Friday, June 6, 2014

Navigating in a High-Tech World: Where the Heck is the Deep Water?

Southern Georgia: throw some deep water our way, please. Creeping along with one foot of water under our keel is not my idea of fun recreational boating.
Unrelenting shallow marshes and mud flats

At the Annapolis boat show last year, I took a seminar called "iNavigation." Cruisers today enjoy three redundant systems for finding channels, identifying buoys and markers, and calculating a course: 

1) Traditional: paper charts, supplemented by the skippers's grey cells processing visual cues such as channel markers, other navigational aids, stars, and birds standing one-legged on a shoal. Used for thousands of years and probably responsible for thousands of wrecks, not to mention arguments between cruising couples and outright mutinies.
ICW chartbook

2) Modern: GPS, a miraculous invention, using satellites, NOAA charts, and little machines that rely on lots of fresh batteries. 

3) State of the art: electronic charts loaded onto a personal iPad or iPhone, allowing frequent updates.

We use all three. We are primarily using the iPad to find the edges of the shallow channels. The most reliable, or so we thought.

We came through the shallowest section at low tide, next to Jekyll Island, Georgia. Not the best timing. Still, how can most sailboats (usually 5- to 6-foot-deep keels; ours is 4 feet) ever get through? Answer: many go offshore in the ocean! Take your choice: shoals or swells?

ICW depths in Georgia continue to be at least 6 feet less than the paper chart and iPad say. Pope says the southern Tea Party won't allow dredging in the Georgia state budget. Which reinforces the fact that grey cells and visual cues continue to have their uses.
The skipper searching for deep water with ordinary eyesight and extraordinary brain power

This trip is easier than last fall; I have lost most of my extreme fears, including the fear of being stranded on a sandbar in a remote marsh. Mostly. Only cried once, when I was at the helm today and the depth got down to 0.6 feet under the keel. I made a decision to hug the red buoys at one side of the channel, when clearly any EXPERIENCED captain would have known that hugging the green buoys (other side) was the ticket. Hrmph.

Pope saved the day by grabbing the wheel and steering directly over top of a shoal, according to the iPad chart. The grey cells at work. Later, he revealed his secret: pure luck. Clearly the shoal had readjusted itself into a more comfortable position without telling NOAA to update the charts.

We make good time whenever the current is with us, and thank goodness we entered Georgia's Mackay River on an incoming tide; 2-1/2 knots of current in our favor!! We flew along at 7.2 knots--faster than our hull speed (the theoretical maximum speed of an individual boat). With the current against us, we would have been drifting backward, headed back to Florida.

I've had enough of the heat, horseflies, and bridge openings there!

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