The principles The first principle is keep it simple! Use the minimum amount of rope you need, so you have less rope to pull and there is less rope to tangle. Where possible use the minimum purchase as this reduces the amount of rope needed and the minimum thickness as this reduces friction.
However before you even start to think about the lengths of rope, you must think which ropes you need. After all if you were going to walk around London you would want to make sure you were not trying to use a map of Paris.
For the sail controls you want to use rope with a minimum amount of stretch. Obviously if you use a stretchy rope then it would affect the lengths required but you definitely do not want to use a stretchy rope for the sail controls otherwise when a gust hits, the stretching of the rope would give you a fuller sail, which is the last thing you want.
Indeed the only place that you want a stretchy rope is on the rudder downhaul so the rudder is held tightly. If there is any slip the rudder does not come up as there is still plenty of rope tension holding it down. I would recommend a 3:1 system here.
The best ropes at the moment are Dyneema for stretch and I suggest using these on all the primary control lines (I also use this on the traveller but I have an outer hard wearing sleeve to protect it). However for the secondary line it is nice to have a softer rope which sits well in the cleats as well as being kinder to the sailor’s hands (not everyone wears gloves), so I use maffoli. Many people also use this as a mainsheet but I believe it is too soft for this and when not under tension it can tie itself in knots!
The primary lines are those which take the main load, whilst the secondary lines are those which go through the cleats and actually end up in the sailor’s hand.
When looking at the lengths it is important to have a good splice. A good splice to me is tapered (so there is no hard edge) with the splice length approximately ten times the thickness of the rope. Remember it will take a little while for the splice to bed in, so make the ropes around 2 cm shorter than you think and then re-measure them after a couple of hours sailing. Fingers crossed you will have got it spot on first time.
So to answer Leonardo’s specific questions.
Kicker For the kicker primary you want the secondary block very near to the primary block when the kicker is all the way off. Just ensure that the splice is not in the top block where the block is pinched as this will affect the smooth running of the rope. The primary needs to be 90 cm long.
For all the secondary lengths it depends on how you tie the handle. I like a nice big handle (so I can put my whole hand in it). If you can put only a couple of fingers in the handle then you are limited by the stretch of a couple of fingers. I also run a length of rope from the handle to attach to my centreboard, so if the handle slips to leeward I can still pull my kicker on. It is also worth noting many of the full time full rig sailors remove some of the secondary purchase but the majority of people don’t. The secondary needs to be 300 cm long.
Outhaul For the outhaul primary I have the system set up so the blocks on the primary just touch when you have the foot of the sail as tight as you are ever going to want it (the clew strap is as far along the boom as it can go). This minimises the amount of rope used. The primary needs to be 100 cm long.
Again for the outhaul secondary I make a generous handle, with the handle sitting firmly by the cleat when the outhaul is fully released. The secondary needs to be 300 cm long.
Downhaul The primary line needs to be slightly overlong so that you can comfortably tie it each time. In light winds I rig the downhaul both sides so as not to twist the sail. At 66 kgs I need to pull the downhaul on alongside the boom, so in around 16 knots plus I rig it down the port side meaning I can pull more on. This slightly twists the sail but it is more important to get enough on (I choose port side to have the advantage on starboard tack off the line and we usually go round marks to port). The primary needs to be 90 cm long.
The secondary length required varies depending on whether the primary is down one side or another. Indeed in light winds it is best to have a small amount of slack in the downhaul to make it really easy to get off. This is not necessary in strong winds, which means you have much more secondary rope. The way I get round this is to make a much larger handle (but not large enough to get your foot through – just in case) and I also leave a bit of a tail. The secondary line needs to be 300 cm long.
All the control lines may be ordered made to measure from: www.thenottinghillriggingco.com Mainsheet I am still testing mainsheets but I have used the Rooster Polite mainsheet for many years. There may be a better mainsheet out there but I haven’t found it yet. I use 13.5 metres. You can order it from www.roostersailing.com Video of me rigging a Laser www.youtube.com/watch?v=W70wB8JJH4E