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Reefing on a small catamaran


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#1 tonyquoll

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Posted 23 December 2009 - 04:26 AM

Hi,

I'm a 57kg flyweight sailing a 14' Paper Tiger catamaran. See: http://www.papertigercatamaran.org/
After a regatta where it blew 20 to 30 knots, I decided to look into using a smaller sail. After some discussion, the best solution seems to be to install a reefing system. Discussion can be read at: http://www.catsailor...TML/000171.html

A reefing system ought to allow me to set a smaller sail in stronger winds, which would provide better power to drag ratio; more speed. Also should allow me to go for it instead of using a survival strategy off the wind. Besides, I like the idea of sailing with a big Reefer (cough)

The sail has a continuous bolt rope in a mast track along the luff. Would this need to be changed to something else to allow reefing?

The outhail attaches to a car inside the boom - with wheels and everything - the has a 4:1 pulley system. Would this need to be re-attached to a diferent eyelet after reefing?

Any suggestions or links to diagrams, pics that might help?

Hoping you yachties can benefit this dinghy sailor with your experience,
cheers
tonyquoll@yahoo.com

#2 TheFlash

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Posted 23 December 2009 - 04:44 AM

Try having a zipper installed - half on the foot of the sail, the other side right below your 1st batten. You shouldn't need much of a luff rope at that spot anyway.

I assume you've cranked the bejesus out of the cunningham, the outhaul, and thought about having a flatter sail cut? Do y'all play with different masts? if so, maybe a softer mast and flatter sail which would allow the top to fall off in the big stuff?

#3 knobblyoldjimbo

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Posted 23 December 2009 - 04:55 AM

Can't get catsailer to work today so here's my thoughts - I'm a newbie Mari sailer. Up till this year I had trouble even tacking it in over 12knots.

I then tried out a redhead triradial and the difference was enormous. I then bought an Eastwind sail - cross cut. Dave built it for my size - 75kgs - he's built two others but they're fuller because the other guys have another 10-15kgs on me.

I also modified the downhaul so it doesn't pull the boom down, just the sail.

The result - I'm still learning but I'm much faster.

The main thing is that with BIG downhaul and big rotation the mast bends and the sail goes really flat (look up pictures of DN ice boats). With Dave's sail when it's like this the leach also lays off in the upper section which effectively depowers it.

Trying this out with an old, tired sail where the bag has gone back will, I submit fail, because whatever you do (and whatever you put on the sail) it'll always sag.

If you're that light then I'd have a sail made for you, make it so that with the mast fully rotated and fully bent it'll be almost board like ("speed creases" on the International Star). You can then fiddle with settings to make it full when the wind is lower.

What convinced me in the end were two pictures in Frank Bethwaite's newest book (Higher Performance Sailing). The pictures were of a Taser main set for full and medium wind. The full wind pic showed an almost board like sail and this is something that I can achieve with my new sail (of course making it go fast is another matter!).

As to reefing, most yachts have masts that bear strong resemblances to power poles - there are no compression problems here! On a 14ft cat not using a halyard lock might cause some unexpected issues.

KO

#4 tonyquoll

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Posted 23 December 2009 - 07:32 AM

Hi,
Thanks for the replies. For lectures on de-powering and flattening sails, click the above catsilor link. Yeah, I've done all that. :angry:
I'm interested in reefing the sail to make it smaller, not flatter. The reasoning is that sail efficiency would be higher with a smaller sail set fuller, rather than a big sail dead flat. The small sail would have less drag for similar power = faster.
Reefing is looking good as it allows me to use the same sail in all conditions, getting around the rule that you cant change sails between races. ;)
I have a range of spare old sails, but am looking at a cross-cut Williams sail that still as some life in it and needs work on the tack & clew anyway. Photo below is that sail with me flying a hull and starting to get overpowered in about 5knots wind. Waddaya mean try and lean out further? At that point I start flattening it out, but reach the limit of what I can do with it at 15 knots. I figure a smaller sail can give me a range of 12 to 25knots, or reefed sail could go the full range.
If it goes well, then maybe later I'll also modify my lovely radial Redhead sail. My precioussss...
To allow the sail to be lowered, I'm thinking the stupid hook & loop at the mast head that rarely works can be chucked out, and my 6mm halyard rope can have a cleat near the mast base, perhaps with markings to indicate appropriate spots. Alternatively, I could use the old-style cable halyard with several jams near the mast head to lock it in at various heights.
Still wondering about the tack & clew... and do you reef at just those points or in the middle as well?
cheers big-ears < :P >

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#5 knobblyoldjimbo

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Posted 23 December 2009 - 09:34 AM

Get the book - that's not a flat sail!

#6 tonyquoll

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Posted 23 December 2009 - 10:43 AM

OK thanks for the recommendation. I see there's an older version & a new one:
http://www.amazon.co...e/dp/0070057990
Which do you like?

The search lead me to this one; "the Sailmaker's Apprentice". It's more the kind of info I'm after.
http://www.amazon.co.../ref=pd_sim_b_6

Pic is full sail, light wind. As wind increases I make it flatter and flatter, but above 15knots cant do any more to it & start slowing down as drag increases but power doesn't. Kembla regatta was ridiculous; in Race 2 (the windiest) the 1st lap took me an hour. Wind and waves driving me backwards, struggled to make any forwards progress. Traveller out, main out, hiked out just to balance wind on the mast! Cartwheeling downwind didn't help the lap time...

For conditions above 15 knots, I need a smaller sail, or reef it... but how?

#7 TheFlash

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Posted 23 December 2009 - 03:50 PM

did you see my first recommendation? I assume you know you'd need a grommet at the luff and leech, but then have a zipper sewn on the sail to gather the foot into a streamlined package. And then you'll need a new cunningham grommet. That and work out what you need to do with the halyard is it. If I was to do something on my Weta(I don't need to) for the halyard swage another ball on the wire up at the mast head as appropriate.


That's all there is to reefing.

#8 markvannote

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Posted 23 December 2009 - 05:39 PM

Hi,
Thanks for the replies. For lectures on de-powering and flattening sails, click the above catsilor link. Yeah, I've done all that. :angry:
I'm interested in reefing the sail to make it smaller, not flatter. The reasoning is that sail efficiency would be higher with a smaller sail set fuller, rather than a big sail dead flat. The small sail would have less drag for similar power = faster.
Reefing is looking good as it allows me to use the same sail in all conditions, getting around the rule that you cant change sails between races. ;)
I have a range of spare old sails, but am looking at a cross-cut Williams sail that still as some life in it and needs work on the tack & clew anyway. Photo below is that sail with me flying a hull and starting to get overpowered in about 5knots wind. Waddaya mean try and lean out further? At that point I start flattening it out, but reach the limit of what I can do with it at 15 knots. I figure a smaller sail can give me a range of 12 to 25knots, or reefed sail could go the full range.
If it goes well, then maybe later I'll also modify my lovely radial Redhead sail. My precioussss...
To allow the sail to be lowered, I'm thinking the stupid hook & loop at the mast head that rarely works can be chucked out, and my 6mm halyard rope can have a cleat near the mast base, perhaps with markings to indicate appropriate spots. Alternatively, I could use the old-style cable halyard with several jams near the mast head to lock it in at various heights.
Still wondering about the tack & clew... and do you reef at just those points or in the middle as well?
cheers big-ears < :P >


The only part of this I am replying to is your halyard issue. I do not think that a 6mm halyard, without lock would work out well for you. I just don't think it would stand a chance against a typical catamaran cunningham system and would stretch like crazy, regardless of what it is made of. You may be better off, if you have a ball lock system, going with a longer wire section and multiple balls.

Okay, one more. How much have you played your rake settings depending on breeze strength?

Thanks.
Mark

#9 tonyquoll

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Posted 23 December 2009 - 09:50 PM

Thanks Mitch; yep read your 1st & 2nd posts. Sorry I had no idea what you were talkng about with the zipper. I'm getting it now; slab reefing can either be done with a row eyelets or a zipper. You say "gather the foot in a streamlined package", so the foot is folded and kep on the boom? I'm looking at shortening the luff upto 1.4m, maybe with 3 rows of reefing points; 0.5m, 1m, 1.4m. Would that still work with a zipper? Any photos?
I found this tip on a Hobie forum; "You simply drop the halyard to the next bead, remove the downhaul and mainsheet from the sail, zip off the lower section, and reconnect the downhaul and mainsheet to the grommets on the 'new' bottom of the sail."
Do they mean completely remove a panel from the bottom of the sail?

The halyard has a 6mm rope as it runs down inside the sail track. Currently it just hauls the sail up to set a SS ring onto a hook at the mast head. The sail is released by lifting the loop up off the hook, over-rotating the mast to move the hook out of the way, then lowering it. Thinner ropes would come out of the track and flap around on the sail, also making it a pain to pull on to release the sail later.
This system would not work with a reefing sail. Possible a single-cam cleat could be set at the mast head, so that the rope runs through it and only a short length is under full load and exposed to streching. Over-rotating the mast in one direction could move the rope out from side of the cleat, or a 2nd line could pull the cam open.
Or, if the reefing system locked the clew to the mast, then the halyard could become the cunningham.

Older masts used to have two wheels at the mast head, with a wire threaded through and fittings on the mast front to sit a ball in. This meant there would always be a halyard rope at front of the mast; creating turbulence exactly where you dont want it. Effective at holding a sail up though! I still have all the parts for that system, so can try it easily; thanks Mark.

Feel like I'm trying to re-invent the wheel. Surely yachts have these systems fully sorted.
Have I tried flattening the sail, raking the mast, learning to sail.... sigh, yes. As I keep saying, I'm interested in making the sail smaller to increase efficiency. You can understand that a smaller sail with some curve would work better than a big flat one? Isn't this why racing yachts carry multiple mainsails?

Christmas? Bah humbug! It's a distraction from sailing

#10 knobblyoldjimbo

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Posted 23 December 2009 - 10:17 PM

Quite right TQ. But there's the Toukley Xmas regatta starting on Sunday!!

This is a response I wrote to a similar question on Careel.com:

1. reefing - use jiffy reefing. There's a really good Catalina 22 site on the net with lots of nice drawings. Essentially you have a front reefer and a back reefer. Front reefer is a line from one side of the boom, through the reef point and back down to the other side, through a cheek block and back to a clam cleat (with a fairlead). Rear reefer is the same but the take off point and the cheek block are a little further back so that when tension is applied the reef point is under rearward tension to keep the leech and foot firm.

We have this arrangement and use 8mm line, some have a single line going through both and one cleat. You'd need to put this nearer the cabin because there's a lot of line when you reef.


This system means that the foot is kept under tension so it doesn't flap around. It's quite effective.

Of course the other thing is props for going out in heavy weather but when it's like that it's just wasting good bar time!


Oh, and the Bethwaite book, mine is the new one $120 but well worth it - a good read too and not as technical as the original. It concentrates on "apparent wind" boats.
You also lose the cunningham once you reef.

Make sure that you do more than just punch a couple of holes in the sail, on my old maricat main the sailmaker used webbing to make a couple of strips to spread the load. Actually that might be better, webbing sewn to the main holding a D ring at the leech and the luff too, doesn't need to be at the luff front, the side would do fine.

You could also use a 2:1 halyard to reduce the tension on the loose part.

#11 TheFlash

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Posted 24 December 2009 - 03:44 AM

I'm not sure a zip off panel could handle the loads of the leech and cunny, so nope, would just use the zipper instead of a row of grommets to gather up the foot. There might be some old photos, some of the I14s used to have this when they had the reefable mast, the mast stepped in a tube with different height bolts. I don't have any of those photos, I had a different main for when I reefed.

#12 Fasterdamnit

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Posted 24 December 2009 - 04:47 AM

Trap.

#13 tonyquoll

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Posted 24 December 2009 - 06:05 AM

The Catalina 22 site with the great illustrations is: http://www.catalina2...andbook.htm#4.1

Unfortunately will be working and cant make Toukley. At least I have nights off to stitch up reefer madness plans.

Trap? As in fit a trapeze? Aside from going outside class rules, I've not liked the feeling of being cabled to the mast. Trapped. In normal conditions I love how hiking out and body movement has immediate effect on heeling & power; at one with the boat, the wind and the elements. In light to moderate winds with a hull flying, sailing is an awesome mind, body and soul satisfying experience. With the reefed sail, I hope it will extend my range and can learn to become the master blaster in a blow.

"Given enough time, any man may master the physical. With enough knowledge, any man may become wise. It is the true warrior who can master both....and surpass the result." - Tien T'ai


#14 tonyquoll

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Posted 26 December 2009 - 12:27 PM

Reefing system diagrams:
http://www.harken.co...sailReefing.php

Furling main outhaul, could be used with reefing system:
http://www.harken.co...ips/Outhaul.php

To lock the halyard, what if there were a sliding car in the mast track that the top of the sail is shackled to, which has horizintal pins. The pins are spring loaded & pop into holes drilled through the mast track at reefing points, locking the sail in place. When halyard is held tight the pins retract. No possibility of rope stretch, no stupid hook and the halyard can stay internal!

#15 hobie17li

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Posted 27 December 2009 - 03:36 PM

hi, when i sailed my tremolino, with older hobie 16rig,
the sail had reef points and the wire halyard had an-
other slug crimped on for masthead halyard lock. i
think i set up stuff on mast and boom like in harken
diagrams, used two line system. you want to be able
to put a lot of down haul on, multi part and also pull
towards mast as clew reef line will be pulling away,
and you don't want to pull sail out of luff groove..doug

#16 pacice

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Posted 05 January 2010 - 05:03 AM

Reefing is only good if you are looking at reducing or increasing sail area while at sea.

I would suggest re-cutting on of your older sails to be flatter. I would also remove area from up high, so you will end up with a more triangle shaped sail.

I have a NACRA F17, and race against Hobie 16's. my sail has a mini square top, where the hobies are pin tops. The Hobies seem to be able to carry their sail into a higher wind range.

#17 Scarecrow

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Posted 05 January 2010 - 05:17 AM

Assuming you're going to be doing the reefing on the beach just make a removable strop the length you want to reef and a car at the head board. Or... Fit a second halyard hook at the hounds. If you fasten it with rivnuts/nutserts you can remove it when using the full sail. If there is a chance you'll want to reef screw it on and you're good to go. Then add the zipper panel for tidying up the reefed sail, a wear patch to protect from the hook when not reefed and the two extra holes (reefed tack and clew) and you're good to go.

Also you can get away with a thinner halyard it won't come out of the track when the sail is in it.

#18 tonyquoll

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Posted 05 January 2010 - 07:09 AM

G'day
Thanks for the advice. :)
Due to class rules requiring 7 battens, but allowing reef points, I'm going with reefing rather than re-cutting. On Paper Tigers, the mast is very light and flexible, so it's possible to flatten a sail out without having it specially cut. I speak from experience about needing a 6mm rope, as 4mm came out of the mast track & flapped around.
For most sailors no modification is required, as racing is cancelled in strong winds and they're heavy enough to cope. For me reduced sail area ought to be more efficient and improve performance above 15 knots. If the reefing system were adjustable on the water, it would add to the advantage as I could adapt to changing winds.
While up the coast last weekend I dropped by a chandlery and sought their advice and parts.

Here's the plan:
- remove 1.4m of bolt rope at the tack and fit 5 sail slugs, to allow the sail to fold as it is lowered (mast track left continuous; sail feeds in at the mast's foot)
- install a series of eyelets to luff & leech, corresponding to the sail slugs, and weave the reefing rope through so that the sail is zig-zag folded as it comes down (Dutch reefing)
- install the reefing rope so that it starts at the gooseneck, goes up the luff, back down into the boom, through the boom to a block on the outhaul car, up the leech, back down through another block on the outhaul car to the end of the boom, through another block then to a cleat near the gooseneck (single line reefing)
- stick with the 6mm halyard and lock it with a cam-cleat on the base of the mast. If stretching adn effort proves an issue, then a block will be fitted to the top of the sail (halving load on the halyard) and the rope replaced with 6mm spectra (reducing stretch)
- the existing downhaul sysetm is retained, which is 6:1 and pulls down the entire boom on a sliding gooseneck
- the existing outhaul system is retained, which uses a 4:1 system and car inside the boom

A diagram would probably help, attached image shows how it will probably end up like. :blink:

Complications are I also need to replace a driveshaft in the car, coupling and suspension bushes on the trailer, rudder pintles and some damage repair to the boat, I'm working full-time and the State Titles are in 2 1/2 weeks.
GO GO GO!!!
Once the reefing system is installed and working I'll post some photos.

cheers & thanks again
tonyquoll@yahoo.com

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#19 tonyquoll

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Posted 06 May 2013 - 06:24 AM

Update:

Since writing the above in 2009, I never got around to making a reefed sial, but have learned a few more relevant things:

- it is possible to gain weight; even us perpetual skinny fellas. I like this book by Michael Blackburn, as he recognises the importance of body weight in sailing performance, and provides methods for altering it: http://www.amazon.co...k/dp/B004APA4HK

- by increasing my mass from 57kg to 62kg, the 10% increase has made a HUGE difference in my ability to handle strong winds. I feel much more in control, and can generate more drive going to windwards. Clearly guys who are 75kg still can generate much more power, particularly driving through chop in strong winds.

- reduced vang/kicker allows the sail to twist and de-power more effectively. Especially downwind, this is critical to preventing cartwheels. I can now sail downwind in breeze over 30knots without cartwheeling, by running at a broad-reach angle with the vang loose. In gusts, rounding up a bit allows the sail to fully de-power. In lulls bear off a bit to gain progress downwind. Oh, and sit all the way back; behind the rear beam!

- talking to people who have tried smaller or reefed sails on these small cats, there is a net loss in performance. While it's true that a smaller sail is more effecient than an over-powered large sail, the large sail provides substantially more speed offwind and overall gets around the course faster.

 

In a recent example, we sailed in 20-35knot winds during races 5 & 6 of the Paper Tiger Internationals at Muritai (Wellington harbour, NZ). I was relatively slow getting upwind, but gain places on the reaches and runs. Out of 50 boats, I think there was only 1 skipper who weighed less than me, but I managed to finished 35th, then 25th.

A large reason for moving up to 25th was that others retired or cartwheeled, while I kept it upright. It also seems that in strong winds, everyone is overpowered so the difference in being light is less than in moderate winds, when I'm overpowered but everyone else is powered up.

While the lead boats finished a full windward leg ahead of me, I believe my poor technique in chop, some bad tacks and bad strategy made more difference than our difference in boat speed.

All good fun.



#20 BalticBandit

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Posted 07 May 2013 - 08:41 PM

I was going to suggest that on small boats reefing is not the thing to do. I'm not familiar with your class rules, but you also might consider changing rig tune settings for more wind.  For example more prebend in the mast will open the leech while flattening the sail AND moving the draft forward. Also contrary to the intuitive practice of using your more blown out sails if it is "fresh to frightening" actually pulling a brand new sail out of the bag for a championship race is the right thing to do, particularly if - as it appears - you are limited to dacron sails.  Because a new sail will be flatter than a blown out older sail.  And while you will turn your new sail into a more blown out older sail, you will have a lot more control of that sail. 

 

The other thing is that upwind, the longer you can sail without cleating the main, the faster you will go.  Because it means you can instantly ease in the puffs and bear off a touch to get speed and then pull back in and feather up above your normal close hauled line with that extra speed.



#21 Rohanoz

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Posted 08 May 2013 - 06:14 AM

Sorry BB - explain to me how more prebend moves the draft forward???



#22 BalticBandit

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Posted 08 May 2013 - 12:06 PM

Think of a triangle handkerchief.  lay it out with one side vertical.  Now stick a pin in each corner.  this is what a main looks like on a straight mast.  Now, mark some vertical stripes on it parallel to each other.  Last step.  grasp the cloth on the vertical side and pull it forward so that now there is a bend in the cloth.

 

Look at what happens to the lines you have drawn.  They necessarily all bend towards the front (mast).  IE cloth is being pulled forward.  Now if you have built in bias cut in that cloth that creates a particular point of draft, that cloth will be pulled "towards" the prebend.   that means both the depth of the Max draft and its location get pulled forward.

 

Its essentially the opposite of what happens to your draft as wind increases.  As wind increase - the leech gets more load on it and stretches... this is like pulling on the top of the triangle in the above example.  Cloth moves towards he leech, which means max draft moves aft.  Exactly what you don't want.  This is why "more backstay" not only opens the leech but also flattens the main and moves the draft forward.

 

And if you don't have a backstay (like this cat does not) - then the only way to do that is by pre-bending the rig at the dock.  On the 49er, the way we measured for various wind conditions was to measure low prebend by pulling the kite halyard to be touching the upper spreader protrusion, then just tangent to the mast and then measure the amount of inches that line is from he face of the mast at the gooseneck.  More low prebend for bigger wind. in <8 the mast was almost straight (this is the old masts) and then it went up in 1/2" increments for every 4 knots of breeze up to 1.5" of prebend.



#23 Rohanoz

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Posted 09 May 2013 - 12:24 AM

I think you may want to do a bit more research on this one mate...  got it a bit arse about.

You are forgetting that a sail is a three dimensional object by design, and that luff round and seam shape prebend will cause your handkerchief to do the exact opposite.

 

Here's a quick refresher for you.  Not a wonderful article, but the concepts are explained in layman's terms.

http://www.sailingwo.../bend-for-speed



#24 Oxygen Mask

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Posted 11 May 2013 - 03:29 AM

I was going to suggest that on small boats reefing is not the thing to do.

I disagree.  When overpowered reefing is nice. And it can save your friggin life!

 

Feel like I'm trying to re-invent the wheel. Surely yachts have these systems fully sorted.
 

Sure but larger boats aren't so weight conscious and often have more room to work and crew to help etc. LOTS of reef options, but most just won't work on your rig.

 

My Tremolino has a Hobie 16 rig and the first thing I did was make it reefable (and add a square top main.)  I took the simplest method and have never had a problem with it.

I HATED the halyard lock, at the dock it was a pain and on the water it was worse.

So I went with a 2:1 halyard (to help reduce the compression load) and a cleat at the mast base.

I then put in a single line reefing setup.  Unhook the downhaul, drop the halyard to the mark, pull reef line till the sail is tight to the boom, cleat it.

While sailing, tie up the sail.

 I have since went to individual short tack and clew reef lines. It's faster to pull each - two seconds each yank and cleat off - than to pull all the line in the single line setup, especially with the wind fighting you.  I put a cunningham hook on each one. When I need them, it takes seconds to reach up and hook them in, then unhook the downhaul, drop the halyard, yank the reef lines tight, and go.  Rehook the downhaul and tie up the sail on the fly if it's during the race.  Usually we don't even bother with the downhaul, after we're reefed it's not as important. But then we aren't a beachcat...

 

The zipper idea sounds cool, but I don't see how you're gonna get a zipper strong enough.

 

I just saw the original post was long ago....



#25 toddster

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Posted 11 May 2013 - 03:47 AM

<_< My (1970) H16 has factory reefing (With accompanying blown out old sail.)  But you can really only do it on the beach.  You have to decide how scared you are before a session.  Basically it has two slugs on the halyard and you use the first slug and tie up the reefing points on the boom.  Not much provision for outhaul tension.  



#26 cal40john

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Posted 11 May 2013 - 06:52 AM

<_< My (1970) H16 has factory reefing (With accompanying blown out old sail.)  But you can really only do it on the beach.  You have to decide how scared you are before a session.  Basically it has two slugs on the halyard and you use the first slug and tie up the reefing points on the boom.  Not much provision for outhaul tension.  

Attach the outhaul to the leech reef cringle.  Tie a loop of line around the boom through the cringle to hold it to the boom like a Laser.



#27 BalticBandit

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Posted 11 May 2013 - 09:29 AM

I think you may want to do a bit more research on this one mate...  got it a bit arse about.

You are forgetting that a sail is a three dimensional object by design, and that luff round and seam shape prebend will cause your handkerchief to do the exact opposite.

 

Here's a quick refresher for you.  Not a wonderful article, but the concepts are explained in layman's terms.

http://www.sailingwo.../bend-for-speed

R the article confirms what I'm saying, though it kinda confuses a couple of things.  Read the paragraph about backstay "pulling out shape".  All "shape" is, is extra cloth  displaced in the z dimension.  its true my handkerchief example was planar,  and intentionally so since the OP seems to be a bit green in understanding how masts and sail work.  Now its true that if you think of vertical profile, as the mast bends the distance between head and tack is reduced, so you get some increase in "depth" in the vertical profile. And where you see that take place is in the leach.  If you look up the leach profile the max impact is around midgirth, but because the chord is longer there than at the head, the percentage impact is lower and so you get what appears to be "more opening" at the top (also because unless you have a squarehead main with the associated batten structure the top of the sail has the least direct lateral support force on it from the boom).

 

 

But bottom line is that as you bend the mast PAST THE DESIGNED PRE-BEND (and on J-24s and J22s in the article that is set for roughly 10-12 knots), the center of the cloth starts to pull forward.  That's why I caveated my point about how we measured 49er pre-bend, because they now have new sails and new masts with a different design pre-bend and slightly different way of measuring it (forestay tension and lowers tension) but the end goal is the same:  as wind goes above the "fully powered" design range of the sail, you start adding pre-bend to flatten the sail.

Now in the J-24 there is an oddity that isn't at first obvious.  You add pre-bend up to about 17 knots, and then you start taking it back out.  But the reason for this is so that you can get more range of travel out of the backstay and thus increase forestay tension.  Essentially your net "bend" in the mast ends up the same, the difference though is that you apply more of it with the backstay and thus you tighten up the forestay. 

 

So all  the controls you have for shaping the sail via bendy rig have lots of interplay, but the core model is still the 3pin handkerchief.



#28 BalticBandit

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Posted 11 May 2013 - 09:35 AM

<_< My (1970) H16 has factory reefing (With accompanying blown out old sail.)  But you can really only do it on the beach.  You have to decide how scared you are before a session.  Basically it has two slugs on the halyard and you use the first slug and tie up the reefing points on the boom.  Not much provision for outhaul tension.  

Right, there various beech cats I've rented are similar  But none of the Hobie 18s that race have that.  I made the mistake of reefing my J-24 once some 22 years ago.  And the mismatch between the luff curve and the main and the subsequent reduction in the effect of the backstay made it not worth doing.  Whether or not reefing works has a lot to do with how the sail and mast are designed to work together.  So OM's approach may work, but its rare on small boats.  and if it is blowing hard enough that you need a reef to literally survive on a dinghy/beach cat, you are probably better off dousing and running on bare poles on a broad reach.   

That said, OP is talking about optimizing for racing since he is lighter than average. And assuming the class allows custom sails, (which it looks like it does ie its not an SMOD) he would be better off getting his existing sail recut to be flatter (ie less power) and simply starting to power it up sooner for the light air.



#29 TornadoCAN99

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Posted 23 May 2013 - 09:45 PM

OP should read Rick White's book on basic cat tuning..."Catamaran Racing for the '90s" I think is the most recent edition. It has good explanations of the soft-rig & pre-bend rig systems...which are quite different in how they are tuned. I'm pretty sure Paper Tiger's still use the classic soft-rigs, so power reduction is more limited.

Never liked concept of reefing a beach cat, esp for racing boats. The upper halyard sheaves on these masts are not designed to take the loading from a powered up sail...the hook takes the load. A halyard cleat at mast base causes a 2x compression load on the mast compared to normal mode.



#30 zerothehero

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Posted 28 May 2013 - 07:08 PM

Older topic here but whatever.  There are a few people over at Watertribe that have successfully developed reef setups for a bunch of small cats.  H18's. H16's, Prindles.  It can be done.  However realize that once reefed you aren't going to get the same sail shape.  The sail and mast are no longer matched up for using prebend to take volume out of the sail.  It works though.  Here is a vid of a H16 in this years race.  At one point you can dee the reef as they launch.  Sorry there isn't more detail, not my video.  Plus it just a funny video.

 



#31 dacarls

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Posted 28 May 2013 - 08:04 PM

Get the book - that's not a flat sail!

YAH-That is called a full sail, NOT even close to a flattened sail. If you cannot downhaul this one better than that, you can't downhaul a smaller one either.

Seriously, dude, we put 16:1 or 12:1 downhaul on high performance cat sails.

I was at the Cape Canaveral Regatta last weekend and was surprised/happy to see a 6:1 downhaul on - the Hobie16s!  Just 30 years overdue.

They never reef.

There is no reefing in beach cat sailing.






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