Main sheet rigging

kloudie1 · Aug 21, 2010

H-34 Mainsheet

Don, this is what is on my 34.. not the original , the PO raced and had modified it.

Alan · Aug 21, 2010

Mainsheet

I never liked the mainsheet setup that came with the boat. It almost always required a winch and was never powerful enough to trim the sail in as the wind increased. I designed and built this setup which is really efficient and easy to use. Pulling both lines together for faster trimming yields a 5:1 advantage. Pulling just one line doubles the power to 10:1 for a very powerful trim.
You can rearrange the mainsheet setup on your boat to whatever suites your needs. I have found that the 'standard' setup is just not effective enough.

Roy Page · Aug 21, 2010

Here is a photo of my main sheet arrangement which is near original I believe.
The system works well and I have just installed a new main sheet.

Alan · Aug 22, 2010

Roy, that setup looks very like the original design. The problem with it is that the H34 has a large main and the boat has a tendency toward weather helm as the breeze increases. To counter this tendency the main needs to be trimmed in with as little draft and twist as possible. The stock design 3:1 mainsheet system is not powerful enough to be capable of doing this.
Claude, your setup is an improvement which increases purchase to 5:1 and makes trimming easier.
Likewise the traveler is under powered. The stock traveler is also a 3:1 system and you well know what kind of force is needed to get that thing up in a good breeze. My re-design increases that setup to 5:1 making traveler adjustment much more doable. Just some thoughts about this that you might want to consider.

Dan Johnson · Aug 22, 2010

Don...

my mainsheet set-up is the same as Roy's and is basically the stock set-up. I've changed out old blocks for Shaeffers and made the sheet run as smooth as possible. The block on the traveller has a becket that yields a 5:1 ratio.

The boom doesn't swing out as easily as I would like it for off-the-wind running. I'm contemplating a smaller diameter hi-tech sheet for next year--current one is 7/16ths Sta-Set that came with the boat and is now showing its age.

Alan, I don't understand this approach: "To counter this tendency the main needs to be trimmed in with as little draft and twist as possible." I drop the traveller to leeward as the wind builds to induce twist at the top of the main to spill off excessive wind pressure and reduce heeling. I also take up on the outhaul to flatten the main as well.

Alan · Aug 22, 2010

Dan the tendency I'm talking about is weather helm. To counter this the main will need to be de-powered. This is done by decreasing the draft in the lower third of the main with the outhaul and the upper part of the main by decreasing the twist. This is accomplished by trimming the vang and mainsheet. The traveler can be played up and down in the gusts as needed to control heel which in turn controls weather helm. Twisting off the top of the main is saved for occasions when the traveler is no longer able to do this. The next step would be a reef which starts out as a fully flattened sail again.
To make the mainsheet travel more smoothly and easily when eased on a reach the mainsheet blocks could be switched out for ball bearing blocks which have a huge reduction in friction over the standard axle & sheave. You are correct that downsizing the mainsheet will also reduce friction in the system.

Dan Johnson · Aug 23, 2010

Alan...

I understand the draft issue, but have always dropped the traveler to twist off the top of the main (make the angle of the sail surface closer to the apparent wind angle thereby reducing the pressure on it).

Once you've dropped the traveler to leeward (Twisting off the top of the main is saved for occasions when the traveler is no longer able to do this), how do you twist off the top of the main--that's the part I'm missing.

Maybe it's a matter of semantics.

Alan · Aug 23, 2010

Dan, I see the problem here. Dropping the traveler does not twist off the top of the main though you are doing the right thing. It's the terminology that is wrong. The traveler deals exclusively with angle of attack. When you say that you drop the traveler to twist off the top of the main you are doing the right thing but you're using the wrong words. Dropping the traveler does not twist off the top of the main, however it does stall the top which is the goal. Twisting is a control of the vang and mainsheet. Further de-powering the main after you have run out of traveler is accomplished by increasing twist by dumping vang and mainsheet. At this point the sail begins flogging which seriously damages it. At this point a reef is the next best option.

Roy Page · Aug 23, 2010

Alan,

You are going to need to spell that out again.

I have never found my main sheet set up a limiting factor when trying to flatten the main going to windward.

Having just fitted a new main, traveler and vang sheets I find that I can control the main sail shape very well.

I am really a dinghy racer [in the previous life] and find that my H34 sails pretty well on all points except dead down wind.

I have not felt that any of the main sail sheets need to be more powerful that stock 1983 Hunter.

What am I missing here ?

And another photo of Morning Mist

Roy

Alan · Aug 24, 2010

Roy, boat looks wonderful. I love the dark topsides. The 3:1 mainsheet is fine for a gentle breeze day but as the wind passes 10 to 12 the load on the sail increases dramatically making it necessary to always have to trim with a winch. Trying to do that by hand is just impossible. When in 'race mode' (which I am half the time) where time is all important trimming with a winch just takes too long. By using a gross/fine mainsheet setup these adjustments can be made quickly and easily without the need for a winch.

Dan Johnson · Aug 24, 2010

Alan...

yes, it appears we are both on the same track, hampered by semantics. After dropping the traveller and popping off the vang, if letting out more mainsheet creates flogging, then the first reef would go in. It's just a matter of sequential steps taken on a non-race sail.

However, at the first rumble of thunder I'm already thinking of reefing, and at the first sight of a squall line, the main comes down and gets bundled on the boom. The boat still sails in heavy air with a hanky of a jib and it doesn't make much sense to beat up the sails when cruising.

On the Chesapeake, when the sky clouds over grey and the air gets "heavy", you can bet there's a thunder-boomer lurking off to the West or Southwest. By the time it clears its throat the first time, you better be holed up or prepared for a blow.

Alan · Aug 24, 2010

I hear ya! ..same type of thing on the Sound. It too is notorious for mid summer squalls that can pack a punch.

walmsleyc · Aug 25, 2010

For my Legend 35, the stock main sheet system of 5:1 required super human strength to trim going upwind in anything more than 12kts. Given that these are mid boom systems, lots of power is needed to properly sheet in tight for upwind.

My system has a triple block on the boom, and a triple block with a becket and cleat on the traveler.

To help out, I added a single block to the becket, to allow me to run the sheet back up to the book, then forward to where the vang attaches, and then down to the mast base, through a deck organizer, back through a clutch right in front of a cabin top winch.

Now I can manual sheet with the existing main sheet cleat on the bottom triple block, and when I can't do that any more, I can crank the other end of the sheet with a winch. It is effectively a double ended system and lets me get it tight.

Dan Johnson · Aug 26, 2010

Don...

that mainsheet set-up is quite wrong. The block on the traveller needs to have a becket on it to tie off the sheet end to it. The center bail needs a block. The sheet is led from the becket up and over the center block, down to the traveller blocks upper sheeve, back to the aft block, back to the traveller block through the larger bottom sheeve, up to the forward block then along the boom to another block which turns it toward the deck block at the base of the mast, then over to the prot-side multi-sheeve organizer, and lastly back through the port-side tunnel to the sheet lock and winch on the port cabin top.

This is the conventional arrangement. See Roy Page's picture and imagine the line end that's knotted comes down from a block in the center and ties off on a becket at the top of the traveller block. I believe Claude showed a different set-up with a jam cleat at the base of the traveller block for more convenience when racing.

If need be, I'll try to remember to get a picture of my set-up when next down the boat.

Alan · Aug 27, 2010

Don, the setup that you and Roy are using is a 4:1 ratio. By adding another block and a becket Claude has increased his to 6:1. The setup on mine is a little different. I have a continuous line set up as a double 5:1. When pulling both sheets together I have a 5:1 system. When either sheet is pulled individually it doubles the ratio to 10:1.

The result is when you exert a 100lb pull on your mainsheet the boom is pulled down at 400lbs of force. When Claude exerts the same 100lb pull he gets a 600lb force. In my case I can get either a 500lb force or a 1,000lb force to pull the boom in. In anything up to 15kts of wind the lighter ratios will work well but in 20+ kts of wind a 400lb pull on your big main sail is just not enough to get it trimmed in properly. That's the reason I developed my gross/fine system.

Steve Dion · Aug 27, 2010

Don:

You can order one from Garhauer Marine. They have good prices.

www.garhauermarine.com

Main sheet rigging

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