Deck machinery and fittings — winches, capstans, windlasses

What the rule requires

Start with the machine in front of you, because most questions on this topic are decided by naming it correctly. The terms capstan and winch should not be confused: a winch has a horizontal shaft and a capstan has a vertical shaft NAVEDTRA 14104 Ch. 10 — Capstans. Shaft orientation is the test — not what the machine is hauling, and not where it sits on deck.

A capstan is a single head mounted on a vertical shaft with reduction gearing and a power source, electric or steam. Electric capstans are usually reversible and develop the same speed and power in either direction; ac-driven capstans run at full, one-half or one-third speed, while dc-driven capstans usually have three to five speeds in either direction.

Winches do the general hauling work: heaving in on mooring lines, hoisting boats, top lifts on jumbo booms, and cargo handling, powered usually by electricity and on some older ships by steam NAVEDTRA 14104 Ch. 10 — Winches. Normally a winch has one horizontally mounted drum and one or two gypsy heads, and the drum is connected to the shaft by a clutch. Electrohydraulic winches are always drum type: a constant-speed electric motor drives the A-end (variable-speed hydraulic pump), which is piped to the B-end (hydraulic motor), and the drum shaft is driven through reduction gearing. An electric winch drives through reduction gears, with a clutch to engage or disengage the drum, an electric brake and a speed control switch.

The windlass and its wildcat

The anchor windlass heaves in and pays out the anchor chain and holds the anchor at the hawsepipe. Its principal parts are the wildcat — a notched, sprocket-like drum whose pockets, or whelps, grip each link of chain — the wildcat clutch or locking head connecting the wildcat to the drive shaft, the brake band that controls the wildcat when it is declutched, and the prime mover, electric, hydraulic or steam. Most windlasses also carry gypsy heads, or warping heads, on the shaft ends for handling mooring lines. NAVEDTRA 14343 §4-3

The clutch is what makes controlled anchoring possible. The locking head allows you to disconnect the wildcat shaft and permits free operation of the wildcat, as when dropping anchor NAVEDTRA 14104 Ch. 10 — Anchor Windlasses. Three types are maintained — electric, electrohydraulic and hand-driven — and hand-driven windlasses are used only on small ships where the anchor gear can be handled without excessive effort by operating personnel.

Which drum on a windlass takes a mooring line, and which takes the chain?

The gypsy head (warping head) on the shaft end takes line; the wildcat, whose pockets are shaped to the link, takes chain. A question that offers both is testing whether you know the wildcat is chain-specific.</details>

Bitts, chocks, cleats and the load path

Deck fittings are the fixed points to which lines are led and made fast. Bitts are paired vertical posts, usually welded to the deck, around which mooring and towing lines are figure-eighted and secured; cleats are horn-shaped fittings for smaller lines; chocks are fairleads — open, closed or roller — through which a line passes over the side, changing its lead without a sharp bend and protecting it from the deck edge; bollards are the shoreside posts a ship's eye is dropped over. NAVEDTRA 14067 §4-1

A line is made fast to bitts by taking a round turn on the after bitt, then figure-eights across both bitts, finished so it can be surged or slipped. To surge a line is to let it slip around the bitts or a warping head in a controlled way, taking the strain gradually. Where the load may surge, lines are tended rather than cleated hard, so they can be eased or slacked rather than parting.

The greatest danger in line handling is the bight and the snap-back zone. A line under load stores energy, and if it parts the ends whip back along the line's lead with lethal force — so hands never stand in the bight, never stand in line with a line under strain, and stay out of marked snap-back zones. Keep the deck clear of stray turns, watch fingers around bitts and warping heads, and never step on a line that is running out.

Brakes, cut-outs and inspection

Brakes are the part of deck machinery that fails quietly. Windlass brakes must be kept in satisfactory condition to function properly: wear and compression of brake linings increases the clearance between the brake drum and band after a windlass has been in operation, so inspect linings and clearances frequently and adjust per the manufacturer's instructions. A windlass is used intermittently and for short periods, yet must handle its load under severe conditions — which means maintaining and adjusting the machinery when it is not in use. Lubricate a windlass that has been idle for some time to protect finished surfaces from corrosion and prevent seizure of moving parts. Hydraulic transmissions are built to close tolerances, so keep abrasives out, use only clean oil, and strain it as it is poured into the tank.

Winches and capstans are maintained alike: where band brakes are used on the drums, inspect the friction linings regularly and replace them when necessary, keep oil and grease off the brake drums, and periodically check brake-actuating mechanisms, latches and pawls. Inspect friction-clutch drums for deterioration of the friction material and check that the locking device on the shifting gear will hold under load.

On cargo machinery the protective devices are themselves examinable. Cargo winch brakes must hold the rated load automatically when power or control is lost NAVEDTRA 14343 §9-4. A load or overload indicator or cut-out prevents lifting beyond the SWL, limit switches stop the hook before two-blocking and stop luffing and slewing at the ends of travel, and a slack-rope or anti-two-block warning is fitted. Wire drums must spool the runner evenly and retain the required number of dead turns. Test brakes and limit switches at the start of the watch, check hoist wire for broken wires and proper spooling, never override safety cut-outs to force an overload, keep clear of the slew radius, never pass a load over personnel, and stow the gear for sea so it cannot work loose. Loose gear without a legible SWL mark or current certificate is not used NAVEDTRA 14343 §9-5.

Deck PPE for cargo or rigging work is a hardhat, ANSI-rated non-slip work boots, high-visibility vest, gloves suited to the task — cut-resistant for wire, leather for line — and hearing protection where engine or compressor noise exceeds 85 dB USCG Boatswain Manual Ch. 4 §4.1.

The numbers the CFR fixes

Each motor must be rated for continuous duty, except that a motor for an application listed in Table 111.25-15, or a similar duty, must meet the minimum short-time rating stated in the table 46 CFR §111.25-15. Continuous duty is the default; deck machinery is the exception. A deck winch or direct-acting capstan rates half an hour, a direct-acting windlass one-fourth hour, direct-acting steering gear one hour, and indirect-drive steering gear continuous operation at 15 percent load followed by one hour at full load. The hydraulic-transmission entries are two-part ratings — a no-load or idle-pump period followed by a full-load period — and you read those figures off the table itself.

Rails are the other set of fixed values worth knowing. Deck rails must withstand a point load of 91 kilograms (200 pounds) applied at any point in any direction and a uniform load of 74 kilograms per meter (50 pounds per foot) applied to the top rail in any direction, the two loads not applied simultaneously 46 CFR §177.900. Rails on passenger decks of a ferry or a vessel engaged in excursion trips must be at least 1,000 millimeters (39.5 inches) high; all other rails must be at least 910 millimeters (36 inches) high.

Telling it apart

The separating criterion is the axis of the driven shaft, then what the drum is shaped to grip.

Winch — horizontal shaft, one drum and one or two gypsy heads, drum clutched to the shaft. Misfiled when a candidate sees mooring line on a gypsy head and answers "capstan."
Capstan — vertical shaft, single head, reduction gearing, electric or steam. Misfiled when it is used for cargo work and answered as a winch.
Windlass — the anchor machine; its wildcat is pocketed to the chain link, with a clutch or locking head and a brake band. Misfiled when the question means the whole machine and the candidate answers "wildcat," or the reverse.
Gypsy head (warping head) versus wildcat — the gypsy takes line by friction, the wildcat takes chain by the link. Both may sit on the same windlass shaft.
Bitt versus bollard — the bitt is aboard, in pairs, and lines are figure-eighted on it; the bollard is ashore and the eye goes over it. Chocks lead a line over the side; cleats are for smaller lines.

Working a question

You are anchoring a 78-foot vessel in 8 fathoms and the question asks for the correct sequence, or for what holds the chain once you are riding. Work it as the machine works.

Establish where the load is before you touch anything. The wildcat is declutched and the brake is holding — declutched so the chain runs free of the drive, brake on so nothing moves until you decide it does.
Clear the holding gear. The riding pawl or devil's claw and any chain stopper are removed. This happens after the brake is confirmed holding, not before.
Ease the brake. The anchor runs out under its own weight, the brake being used to control the rate and to stop the chain. The brake is the control, and the anchor's own weight is the power.
Watch the stowage below. Keep the spurling pipe and chain locker clear so chain stows without piling and jamming.
Transfer the load off the windlass. Verify the chain stopper — pelican hook or pawl — holds the load, so that the windlass brake is not the sole holding device when riding to anchor. This is the step candidates skip, and the step questions are built on.
To heave in, reverse the load path. The wildcat is clutched to the drive, the brake released, and the windlass walks the chain back aboard while a crew member hoses mud off the chain and reports the direction and tension — "up and down," "anchor's aweigh," "clear anchor."
Keep bodies out of the geometry. Never stand in the bight of the chain or between the chain and a fixed object, and keep the brake and clutch in known positions.

Where four options all sound like plausible anchor work, the correct one is the one that leaves the strain on the stopper and the wildcat declutched.

Where candidates lose the point

Answers "gypsy head" when asked what engages the chain. Both drums live on the windlass and both handle a load, so the names blur. Only the wildcat has pockets shaped to grip each link.
Answers that the windlass brake holds the vessel at anchor. It is the last thing they used, so it feels like the holding device. The chain stopper is set precisely so the brake is not carrying the load.
Calls a vertical-shaft warping machine a winch because it is heaving a mooring line. The load being handled never decides it. Horizontal shaft, winch; vertical shaft, capstan.
Reads the duty-cycle default backwards and answers that deck machinery motors need only short-time rating generally, or that every motor aboard must be continuous. Continuous duty is the general requirement; the table names the applications that instead need a minimum short-time rating.
Makes the line fast hard on bitts where the load will surge. It looks like the seamanlike answer because the line is secure. A line under a surging load is tended so it can be eased, and surged around the bitts or warping head to take the strain gradually.
Treats snap-back as a hazard only at the drum end. The ends whip back along the line's lead, which is why standing in line with a line under strain is as dangerous as standing in the bight.
Picks the option that overrides a limit switch or load cut-out to complete a lift. Distractors phrase this as getting the job done. Cut-outs are never overridden to force an overload, and brakes and limit switches are tested at the start of the watch.
Answers 36 inches for rail height on an excursion vessel's passenger deck. 36 inches is the catch-all figure; passenger decks of ferries and excursion vessels take 39.5 inches.

Check yourself

You are told to rig a line to the machine with the vertical shaft. Which machine, and what does that tell you about its speeds if it is electric?

A capstan. Electric capstans are usually reversible, developing the same speed and power in either direction; ac-driven units run at full, one-half or one-third speed and dc-driven units usually have three to five speeds in either direction.</details>

The mate orders the anchor let go. The brake is holding and the devil's claw is on. What is the state of the wildcat clutch, and what comes off first?

The wildcat must be declutched so it runs free of the drive. With the brake holding, the riding pawl or devil's claw and any chain stopper come off, then the brake is eased and the anchor runs out under its own weight with the brake controlling the rate.</details>

You are riding to anchor overnight in an exposed roadstead. What must be carrying the strain of the chain?

The chain stopper — pelican hook or pawl. It is set and verified so the windlass brake is not the sole holding device.</details>

A deck winch motor on a vessel under inspection is nameplated for short-time duty. Is that acceptable, and what is the figure for a direct-acting windlass?

Acceptable, because a deck winch is one of the listed applications exempt from the continuous-duty default. It must meet the table's minimum short-time rating — half an hour for a deck winch or direct-acting capstan, one-fourth hour for a direct-acting windlass.</details>

A mooring line is coming under heavy strain as the vessel is warped alongside. Where do you stand, and do you make the line fast?

Out of the bight, out of any marked snap-back zone, and not in line with the lead of the line. Where the load may surge the line is tended rather than cleated hard, so it can be surged around the bitts or warping head and eased or slacked rather than parting.</details>

You inspect a windlass that has been out of service through a lay-up. Name the two conditions most likely to have changed.

Brake lining wear and compression, which increases clearance between the brake drum and band and calls for adjustment to the manufacturer's instructions; and loss of lubrication, since an idle windlass needs lubricating to protect finished surfaces from corrosion and prevent seizure of moving parts.</details>

Hoisting cargo with an electrohydraulic winch, control is lost. What should the brake do, and what device should have stopped the hook before it reached the block?

The brake must hold the rated load automatically on loss of power or control. A limit switch stops the hook before two-blocking, backed by a slack-rope or anti-two-block warning; these are tested at the start of the watch and never overridden.</details>

A line is led over the side through a roller fitting on the deck edge. Name the fitting and its purpose.

A chock, used as a fairlead. Chocks may be open, closed or roller, and they change a line's lead without a sharp bend while protecting it from the deck edge.</details>