How do I plan my passages?

Post date: Jul 05, 2015 2:53:59 PM

You might think it’s just a matter of choosing the next harbour about 40 miles on, getting up at 8 for breakfast, away by 9 to be there in time for tea.

Not so. Passage planning is a big part of this challenge and it’s something I really enjoy doing. I spend a lot of time on the task. Sometimes it may only take 15 minutes but most times it’s much longer and on occasion I’m sitting in my boat spending hours analysing the options.

There are many variables and it’s always a compromise. In effect, you are looking for the most parsimonious solution. An optimisation process, really. It’s fascinating. There are passage planning computer programs, except no where near sophisticated enough to take into account everything I'd really need, besides, it would spoil the fun. For my passages, there are a lot of considerations to take into account and that’s what would be difficult to automate - the breadth and depth of the “inputs” is considerable.

So, starting from the top I need to:

To do all this I have:

Taking all the above into account, one comes up with a place to head for and a time to start with an ETA. That’s what I tell the coast guard before I set off. What makes it more complicated is that if your passage is going to be many hours (as mine usually are) you have to take into account the changing weather and tidal situations over that period based on where you think you will be.

For example, for passage 24, I could (unusually) totally compromise on the wind and tide direction. Because the other factors overwhelmed their disadvantage (enjoyable weather, short passage). Of course, If I had wind and tide with me for passage 24 I’d be laughing, but then I’d probably plan to get farther (because it would have taken me a third of the time to do the passage). then again, I would probably have had a completely different medium term objective if I knew the winds were not against me.

Apart from the obvious objective of getting further around, the wind strength and direction is the single most determining factor of what I do.