Monday, June 1, 2009

Turning around in close quarters

With my office window overlooking a channel with 6-knot tidal currents and a fairly low bascule bridge, I get to see lots of interesting things. If the tide's going out and boats are waiting for the bridge to open, nearly everyone will race downstream with the current, perform some highly interesting maneuvers involving the entire width of the channel and generous application of emergency full ahead and reverse, especially with a following wind, and churn back upstream, kiting from side to side, until the bridge opens and they all charge for the gap like so many hamsters heading for a gas turbine intake.

Outta my way! No, outta my way!

Five minutes after this brilliant display of precision seamanship, a small bulk cargo ship will glide placidly through, engine barely ticking over, crew waving down at me in my second-story window while the bow is already passing the bridge 100 yards downstream. The channel dead-ends in a tiny harbor with two branches that are nowhere wider than the ship is long, but I know they didn't back 6 miles up the channel, so they must have somehow turned it around. So how come these little boats that could fit four end-to-end across the channel have so much more trouble turning around than this massive ship, which practically scrapes both sides of the channel and has more steel sail area than the entire fleet?

Room to spare

Next time you get in a tight spot and need to turn around, try this:
  1. Get a cup of coffee and have it close to the helm.
  2. Slow down to a near-complete stop, and throw the helm hard over to one side (to starboard if you have a right-hand prop, or to port for a left-hand prop). If you're not sure, check under the boat. If you're still not sure, install a bow thruster.
  3. Apply generous forward power only until the boat starts to turn, but not until you have on any appreciable forward motion.
  4. Don't touch the helm!
  5. Now give it plenty of reverse, again watching to make sure the boat doesn't start moving backwards or turning in the other direction.
  6. Repeat from step 3 until you're facing the way you want to be.
  7. If anything goes wrong, take a sip of coffee. It helps you to focus without panicking, and it makes people watching think you know what you're doing. Try it – it really works!
The trick is that prop wash makes the rudder work really well in forwards, kicking the stern around, while prop walk (a term that describes a couple of different forces) continues to pull it sideways in reverse before the boat actually starts backing.

I'm giving her all she's got, Captain!

So how did that big ship turn around so easily? Answer: they practiced this maneuver and others before heading out in such close quarters with so many people looking on!

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