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Center Sheeting

Posted By: rehmbo

Center Sheeting - 08/03/13 12:02 PM


I acquired a C2 late last year with center sheeting. Looks like the same setup as in this pic:

[Linked Image]
(is that you John?)

I'm still not sure if I like it or not.

Pluses:
- Sheeting angle for the crew is nice.
- 8:1 purchase is responsive in light and medium air
- Line management during tacks seems a bit easier.

Negatives:
- Difficult to uncleat in certain conditions - especially lighter air. I can probably blame several blown tacks on this.
- Seems like a lot of force on the center of the tramp - is this going to cause premature failure?
- Sheeting load in heavy air is pretty high. My 17yr old son who's in decent shape was dead after two races.

Noticed that this has not caught on - only the A-Cats seem to do center sheeting these days.

Replacing it with a more standard setup is going to kill my beer budget.

Let me know what you think.
Posted By: John Williams

Re: Center Sheeting - 08/03/13 04:11 PM

Hey Jeff - Yes, that's me and Dennis Key on a C2. I had the center sheeting on all three of my F18s. I loved it.

Mine was a 9:1 and I never used a cleat - just a Ronstan ratchet block. The first time I used it, I couldn't take my eyes off the tramp. But in practice, I never had any pucker, stretch, wear or damage there, so I just quit worrying. The tramp for center sheeting should be reinforced at the point where the block attaches. AHPC uses fabric straps, but I've seen a Nacra with an eye-strap on a backing plate sewn in, too. I had my first tramp worked on to add the reinforcement, and ordered the next two boats with the option.

I think it is fast. Without a cleat, I worked harder, but it made us faster as a result. It was still a lighter load than the kite - as you can see in that pic, we're double trapped and I could easily hold the sheet with one hand. Dennis never had to worry about the sheet in the tacks, and I was surprised that the block in the center of the tramp never really felt like the obstacle I thought it would be.

You need consistent crew if you're going to use this setup, I think. Managing the main in a tack is a new skill for some crews, and teams will need a couple of tacks to sort out the timing.

If I were buying another boat as crew, I wouldn't hesitate to add the option again. If I were a skipper and knew I didn't have steady crew, I'd probably not.

It was great to break the tension on the boat after a bad race - I could look at Dennis and say, "You had ONE job."

Here's the same setup on a Cap.
[Linked Image]
Posted By: rehmbo

Re: Center Sheeting - 08/05/13 01:23 AM

Thanks John. Indeed - I sail with a lot of green crew, so that probably explains my bad cleating habit. Fortunately, cleating from the trap is pretty much impossible, so at least we have that.

I'm going to have Collin (my primary crew) try some different ideas and look more closely at his sheeting technique.
Posted By: John Williams

Re: Center Sheeting - 08/05/13 03:06 AM

Goodall taught me a great main trim mantra: half as much, twice as often.

Good luck, and stick with it if you can. Once it is working, it is like beer flavored boobies.
Posted By: samc99us

Re: Center Sheeting - 08/05/13 02:06 PM

We have the stock 10:1 system on the Infusion. Unlikely to change it ($$), though I like 9:1 myself as it's less line than 10:1. For what it's worth we don't use the cleat either. Couldn't find a spot where it was easy to re-cleat and uncleat, so now it's in a spot where it's impossible to cleat going upwind but can be cleated coming in off the wire during a tack. That is how the pros do it anyway (we are NOT pros but we can try).

My question on the center sheet without a cleat:

1) How does the skipper cleat the main going downwind?
2) Is the traveler still tied/spliced to the end of the main sheet? It hard to tell in the photos.
3) Does the center block interfere with the spin sheets/crew in a wire-wire gybe?
Posted By: rehmbo

Re: Center Sheeting - 08/05/13 05:12 PM

I can answer #2 - yes, at least in my setup, its still tied to the traveler line.

For #1, I have a cleat, so obviously I use it. Good question if there's no cleat. I prefer to use the traveler downwind (especially when I'm overstood smirk ), so trying to manage the main sheet, traveler, and tiller ain't going to work too well. I have a hard enough time with just one of the three.

As for #3, we really haven't had conditions this year for wire-wire gybing. I'm a little-bit embarrassed to admit I hadn't really thought that one through yet. Not sure there'd be enough room behind the center block for both guys to cross at the same time. I assume crew would go first and there would have to be hand pass of the spin sheet around the front of the main sheet.

Let's see what JW says.
Posted By: samc99us

Re: Center Sheeting - 08/05/13 06:20 PM

Thanks Jeff. I assume your cleat is on the block in the middle of the boat?

I already crown my 125 lb, 5' 4" helm in the gybes, but part of the issue is the board location is pretty far aft. Maybe it isn't an issue. I like the idea of getting the mainsheet of the helms hands in the tack. That would make her job easier.
Posted By: rehmbo

Re: Center Sheeting - 08/05/13 07:08 PM

Yes. The cleat is attached to the block. Don't have the boat with me, but I'm pretty sure its a Ronstan RF56121. Its installed loop end to the tramp. Cleat angle is fairly high so you don't accidentally engage while your out on the wire.
Posted By: John Williams

Re: Center Sheeting - 08/05/13 11:55 PM

Hi Guys -

Jeff, do you have the Adventure Wines boat? That's the only one I know of that was ordered with center sheeting and a cleat. Hell of a coincidence if it isn't Ian and Paulo's old boat (USA 222). That thing is fast. Right-click and open in a new tab or window for more detail. HERE is the link to the first event that boat was raced. Ian raced with Bobby Kleinschmit, who has been working on ETNZ for the last couple of years. There are multiple high-res shots in that album that show the center sheeting clearly.

[Linked Image]

Obviously, because the standard center sheeting system has no cleat, the skipper hand-holds it on the run. As with the beat, not cleating forces the team to work the main much more often, which is faster. Squeezing the main in the puffs when you have the kite up is very effective. The main traveller is a gross adjustment and less effective in trimming. When we overstood the gate, Dennis would put the mainsheet in his tiller hand to keep our backstay, and drop the traveller with the other hand. It never looked like much of a headache from my perspective. I drove for a couple of years (2006-2008), and only infrequently since, and I don't recall ever having a problem dropping the traveller when needed.

AFA the traveller line, I have sometimes used a separate line (tied to the mainsheet), and Trey once made me a gorgeous, tapered mainsheet that was a split-tail on the end for the traveller. We liked that line best and used it up. We just had a figure-8 knot on the traveller side to keep the car from hitting the stops.

Finally, gybing: there's several different ways to run the spin sheets these days, most of which will not be a problem with the center sheeting Jeff pictured above. One of the recent (last two years?) setups that I tried and liked was the one where the spin sheet isn't spliced or tied together, but instead the ends are taken up on bungees run through the tramp. That method of rigging certainly wouldn't be in the way for the skipper or crew.

Posted By: rehmbo

Re: Center Sheeting - 08/06/13 03:37 PM

Interesting - all 3 C2s in the pic are using center sheeting. I appear to have the same stack as USA 70 - 4 on top, 4 on bottom, with a tie-off through the center of the bottom.

BTW - I can see the downwind sheet management a bit as you described in your pic here
[Linked Image]

As for the boat, you're close - mine is hull #224. Purchased from Dan K out of Omaha, NE. He did a nice job getting it dialed in for me smile it has proven to be really quick upwind. Still working to get my downwind technique perfected though.

You guys are obviously at a different level than I. I'm still well on the learning curve regarding the finer aspects of getting the best VMG out of the downwind run (but that's a whole 'nother thread).

Curious about the spin sheet takeup method you mentioned. Do they cross the tramp at a diagonal, diving under the aft part of the tramp? Which grommets do you use?
Posted By: samc99us

Re: Center Sheeting - 08/06/13 06:00 PM

Jeff,

I'll start another thread on the downwind VMG. We have work to do upwind in over 13kts of breeze and downwind in big waves.

Relevant to this thread, the cross the tramp spin sheet method I've seen on the Falcon and tried on the Infusion crosses the sheets on the tramp, in your case right in front of the center sheeting block. One corner goes to a grommet that is on the aft starboard side of the tramp and the other to a grommet on the aft port side of the tramp. I think on the Infusion these may be used to tie off the tramp to the boat, but I'm not using it for that purpose. From left to right, the shockchord gets tied to the starboard spin sheet on the port side of the boat, goes through the port side grommet, forward to a ring under the mast, then back aft to the starboard side grommet and then tied to the port spin sheet that is sitting on the starboard side of the boat.

I have since dumped this setup and gone back to tying the tails on my spin sheet together on the tramp with a single shock chord holding them. With the crossed setup above life was great while sailing upwind. It was not happy when we gybed, my feet ended up tangles in the spin sheet mess.
Posted By: Dan_Delave

Re: Center Sheeting - 10/21/13 05:05 PM

We use the crossed spinnaker sheet setup and like it a lot. It keeps the sheet on the boat better than if it were end to end. I did not like the sheets tied back to the boat with a bungee so had them loose on the boat. Now that they are crossed they do not fall off the side and I can always get to it around the weather mark so I can hand it to my crew without her (Eileen, the super crew) looking for it. If you do this I think it best to have the one on top from the port side to aid in the usual first mark rounding.

Later,
Dan
Posted By: bacho

Re: Center Sheeting - 05/05/14 10:37 AM

How far back from the front beam is the block in the tramp mounted?

I'm considering going to a center sheeting setup as I do all of the sheeting on our boat from the crew position.
Posted By: rehmbo

Re: Center Sheeting - 05/05/14 11:49 AM

Won't be able to measure until the 16th. Perhaps somebody else has this setup.

Basically, its pretty close to the middle. I don't think exact position is critically important as long as it matches up with the block on the middle of the boom. If you right click the pics on the 1st page of the thread and open in a new tab, you might be able to zoom in a bit more and get a good idea.

Will post an update when I set up for our first regatta on the 16th. Can't wait!!!
Posted By: samc99us

Re: Center Sheeting - 05/05/14 12:16 PM

Hey Jeff,

Would love some detailed measurements, location is critical IMO. Yours was in a good spot, easy to access for both helm and crew.

Likely to modify our next boat for center sheeting, though I have one question left. In bigger breeze when tacking, the helm takes the main and has complete control of the boat through the tack. This frees up the crew to quickly cross the boat, and most importantly ease the jib a little to prevent getting stuck in irons. As crew, I'm a little concerned I'll have too many lines in my hands with both main and jib to make a smooth crossing??
Posted By: Karl_Brogger

Re: Center Sheeting - 05/05/14 09:25 PM

I always thought the crew taking the sheet made the most sense. Allows the skipper to maintain good control of the rudders and not have to worry about passing a sheet behind yourself. Especially one that doesn't have a cleat on it.
Posted By: bacho

Re: Center Sheeting - 05/05/14 10:31 PM

Jeff, Are you using a stand up spring on the tramp? Do you notice any less freedom for the main to travel out while still being sheeted?

I have a spare 10:1 system I could use with this, that way I could switch back easily if I needed to.

I'm at a point now that I am replacing much shock cord under the tramp before the next event and it would be a great time to get the reinforcement installed.
Posted By: rehmbo

Re: Center Sheeting - 05/06/14 01:55 AM

Bacho - I don't have a stand up spring in my setup. 95% of the time the tension of the main sheet is enough to hold things up. However in super light air one might be helpful as I've had a few instances of the main getting cleated and was not able able to flick the sheet to release it.

Sam - I didn't have Collin messing with the jib during tacks (although I realize its a good idea for a bit more acceleration out of the tack). I had him manage the main sheet all the way through. Sheeting out as he came in off the wire and then slowly sheeting in as he went back out again.

Also, I have the tail tied in to my traveller which means clearing the sheet has to go behind the cleat on the tramp. I had a thought that separating them might be an interesting idea.
Posted By: samc99us

Re: Center Sheeting - 05/08/14 01:10 PM

Jeff,

Seem to recall your boat being OK in super light air but a little spring up would help for easing the sheet.

In the tacks, it is critical to ease the jib sheet about 2" in big air w/ waves, just about the same time you pop the main sheet. This relives the pressure the jib puts on the bows and lets you drive through the tack more easily. If you don't do this, it is easy to screw a tack. Part of the reason it's more important in breeze than any other time is the amount of sheet tension on the jib is ridiculously high to trim for proper upwind sailing.

In these conditions, I suspect it would be fastest for the helm to grab the main through the tack, still very possible with center sheeting. The traveler part was annoying if I recall correctly, forcing the main to still be passed around aft of the block. Maybe running the traveler to the helms trap wire would work, or a few other creative solutions.
Posted By: bacho

Re: Center Sheeting - 05/09/14 11:57 AM

I'm working on the thought of a traveler system that lead to the trap wire. Seems like it might be difficult to use downwind sitting on the boat.
Posted By: samc99us

Re: Center Sheeting - 05/09/14 02:28 PM

It was a random thought...I have other ideas, but none get the traveler to the crew on the wire upwind when you need it.
Posted By: bacho

Re: Center Sheeting - 05/09/14 07:24 PM

I like the idea of a continuous traveler line on the trap wire. If the cleats were 2'ish in from the end of the beam it may be pretty controllable from sitting on the deck.
Posted By: wildtsail7

Re: Center Sheeting - 05/10/14 10:08 PM

In the 5 seasons I've been racing f18s I've dropped the traveler once because of breeze. It's a complete last resort. I don't think it's worth spending the time to route to the traps.
Now distance racing it's dropped a bit more.
Posted By: bacho

Re: Center Sheeting - 05/11/14 10:58 AM

I want my skipper to have it available as peace of mind that she could dump it in an emergency. It seems that if it went directly to the trap that it could be a little cleaner during tacks.
Posted By: samc99us

Re: Center Sheeting - 05/12/14 02:29 PM

I agree with Todd it is a last ditch resort as far as upwind in breeze is concerned. We play it a bit more downhill, but then the skipper is on the boat. It would be good to hear from some Nacra 17 teams on what they are doing with the traveler downwind double wired.

Bach,

This isn't trivial...I threw it out there to get the minds thinking, but in my head it isn't possible. The crew is on the helms wire downwind and I don't want anything attached to that wire to trip me up in my already clumsy jibes (just ask Keki Figueroa). I also don't want the helm to get tripped up on the traveler in the tacks.

What's the verdict of center sheeting off the boom?
Posted By: bacho

Re: Center Sheeting - 05/12/14 03:33 PM

I got out my spare 10:1 and reeved it to make she the sheet I have for it will be long enough for center sheeting. I also marked out where I thought my blocks on tramp and boom should go. I don't know when I will get around to removing the tramp and making the mod but I'm guessing it will not be until the summer. My next race is a short distance race, I'm thinking I am going to use the tried and true system for that and then play with center sheeting around some buoys later in the summer.
Posted By: samc99us

Re: Center Sheeting - 05/12/14 06:00 PM

I wouldn't make a major change like this before an event...needs at least a weekend of practice me thinks.

I've been reading a few threads on here and elsewhere. Haven't found a great photo, but I'm thinking of running the terminated end of the sheet through another block on the bottom, to a turning block on the boom and forward to a head-banger style block sitting right on the boom that the crew can sheet from. The current lazy end of the sheet would stay rigged the way it normally is, for the helm downwind.

A few other notes:

1) AHPC uses a different style boom for mid or center sheeting (beefier), 50mm diameter x 1.6mm wall thickness. According to wouter anyway, so that data may be incorrect.

2) Some teams have an additional block to create a 2:1 floating purchase between the back of the boom and center of the boom. Your purchase is increased but you are limited in the amount of sheeting you can do from the mid point

3) Darren Bundock has a normal aft 10:1 purchase system on his C2 used at Catacup. Keep it simple stupid.
Posted By: rehmbo

Re: Center Sheeting - 05/12/14 07:30 PM

I'll have pics and measurements of my setup posted on Friday.

One other advantage I thought of was the more perpendicular pull of the sheet from the middle of the tramp would allow a better trapping/hiking angle. Its not just easier, but should also get your CG further out.
Posted By: samc99us

Re: Center Sheeting - 05/12/14 07:44 PM

Jeff,

Thanks Jeff! That's one of the bigger advantages I can see in breeze. I suspect more boats aren't rigged this way because the crew is variable. With my setup idea, it shouldn't matter too much, as the skipper can still drive it from the back like they do already.

-Sam
Posted By: rehmbo

Re: Center Sheeting - 05/17/14 10:36 AM

As promised here are the pics. Not saying this setup is right, wrong, or optimal. Simply what I got when I bought the boat. I assume it is representative of what AHPC was selling as an option at the time (circa 2010). I have higher resolution versions of the pics if needed.

Overview
[Linked Image]

Measurement from aft edge of front beam to center of main block eyestrap 42 ¼" = ~1.073m
[Linked Image]

Measurement from aft end of boom to turning block 50 ½" = ~1.283m (sorry for the parallax)
[Linked Image]

Measurement from fore end of boom to turning block 40 ¼" = ~1.022m Note that the turning block straps had apparently been moved foreword approx 3 ½" from their original location. PO never mentioned why.
[Linked Image]

Tramp reinforcement (viewed from under the tramp) No idea what the second grommet is for behind the main block.
[Linked Image]
Posted By: bacho

Re: Center Sheeting - 05/17/14 11:01 AM

Thanks Jeff,

That is a little farther back than I was imagining. If it was further forward to be equal with that block on the retrieval line, do you see it as a problem with running other things near the front of the boat?
Posted By: rehmbo

Re: Center Sheeting - 05/19/14 11:12 AM

If it were further forward, it might require the crew to cross behind it, crowding the back half of the tramp. Otherwise it shouldn't be an issue as long as the spin sheets are properly routed/managed.
Posted By: JACKFLASH

Re: Center Sheeting - 06/10/14 02:58 AM

Is there a reason you cant have a turning block and cleat on the boom versus having it on the tramp. I am thinking a turning block and cleat like we use on the spin halyard.
Posted By: Dazz

Re: Center Sheeting - 06/10/14 04:44 AM

you could potentially be pulling the boom over the windward side of the boat in light to medium weather.
Posted By: C2 Mike

Re: Center Sheeting - 06/18/14 05:27 AM

Originally Posted by Dazz
you could potentially be pulling the boom over the windward side of the boat in light to medium weather.


I think 49'ers and other boats have done it that way for ages
Posted By: Dazz

Re: Center Sheeting - 06/18/14 07:06 AM

true, but the 49'er has their main sheet setup with a V so that it can't be pulled to windward.

its probably wouldn't happen but still...
[Linked Image]
Posted By: bacho

Re: Center Sheeting - 09/16/14 10:32 AM

Jeff,

Got my tramp modded and ordering the blocks finally.

I have a 10:1 system that I was basically planning to run upside down with the cleat removed of course. Do you see a reason why I would need the additional single block at the rear of the boom?

Where is the ratchet in your system? My 10:1 stack is not equipped with one. debating on one on the boom or the tramp.
Posted By: Anonymous

Re: Center Sheeting - 09/16/14 09:42 PM

The single block aligns to the loads better cutting down wear and friction. You can get close to fixing the issue by locking the top block at 90 degrees to the boom and/or leaving the guides from the cleat in place as it will force the top block into alignment.
Posted By: Karl_Brogger

Re: Center Sheeting - 09/17/14 07:09 PM

You still want all of your purchase at the back of the boat don't you, and not pulling on the middle of the boom?
Posted By: rehmbo

Re: Center Sheeting - 09/18/14 01:10 AM

I have a Ronstan auto-ratchet RF56121 on the tramp. Its mounted upside down relative to the pic on the link here: http://www.ronstan.com/marine/product.asp?ProdNo=RF56121
Posted By: Anonymous

Re: Center Sheeting - 09/18/14 02:12 AM

If you mount the ratchet on the boom and a normal block on the tramp, you'll greatly reduce the static load on your tramp but it'll have minimal effect on the load you have to hold
Posted By: bacho

Re: Center Sheeting - 09/18/14 02:29 PM

That's the conclusion that I came to as well. That means I purchased the wrong parts.
Posted By: Anonymous

Re: Center Sheeting - 09/18/14 09:45 PM

why can't you just swap the blocks you bought for the boom and tramp?
Posted By: rehmbo

Re: Center Sheeting - 09/19/14 01:10 AM

From a durability standpoint, I don't think its a big deal either way - at least with the C2 tramp construction.

In fact - as I think about it, there might be a problem with having the ratchet up on the boom. The first portion of sheeting out/in will result in the tramp flexing up/down before the line starts to feed through the ratchet block on the boom.
Posted By: bacho

Re: Center Sheeting - 09/21/14 11:00 PM

Wound up putting it together this weekend with the help of some borrowed parts. I wound up with an auto rachet on the tramp and I am really liking it. I put my blocks 18" forward of the stock location, I decided I was too big to go between them and the mast.

I think I am at 11:1 total purchase and my hands are happy with that.
Posted By: rehmbo

Re: Center Sheeting - 10/30/14 03:35 PM

Bacho - Now that you've had this setup for a while, what do you think?
Posted By: bacho

Re: Center Sheeting - 11/03/14 05:32 AM

I like it in the breeze for sure. It's a major upgrade for our situation.

In a drifter, the system doesnt unload as freely as I would like. It's also a little messy up there with the spin sheets. If I know we won't be trapping, I may switch back to the traditional system for the day.

I have a tube made to contain the sheet running down the boom, haven't gotten around to installing it yet though.

I did find myself today yanking on the traveler side trying to sheet it. I guess it hasn't become second nature yet.
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