The perfect crew is always ready to sail when you want to sail, does the right thing at once without being told, never answers back and takes up no room in the boat. Since the prime function of the crew when sailing is to work the jib, we are therefore talking about a self-acting jib.

Almost all my cruising, some parts of which have been reported in the Bulletin, has been done under mainsail only. There are several advantages to the single-hander in using just one sail. With continued use, it becomes part of oneself, like a wing, not needing conscious management. This is particularly true when sailing on rivers when you may find yourself tacking twice a minute by the hour. Under these conditions a conventional jib is only a nuisance. Again, when sailing among real traffic, as opposed to other dinghies in the same race, the absence of the jib allows you to look out over the front end to see where you are going.

Several fast boats are designed for a single sail, and Ian Proctor has described how the Gull was given a jib only after the first owners had said it would be nice if the children could be given something to do. My Otter sails very well under its mainsail. I know because I have done hundreds of miles that way. Nonetheless, there are times in light airs when I have felt that another bit of Terylene up front to move some air round the back of the main would help to gain some mileage. I pondered on how to arrange a self-acting jib that would be compatible with the Otter, using the standard sail, and without any modification to the boat or sail so that the conventional jib arrangement or the self-acting version could be used at will.

I measured up to see if the jib could be used on a balanced boom, as is sometimes seen on yachts. In this case, the strong boom is tied to the fore-deck about one quarter back from the front end (of the boom). When the jib is hauled taut, independent of the forestay, it hinges about the nether cord. Because of the position of this cord under the boom, most of the hoisting tension goes into the luff rope of the jib, while the rest goes into the rear edge of the sail and holds it to the proper shape under the press of the wind.

The Otter jib is shackled right down to the bow fitting, and at first sight there is not enough room under the sail for a boom to be held by a cord long enough to allow the boom to gyrate freely. But lo!, when the luff of the jib is untied from the bow fitting and is drawn forward enough for the sail to be able to swing sideways clear of the mast, about six inches appear as if by magic below. See diagram. The rest is then easy.

The diagram shows what has to be achieved. For clarity, the forestay of the mast is not shown, but it is in its usual place and in effect the balanced jib hinges around it. On one tack — in my case the port tack — the sail will press against the forestay, whereas on the other tack it blows clear. As far as I can tell, it is equally effective on either tack.

There are as many ways of achieving the details of this as there are of killing the proverbial cat, and precise measurements will be of no avail here, because Otters are built with love and by eye, rather than coldly with a ruler, and the sailmaker expresses his individuality from sail to sail. In my own case, the jib boom is 54” long, and it was cut from a carefully selected piece of firewood which came to 1½” x ⅝” when planed. The 1½” dimension was tapered off aft of the tie point to relieve weight, and enough lead pipe (9 oz) was screwed to the front end — after melting and casting the lead into a nice shape — to achieve a balance.

My tie cord, of ⅝” pre-stretched Terylene, passes through an in-line hole in the boom, through the eye on the bow fitting that is also used for the forestay, and comes back to be tied to the port jib-sheet fairlead. In this way I can set the self-acting jib or remove it entirely from within the boat; and, at any time, letting go the jib halyard lets the jib fall onto the foredeck because it is set flying. (Note: The Otter does not have a foredeck, but I have a clip-on one for cruising. I do not use it for day sailing.)

The usual jib sheets are used, but they are shackled to the boom rather than to the sail. Jamming cleats are essential on the jib sheet fairleads. In use, it is the jib sheet on the helmsman’s side of the boat that controls the position of the jib boom. This is handy, especially if you have to let the jib fly at short notice.

This self-acting jib has worked beautifully during three seasons on the Thames. It draws at the same heading as the mainsail. Once the jib sheets are set for beating you can forget about the jib: it will always be doing just the right thing. It certainly accelerates the progress. Then it has other advantages. Off the wind it will goosewing itself because of the counterbalance, and one can run comfortably before a heavily gusting tail wind without the mainsail because the boomed, balanced jib acts as an inverted squaresail.

In conclusion, a word of caution. Moving the jib forward to make this self-acting arrangement will tend to decrease the amount of weather helm available to bring the boat safely head-to-wind in a blow. My own boat needs the plate to be right down to ensure weather helm.