Yacht Sails A conventional bermudan rig for the average cruising boat requires the minimum of a mainsail and one headsail.
With a furling headsail, this is probably enough for most of the season.
However, it is always worth carrying a small second jib for safety, rather like carrying a second anchor, just in case the furling genoa tears.
Anyone cruising one weekend and racing the next may need more sails.
The furling headsail does not lend itself so well to racing because as it rolls up the sail tends to become fuller, which is not ideal when sailing to windward.
Several sizes of headsail would, therefore, be necessary.
The minimum wardrobe for occasional weekend racing is a mainsail, mediumweather genoa, a No.
2 and No.
3 genoa and a spinnaker of medium weight.
For cruising or racing offshore, a storm jib is essential, both to comply with the rules and for safety.
The movement in sailing today, however, is towards ease of handling.
As the conventional bermudan rig involves the expense of a large crew and a full wardrobe of sails to achieve maximum efficiency, new solutions have been sought.
Fully battened mainsails and in-mast mainsail furling systems, together with better cut roller reefing genoas are increasingly being specified.
These give a good account of themselves to windward as well as being controllable from the cockpit.
Other more unusual rigs include the Freedom style rig.
Here the mast is supported in the deck alone and is unstayed.
The sails can either have wraparound tuffs or more conventional bolt rope grooves or tacks.
The junk rig is also set on an unstayed mast, but differs in that the sail extends forward of the mast as well as aft and uses full length battens to support the sail itself.
When buying sails, beware of sales talk circulated by manufacturers.
Invest in strong, well constructed sails that may be expensive, but should remain in good shape for seven or eight years.
For cruising, choose a good-weight cloth in preference to plastic laminate which is more fragile.
How a boat sails A boat will not sail straight into the wind, but needs the sails to be full on one side or the other to make it move efficiently through the water.
The angle to the wind determines the sheeting position of the sails and which sails to set.
The ideal angle for the wind to strike a sail depends on its shape, the type of boat and the tautness of the rigging.
However, in all sailing vessels and on all points of sail, the sails need to be trimmed to keep the boat sailing at this optimum angle.
The strength of wind dictates the amount of sail area to be set.
The wind exerts a constant pressure of 4.
9 kg/sq m (1 lb/sq ft) in a 16 kn or Force 4 (29.
6 km/h) breeze.
However, if the wind speed increased to 35 kn or gale Force 8 (64.
8 km/h) the pressure rises to almost 24.
4 kg/sq m (5 lb/sq ft).
To keep the same amount of pressure on the boat in Force 8 as in Force 4, and so prevent the boat heeling excessively, the size of sail will have to be reduced.
Sails should be reduced equally to prevent the boat becoming unbalanced.
Too much main and not enough jib creates weather helm, which pushes the boat up into the wind because the centre of effort is too far back.
If there is too much headsail and not enough mainsail, the driving force is too far forward and the boat bears away from the wind.
The keel prevents the boat moving sideways when under sail.
It also provides stability as well as preventing most sideways slip.
Thus, since the boat cannot move sideways through the water, the resulting forces drive it forward.
The angle of heel is important to the speed of the craft.
An excessive angle of heel causes the boat to slow down, even though it may appear to be going faster.
It is, therefore, more efficient and more comfortable to keep the boat on a reasonably even keel.
The ballast on the bottom of the keel provides a righting lever counteracting the pressure of the wind on the sails, and prevents the boat sailing on its beam ends.