BETTER BOOMS

Ian Nicolson

(Ian is a founder member of the OCC, having qualified back in 1952, and has long been Port Officer for the Clyde. He combines dual careers as a technical writer and a designer of yachts and all things related to them - see Reviews fora review of his latest book, Understanding Yacht Design - but frequently champions the principle that 'simplest is often best'.)

In a world a-whirl with clever electronics, we still have age-old problems. Gybing in a severe breeze is not something that can be smoothed over by a little black box full of micro-volts. Unwary heads in the cockpit are still vulnerable to a raging boom crashing across without giving due warning. It's a wonder the government has not brought in laws against chinese gybes. Those of us who live in the real world have to expect a little risk, so here are a couple of ideas to make life afloat safer and even more fun.

Figure 1 shows an improvement on the usual small cushion on the boom to protect crews' heads. This is a lengthy pad, extending down one side of the boom, across the bottom and up the other side. The length is the full standard cloth width of that bright orange pvc cloth used for winch weather-guards and vent covers by the RNLI.

An area of day-glo orange this size shows up well in thick weather, so it enhances the chances of being seen before being hit by a big brutal ship. The size also makes it a screaming warning to the crew as the boom starts to swing across in a gybe or tack.

The cloth is in two thicknesses, stitched together all round the edge and across the middle, with a layer of closed cell foam buoyancy about 6mm (¼") thick in the middle. At each corner, and at about 50cm (20") intervals round the sides, there are long lengths of thick, soft 12mm (½") wide terylene tapes.

The cloth is folded and secured to the boom with velcro straps at the ends and along the length, roughly every 50cm. This means that in a shrieking emergency the cloth can be whipped off the boom quickly.

It has a lot of secondary uses in addition to protecting heads when gybing:

• As a waterproof insulated cover in a dinghy or liferaft.

• As a temporary sail, for downwind progress in dinghy or liferaft. The internal padding will enable the sail to set downwind, after a fashion, without spars.

• As something large and highly visible for waving, to attract help in a crisis.

• As a rain catcher. Here the double thickness and the interior padding will minimise the support needed to form a trough.

• As a back-up or even a substitute for a lifebuoy or lifejacket. A 2m (6ft) length of this padded cloth has more buoyancy than a lifejacket or lifebuoy.

• As a fender, used single or double (or more) in thickness.

• As a marker float on a line extending down to the crown of an anchor. No one is going to pick up this cloth, as they sometimes do when a small fender is used to mark an anchor recovery line.

... and so on. It will even make a temporary cockpit cover to keep off the sun, rain or snow.

Figure 2 shows another safety gadget on the boom - a low-strength stretchy lashing on the top of the kicking strap (or vang as they say on the eastern side of the Atlantic). This has a dual purpose:

• In a stressful situation it stretches and reduces the shock loading.

• In the final count it breaks instead of the boom. The rope to use here is nylon and the size as well as the number of turns is given in the following rough guide:­

Approx mainsail Max. sensible Suggested rope Typical breaking

area tension load

20sq.m (220sq.ft) 1300kg (2900lbs) 4 turns 4mm (3/16") dia. 1280kg (2800lbs)

24sq.m (260sq.ft) 2000kg (4400lbs) 6 turns 4mm (3/16") dia. 1920kg (4200lbs)

30sq.m (330sq.ft) 3500kg (7700lbs) 4 turns 6mm (1/4") dia. 3000kg (6600lbs)

Note: This arrangement is designed so that the kicker top lashing should break before the boom does, assuming the boom is ruggedly made for deep-sea cruising. This means that rope failure must not come as a surprise in severe conditions. When it occurs the aft end of the boom will go skywards. Beware!

Figure 1 - This boom pad's main job is to stop the crew being bashed on the head. However it has a lot of other uses and it is cheap as well as easy to make.

Figure 2 - If a boom is going to break, the chances are it will be at the kicking strap fitting. Deliberately putting in a 'weak link' at the top of the kicker is a super-simple precaution.

(756 words)