Sailboat sheets and guys are ropes or lines that are used to trim a sail. Sheets are attached directly to the clew of most sails, the exception being the mainsail. Unless they are loose footed, main sheets are attached to a boom which is then attached to the clew. Guys are commonly used in conjunction with spinnaker poles and are attached to the tack of the sail. The demands on sailboat sheets and guys vary a great deal for different applications and types of sailing. Increased loads on bigger sails mean that diameter, construction and the fibre content all need to be considered when optimising for performance or cost. You will find more information on the types of rope available in ourRope Selection Guide

Feel free to use the filters to determine the size of line you require. There are filters for racing specification and cruising specification. Once you have chosen the size and type of your sheet, you can apply the rule of thumb below to calculate an approximate length required. 

Mainsheet, simple purchase - distance from the gooseneck to the mainsheet attachment on boom x number of lines (purchase) plus 1.5
e.g a mainsheet attached to the end of a boom 3 metres long with a 4:1 purchase would be approximately 3m x (4 + 1.5) = 16.5 metres
N.B. The swept back angle of the mast spreaders will limit the distance the boom can go out and therefore reduce the length of the mainsheet.
Don't forget to allow for a tail.

Mainsheet with dedicated winches - draw a plan of the arrangement for a rough guide.

Genoa Sheet - 1.5 x boat length
An inner forestay will increase the length required. The lazy sheet will need to go around this as well as the mast

Jib Sheet - 1.25 x boat length

Spinnaker Sheet or Guy - 2 x boat length
Code Zero or Gennaker Sheet - 2 x boat length

There is no better way to gather the correct length than to use an old line and measure it before ordering a new sheet
N.B. make sure that it is long enough for all points of sailing

If you need any further assistance, The Jimmy Green Marine Rigging Team can help you. We have a wide choice of ropes in both categories but it doesn't take long to get a quote. You can simply buy the rope cut to length or choose from a variety of Jimmy Green Professional finishes. We offer soft eye splice, hard eye splice, whippings and cover stripped eyes amongst many other options for use with a wide range of fittings.

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