Passage to Charleston, S Carolina
Shelena
Phil Scourfield
Tue 14 Jun 2016 14:33
14th June, 2016
The passage from the Hyatt slip in Savannah to Charleston, South Carolina was to be about 110Nm which was likely to take 13 -14 hours. This is approximate. Before departure I set out waypoints to create a route from our present position to the planned destination. This takes time to do because the straight line route may have obstructions, too little water depth, strong currents or simply uncooperative wind direction. The route is rarely a straight line so waypoints need to mark each change of course. I check my route created on our Raymarine plotter at the navigation table and the route is repeated at the helm where there is s repeater chartplotter screen. As a backup I have a yacht pc with a program called Maxsea. It too will have a similar route planned on it. It is a separate with different features but it makes for a useful double check. Nowadays in the USA it is difficult to buy paper charts unless especially ordered on line.
During our passage too I spend time checking our planned route against actual course over the ground. Helen does the same during her watch. Frequently the planned route and COG vary slightly. Our navigation also involves constant eye ball watch at sea for other vessels. Reliance on the screens are especially so at night. The chartplotter and pc have the capability to identify vessels using AIS (automatic identification system). AIS usually includes the name of the vessel, it's unique call sign and its MMSI (Maritime Mobile Service Identity) which is a unique number that allows direct VHF radio calls to other vessels. We use the radio frequently to call other vessels to make them aware of our presence or to request that vessels change course if we are on courses that are too close for comfort. I like to have a CPA, (Closest Point of Approach) be no nearer than 2Nm from a large vessel.
On this passage we saw no AIS profiles at all. Yes, we were coast hugging where larger commercial traffic will not be found, but even so to see no vessel for 12 hours seemed unlikely. It turned out that our AIS had failed. Fortunately, we get is replaced in Charleston with excellent support from Oyster and Raymarine.
The interesting thing to note about the US east coast to date is just how shallow it is. We can be 20Nm out to sea but only in 15 metres of water.
All is well on Shelena.