Explain to an idiot what spring lines are for

[mdenize]

Originally Posted by Dockhead

I'm surprised no one has mentioned the other purpose of spring lines -- not only are they intended to prevent movement fore and aft, but the fact that they go off at an angle dampens lateral motion. If you rig your bow and stern lines as breast lines -- perpendicular to the dock -- then they will snatch up if there is any wave action. Better rig these also at an angle, as proper bow and stern lines, and then once you've added your spring lines, then you are holding the boat against the dock but with plenty of elasticity in the system so you don't have snatching

This is at least part of what we use them for. The main function though is to keep the boat parallel to the dock (jetty in NZ) while it is snatching at the lines to stop either the bow or stern going under the jetty or touching it (we live in place that more exposed than most)

In the attached photo you will see it all in action during one of our zephyrs... three bow lines three stern lines and two springs on day I would rather have Stingray on the trailer

[Sea Wolf]

We wouldn’t tie up or raft up without them. Simply put, they keep the boat from going fore and aft. The boat stays in one place with minimal rubbing. The longer the lines, the tighter the lines, the better the tie up will be. If spring lines are loose, they won’t do much

[Axel Rappe]

As a ships officer rather than a yachts man...

Spring lines are also a good aid to maneuvering.

When leaving a dock:

Reverse on the aft spring to point your bow out from the dock. Go forward on the forward spring to get your stern out.

When docking:

Go forward on the fwd spring line to get your hull along the dock. Or go in reverse on the aft spring.

Using one line like this is very helpful, particularly in adverse wind conditions. If doubled around the bolkard on the dock, the line can be easily retrieved.

The fwd spring points aft from the bow. The aft spring points forward from your stern. Both will help your bow and stern lines in maintaining position alongship. Brest lines hold your vessel athwartship. If you have big movements due to waves or tides, try to keep lines tight but long so you don't have to adjust them all the time. Brests can be placed from the other side of the boat to allow you the extra length, as well as doubled to allow more stretch.

Not an idiotic question at all. Takes some practice to work with springs, but once you get a grip of it it really helps you in all sorts of situations when docking or coming alongside other boats. You can also set up a spring to an anchor line to adjust your heading which could potentially help with your motion at anchor when for example wind and current are not working well with the sea.

Practice

And have fun.

[skenn_ie]

Head and stern lines mostly prevent the boat from moving away from the quay. Springs prevent the boat from moving parallel to it. If one does both, it won't do either well.

[Axel Rappe]

Originally Posted by skenn_ie

Head and stern lines mostly prevent the boat from moving away from the quay. Springs prevent the boat from moving parallel to it. If one does both, it won't do either well.

I'm sorry, but this is simply not correct.

A combination of springs and bow/stern lines will, apart from stopping movement forward and aft, also limit swinging motion, keeping you parallel to the dock. Shallow angels will prevent forward / aft motion. Greater angles will hold you alongside, helping a brest line if you have one.

[Coast Wanderer]

I use my fore and aft dock lines to keep the boat from moving away from the dock. I use a single long spring line that is tied to the dock next to my main dock lines and it is on a center cleat on the boat. The spring line keeps the boat from moving fore and aft so as not to burden the dock lines with that force, while the dock lines keep it at the dock. Since we can only tie up on one side this has worked very well through all the storms we've had here in the Pacific Northwest. The spring line in action will pull the bow or stern toward the dock (onto the fenders) as the boat is pushed forward or back by the wind/waves.
If you tie to a bukll rail, make sure the spring lines are tied with a rolling hitch or something that will not allow the tie to slide along a wet, slimy bull rail. I check on the boat regularly and end up retying them, just to be sure. Well placed cleats are so much better!

[no1engravr]

Originally Posted by Montanan

Be assured that you are NOT AN IDIOT. An idiot doesn't know what they don't know and is incapable and / or unwilling to ask relevant questions or seek guidance on subject matters. You may have been ignorant of the purpose, benefit and proper deployment / configuration of spring lines, but given the able responses of the CruisersForum you now have a much better understanding of spring lines and you should take away that knowledge along with a motivation to utilize such the next time to moor your boat.

Couldn't have been said any better. For the most part, no matter what your situation is, you will want spring lines. Keep asking till you get the answer that fits your need. As some one else mentioned, it would help to have a diagram and knowledge of your boating area.

[Spring-Fever]

[it could not be better explained than his response above. (Related to the axis of the rope). Adding, that perhaps one spring line of your docking configuration could add a nice REDUNDANT line of protection - should one of the lines on the Seward side should fail or loosen).

Great question. And really great response.

[Djsubzro]

I find that pulling on the spring line is handy to move the boat closer for boarding supplies.
I just step on the center to aft dock cleat line and it brings the back close to the dock.

[Spring-Fever]

@djsubrzo. another great tip/idea!

[skenn_ie]

The idiot is the one who doesn't ask until (s)he has learned the hard way. There are plenty of undiscovered mistakes to find without repeating ones that have been discovered.

[skenn_ie]

Originally Posted by Axel Rappe

I'm sorry, but this is simply not correct.

A combination of springs and bow/stern lines will, apart from stopping movement forward and aft, also limit swinging motion, keeping you parallel to the dock. Shallow angels will prevent forward / aft motion. Greater angles will hold you alongside, helping a brest line if you have one.

"if one does both", I meant that if bow and stern lines were partly diagonal, it doesn't do a particularly good job of keeping the ends of the boat in, or prevent it from surging along the quay. If there is no sea running, two such lines would be adequate though.

[Ballsnall]

Originally Posted by wtmf

In my ABC classI was taught the spring lines went from the bow of the boat to aft of the stern on the dock and the aft line of the boat goes forward of the bow on the dock

wtmf is correct in how spring lines should be set. The main purpose of spring lines is in the name. They act as springers to absorb shock loads from fore & aft forces and also from laterally away from the dock. The purpose of all dock lines is to hold the vessel in position but springers also have the advantage of being able to accommodate a wide range of tidal movement without affecting the vessels relationship with the fixed dock. You would set the springers to hold the vessel in the exact position and then set bow & stern lines loosely more as a backup should a stringer fail.
Generally, springers are made of larger diameter mooring line, approximately the length of the vessel or slightly more and with a large eye on one end, or for vessels using the same dock are made to exact size with eye each end and make regular docking a breeze. They are also the perfect line for bringing a vessel into and off of the dock lines in a cross breeze.

[skenn_ie]

IMO, the first purpose of a spring is to minimise the momentum that the boat can build up, THEN to absorb the momentum to bring the boat to a halt. Unfortunately, they aren't very good at dissipating energy, if they stretch, that "spring" returns most of the energy in the opposite direction. The exception is Dynema which is designed as a shock absorber, to dissipate energy (when climbers fall), but the rope degrades with every shock dissipation.

[sailfly]

I use 6 lines in a slip. bow and stern lines primarily to control side to side movement. Fore and aft spring lines control movement fore and aft.