Deciding to Tow Under Sail

Towing another yacht under sail is one of the most rewarding skills in coastal seamanship, but also one of the most demanding. Before you pass a line, ask: is the weather suitable, is the destination reachable without risking either boat, and is there a safer alternative such as anchoring? If the wind is fresh and the sea confused, towing under sail becomes a battle. A calm day with a steady breeze and a clear route is ideal. The towed vessel will steer poorly and may yaw wildly, so you need sea room and patience. If either boat has engine trouble, consider motor-sailing instead. The decision to tow is a commitment; changing your mind in a crowded channel is difficult.

Rigging the Tow Line

Strength and stretch are your friends. Use a dedicated tow line of nylon or polyester, at least 18mm diameter for yachts up to 12 metres, and longer than you think necessary — 30 to 40 metres allows a catenary that absorbs shock. A bridle spread across two strong points on the towing vessel, such as bow cleats or a mast base, reduces strain. On the towed boat, lead the line over a bow roller and secure it to a cleat with a round turn and two half hitches, then a second line as backup. Protect against chafe with leather, rubber hose or purpose-made sleeves wherever the line runs through a fairlead. Attach a weight — a length of chain or heavy bag — to the tow line about a third of the way from the towing vessel; this keeps it submerged and clear of propellers. Never use a sheet winch as the primary attachment; a sudden jerk can tear it from the deck.

Signals and Communication

Agree hand signals before you start. Shouting across a gap is unreliable, and VHF may be needed for other traffic. Simple, unambiguous gestures work best. Practise them alongside before getting underway.

• Pointed finger — steer to port or starboard; indicate the direction clearly.
• Raised clenched fist — stop or hold course.
• Thumbs up — all good, increase speed.
• Hand waved horizontally — slow down.
• Palm held forward (from towed vessel) — I need to cast off.

If you have VHF, agree a working channel and keep a listening watch on Channel 16. The towed boat's crew may be seasick or cold; keep instructions short and repeat them. A pre-agreed word such as "ready" and "go" for casting off and taking up slack prevents confusion.

Route, Speed and Sea Room

Plan a route that avoids narrow channels, shoals, lobster pots and busy ferry lanes. Check the tidal stream: towing against a spring tide can halve your speed and set you sideways. Aim for a speed that keeps both boats moving but does not overload the tow line — typically 4 to 6 knots for a yacht under sail, or slower if the sea is choppy. Use the engine if you have one, but keep it ready to adjust. Allow at least three times your normal stopping distance. When turning, make wide, gentle arcs; the towed boat will cut the corner. If you must pass a mooring or buoy, give it a wide berth. Monitor the tow line's catenary: if it lifts clear of the water and snaps tight, you are going too fast or the towed boat is yawing. Ease off, let the line sink, then resume.

Techniques for the Towing Vessel

Your job is to be predictable. Keep a steady course and speed, and avoid sudden throttle changes. Use your sails to balance the load: a reefed mainsail and a small headsail reduce rolling and help you steer. If the wind builds, reduce sail early rather than risk a broach. Watch the towed boat constantly; if it sheers, slow down and let the line straighten. A spring line from your bow to the towed boat's quarter can help control yawing, but only if both crews understand the setup. In tight quarters, consider an alongside tow instead, with fenders between the hulls and springs fore and aft. Under sail alone, you cannot easily go astern, so plan every manoeuvre well ahead. If you need to stop, head into the wind and luff, letting the tow line go slack gradually.

Being Towed: The Crew's Role

On the towed vessel, your main tasks are to steer a straight course, keep the line clear and stay ready to release. Steer with small, deliberate movements; the towing boat's wash and the line's pull will fight you. Keep a sharp knife at the bow and a second at the stern. Fenders should be ready on the side facing the towing boat. If the tow line parts, let it run free — do not try to grab it. Once safely alongside or anchored, inspect every line for chafe and deck fittings for stress cracks. Rinse the lines in fresh water, dry them and store them loosely. Finally, thank your crew and the other skipper; towing under sail is a team effort.