Going by a few search box questions, here are a few ideas for rigging the Mirror dinghy, or indeed most light sailing boats.
The outhaul and the downhaul are terms we often come across. There is no ambiguity about the term outhaul, which can only mean one thing, but the term downhaul can be taken to mean what most of us sailors call the cunningham which tightens the luff of the mainsail or the boom vang. These three devices are used to trim the sail to get it into the most efficient aerodynamic shape for the point of sail.
For convenience, I will call the boom vang the downhaul, the pulley tackle used to prevent the boom rising as the sail fills with wind as the boat sails downwind. The device for tightening the luff of the sail is the cunningham.
Generally, the outhaul is loosened for light weather conditions, and tightened to de-power the sail as the wind rises. The foot of the sail should never be further from the centre of the boom than the span of one hand, about seven inches.
The downhaul is loosened for light weather conditions or for sailing downwind. It is tightened for beating and close reaching. It tightens the leech of the sail to enhance the sail’s aerodynamic properties.
The cunningham, when tightened, moves the centre of effort of the sail from the luff to the centre. Instead of pushing the boat, the wind creates a Bernoulli effect and the boat is drawn forwards, making upwind sailing (outside the windward angle of 80-90°) possible.
Using these three devices, the sailor trims or adjusts his sails to get the best out his boat. This is what they teach us at sailing school. On a dinghy, you feel whether everything is right, with a glance at the sails to check.
Many older boats do not allow for adjustment of the outhaul. The clew of the sail is simply tied to the end of the boom. Similarly, the cunningham is fixed, and the sail will not set properly for upwind or downwind sailing. Looking at some classified ads for the Zef dinghy, I noticed that the early ones had no downhaul either, relying only on the mainsheet to control the rising of the boom, even when running downwind.
Not being able to trim the sails seems to me like driving a car with no gears, just one ratio for getting the vehicle to move from a standstill up to running at top speed! A boat is trimmed not only by setting the mainsail, but also by using the jib for increased weather helm or lee helm. A dinghy’s ballast is the body of the sailor who sits on the gunwale and moves fore and aft depending on his point of sail. A bigger boat has a fixed ballast, as low as possible on the bottom edge of a generously-sized long keel. We constantly trim the boat by the rudder, the trim of the sails and where we sit.
So, I would say that all boats need to have these devices for trimming the mainsail. It suffices to learn how to use them. There are many inventions of easy-to-sail boats, but they don’t appeal to me. I like everything the old-fashioned way, and especially the traditional gaff rig. My kind of boat doesn’t win regattas, though I have to say that my little yellow gaffer with the red sails was not that far behind the Lasers and Europe Moths a couple of Saturdays ago. I prefer cruising and exploring to racing around the three buoys!
Another precise question was the form the outhaul would take. The simplest is a pulley at the end of the boom and a piece of rope cleated somewhere along the boom. My own system is the pulley at the end of the boom, a pulley about two-thirds along the outhaul rope, and the longest part running through a pulley attached to the mast, back to the pulley on the rope, back to a second pulley on the mast, and then to a cleat on the foredeck at the base of the mast. The three pulleys reduce the effort needed to haul out the sail’s clew. I can thus control the outhaul even when the boom is far out for running before the wind.
All my ropes are within easy reach – the downhaul, the cunningham and the outhaul – just afore of the centreboard. It is the Laser system I was taught with at the Glénans. This arrangement is so convenient, like leading all ropes back to the cockpit in a yacht, so that the skipper can reef (shorten) his sails when the sea gets big and the wind really starts to blow. It is a question both of convenience and safety.
See this useful presentation to get you to understand the principle of setting your sail, especially from the point of view of the outhaul (and backstay on a yacht).
Also see my older posts on rigging:
Also see this video by a very friendly-looking Australian on single-line reefing. I have installed this system on my boat, and it works.