George Morris's Mainsheet Mod, Findhorn Bay, Scotland

July 31st, 2018

I devote about 23 hrs a day to fiddling with the Weta mainsheet system in the hope of finding a geometry which feels comfortable. The latest iteration is described below. Before you collapse in a paroxym of hysterical laughter let me set out the drivers of this design.....

In winds which are too light to require you to sit on the rail you have to sit on the cockpit sides. In every other boat you have ever sailed the mainsheet comes down from the boom about half way along, goes through a swivel jammer in the middle of the boat and comes to rest in your front hand. The tiller is in your back hand and to steer, tack or whatever you push it across the cockpit.

So: to achieve this standard and desirable layout I have split the mainsheet using a Laser-style strop, although the mainsheet is attached to the centre of the strop and does not run to the corner of the boat; it is thus not a traveller. One complication is that I use the Dotan rudder so the strop has to be slack enough to allow the up/ down movement of the tiller required to move the rudder up and down. This is achieved by routing the strop through a block on the floor attached to the existing mainsheet anchorage and then up to the existing jammer on the side deck. When coming ashore you simply pull the free end out of the jammer and enough slack runs through to allow operation of the tiller/rudder.

The strop is attached to two ring bolts drilled into the flange of the hull-deck join. But this is not new. What is new is that I have modified the mainsheet tackle to be double ended and continuous and led the tails forward along the side decks to a turning block near the jib jammers. A second turning block takes the tail back towards the forward beam where there is a mainsheet swivel jammer on each side attached to the reinforcing plate under the trampoline attachment point. Sitting in the cockpit, the jammer comes nicely to hand while the tiller is free to move unobstructed by the mainsheet. The devil is in the detail and it has been necessary to lengthen the tiller, hugely modify the mainsheet tackle and also modify the Selden swivel jammers. But it works. Yes, there is a lot of string running across the forward end of the cockpit but all sheets are continuous and cannot tangle (it says here).

When sailing in boisterous conditions, sitting on the rail, the mainsheet jammer is just below your knee - within easy reach. When sheeting in there is a certain amount of friction but it is not difficult to use two hands if necessary. Releasing a foot of mainsheet in a gust is easy. You do sometimes find yourself sitting on the return line but that is true of the screacher sheets as well.

For additional usability I have put two more ring bolts nearer the transom. When using my oversize square top mainsail I simply unclip the whole strop from the forward ring bolt and move it to the rear position. A quick release system using fast pins allows me to rake the mast forward to compensate. Time to change rigs? Less than a minute.


Above: View showing one of the two mainsheet jammers, the strop and the mainsheet tackle.


Above: The strop and the mainsheet tackle. Note that the arc of the tiller clears the strop provided the extension is articulated to 90 degrees.


Above: The cats' cradle. Pull the blue string for mainsheet, black and white fleck for jib and red for screacher.


Above: View showing the attachment point of the combined strop and mainsheet. Note that there is a second set of ring bolts at the transom for use with the 'monster main'


Above: For interest only, not part of the mainsheet system – this is my instant shroud length adjuster in the short (ie mast raked back) position. When the monster main is to be used, remove the fast pin, reverse the shroud adjuster and replace fast pin at the other end. Take up rig tension using the 2:1 furling jib halyard tensioned with the downhaul until the slider on the mast engages.


Drill two holes in the deck flange and insert eyebolts at positions A and B. 

Run a strop from eyebolt B to A and then through a block on the floor at the existing mainsheet attachment point and then up to the existing jam cleat. 

Attach the mainsheet tackle to the mid point of this strop (it does not run so it is not a traveller as in the Laser). 

The mainsheet tackle (C) is modified to make it double ended. 

The mainsheet runs through a block on the end of the strop and then to a turning block (D) forward of the front beam in the vicinity of the jib jammer and then across the cockpit to a modified Selden mainsheet swivel jammer. The tail goes to the helmsman's hand and then in a continuous loop back down the other side. All components go through the existing reinforcement patches of existing fittings. 

This enables the helmsman to face forward at all times, with the mainsheet in the forward hand and the tiller in the rearward hand. When sitting inboard the swivel aligns with the natural direction of pull.

By George Morris

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