Fig. 29.
The tack is a most important rope in a balance-lug boat, for after the sail has been hoisted with the halyard and it is required to give that last haul on the sail which brings it to its proper tautness, a much smaller amount of power will do this when applied to the tack than if applied to the halyard. An efficient tack purchase is what is known as a watch tackle, which is represented in ([Fig. 12]. When after sailing awhile the ropes have stretched, and the sail is no longer flat, it is with this tackle, and not with the halyard, that one sets it up again. A balance lug requires more frequent setting up to preserve its flatness than any other sort of sail.
In a small dinghy, no purchase is needed for the halyards; the sail will lower more easily and quicker without one. The tabernacle also is unnecessary, as the mast can be easily unstepped.
The sail is kept close to the mast by an iron traveller; but if the sail be cut with a high peak it will be found that the traveller has a tendency to prevent the sail from lowering completely. A traveller is also liable to jam if the mast is not kept well greased.
On this account the iron traveller is dispensed with on most of the Upper Thames boats, and instead of it, a line is fastened to the yard, which passes round the mast and is rove through an eye on the yard. When the sail is up, this line is hauled taut, and prevents the yard from blowing away from the mast. This method will be understood by referring to ([Fig. 30].
Fig. 30.
A well-cut balance lug properly hoisted should be nearly as flat as a board. The fact of the tack being some way down the boom prevents the pressure of the wind from lifting the after-end of the boom and so forming a belly in the sail, as is the case with the ordinary fore-and-aft sail. A balance-lug sail is always rigid; the boom and yard can only move together, and this rigidity renders it somewhat unfit for rough water, where it is apt to considerably strain mast and boat.