Tidal calculation channel crossing

[STATUE]

Well, thank you everyone for responding, certainly given me food for thought.

 

[Topcat47]

10 deg = over 60 miles ?????

I don't know how good you are steering, but I find +/- 10 degrees is the best I can do with my boat compass. There's little point in minimal course corrections every five minutes and what I do is a practical approach to channel crossings. If you keep an eye on your progress, and I do, course corrections can be made every couple of hours if you really get it wrong. The tides on the french side tend to be a bit stronger than this around the IoW but for a 26'er the 14 hour passage is a reasonable starting point, as is the 10 degree window. I've sailed with skippers who course correct for tide on a hourly basis but if you lay your best course on the chart (I use a feint line), yo can judge the tidal flow and your progress quite easily, using hourly or two-hourly fixes. I'm cruising, not racing so ETA is a moveable feast that bothers no one else.

 

[johnalison]

I think you are being a bit defeatist. On a reach I reckon to steer within your 10 degree range or better, but I expect my course steered to average much closer. Because errors may add up rather than average out on a passage, I prefer to work to as much accuracy at each stage as possible, whatever I may have implied earlier.

 

[NOHOH]

The passage planning I used to do when I had no gps and only a paper chart and a set of tide tables to get from the solent to Cherbourg was to arrive at the Needles on the last of the west going tide...then steer 180° for about 10 to 12 hours....I knew that any `lateness` would be failsafe as it would again encounter an east going tide. Simples. I did this many times and the only time it went wrong was when I accidentally left my portable LW radio too near the cockpit compass after listening to the early morning shipping forecast... giving an an offset..and making me 20 miles further east than I had thought. You only do that once.