Updated: Apr 19
It comes up regularly on phone calls, the question about what dock hold is. Let me take a shot.
Basically, "dock hold" is a mode of operating the bow and stern thrusters together above and beyond the usual thruster operations of kick the bow left/right or kick the stern left/right. Once you get the boat all or at least most of the way into the slip along side the dock finger, you hit the you hit the LEFT HOLD or RIGHT HOLD button and the bow and stern thruster will both push the boat up against the dock. You can adjust the amount of force through I think 8 levels to overcome windage and such.
For me, this capability was all about single-handing my return to the dock from a sortie. What you usually get at my marina was lot of folks running down to meet your boat and as you got into the slip, them taking ropes off the deck... pulling on the ropes as they saw fit.... tying the ropes off as they saw fit. It's extremely nice of them but at the same time, any docking plan you formulated upon re-entering the marina is out the window and it's essentially pure random. Dock hold will let you snug the boat up to the dock finger while you do your own lines. My method was to ensure I made a breast line fast before dismounting and tying off my other lines. I did not want to be the guy who let his boat take off without him (despite the privilege that being officially "not under command" affords in rules of the road).
My last full season operating Clock Work, I had a stern thruster added, and at the same time I replaced the bow thruster. It was fully operational and is sitting in my barn waiting for a project to use it on, but replacing it allowed me to upgrade it from all-or-nothing operation to proportional (the thrust force is proportional to the displacement of the joy stick). Proportional buys you more battery life and greatly reduces the possibility of either depleting your thruster battery before you're done maneuvering or "thermaling out" where the thruster shuts off to protect itself because your pushing too much current through it. What I wanted it for was only the dock hold. Frankly I didn't want it for and didn't use it for close quarters maneuvering. I much prefer to use my main engine and rudder-diverted thrust in tight spaces and if I have to the bow but not the stern. It's about keeping a potentially necessary emergency skill sharp.