My traveller string seems to need replacing quite regularly - iam using 4mm excel - is there a better solution, that wont ware in the cleat quite so quickly?

yes it wears regularly.
One of the less expensive maintenance issues. Doesnt take long to change, the length is pretty critical.  Watch how you thread the strings.  Cost me several/many pounds to have pipes fixed under the thwart and Phil Scott a lot of cursing.

I found 4mm to thin and slips.

What boat is this on?

For some reason the newer Winder boats after about 3650 seem to eat traveller strings. They need 5mm and some are now using D12 which should last well, though possibly at the expense of the cleats in the long term!

Older Winders with the old style hoop seem to manage on 4mm.

Older Winders had the traveller car attached to shorter lengths of string with a block attached.  The "business end" of the control lines went through the blocks - one end secured through a hole in the central console with a knot and the other leading through the central console via a cleat and release system and thence to be attached to the traveller control line.  On the more modern Winders the line runs direct from the traveller car down through the console, cleat, etc. and there is more load on the line where it goes through the cleat.  (The 2:1 purchase appears in the system is out of sight under the console.)  This is probably the reason for greater wear on the control lines.

I keep a small stock of control lines - pre-cut to the correct length - so I can replace the worn ones as necessary.  The job only takes 5 minutes.

Is the excessive wear because the line is under tension when it is pulled out of the cleat?
Supprised that Chris M did not mention system on 3547  - but this might not work on all layouts.
Over to you Chris.

Barnsie put me right on this when I was having trouble on 3672 at the 2007 champs.  You need 5mm prestretched - it works fine with no slip but you do need to replace it every six months or so (if short tacking on a river probably more often).  You need 3 metres (1.5 metres each side).  As Mike Anslow says, keep spares!

I'd assumed this is on a Winder hull and the 3442/3547 system won't work without surgery because everything is hidden.

There are pictures of this on Richard Turner's boat in the rigging guide.

Its the latter winder system, with the 2:1 section under the console. Maybe i will use 5mm as suggested next time. Its interesting though, i wonder why the change in system.

Here's the simple version as seen on Richard Turners boat.

Only replace the string on mine every couple of years - now use blue plaited cheap stuff (sure there is a more technical name) for the stuff that goes through the cleat - this was a tip from the guy who used to do the rigging at P & B.  Have moved on to stainless rins for the release mechanism and now use 12 strand dynenma or vectran for this as you can splice so easily - only problem found with CM's patented method is that the ring managed to get itself on the other side of the cleat this year and was a b****** to sort out while sailing.

Yes mine has the 2:1 under the console.  I should have said use 5mm plaited prestretched.  Do not use a rope that has a core and an outer cover (ie Excel) as the cover will wear quickly, then part leaving you with the core intact which will slip and the worn cover can jam.  The prestretched just goes furry, and when it is too furry you change it!
I believe the newer boats have different cleats, mine are Servo which are hard on the rope but grip really well - but better to change the rope than try and change the cleats by using too hard a rope.

One of the reasons for the change was to reduce the wear on the cleats.  With the 2:1 above the console there was twice as much string going through the cleat, causing it to give out quite quickly.  As it now is, there is less wear on the cleat, but the string in the cleat is under higher load, so wears out quicker.  On balance I'd rather replace the string more often than faff with the cleat!

GGGGGgggg

In my experience it is the string coming out of the deck bushes that wears out the fastest. But that probably specific to me, as we (Natt & I) always sailed with the crew operating the traveller - even if the crew is staying to leeward, the angle through the bushes is quite extreme (90 degrees.

On Chambulls (Winder 3580) we changed to 2 to 1 under the thwart and also changed the cleats to Harken. We had no end of trouble with uncleating under pressure, we tried all different ropes, spacers, what ever. But we put in new servo cleats and restrung and now it works as smoothly as you could imagine.

I have broken and therefore replaced both the rope you pull and the traveller rope since I have had the boat ( 6 months) it just seems the load means this needs doing often!

Interesting set-up from CM and PJM.  I can feel a bimbling session coming on.  Looks nice and simple but like a lot of other Merlin systems depends on getting the string lengths just right.  Just to add my voice to the initial discussion, I've always just accepted traveller string is not going to last long and bought cheap 8-strand prestretched.  The advantage of replacing it before it breaks is you have the old bit for the length!  And anything with a cover and core is a liability as the cover bunches up and won't go through things while the core still holds so you can't even unthread it without cutting it out.  High tech rope seems complete overkill on this system to me, a bit of stretch probably helps.