Question is which spreaders should I use. I could use a H18 set and just buy some longer aluminum round bar. Just from looking I think the square has slightly wider arms. Some other boats have a turnbuckle adjustable type which I like. I could probably weld a setup that would use that but not sure if I need that fine of adjustment really.
Edited by tamumpower1 on May 17, 2017 - 12:57 PM. -
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Posted: May 17, 2017 - 01:37 PM
Tip:
Pay attention to anything Jay says about 18 Squares.
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Damon Linkous
1992 Hobie 18
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Posted: May 17, 2017 - 05:19 PM
Thank you, Damon. Hope you're doing well!
FYI
"TUNING THE NACRA EIGHTEEN SQUARE METER
John Brink - 1980 Class Secretary
The NACRA 18 Square Meter is one of the fastest sailboats in the world. However, it is very sensitive to sail and rig adjustments. While there is no guarantee that you will have the fastest NACRA 18 Square Meter on the water, if you set your boat up as follows, you will have a good starting point for further adjustments and your boat will be very pleasant to race.
Believe it or not, the best starting place is at the top of the mast. The NACRA 18 Square Meter is set up so that, if you wish, you may convert to an internal halyard by adding a sheave in the after side of the section near the top. Consequently, the geometry of the rig is based on the premise that the sail doesn’t go all the way to the top of the mast section. Make sure that when your halyard lock is engaged, the sail is a few inches shy of being fully hoisted. If the sail goes up all the way, the boom will be too short.
Now, to adjust the rest of the battens. The theory behind modern (1980) sail batten combination is to use relatively flexible battens and tie them in without much tension. Because the battens are flexible, the sail will take a nice shape in light air without much tension, and when the breeze comes up the sail will flatten itself as you sheet harder and as the wind blows the leech open. If you tie the NACRA 18 Square Meter battens too tight, the sail will be hopelessly full.
Let’s go back up to the top again. The three upper battens should be very loosely tied, perhaps not even quite taking the slack out of the line. The fourth batten down should be slightly tighter, perhaps just barely taking the slack out of the line but no tighter than that. With the fifth batten and on down, tighten the lines just enough to take out most of the vertical wrinkles along the batten pockets. However, sometimes even this may be too tight. Loose is better than tight!
Next, adjust the diamond wires until you can touch them both against the mast about three feet up from the lower diamond tangs. This is a good starting point. There is some give and take between the tension on the lower battens and on the diamond wires. The diamonds can be looser with tighter lower battens. Finding just the right combination is a matter of trial and error.
Now let’s rake the mast back to where the sail is sheeted as hard as you ever want it and with the sheet blocks almost together. Set the shrouds up with plenty of tension so that the mast won’t jump around when going through the waves. The shrouds will stretch some when new, so you might as well sail the boat hard a few times before you get too concerned with rake adjustments.
Another adjustment that is critical to both good handling and speed is rudder alignment. It helps to bend each tiller arm inboard about six inches. Whether you do this or not, you should check to make sure you have the rudders set with a slight amount of toe-in. That is, the leading edge of the rudders should be slightly closer together than the trailing edges. If the reverse is the case, besides slowing the boat, they will make the boat difficult to steer.
Now, to steer it fast. When sailing a sloop, most good sailors will pay very little attention to the main. They sail by the seat of their pants and keep an eye on the jib. With a uni-rig, there is no jib to keep an eye on and many sailors may make the mistake of transferring their attention to the main. If you look at the main, you will inevitably end up sailing too high and going slow. Sail the boat by the seat of your pants and direct your gaze ahead. You don’t have too pinch the boat (sail too high) as the extra width that comes with a NACRA 18 Square Meter allows you to drive off and build speed – perhaps covering more "ground" but at a much faster rate of speed. But, on the same hand – don’t be afraid to sail high to cover an opponent or force them over the line early. The uni-rig NACRA 18 Square Meter will out-point and sail higher and faster than most boats, especially those that are sloop rigged. You can pinch, you can foot, but either way you will be the fastest one out there after some practice and experimenting with different setups." -
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Posted: May 17, 2017 - 07:42 PM
Did you personally play with mast rake very much for different conditions. I'm assuming the reason the little guide is calling for rake is to help out with the bows givin how hard you can drive the boat. I got the rake position the previous owner used and he said he more or less always ran it in that position but I haven't stepped the mast to see what rake that is.
Edited by tamumpower1 on May 17, 2017 - 08:51 PM. -
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Posted: May 17, 2017 - 09:53 PM
Be conscious of one thing on spreaders for that mast. The old style round ones from before pre-bend do look crude now BUT since the shroud is not fixed to the spreader tip (seizing wire and tape do not count) it is essential that the spreader tip does not move up and down because if it gets started doing that it will collapse rather than spread. One of the original engineers and Roland had a big fight about that. You do not want to lose that mast. If I were you I would stay with the original spreaders (which were round for a reason) but if you choose not to be careful. -
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Posted: May 17, 2017 - 11:45 PM
I don't understand what you are saying to do. My current spreaders are indeed one solid piece inserted through the mast with wire holding the diamond to the tip. I guess I can wire the crap out of them?
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