Centre Mainsheet

[Michael]

I'm new to the 12 (foiling moth for the last 2 years).  I can't get my head round the idea if transom sheeting.  I buy the idea that a bridle at the back gets the main in the centre but would still want to lead the sheet along the boom and then down to a block aft of the thwart.  That leaves the problem of getting the tiller extension thrrough.  How about twin ectensions?  Help appreciated:-/

[andymck]

Michael
Unless you take it off the boom it will be a nightmare. Its not the tiller extension s that get in the way, its the fact that the crew needs to often be just where the centre main comes down to. Although the DCB has some control by from the rudder, so seems to not need as much crew movement fore and aft, the boat is still only 12 feet long, and as you will see from all the pics of Joe at the nationals, they are often well behind the thwart. Joe tried the centre main option and got rid. The other possible way of doing it is to lead it from the back along the floor, I think Rich Perkins tried this. There may be too much in the way given rudder control in a DCB.
I agonised over this when returning to twelve sailing, and decided that re learning the rear mainsheet was by far the best option.

Andy

[Antony (Guest)]

Michael,
Having sailed 12s for 20 years and had a bad back for 15 I have often considered trying a centre main.  I am convinced my 12 would have gone slower, and so never did. 
If I have another new boat one day I will seriously consider doing what Rick did, leading it all the way forward along the boom, down the back of the mast, aft along the floor and then up from the floor to come out at the aft edge of the thwart (I think).  It needs lots of good ball-bearing blocks but both Rick and an old friend in a Fireball seemed to make it work. The new issue that arises is obviously leading it around all the other control lines. It seems to have all the positives of a centre main system and only the small issue of friction.  There must be some occassions when it is in the way of the crew, but many less than if it comes off the boom or in a normal way.  Perhaps Rick will drop in to this Forum to correct or add to the above....
People that have sailed with centre main in the past have either:
Ended up coming too far aft in the boat to tack, been told by their crew to get rid of it or taken it from the boom and found it very hard to sail upwind with the necessary downward pressure being exerted in light/medium wind and into a tack.
My solution was to stick with the aft main, and take up pilates.
Antony

[Phil Brown]

I've tried Antony's suggestion.
 Along the inside of the boom (in a tube to avoid friction and getting caught in the outhaul) down through the boom at the front through a thru deck block, down to the hog to a 40mm cheek block, along the side of the c/b case to an auto rachet block mounted on the aft end of the case.
A pretty good system. The sheet comes off the bottom of the boat and doesn't get in the crew or the tiller extension.
The BIG problem with it though is the twist that develops in the mainsheet. When the boom's let out, the sheet runs out quite loosely. However, when you sheet in, particularly in a blow when there's some weight in the sheet, the sheet doesn't rotate on the blocks and as the boom is brought in, the sheet gets a twist in the bit between the boom and the hog. That eventually builds up and ends up as a twist in the 2:1 at the back.
I persevered for most of this year with this system so it's had a good try. It's OK in light winds but it only lasts 1 race in any breeze before it gets too twisted at the back to run freely and you end up having to untie and remove the twists, a bit tricky sailing back to back races on a lumpy sea, trust me!
Next one to try is straight off the boom, skiff style, but the issue there is control of the leech tension, we'll give it a go though

[John Meadowcroft]

My advice would be try and get your head round transom sheeting.  If this does not work then plans B-K have probably been tried and rejected by many so you need "plan L"...
I have had a go - and the only problem i had was the crew - i changed it back.  my system was split end at the end of the boom along boom round block in middle to ratchet lashed to the back of the thwart.  Controlling leech tension is the key thing to do, and i think at times that it can be difficult.  People do, however, make it work, but the majority of the leading boats in the Class are transom sheeted and this either means they are too conservative or they know something!

[Michael]

Thanks all for your replies.  Sounds like many have tried and some are still trying.  I will probably come up to Northampton on Sunday and have a look at a few boats.  My boat wont be finished for another month at least so I have a bit of time.

[beans]

We have our main lead to half way along boom then take directly off the boom per the postings above.   Works fine for me, only draw back is that you lose benefit of centre jammer which can be useful sometimes to free up one hand.
My daughters have started to sail our 12 as well in the last few months and since they were used to a centre block on the thwart, I fitted one.  Mistake!   Boat is too short, or tiller extension was too long to get through the gap.  Also the crew has to move all over the shop in windy conditions and the centre ratchet block and the sheet was always getting in the way.
Gone back to taking it direct from the boom, works for me.

[darebarry]

I have sailed with a c/main for longer than most 12 sailors have been sailing, its not a problem. The boat will be at Northamton this weekend. 3521. The Ginger Pudding 

[GregPitt]

Crew issues were the problem for us. We looked at the system of going down the boom to the goosneck. this added loads of friction at the mast gate like mentioned in this thread. The solution we have now is tobring the mainsheet out of the boom half way between the aft end and the kicker then allow it to follow the line of the kicker to a big BB Block which can rock in all directions, the sheet then runs aft through the centreboard case and to a ratchet block and to hand. Finaly got it working really well, as long as you have some set strop lengths to match your mast rake you have really good control over your leach tension. We use a 6mm sheet tapered to 3.5 for turning all the corners!
 
Hope this helps!
 
Greg N3473  (FOR SALE)  Still have all fittings to convert back to aft sheeting!! 2 min job! 

[Michael]

Thanks Dare, I will have a look at your set-up on Sunday.  Michael

[Michael]

Thanks Greg.  Not quite sure what you mean by the strop.

[Jeremy C]

Michael,

I think that Gregg is talking about the Bridle at the back of the boat. You need to get this the right length so that when you have the leech tension correct you are holding the boom on the centre line. As you rake the mast back in strong winds it might be necessary to shorten the bridle.

Jeremy