function plotMapData(data) {		
		var polylineData=[];
		
		// mark each port on the map
		for (i=0;i<ports.length;i++) {
			map.setCenter(data[ports[i]], 13);
			var marker = new GMarker(data[ports[i]]);
			map.addOverlay(marker);
			marker.openInfoWindowHtml(ports[i]);			
//			polylineData += 'new GLatLng'+data[ports[i]]+', ';
                        polylinData.push(data[ports[i]]);
		}
		
/*		// strip the trailing comma from our polylineData string.
		var stringLength=polylineData.length-2;
		var polylineData=polylineData.substring(0, stringLength);		
*/		
		// draw the line
		var polyline = new GPolyline(polylineData, "#FF0000", 10);
		map.addOverlay(polyline);
	}
}