Docking demystified

Mark Robinson | VOLUME 26, ISSUE 1
Essentially, the boat ‘springs’ or ‘works’ against the lines. Hence, the term ‘spring lines’.
Mark Robinson shows us the ropes.

A while ago, I watched from the comfort of a friend’s marina-based apartment as a boat cruised lazily up to a pontoon and nudged into a berth. It was a mid-sized power cruiser, and the skipper appeared to know what he was doing – or so it seemed, at first. The pontoon was, fortunately, in a protected little cove surrounded by apartments, so the wind was blunted to some extent.

As the occupants of the boat left the marina carrying their gear, I happened to look down at their boat, which seemed to be swaying a bit on its lines. An hour or two later, I looked down again. The boat was no longer where it had been left. In fact, it had actually departed its pen and was conducting a solo tour of the marina, minus skipper and crew, with lines dangling uselessly in the water and occasionally bumping gently into other boats as it was carried along in the current.

Fortunately, a nearby boatie spotted the errant craft and soon had it in tow. A few minutes later, it was safely back in its pen, with a chip or two in its gelcoat – and, no doubt, equivalent scrapes on some of the surrounding craft – but at least its lines were now secured properly.

As many boat owners would appreciate – some to their considerable personal cost – this is not such a rare occurrence. While securing a boat in a berth is not rocket science, it still requires some basic knowledge to be done properly, especially if the boat is to be left unattended for lengthy periods of time.

Nautical jargon confuses most people, and not just those new to boating. And the term ‘spring line’ is high on the list of secret squirrel terminology. But as we will see, the much-misunderstood term simply means ‘a line led diagonally from the bow or stern of a boat and tied to a point on a wharf to help keep the vessel from moving fore and aft while docked’.


In pictures 1 and 2, four lines fasten a craft to a floating pontoon. There is a bow line that runs from the bow cleat forward to the pontoon and there is a stern line running from the stern cleat and attached to the pontoon slightly astern of the boat. In between are two spring lines, both attached to the centre cleat of the boat. One runs forward, one runs aft; both are tied to the pontoon.

While looking at picture 1, imagine there is a tidal current flowing from bow to stern of this craft. This current will exert a pull on the craft towards the rear. Therefore the bow spring line will tighten (as shown, pic 1), while the stern spring line will go slack (also as shown, pic 1).

When the tidal current reverses, the forces acting upon the spring lines will reverse too, with the stern spring line tightening and the bow spring line relaxing (as shown, pic 2). Essentially, the boat ‘springs’ or ‘works’ against the lines. Hence, the term ‘spring lines’.


If your craft is not fitted with a centre cleat, there is another way that the spring lines can be set up, as shown in pictures 3 and 4. In this situation, the bow spring line is run from the bow cleat of the craft to a pontoon cleat astern of the craft. The stern spring line is run from the stern cleat on the aft quarter of the craft right up to the pontoon cleat forward of the bow of the craft.

What knot to do

Using an old Boy Scout trick to effectively tie off your boat.

To secure your boat to a dock, you need a length of line and a method of attaching it. While an eye-splice is the preferred method of attaching the inboard end to your vessel, the bowline is a quick and simple alternative.

The bowline knot, which is easy to tie and untie, is used to form a fixed loop at the end of a rope. For many years, Boy Scouts were taught to tie the bowline knot using the ‘rabbit and hole’ method – a very simple and effective technique, reproduced here, to help you get a knot that won’t tighten or slip.

B1: Imagine the end of the rope as the ‘rabbit’ and make a loop as shown, crossing the ‘rabbit’ end of the rope over the main section. Now imagine the main section to be a tree trunk.

B2: The ‘rabbit’ now comes up out of his hole and goes behind the tree.

B3: Now he continues around the tree and goes back down his hole.

B4: The knot is completed by pulling both ends tight.


While there are various ways to achieve this, the method outlined below is straightforward and easy to learn. The part of the line which is not attached to your vessel is referred to as the ‘bitter end’.

Either of these line rigging arrangements will work satisfactorily in a situation where the wind or tide is pushing the craft away from the pontoon. Should the situation be reversed, with the wind or tide pushing the craft toward the pontoon, either of these line rigging arrangements will still work, as long as appropriate fenders are deployed to keep the craft’s hull from rubbing against the pontoon.


Picture 5 shows how attaching two extra lines can provide additional security for the craft. One line runs from the port aft quarter stern cleat and another runs from the starboard cleat amidships. Both are tied to the same pontoon cleat.


It’s important to note that all of the lines in these pictures are tied up to a floating pontoon, which will rise and fall with the tide and will not alter the height relationship between the craft and the pontoon.

However, when you tie up to a fixed structure, such as a piling, you need to allow for the tidal rise and fall. The recommended method of doing this is to tie the lines at the level of the boat during a medium tide so that they rise up to the boat at high tide and fall down to it at low tide. If the lines are tied too high on the piling, they will be excessively taut at low tide, which presents the very real possibility that they will snap. Meanwhile, at high tide, the bow and stern lines will be overly slack and ineffective.


If the forces that act against your craft have a likelihood of building up excessively, such as in a severe storm, there is a way to tie up more securely – as long as you have the room to do so.

As shown earlier in pictures 1 and 2, the bow and stern lines are set up on the port side of the craft, along with the bow spring line and stern spring line. In addition to these, and as shown in picture 6, a bow and stern line are attached to the starboard side of the craft, along with a bow and stern spring line. And an extra line, the so-called ‘breast line’, is added amidships.


Always approach the pontoon very slowly and at a shallow angle, preferably with the wind or the current on your bow. Your fenders should be in position before coming along side the pontoon and lines should be attached to both bow and stern cleats and ready to deploy.

Your crewman should be holding the ends of both dock lines and should only step aboard the pontoon when your craft is virtually at a standstill. Leaping ashore is an invitation to injury. Crew need to be instructed to never place themselves or any part of their bodies between the craft and the dock as the force generated by a craft of any size can cause serious injury.

Once ashore, the crewman should secure either the bow or stern line, depending on how the wind and tide are affecting your vessel. If you have docked with the current or wind on the bow, then the bow line should be secured first. If you have docked with the current or wind at your stern then the stern line should be secured first. The second of the two lines should be tied off next, and then the spring lines are attached.

Spring lines can be used in an active way to manoeuvre a craft in various fashions, both approaching a dock to tie up, and in leaving one in difficult circumstances. However, mastering their passive use as described in this article is the first and most important step in tying up competently.

How to-Safety