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Dock Lines For A Bouncy Harbor


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The yacht basin at Marina Coruna is a little bouncy with northerly quadrant winds. We and everyone else are surging against our dock lines. There are comfort issues with jerking and noise which we have solved with a combination of dock line materials.

We are connected to the dock with three different types of rope. The small diameter blue lines are our normal Spectra 11mm (7/16″) material. As strong as the other lines of larger diameter Spectra has very little stretch which in this situation is uncomfortable.The braided material is a Gleistine “brait” a super stretchy nylon construction. It is being used as a bow line to minimize shock load when the boat rolls. The third line is a Yale Ropes polyester which is being used here for springs (the brait is too stretchy and would allow excessive surging). Both of the latter are 24mm (one inch).

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A major consideration is the angle from the boat to the dock. That is why the stern line has been run across the dock. The angle is flat enough that we did not bother switching to a stretchier construction rope. Note that stern and bow lines are doubled up and adjustable from the deck.


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Speaking of adjustments, you will no doubt have noticed the winches on deck. These are ideal for windy or surging docks where adjustment under load is a requirement.

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Note the angle of the spring lines. These are attached to the widest part of the hull to minimize lateral angle, which is more comfortable than positions further off forward or aft which induce a side load as well as fore and aft load.

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Both polyester springs are attached to the welded stanchion base. These are 50mm (2″) schedule 40 pipe welded all the way through the rub rail and very strong.

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Finally, a shot of the normal spring, rigged for ease of docking and adjustment. The stanchion bases are used to position and turn the line, which is terminated at the deck winch. The bowline knot is about 3 meters (ten feet) off the dock so that we can reach  it from the boat. In normal docking with these knots and bow and spring lines doubled up all four lines can be adjusted or cast off from the deck. However, if the boat is surging the lines squeak as they stretch slightly around the stanchion bases.


Posted by Steve Dashew  (June 11, 2010)




7 Responses to “Dock Lines For A Bouncy Harbor”

  1. Tedgo Says:
    I was wondering what knot you are using on the spring lines in picture 5. Is it a normal bowline or a Panama/Eskimo bowline. Just curious as normal bowlines can shake loose.

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    Steve Dashew Reply:

    Those are standard bowlines. If this were an anchor rode we sieze the knot or at least put a half hitch on the end. However, we have not had problems with dock lines coming undone in the last 40 years so they work for us. Note that the bowlines in the Spectra are left soft. Otherwise, under load they tighten up and cannot be undone.

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  2. Richard Elder Says:
    Just returned from a delivery of a large Swan with the owner aboard who refused to use breast springs when docking. At least the resulting damage was to his bow rather than to the dock—. Which brings out two observations about your post on Docking procedures: 1- Relying upon a stanchion base to attach spring lines to is a poor practice. With your strong bases it may work, but the practice will rip the average stanchion out of the deck of a production sailboat in an extreme surge. Why are no cleats welded to the rail for this purpose on your design? 2- The hitch used to attach the primary dock lines to the dock cleat is improperly tied. When the tie is made backwards like a granny knot extra hitches are needed resulting in an unsightly pile of line that precludes your neighbor from attaching to the cleat if needed for the better angle you suggest. The proper way to tie a dock line to a cleat is to take a full turn around the cleat to create the restraint friction, followed by two half hitches with the lazy end finishing cleanly alongside the first crossover hitch.

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    Steve Dashew Reply:

    Hi Richard: With two inch (50mm) schedule 40 pipe welded through the rub rail (forming a bond beam) we have a huge factor of safety on the break strength of the dock lines. But we agree for a normal boat this would be poor practice. The bowlines are tied backwards as they stay lose this way and do not lock up. Tied properly, with a surging situation,the tighten up over time. Finally, half hitches on cleats are debatable. In some cases they will work themselves tighter and require a knife to get free.

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  3. Mick Says:
    Hi Steve – In picture 2 there’s significant rust stain. Regardless of aesthetics, I’d assume something is corroding badly. Just curious as to the cause. BTW, great website, I’m enthralled by the whole build process.

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    Steve Dashew Reply:

    Hi Mick: That stain is from a now replaced heater exhaust stack which was not stainless enough. In the next week or so we’ll get after it with Ospho.

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  4. Richard Elder Says:
    Looks like there is some confusion about my comment about the proper way to tie to a cleat. Hard to describe without an illustration. This happens to be one of my pet peeves along with halyards banging against a mast on a boat in an adjoining slip— comes from living aboard in too many marinas instead of crossing oceans—-. I’m not referring to the bowlines, but rather the dock line with the green tracer where it is being used to attach the free end to a dock cleat. As tied, the line passes around one horn, over the center of the cleat, around the other horn, and the process is then repeated five times creating a bulky stack of “half hitches” that resembles a granny knot (a square knot tied backwards) If the tie is done as follows it has equal or better holding power, looks seamanlike, and leaves room for the cleat to be tied to with an additional line. 1- Pass the line around the cleat horn opposite the load direction with the line coming from the boat side. 2- Take a full turn around the cleat base. 3- Cross the line over the center of the cleat and around the horn that is closest to the load direction. 4- Finish by taking the line around the horn opposite the load direction with the lazy tail exiting parallel to the previous crossover line and lying over the top center of the cleat forming a “half hitch”. The procedure is similar to the illustration except by starting with a full turn around the base you do not end up with a stack of ass backward “half hitches” working at cross purposes. Sailors sure can be picky over details sometimes, can’t they! Fair winds, Richard

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