Explain to an idiot what spring lines are for

[Greg Mason]

Great post for those who do things because they were taught that way. For those who philosophize, let's go to the word used to describe the line. Spring. Many of us mono hull marina bound yachts share a slip with another vessel, often with limited beam. 2 lines, bow and stern could be used successfully if they were really tight, stopping movement in almost any direction, but adding a chafing element to the hull and fender area. 2 additional spring lines allow some slack but restrict forward and aft movement, as the bow and stern lines restrict lateral movement. 4 lines will always have more strength and stretch than 2.

[KimSails]

Originally Posted by valhalla360

On Lake Erie, we were in a marina one night with a bad storm. By morning the boat was 7-9ft down sitting on the bottom as the water was literally blown out of the marina. We had to adjust lines 4 separate times. Lots of boats with cleats pulled out as the staff couldn't keep up with adjusting the lines as most owners were gone.

That exact thing happened to my Catalina 27 some years ago on Lake Erie near Monroe, Michigan. Arrived at the boat after leaving her during the week to see a stern cleat pulled out and the water level way down. It is not a tide, just the way the wind blows the water east across the shallow, pan-shaped lake bottom to Buffalo. That taught me the value of spring lines on a fixed dock. I still use them on a floating dock.

[S/V Illusion]

To be blunt, on a 27 foot boat, it doesn’t make much difference.

[MJH]

Originally Posted by ferrailleur

Don't understand the usefulness of spring lines when docked at a slip. I read many manuals and asked many sailors..... No cleat cut/definitive answer. I still don't understand. Am I missing something big or an I a total idiot?
Don't hold back your comments please.


My docking situation: I have two bow lines (secured on pilings) and two stern lines cleated on the pier.... (reverse situation if berthing the other way).

The boat can move a little fore and aft and side to side to adjust with a max three feet tide.

How in the world a spring line going to help with fore/aft movement of the boat which is already tied four way fore and aft?

Thanks

If you cruise to non-home marinas, you will almost always only be tying to one side only; thus the spring-line will be necessary.

Always helpful, but most common only on larger boats, there will be an amidships cleat. Using one longer line to go both forward and aft to the dock serves as the spring line.

~ ~ _/) ~ ~ MJH

[OS2Dude]

Spring lines can also help you maneuver your vessel in tight situations, or even to dock. A line on the midship cleat to the dock, boat in forward turned about 45 degrees away from dock will bring you to the dock and keep you there while you tie up. If the dock end is only over the aft horn, you can put the boat in gear, untie the other lines and reverse away and the line will come off the dock cleat as you back away.

[FabioC]

Spring lines have two key uses:

1. When you are docked: to limit the fore/aft movement of the boat. Since typically you dock in a slip not much longer than your boat, you cannot afford the boat to move fore/aft too much (as she would either hit a dock or another boat). The spring lines limit the allowed movement much more than bow/stern lines only. If you only need to limit movement in one direction (e.g., you dock with your bow very close to an obstacle), you can just use one spring line, if you need to restrict movement in both directions, you need two spring lines.

2. When docking or leaving the dock, you often use spring lines. If used properly, even one spring line gives you complete control of the boat (e.g., if you need to stop the boat alongside the dock, you can just set a spring line as you approach and motor against it), or it can provide steering of the boat without forward movement (e.g., when leaving the dock with wind pushing you into the dock, you can set a spring line and a fender, and motor into it until your bow or stern is free).

There are many youtube videos explaining the use of spring lines in docking, and the bottom line is that there are many docking situations that can only be solved using a spring line.

It takes a little bit of thinking to understand the "physics" of the spring line (especially in docking maneuvers), but once you master it, it becomes a very valuable tool (and an impressive demonstration of seamanship).

[Chuck Hawley]

When I teach powerboat classes for US Sailing, I get asked about spring lines all the time. In this context, I am not talking about their incredibly useful function in getting away from or alongside a dock under certain circumstances.

Spring lines create triangles that more accurately locate the boat alongside a dock or in a slip. By having a line that leads forward from the bow (generally called a bow line) and also aft from the same cleat to the dock (or piling) the skipper creates a triangle which keeps the cleat from surging either fore or aft. Spring lines act in opposition to the bow and stern lines, but do not force the boat against her fenders.

IN other words, what the other guys said...

Chuck

[Poeme]

I spring a line from a mid-ship cleat forward, which tends to pull the stern in...can control boat's angle making boarding to the aft cockpit easier and safer.

[Woodland Hills]

I thought they were for tying up in March and April winds.......No?

[jmschmidt]

It's not possible to explain this to an idiot so here's hoping that you were kidding about your mental capacity. There are very good explanations here from the others, especially the diagram.

[grandmaR]

When we expect large tides, or even when we don't but are leaving the boat for a time, we use spring lines because spring lines allow the boat to ride up and down with the tide without moving forward/aft or side to side.

[singlespeed]

Most new boats appear to built to a price point and have woefully inadequate backing plates on deck hardware. Many fittings, like deck cleats have their backing plates and fasteners hidden under interior cabinetry or liners. Using springlines helps reduce the loading on the fore and aft docking cleats, always a good thing.

[Mike Banks]

The bow ans stern lines need to be as long as the springers if you are not tied to a floating dock, which means widely separated cleats.

[Montanan]

Originally Posted by ferrailleur

Don't understand the usefulness of spring lines when docked at a slip. I read many manuals and asked many sailors..... No cleat cut/definitive answer. I still don't understand. Am I missing something big or an I a total idiot?
Don't hold back your comments please.


My docking situation: I have two bow lines (secured on pilings) and two stern lines cleated on the pier.... (reverse situation if berthing the other way).

The boat can move a little fore and aft and side to side to adjust with a max three feet tide.

How in the world a spring line going to help with fore/aft movement of the boat which is already tied four way fore and aft?

Thanks

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.

[Dooglas]

Originally Posted by Poeme

I spring a line from a mid-ship cleat forward, which tends to pull the stern in...can control boat's angle making boarding to the aft cockpit easier and safer.

You are the first person to mention this obvious and common use of a spring line. Yes, spring lines limit fore and aft movement of the boat, and accommodate significant tidal ranges. But they are also useful to hold the boarding area of most boats near the dock, rather than trying to match up a pair of dock and boat cleats, and then secure them with a short and tight mooring line. As others have noted, that puts substantial strain on the line, causes the boat to jerk when struck by a wake, and can limit the ability to accommodate tidal changes.