I started out with the intention of sharing all there is to know about sails; but got snagged in the rigging. Literally!
A sail boat needs sails to move and these sails need to be held up with a mast and a boom. The mast in turn needs to be held in position by stays and shrouds.
In the old days the mast and boom were made of wood as was the rest of the ship. These days they are more commonly made of Aluminum alloy to make them light. In high end racing boats such as those used for America’s Cup or the Volvo Ocean Race they are made of Carbon Fibre which makes them even stronger and lighter. On Antara, we settled for Aluminum alloy, being the most economical and durable option.
Masts can be deck stepped or keel stepped depending on the part of the boat’s hull they sit on. Antara has a deck stepped mast placed on a mast step bolted to the deck. A solid teakwood kingpost connects the bottom of the mast step to the keel. This transfers considerable load from the mast to the keel instead of loading the deck, which isn’t designed to take on such a heavy load.
A keel stepped mast is considered a sturdier option but a deck stepped mast has its own advantages, the chief being the ease of stepping and unstepping it. We opted for the later as we have to unstep the mast every year to motor Antara to her monsoon berth at Divar Island under the low Mandovi bridges. Here’s her homeward journey for the Monsoons 2020.
Antara’s mast is around 15 meters tall and had to be shipped in two pieces from Cape Town, South Africa. The two pieces were bolted together at Aquarius Shipyard before finally being set up. The mast is hollow which reduces its weight considerably; and, also allows for the various ropes used for raising sails and the conduits for the wires of equipment fitted on the mast to be passed through it.
When you sail with us you will notice sheaves for passing ropes in and out of the mast, stoppers for holding these ropes in place and winches for pulling these ropes. These ropes are collectively called the running rigging with each having a name and specific purpose (more about this later). The running rigging provides a nice profile to our guests, Vikram and Aparajita, below:
The aft side of the mast has a track and a series of sliders for fitting the mainsail. Almost equidistant between the mast step and the mast top, there are two sets of horizontal spreaders. These ‘spread’ out the side stays which are connected from the mast top to the deck. In addition, we have diagonal stays between the mast and the spreaders too. The spreaders help in rigidity and strength to the mast.
The mast is held in place by a set of wire ropes or rods collectively referred to as standing rigging. These include the shrouds or various stays. The most commonly used rigging is wire rigging which what we use on Antara. This stainless steel wire rope is made by tightly winding together about 9 strands of stainless steel wire. One end of the wire rope is swaged into an end fitting for connecting to the mast while the other, lower end, is attached to a bottle screw to connect it to a chain plate on the hull. The bottle screw of the short stay is captured in the image below:
The bottle screw helps adjust the length and tension of the stay. A chain plate is a flat stainless steel plate, almost a foot long and over a 1 cm thick, bolted with half a dozen nuts and bolts to a strong point in the hull. Once the mast is placed vertically on the mast step, all the bottle screws are tightened and the stays tensioned. This firmly pulls the mast down and keeps it in place while distributing the considerable stresses on it throughout the boat’s hull all the way to the keel.
The stays are named after their locations. Thus the side stays pull the mast down from the sides, the forestay connected at the bow pulls it forward and down while the backstay connected at the transom pulls it aft and down. We also have a short stay and a baby stay between the forestay and the mast. The profile of Antara below shows her mast, side stays, diagonal stays and spreaders:
The horizontal spar connected to the mast is called the boom. The joint connecting the two is called the gooseneck and is designed in such a way that it can be moved in the horizontal as well as vertical plane. It’s clearly visible in the image above with our guests. Like the mast, the boom too is hollow to make it lighter and allow running rigging to go through. Since the boom can move in a horizontal plane one needs to be careful with it as it can knock a person off the boat if mishandled. Watch how carefully the Skipper treads.
That’s a lot to chew on! With the standing rigging set up, we can attach or in sailor speak, bend the sails to the mast; but after a well-deserved break. Watch out for that yarn in our next newsletter.
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