photos are linked for size

Tappered 15'8" out of a 48 foot mainsheet.
http://www.wildergfx.com/temp/mainsheet/DSC02092.JPG

Some may say, I went crazy and tappered too much, but I am sure I will be fine. I will test drive it this weekend. My boom does NOT sit too low to the trampoline, plus the core is thick enough where the cleat will hold it with no issues. I was seriously tempted to pull the entire outer shell off, but I did not. What I did was, I sewed where I wanted the taper to finish, I made sure the cover, was sewned tight to the core, then I cut the outer shell, and the left the core exposed.

Another reason I tappered so much was, I am upgrading to a 7:1 purchase mainsheet so this line will be a spare soon enough. If anyone has a spare lower block for a 7:1 purchase, I am interested.

I also replaced the top Ronstan block with a Harken 2605 carbo airblock.
http://www.wildergfx.com/temp/mainsheet/DSC02093.JPG

The Harken block is SO MUCH LIGHTER. Now I need the bottom block (Harken 2620) in order to match the top block. If anyone has the block I need PM me. I will also have the ronstan hardware if anyone is interested.
http://www.wildergfx.com/temp/mainsheet/DSC02094.JPG

Here is the mainsheet sheeved and put together. NOT TOO SHABBY if you ask me.
http://www.wildergfx.com/temp/mainsheet/DSC02095.JPG

Well, if we're comparing mainsheets Robi.....


Here's a pic of my 7:1 off the Stealth. The system is set up so that I can't quite get it block-to-block (but very nearly) So the taper is only 5ft. It's made up the old way - two separate lines. The handheld part is 8mm braidline with a dyneema core. The taper is 4mm dyneema. The overlap of 4mm inside the 8mm outer is about 18".

I started by exposing 18" of core which I then cut off. I then sewed the new thinner piece of dyneema to the core. This joint was then tightly whipped over about 1" either side of the join.
The outer cover was then pulled back over the join effectively burying it 18" inside the sheet. I then sewed through the sheet over the length of the overlap, and finally stripped back some braids from the outer to form a 'smooth' transition from 8mm down to 4mm. This part of the taper was again whipped to make the taper fairly even and I finshed it with a tightly wrapped piece of tape.

It's been in use on the boat since I got it in March and we've been out in quite a few blows since. It runs beautifully and having unwrapped and checked the taper a few times I am happy that it has not moved at all. You'll note that I have shortened the anchored end slightly and that is what is tied to the top shackle of the upper block as a temporary measure - I'll get round to cutting it sometime!

Blast! after pontificating about making sure pics were the right size to fit in a post without spoiling the page format I got it wrong..

I definitely set the pic size to fit ( I think it said 660x429 but it looks much bigger )

Don't waste money Robi ! Just grap or buy a small (series 30 I think) block, release one bolt that goes through the eyestrap (and cleat) from the becket. twist the eyestrap away a little, run the little block over the eyestrap and fix the bolt again. Now you can run the sheet through this small block and tie it off to the becket on the upper block. Presto ! A 7:1 system for the expense of no more than one small single block.

I upgraded my mainsheet like this in literally 10 minutes. (I spend about 6 minutes of this rerunning my sheet line to make it rub less against itself)

If you have a graving for Harken than go ahead an buy a new block. Otherwise save yourself a 100 to 150 bucks and upgrade your current system.

Wouter

Personally I like a bit of space between the blocks. It allows the lines to pass one another without rubbing against one another and the lines are less twisted (over the sheeves) causing extra drag. I also feel that when the blocks are too close together that the fine line part is to short to work well enough. The more the blocks are apart the more the join (taper) stays between two sheeves when sheeting allowing the turns over the other blocks to be done by the thin section . When the blocks are too close than even a small amount of sheeting pulls the thick part of the sheet over several sheeves. THAT is not efficient in my opinion. Pretty much one want thick in the hand, cleat and ratchet, but after that the thinner the better.

But then again my top block is NON-swiveling so for this I need more space between the blocks as well, otherwise the sheetline looks really funny !

Everything on the cheap on my boat ehhh !

I used quite some parts that I had lying around from my other boats. Saved me a bundle

Wouter

I plan on doing this, but I will keep my eyes pealed, specialy on E-Bay for the harken block. They are hard to find unless new. Harken is a lot lighter than ronstan, so eventually my entire hardware suite will get changed to harken.

Could someone explain the benefit(s) of a tapered mainsheet? Ideally, is the length of the taper so that the thick part is cleated or is it ok to cleat on the taper?

Thanks

The tapered part runs through the blocks, allowing them to run better. The smaller line moves faster through the blocks and the larger line is easier on the hands.

As Lance said, plus the sheet is lighter overall. Playing the main upwind is much easier with this system as it runs more easily.

You should aim to cleat on the non-tapered section. If you find yourself regularly cleating on the smaller section then your taper is too long or your strop is too long. Either way some adjustment is needed.
As I said earlier, my sheet is set up so that I can't quite get block-to-block and the thicker part of the sheet runs only through the ratchet and the cleat.

' have to disagree Wouter.

I want the overall amount of sheet on the boat as little as poss. THAT is efficient. To achieve it all you need is as long a strop as you can get away with on the boom and your system setup so that when sheeted hard for upwind, the blocks can't quite touch. OK, so you need to put a swivel on the top block - no real hassle there? and by using a tapered sheet, even if I could get the blocks to touch, the sheet feeds don't rub.

Finally, a properly constructed taper doesn't slow or hinder the movement of the blocks to any great extent - the sheaves are already designed to take the larger diameter line.

Simply put.

You can create higher leech tensions with less pull on the sheet line as the pully setup looses alot less force on bending the sheet around the sheeve. One great way to feel this to pull the two block apart and see how much force is needed to do that. Any mainsheet that uses a plain 8 mm sheet will require ALOT of force to pull the two blocks apart. When using a tapered sheet this force is MUCH less.

In lighte winds the sheet will continue to run smoothly because there is so little drag in the system, so improved control here.

The thin line are less likely to rub against one another when sheeting tight = again less loss of force in the system.

A small amount of weight savings.

By having a more efficient force creation often you can drop a purchase. Meaning go from 8:1 to 7:1. => cheaper blocks, less sheet line etc.

All in all there are only advantages, as long as the taper itself never passes the ratchet wheel.

This is one of those things that everybody should have on their catamarans.

Thanks for the replies. What is more common, using two lines or a single line like Robi did? If using two lines, do you notice the bump where the two lines are spliced together?

I think Robi's methode (single line) is more common. My methode is rather unique, but that is because I fiddled around with what I still had laying around (former cut-offs). Splicing two seperate lines to one another I think is the most difficult way to do it and probably the most weak version. But I also learned one thing and that is when you take care to work cleanly and pay attention to attaching it right (splicing or sewing) that it will as good as always hold. For example I sew my trap lines together and none have failed on me. Same for things like foot straps and such. Hell , a spinaker sail is glued together and stand force 6 winds just fine.

Besides what is the damage is the line fails and you will have to give is a second try ? Not much.

If you taper the join well enough than you won't notice the "bump" at all. There are various ways to make the taper. Cutting out strands at different locations is one of the more easier ways. Do a search on the net or look at how eyes are spliced, you can quickly learn alot there.

One tip I would give is to make the tapered section flexible. One can get a perfect taper but then the methode used make that section of the join rigid then you'll feel a bump just the same. So get as much taper as you can without making the join to rigid.

The rest is just giving it a try and iterate to the right contruction. Ohh and make a prototype using old lines helps as well. The second time the tapering goes much better.

Wouter

Forgive my if I might a take a different approach. I was looking at 4mm D12 line (which is pitless) and will run very smoothly through the blocks. Just where you want to grab it during sailing I would like to put in a conventional but souple 4 mm line as a filler. When you compress D12 line lengthwise its diameter increases to such an extent that you can peel it over the conventinal line easily. It also provides a smooth transition point where the thin line thickens. Byu pulling the D12 line it wil tighten itself over the filler.
Has anyone tried this before?