A few years ago I was asked to quote on a headsail. It was a big boat, the mast was forty meters tall and unusually the sail used hanks in the classic manner. Excitedly I researched the subject and with confidence arrived aboard to present my project. The owner immediately informed me that he never went forward when sailing and that he employed crew to handle the sails.
Most of my customers today have one or more furling systems. To try to answer the question about suitable headsail size, let’s apply a logical format and presume that you don’t have paid hands and that the crew you have you love and respect.
Initially, I would like to consider fairly modern cruising boats. Many can carry genoas of 150% but smaller sails are common in the Caribbean. As a rule I think that there are two checks to be made aboard. Firstly, how does the boat balance? If the conditions are good, go on the wind, sheet in, and establish a small heel and get an idea of how much helm you have. The boat should try to luff but hopefully you are not fighting it with the boat’s rudder, which will apply the brakes. Take a good look at the headsail and record its shape.
Next, look up at the spreaders. Do they, or with sail size changes are they likely to, interfere with the leech of the sail?
A sail maker will generally take rig measurements to ensure the sails fit with the rig but it’s good to have your own idea on things. There are shapes and sizes that just don’t fit.
One needs to keep in mind that a new sail should perform better than an old one. With time tapes shrink, this can have a radical affect on sail performance. The simple procedure of removing the tape then sewing it back on will often return the sail close to its original flying shape. Leech tapes shrink as well increasing hook. This can be made much worse if poor repairs are made, adding tapes and UV cover upon old.
If you are happy with the sail and especially if you have in line spreaders then fine tune. If you’re a pure cruising person then don’t make the clew too low. It makes the sheeting angle critical and you loose visibility. Check the helm. Check the fit. Old sails can be used as a guideline but be careful, they must be truly stretched out if measured.
If you have sweptback spreaders then you do have another option. You may have sheeting issues but you can consider non-overlapping battened sails. The battens can be used to reduce leech hollow or add positive roach. To windward a well built blade has a clean exit and will twist easily. Off the wind, it may normally require a Barber hauler. Typically such battens are vertical. They are generally tapered and front loaded, and that can be confusing. Keep the taper towards the luff. The sail must be furled with the batten on the inside of the furl so as not to rip off the pocket. The sail needs to be overbuilt a little. If the sail flogs then the inertia of the batten can cause damage. Longer battens are probably better once installed but in a breeze can be extremely difficult to handle on the foredeck. The sail, when hoisting, has a greater tendency to pull backwards and out of the head furl grove. If possible motor backwards in a sheltered bay to reduce apparent wind while hoisting. This can really help.
New roller battens by C Tech from New Zealand appear to be a practical alternative.
In light airs one has to ease and lean on the sail longer than one thinks and to keep things working at the lower end of the range requires concentration and technique. Maybe to compensate one has to accept to motor a little more or consider the addition of a code sail of some kind. When the wind picks up these big blades are powerful through the waves and with all headsails a good rope luff should maintain reasonable sail shape when partially furled.
One thing is certain, try to own your choice. Understand its advantages and disadvantages. When that squall does hit you after the sun has set and you’re wet and hungry, the sail maker may well be in the comfort of his home and you may wish you had ‘paid crew’.