Mooring Line Set Up

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We can supply quality black polyester lines, hand spliced by us and delivered via Australia Post at very competitive prices. And to help you select mooring lines of adequate strength we have included a basic line rating chart on our mooring line page.

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All Lines need to be of a sufficient rating (strength) and
need be protected from sharp
edges and chaffing.

No fibre rope is immune to cutting or wear

All moored vessels need to be checked regularly as lines do chafe and wear
Don't forget to also check the condition and security of cleats, bollards and other fittings!

To get the best performance out of your mooring lines - Firstly lets get an understanding of what each of the different mooring lines does

Lines are properly named after what function they perform - the movement they control

This is the Aft Spring - but on the for'ard cleat
 This is a For'ard Spring - but on the aft cleat

Springs are named after the movement they prevent

An advantage of shorter springs like these (if only using two) which do not cross is that they can serve a secondary purpose of controlling movement of either end of the vessel away from the berth. For example the bow cannot move very far from the berth unless the vessel can move forward. Unlike crossed springs which will act to prevent the movement of the boat sideways from the berth but on their own will not prevent the boat from "pivoting" and allowing either end to move away from the berth. - Longer crossed springs are really only necessary in a wharf or jetty situation where the range of rise and fall of tide needs to be accomodated, but generally a longer line is able to cope better with dynamic loading.


The MAXIMUM angle away from the horizontal for any line under strain, should be 45 degrees

Some boats roll, some pitch, some yaw -
ALL BOATS move up and down relative to the berth pontoon

Under no circumstances should you have a mooring line which is nearly vertical between the pontoon and the boat - and is tight!!

A line like this tries to prevent vertical movement

That's a sure way to end up with a broken mooring line - or worse

Crossed springs on the after half of the boat (if they are tight) will have the effect of holding the boat alongside

A stern line is still used - but must be sufficiently slack when the boat is close alongside, to prevent it taking up and being subjected to sudden jerking forces as the boat rolls or moves up and down in opposition to similar movement of the berth pontoon

The Golden Rules for Mooring Lines
1. Spring Lines should have no slack
2. A Spring Line should not be more than 450 from horizontal
3. Any Line with greater than 450 from horizontal must not come taught when the
     boat rolls or bobs up and down
4. If possible don't have any lines that are closer to perpendicular than 450 
5. All lines need to be protected from sharp or rough edges

Springs should be kept tight! to prevent the boat rocking backwards and forwards from slack take up, to slack take up. This will minimise the "run up", the dynamic force, that the weight of the boat gets against the lines.

Every possible circumstance or combination has not been shown -
the examples are to demonstrate the purpose and function of the lines


In all of the examples above the lines all have reasonable length, and are set up to prevent horizontal movement of the boat - forwards and backwards, and sideways

This is possible due to the boat being far enough into the berth to allow the stern line to pass from the pontoon to the far side stern cleat

This is not always possible and leads to that common mistake which causes real problems like breaking mooring lines, stress and damage to boat and pontoon fittings

We recommend lines with a soft spliced eye (loop) on one end and an anti fray finish such as a sailmaker's whipping on the other end.

This way, on for example a vessel berthed bow in, the for'd spring (that stops boat moving for'd) is belayed to the berth cleat with the spliced eye (loop) able to be quickly dropped over the boat's cleat or bollard, to limit for'd movement and position the boat at a predetermined place in the berth (adjusted with the belayed end).

The Aft Spring is fitted to the berth by "threading" the eye through the hole in the berth cleat and doubling the loop back over the horns of the cleat. The straight end is now ready for you to use to tension against the for'd Spring to hold the boat snugly and prevent it moving back and forward.

From there it is really personal choice whether to fit the bow and stern lines to the berth with a belay and put the eyes to the boat, or the other way around. Unlike the Springs, the bow and stern lines don't need to be (and shouldn't be) tight. They need to allow a range of movement depending on the characteristics of the boat.

Splicing all your mooring lines directly to berth cleats, with drop over loops does not allow for re-tensioning.

If you need to get an idea what rating of mooring lines you need for your boat - refer to the chart on our Mooring line page,
it should be used as a guide only.

The advice on this page is valid only for floating marinas, and is of a general nature only.
If in any doubt seek advice from your Marina Manager or local boat club

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