Duet Docking - A Pictorial
These pictures are courtesy of Lee, First Mate of the motor yacht, Smr Brezze, which was tied up in the slip next to ours at Sunset Marina in Key West. While we're not certain why she took them other than because she is a very nice person (although possibly they were for her insurance company once she saw us approaching) we greatly appreciate her kindness and wish her and Captain Ed well on their travels.
Here Duet is approaching the outer marina breakwater.  You can just see the marina chase boat ahead of her (more on that below).  The outer marina breakwater is in the foreground.  At this point we are about 1/4 mile from the marina entrance.  We are traveling at about 6 miles per hour, slightly slower than our standard cruising speed.
This is the actual entrance to the marina.  It is about 100 feet wide. Duet is 15 and 1/2 feet wide.  On this particular day there was very little wind (the kind of day we really like) so fitting Duet through this opening was simple.  A crosswind of any strength would have made life more interesting.
Here we see Duet just approaching the marina entrance.  Just ahead of her is the marina chase boat which came out to guide us in.  The entrance is marked but the marks aren't on our charts since they are private.  The entrance to this particular marina is surrounded by coral reef.  Hitting a reef has several disadvantages.  First, it can make a serious hole in the boat.  Second, it damages the reef.  Third, the Coast Guard fines for damaging a reef are in the thousands of dollars. Hence the guide boat.
In the next photo, Duet has just made a sharp right (starboard) turn from the entrance into the alley for her slip. At this point she is in forward gear with the throttle at idle and Ron is using her bow thruster to turn her. When she is moving this slowly there isn't enough water flowing over her rudder to steer well. It's possible to speed up and gain steerage but since boats don't have brakes this decision has significant implications in close quarters.

Note the fenders on her starboard side as she will tie up to the dock on that side.  The principle with fenders is the more the better, preferably on the side of the boat which meets the dock. Normally when we enter a new marina, Nancy puts out fenders and lines while Ron drives. Nancy can drive but doesn't have as much experience with close quarters as Ron. Hence with new marinas, we adopt the roles we are best at, to reduce both the dockside entertainment factor and the insurance claims.
Duet is now approaching her slip, which is to her left, in front of the photographer. Nancy is gently telling Ron how far he is from the dock so he knows when to turn, because once Duet gets within a certain distance of an object Ron can't see it over her bow. Duet is hardly moving at all by this point.  Ron will use the bow thruster to turn her bow to the left from here and very little propeller to ease her into the slip.  When there is wind it is key to keep her bow into it to prevent her from being blown onto something we don't want to hit, such as another boat or the dock.  If it's not possible to dock into the wind then the propeller must be used more authoritatively, with the attendant risk of losing control.  Boat handling in close quarters is all about experience. Anyone, even with extensive experience, who says he's never hit anything is either lying or has never taken his boat out of the dock.

If you look closely in this photo and the next one, you can see the radio headset on Nancy's head.  Radio headsets are not as much fun for bystanders, but are less embarrassing for docking participants.  These headsets are available for $20 per pair at FAO Schwartz. The key is to be sure the batteries are charged before undertaking a complex docking or anchoring maneuver.  We think these headsets are superior because they allow both parties to speak and hear simultaneously.  This feature is very important during stressful situations, such as docking, even for couples like us who've been together for nearly 25 years.
Now Duet has turned to the left and lined her bow up with the slip.  Nancy is positioning to throw the bow line to a dock person.  In this case we used a bow line rather than a mid ships (aka spring) line.  Choice of the first line to throw depends on the wind and the dock but we prefer to get the amidships line on first. Once that line is tied Duet is pinned by her rather substantial middle and can't swing very far. If she is pinned at her bow or stern only, the other end can swing quite a distance, usually in the opposite direction from where we want it to go.  Also note that the line passes through the hawsehole and under the rails; if it goes over the rails the force when Duet takes up on it will quite likely bend the railing.  Since Nancy just polished those rails she is cautious about this.
And here's the throw!  What a great action shot, with all the credit to Lee who took it. The throw comes early as Duet is just starting to enter the slip. This is a judgement call; you can wait until the boat is further into the slip but you may run out of time to run to the stern and get another line to the dock to stop her before she runs out of room in the slip.  In the perfect world, all 3 lines, the bow, the amidships and the stern line, are neatly handed (no throwing) to waiting dock persons. In the real world, if you can get one or two lines to someone (preferably someone on the dock) you are doing relatively well. The other key is to try not to hit them on the head, or if you do, don't lasso them around the neck.
This is the marina breakwater (the entrance is slightly to the right of the photo) on a day when the wind was in the upper 20 knots, with gusts to the mid 30s.  This was during the passage of a low (called a norther) and we were very glad we were safely tied up, not trying to enter the marina.
What we don't have pictures of is the process after that first line is thrown.  By the time she's fully tied up Duet should have 6 lines deployed, 2 forward, 2 aft and 2 amidships, plus at least three fenders in key spots.  She also has 2 50 foot electric cords with a separate dual adapter, a dock hose and sometimes a telephone line. Getting her settled is a complex process, including stepping back and contemplating the different forces of wind and wave which might impact her during her stay, and pulling on various lines to simulate pressure from varying directions.  Finally, she gets a fresh water wash down as soon as possible to remove salt from her  deck.  This entire process reminds Nancy of an old calvary saying regarding who gets what when at a campsite; "first the horses, then the men, then the officers", where Duet is the horses, Maggie and Tristan are the men and Nancy and Ron are the officers, so it's pretty late in the day by the time we get a well deserved sundowner. 
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