NavList:

Here's a common situation in a yacht passage, based on some previous passages of mine, that explains my interest.

I have sailed southwest from Point Lonsdale 38 17 S 144 37 E planning to round Cape Otway and then sail WNW to Portland 38 21 S 141 37 E. The wind has been building, blowing its typical wintery NWly but a front is clearly approaching from the SW on our fast reach to Cape Otway. Nearing the Cape, the wind backed sharply with the front's passage and blew hard from the SW for several hours. I am now beating into a force 7 unable to make any westward progress and slowly moving off course. In Bass Strait, the wind is squeezed and accelerated by the topographic effects and the waves stand up short and steep as the southern ocean meets the shallow continental shelf. The next day, as conditions eased, the wind moderated and backed further, the sky cleared and the Sun emerged from behind us close to noon. It shone on the high white tower that is Cape Wickham lighthouse at the northern point of King Island. The GPS position from my watch agrees broadly with my bearing to the light crossed with an approximate noon latitude sight. I need to set a new course for Portland from my position 60 miles SSE of where I had expected to be.

During the long hard beat, much water washed over the boat and made its way into the cabin and over the chart table. My chart was wet so that I didn't want to use it for plotting for fear of tearing it. My calculator flickered briefly then died. I determine my new dLat, dLong and dep. What course to steer and how far is Portland? I can use a dry blank plotting sheet to do the graphical method. Or can I use my TT?

Of course, even a very rough and ready eyeball of that table will be sufficient in practice.