Hey folks,

I'm from Germany. Sailing a 1994 Nacra 5.0 which is a super fun boat.
When its blowing harder I would love to get the main more flat. My mast points nearly 90° to the hulls.

The 500 have a rotation device but unfortunatly the manual says nothing about how its made.

Have someone pics of a 500 with rotation or a retrofitted 5.0?

Also interesting is a boom. The main is very close to the tramp so for a really good way the do it, the sail foot must be shorter. Or with a bend boom like the decksweaper F18's.

Thanks, Hannes

If you are evaluating adding a boom, that decision comes first because the mechanism is opposite. With a boom the outhaul tension works against the mast producing rotation, the mast rotation device restricts the rotation produced by the boom. The rotation arm points back and restricts the rotation.
Without boom the rotation arm points forward and you pull it from the windward side against the front beam (typically) to increase the rotation, normally downwind, that system cannot restrict rotation.
I'm not sure that mast rotation is your first alternative to flatten the sail, outhaul and downhaul come firts. You don't have an outhaul but you should have grommets to attach the mainsheet hook.

mast rotation actually flattens the sail, doesn't it? Rotated mast will bend more and therefore flatten the sail.

Downwind isn't my problem here, its more upwind. As I said, the mast nearly points 90° to the hulls. This makes the sail deep and give much of profile. Most books and text i have read till now says the rotator should point towards rear beam end (lee) when it comes to upwind. And towards front of daggerboard or stays when sailing downwind.

Downhaul clearly comes first. But the mast rotates it self due to the tension in the sail and the cut.
Sail is quite new, and comes from probably the best nacra sailmaker around here, shouldn't be the problem.

My 5.0 hasn't got a boom. The 500's also hasn't as long as i know.

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Most books and text i have read till now says the rotator should point towards rear beam end (lee) when it comes to upwind

That is with a boom
In this picture you can see one case without boom, here it seems to go under the tramp but it can also be cleated at the beam, in that case there is an arm wider at the tip that works better, with two attachment points rather than one, so you can overrotate (not really but works better when you want to produce 90° rotation) (I know it's not what you want, just explainng what it's used.
More interesting on the picture is the traveler clew, which I believe migh be a good option for you, instead of a boom. I have that on my 5.5 and like it very much. Still, a 90° rotation upwind is not right, that deserves some root cause analysis before fixing the problem, not sure why that might be happenin.
https://www.thebeachcats.…4ffb682a7d8c8b0735a7bfee

The Clew plate on the sail is there to flatten sail. Attach main block further aft to flatten and further forward to put more belly in the sail. Down Haul will do the rest. I wouldn't mess with the natural operation of a boom less rig. I also use a roller furling jib to depower boat in a heavy blow and sail main only.

--
Pete
2001 NACRA 450 SOLD
2000 NACRA 500 TOTAL LOSS
2004 NACRA INTER 20 SOLD
2016 NACRA 500 Sport
DeLand, FL
--

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Attach main block further aft to flatten and further forward to put more belly in the sail

I'd say the other way around?

@saltlife77
I'd also say that cleating in forward will flatten the main and other way around.

Sailing without the jib in heavier conditions is quite difficult when it comes to tacking. Do you have any tips? Normaly I use the jib backwindig in tack.

@Andinista:
thanks for the article! Great to read and very inspiring. The sheeting in hardly section makes me laughing.
But I still didn't get 100percent of the message with the mast bend, rotation and shroud tension.

To depower the main above 14kts I use a spreader rake of about 45mm (should be about 1,8") while in softer conditions 25mm (1") doing just fine. In both situations a 90° rotation is normal.

Probably I have an issue with the shroud tension. My shrouds are as tight as I get them with the standart adjusters (holes are far from another due to the "one hole line")

To set up shroud tension i ask the heaviest guy in range for help (pulling a trapeze line as hard as he could while i set the shroud)
Maybe this isn't enough. Are there any tricks to achieve more tension (using mainsheet or something?)
I didn't own a tension gauge cause they are that pricy.



Edited by hannes-neo on Aug 14, 2020 - 04:12 PM.

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My shrouds are as tight as I get them with the standart adjusters (holes are far from another due to the "one hole line")

That should be enough, set one hole above and you should notice that it rotates easier but with shroud tension it’s not like you will limit rotation completely. If you feel you may go a bit further it’s not a problem to set one adjuster one hole lower than the other. Or for testing with rotation at least, but under human weight limits It seems reasonable, you don’t want to crank your shrouds like crazy.



Edited by Andinista on Aug 14, 2020 - 09:57 PM.

Maybe have the heavy guy hang on the trap rather than pull it.
About tacking, stupid as it may sound it’s very common to forget about the tiller in critical instants, like when you are moving to the other side or when it’s time to revert the steering and complete the turn backwards. I never sail without jib though but I guess that is still a point. Also start tacking close hauled.

I did it the most powerfull way. Proper tension measurements without expensive tools would be nice anyway.

Tacking is mostly correct performed I think. But I definitly i forgot to steer correct in the first days (long time ago).

I wonder how saltlife77 is doing his tacks. Would be nice to read about.

So does no one retrofitted mast rotation on a 5.0/500?

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The Clew plate on the sail is there to flatten sail. Attach main block further aft to flatten and further forward to put more belly in the sail.

That is backwards. Hooking to the forward holes allows more mainsheet tension, which flattens the sail.

I installed mast rotation on an N5.7, but removed it, just wasn’t worth it.
http:// https://www.thebe…4c71c44ce2c5b05ea8a4343a

--
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
--

I didn't feel I needed one when I had a N5.0. Now my N5.5 has one and I like it very much to lock rotation completely (cleat both sides) when trailering or the very few times that I’m out with waves and little wind. But for sailing I don’t really use it. The few times I did it, too often i forgot about it before tacking.

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I installed mast rotation on an N5.7, but removed it, just wasn’t worth it.
http:// https://www.thebe…4c71c44ce2c5b05ea8a4343a

Fixed the link, for some reason when using an ipad the links dont work. The lines in this photo are wrong, each side should dead end on the beam eye just inside the cleat on the beam. You run the line from dead end to rotator-back to cleat- around mast- through opposite cleat- to rotator - back to dead end. This gives a 2:1 for positioning the rotator, & it does require some force with higher wind loads.

As Adinista said, I didn't use it much, especially solo.IT was handy when in choppy seas & light wind. The mast would bang around, shaking what little wind ther was out of the sail, & generally annoying the hell out me.



Edited by Edchris177 on Aug 16, 2020 - 12:09 PM.

--
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
--

Edchris177

The lines in this photo are wrong, each side should dead end on the beam eye just inside the cleat on the beam. You run the line from dead end to rotator-back to cleat- around mast- through opposite cleat- to rotator - back to dead end. This gives a 2:1 for positioning the rotator, & it does require some force with higher wind loads.

This may be the best and simplest forced mast rotation I have ever seen. This would give you what you want with a soft rig (not pre-bend) mast in a big blow on a broad reach. Or travel in and employ a boat load of leech twist.

--
Sheet In!
Bob
_/)_____/)_/)____/)____/)_____/)/)__________/)__
Prindle 18-2 #244 "Wakizashi"
Prindle 16 #3690 "Pegasus" Sold (sigh)
AZ Multihull Fleet 42 member
(Way) Past Commodore of Prindle Fleet 14
Arizona, USA
--

LOL...yes I did get that backwards didn't I...That's what I get for chiming in while I am at work LOL.

--
Pete
2001 NACRA 450 SOLD
2000 NACRA 500 TOTAL LOSS
2004 NACRA INTER 20 SOLD
2016 NACRA 500 Sport
DeLand, FL
--

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Without boom the rotation arm points forward and you pull it from the windward side against the front beam (typically) to increase the rotation, normally downwind, that system cannot restrict rotation.

What I said is wrong, you can restrict rotation with this system on a boomless boat, just pull on the other side. It's just unusual I think.

Here is a video of my buddy's g-cat with positive mast rotation - lots of footage of him setting, using it, how it's reeved, etc (he runs the lines back to deck cleats near the skipper)

lots of good footage of him using it - then we pull out his spin to "dry it off" around 1:15
then it gets "un dry" :)

https://www.youtube.com/watch?v=o-ajtJfs-Sc

Here is a video of my buddy's g-cat with positive mast rotation - lots of footage of him setting, using it, how it's reeved, etc (he runs the lines back to deck cleats near the skipper)

lots of good footage of him using it - then we pull out his spin to "dry it off" around 1:15
then it gets "un dry" :)

https://www.youtube.com/watch?v=o-ajtJfs-Sc

Thanks for all the tips and inspiration.
I'll build some kind of rotation device in winter 2020 and will let you know about it.

If there is any 500 sailor with nice pics of his rotation or boom setup it would be nice to read about.

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To set up shroud tension i ask the heaviest guy in range for help (pulling a trapeze line as hard as he could while i set the shroud)
Maybe this isn't enough. Are there any tricks to achieve more tension (using mainsheet or something?)
I didn't own a tension gauge cause they are that pricy.

The easiest way to get rig tension when you are by yourself through the headstay. Have a shackle or a ring at the apex of the bridle and a bow shackle at the end of the headstay. Simply tie a length of 3/16 to either place and loop it around a few times to get purchase and finish with some half hitches.

--
Bill Townsend
G-Cat 5.0
Sarasota
--

shortyfox

The easiest way to get rig tension when you are by yourself through the headstay. Have a shackle or a ring at the apex of the bridle and a bow shackle at the end of the headstay. Simply tie a length of 3/16 to either place and loop it around a few times to get purchase and finish with some half hitches.

this is the Portuguese turnbuckle method (my preferred method on both my cats). lashing a line.

When i owned an h18, i rigged with a loose sidestay, hopped in my harness and adjusted my sidestay adjuster, OR i learned another method was (main up) to point bows into the wind (in the sand)- travel all the way out and sheet my main

once sheeted hard, you will have a loose sidestay: you can tighten your side stay adjuster.

caveat is to stay alert of ANY wind shifts and be prepared to uncleat the main if the wind picks up and things get silly
You can always be on the wire at the same time as an added safety measure.

Can be done in the water too - but it helps to have someone hold the bows or put them on the beach if the wind is accommodating.

You guys are over thinking all this. Remember the old adage "if it works, don't fix it". I owned a Nacra 500 for ten years, bought new, and it did not come with any positive mast rotation device. Nacra marketed the 500 and the 570 as their "recreational boats". They are all recreational, I guess they should've touted them as their more user friendly boats and that they are with no boom, no boards, no mast rotation inducer and jib blocks mounted on the main beam. What you give up in performance you make up for in ease of rigging and handling. The boat was designed for the mast to rotate just from the pressure of the luff with diamond wires limiting the mast bend. Any additional performance obtained by increased mast rotation won't be worth having to reset the rotation device during every tack. Adding a boom will only help if the boom is long enough so when the mainsheet is attached to the rear of the boom it actually pulls forward inducing mast rotation and that would make it possible to put a much simpler rotation limiter on it. One more thing I'm not sure of is the mast bases on boomless and booms might be different. The socket where the ball fits in might be further aft or forward depending. That location would certainly have some affect. If you're real fuss an easy thing to do that will help a boomless rig in lighter airs is a camber control along the foot of the main. Basically this is a small line attached at the clew and the tack of the main with a two way fiddle block with cleat somewhere along it's length. Use this when it becomes apparent that the lower part of the main is too flat because on a boomless rig the mainsheet is pulling aft. As for me, I'd keep the 500\5.0 stock and have fun!

--
Bill Townsend
G-Cat 5.0
Sarasota
--

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Any additional performance obtained by increased mast rotation won't be worth having to reset the rotation device during every tack.

all due respect: that is for the owner to decide

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When its blowing harder I would love to get the main more flat.

this is the only reason i would ever agree with adding rotation control to this boat
this is the exact reason my friend on the g-cat uses it - and it is one more step during tacking, but he is one of the fastest people to ever sail a g-cat (we sailed with the designer for over a decade)

MN3

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When its blowing harder I would love to get the main more flat.

this is the only reason i would ever agree with adding rotation control to this boat
this is the exact reason my friend on the g-cat uses it - and it is one more step during tacking, but he is one of the fastest people to ever sail a g-cat (we sailed with the designer for over a decade)

And how is it done, by forcing or limiting rotation? The former supposedly would reduce sail draft because the mast angle would be better aligned with a flatter sail shape, but the latter helps increasing mast bend which flattens the sail.

Assumptions:
- mast type = classic, no wing mast
- upwind sailing



Edited by Andinista on Aug 26, 2020 - 11:18 AM.

There's been a lot of opinions on this one, only his time I have a question instead. I recently downsized from a G-cat 5.7 to a 5.0. It was a good move because I sail alone most of the time, only 150 lbs and 70 years old. The 5.0 has a boom and a mast rotation limiter. I do use mast bend to help flatten the sail. I would be inclined to use a lot more mast bend but the 5.0 lacks diamond wires. Is there any danger in breaking the mast if I let it rotate almost 90 degrees and sheet down really hard?

--
Bill Townsend
G-Cat 5.0
Sarasota
--

Hard to tell.. I've read that mast prebend is more relevant on modern wing masts and not so effective with older ones, not quite sure though. Have you considered more purchase on the downhaul? The 5.0 comes with what, 3:1? a lot more is commonly used on many other boats. Also, the 5.0 doesn't have a boom, yours is either modified or a 5.2?

Oh.. you are not talking about a Nacra but a Gcat 5.0 I think...sorry

IMHO: lots of factors here make it boat specific
mast stiffness
spreaders/not (prebend)
boom/not
rotator/not
sailcut (cut for prebend or not)

Here is some data i found on this site that seems to give some insight here:

"Loose diamonds and use mast rotation to allow bend along minor axis (sideways). When mast is rotated near 90 degrees, it will easily bend sideways and flatten the sail. Reducing mast rotation aligns major mast axis with the sail and keeps it full. Downside to this is the bottom of the mast can bend into the slot between the jib and main.

Pre-bend is the other method. Set spreader rake about 2-3 inches and tighten diamond wires extremely tight. Get a loose gauge to measure it. Then use downhaul to bend the mast back along its major axis. The tight diamonds keep the mast from bending into the slot. It also allows the top to twist off during a gust."


I hope someone with better theory knowledge will pipe in but it is my understanding inducing heavy rotation will flatten the entire sail and allow the mast to bend

as cunningham (downhaul) will bend the mast to match prebend cut into the luff and will flatten the sail mostly at the top and allow more twist

shortyfox

The 5.0 has a boom and a mast rotation limiter.

Could you post some fotos of your rigged boat? Would be great so see how its made.


The bend thing: when sailing in double trapeze conditions I increase the spreader rake. This hasn't that much impact on the visible sail shape but huge impact of what I can handle. More prebend takes huge loads of power and allow to sheet in very hard. This also is extremely necesarry because the mainsheet is the most powerful method to get the sail flat.

Anyway I will make some changes to the boat over the offseason and I'll share it with you guys.



Edited by hannes-neo on Aug 27, 2020 - 05:25 PM.

Message deleted... wrong thread..



Edited by Andinista on Aug 28, 2020 - 07:07 AM.