BOAT-COMPARATOR Guide

Rafting Up: Mooring Alongside Another Boat Without Drama

Crowded harbours, lock waiting quays, festivals: mooring alongside another boat is routine. Technique, crossed lines and the etiquette of rafting up.

On an August evening in a Breton harbour or on the waiting quay of a lock, the harbour office will announce it over the VHF: “You will raft up alongside the blue sailboat.” Mooring side by side against another boat is a perfectly routine manoeuvre — and a needless source of anxiety for many charterers. Here is how to get it right, and how to be a good neighbour afterwards.

Prepare the boat before approaching

Everything happens before contact: plenty of fenders on the mooring side, set at the height of the receiving boat’s rubbing strake — not the quay’s —, one line made fast forward and one aft, each coiled and ready to pass. Warn the receiving boat by voice or VHF and brief the crew: nobody jumps, lines get passed. Our guide to fenders details the placement, and the basics of docking in a marina remain the prerequisite.

The approach: slow, parallel, offset

Approach at walking pace, parallel to the receiving boat, aiming slightly offset: on two sailboats the masts must not line up, so the spreaders cannot lock together if the boats roll. The water flowing between two nearby hulls creates very real suction and repulsion effects — measured in towing tanks by Vantorre and co-authors in their reference campaigns on ship-to-ship interaction (see the study on Google Scholar): the slower the approach, the more negligible these effects stay. A bow thruster helps tuck the bow in gently at the last moment.

Making fast: bow, stern, springs… and the quay

First pass a bow line and a stern line to your neighbour’s cleats, then two crossed springs to stop fore-and-aft surging. Golden rule of the raft: if you stay the night, add your own long bow and stern lines led all the way to the quay — your neighbour must not carry your weight alone, especially in tidal waters where the whole raft rises and falls together. Check your knots: a round turn and two half hitches on solid cleats, never a fancy knot on someone else’s line.

Rafting etiquette

It comes down to three customs: ask permission when possible, cross the neighbouring boat forward of the mast — never through the cockpit —, and keep quiet early morning and late evening. Exchange departure times as soon as you are moored: if the inside boat leaves before you, the raft opens, lets it slip out and re-moors — a simple manoeuvre with two coordinated crews. When leaving the raft, re-make your neighbours’ lines properly for those who stay.

And what about damage?

Rafted up, a gelcoat scratch happens fast — and that is exactly the kind of detail that gets settled at hand-back. Photograph both sides of the hull on arrival and departure as our check-in/check-out guide recommends, and re-read what your deposit covers. Done properly, the manoeuvre leaves no trace — only pontoon neighbours to share a drink with.

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