Why bow-to-stern berthing suits a catamaran

A catamaran's beam is a joy at sea and a puzzle in a packed harbour. Where a monohull slides into a gap with centimetres to spare, your six or seven metres of width needs a plan, a slow approach and a crew who know exactly where the lines go. The reward is a boat that barely stirs when a spring comes tight, and twin engines set far apart that will spin you on the spot like a shopping trolley.

Bow-to-stern berthing — bow to the quay with a line aft, or lying fore-and-aft between mooring buoys along a trot — is how crowded harbours fit everyone in. It saves space, it keeps the fairway clear, and once you have the technique it is calmer than trying to squeeze alongside a neighbour. The principles are the same whether you are sliding into a narrow slot between two moored boats or picking up a buoy on a busy trot line.

Prepare the boat and the plan before you enter

The manoeuvre is won or lost before you pass the harbour wall. Sort everything in open water, where you have room to think.

• Lines ready and led: bow line flaked and led aft along the deck outside the stanchions, stern line led forward the same way. A line that has to be passed through the guardrails at the critical moment will jam.
• Springs: a bow spring and a stern spring, each at least the length of the boat plus a generous tail. On a catamaran, a short spring from the midships cleat to the quay is your handbrake.
• Fenders: four a side as a minimum, hung vertically at the widest point of each hull, not left dangling at the waterline where a falling tide will leave them useless. A fender board or a couple of horizontal fenders protect you against rough piles and old stone walls.
• A brief: thirty seconds is enough. Who takes which line, which side, who fends off, and what the tide and wind are doing. Speak it out loud — the crew cannot guess your plan from the helm.

The approach: slow, square and steady

Come in at half a knot. A walking pace feels alarmingly quick when the gap is three metres wider than your beam, and the throttle response of twin diesels is instant. Use idle ahead, then neutral to coast, and let momentum do the work. If anything feels wrong, stop, hold station with a touch of power against wind or tide, and look again. There is no prize for hurrying.

Approach into the tide where you can, so the current is helping you brake rather than pushing you onto your neighbour. With wind or tide setting you towards the berth, line up your bow slightly up-current and let the elements do the closing. With twin engines you can walk the boat sideways: a touch of ahead on the outer engine and astern on the inner swings the bow across, and reversing the pair swings it back. Practise this in open water until it is instinctive.

If you are picking up a buoy on a trot, take a bridle from both bow cleats through the buoy ring rather than a single line. The load is shared, the boat sits straight, and she will not sheer about all night.

Springs: your brakes, your pivot and your parking brake

A spring is simply a line led fore or aft from a cleat to the shore or another boat's fitting. Get one on early. A bow spring led aft from the bow to a bollard stops the boat's forward motion dead without any drama; a stern spring led forward does the same for reverse. Once a spring is on, you can leave an engine in idle ahead or astern against it and she will sit still while you sort the rest — this is the calmest way to hold a catamaran in a tight slot.

Use the springs to pivot too. With the bow spring fast and a touch of ahead on the inner engine, the stern swings in. With the stern spring fast and a touch of astern, the bow comes round. The lines do the work; the engines only nudge. Keep hands and feet clear of a spring under load — it will part with a crack if it is going to, and it will not warn you.

Talking to your crew, and being understood

Voice travels badly over water, engines and wind, so agree your words in advance and keep them short and unambiguous: "bow line on", "hold", "make fast", "let go", "stop". Never shout a sentence when one word will do. Repeat back what you hear if there is any doubt — a misheard instruction is how gelcoat gets damaged.

Agree hand signals as a backup, and agree which side of the boat the crew will work on so nobody crosses the foredeck at the wrong moment. If someone is fending off, they should push and release, never hold on. Brief a nominated person to watch the stern while you watch the bow, and remind everyone that a catamaran has two hulls to mind, not one.

Settled in: lines, tides and an easy exit

Once the lines are on, walk the deck and check the whole boat. Look for chafe where lines cross a toe rail or a fairlead, and adjust the springs so the load is spread rather than all on one cleat. In a harbour with a big tidal range, leave enough slack for the fall and rise — a line bar-tight at high water can lift a cleat at low, and a slack line at low water becomes a snatching hazard as the tide comes back. Check the fenders again as the water moves.

Finally, think about tomorrow. Note which way the wind is forecast to blow overnight, and make sure your slip line or the outermost line can be let go first when you leave. A calm arrival and an easy departure are the same manoeuvre, run in opposite directions. Take your time, keep the crew talking, and let the lines — not the throttles — do the heavy work.