Seamanship

Pete asked a really interesting question about how we picked up the buoy on Saturday.

We were running on starboard tack up the Ray and we turned to port to pick the buoy up.

Pete wanted to know why we gybed instead of tacking.

I had to think really hard about the answer, and then just as hard about how I actually made the decision at the time!

Here are my thoughts on the theory.

We were doing about 3 knots up the channel. If all of this had been due to the wind then we would have had 3 knots of speed to kill. So we would have wanted to go well past the buoy and beat back up to it. For this, we would have wanted to be in the middle of the channel so a tack to starboard, followed by a fine reach and then turn up at the last moment to stop dead would have been the right approach. Thats what the theory says, and its great for man-overboard and for picking up a mooring at slack water, or in the Med', Baltic, Caribbean, ...

In fact, our 3 knots were a mixture of tide and wind. And the tide had kept washing us towards the buoys so I knew it was setting a bit across us, starboard to port. The sail set told me that the wind was similar.

So by turning to port and going round more than 180 degrees we ended up head to wind and head to tide with the tide now subtracting rather than adding to our momentum. We were effectively already on that very last bit of the track with the tide washing us away from the buoy and the last of our momentum taking us towards it and the wind bringing us to a halt.

Turning to port put us in danger of going aground. It was OK because we didn't have far to go.

The gybe was very gentle because the wind was light and the apparent wind was even less because the tide was subtracting from it. (Add the wind to the tide to get our progress over the ground, subtract to get the speed of the wind over the boat).

How much of this did I work out at the time, consciously or unconsciously ? I remember thinking that the wind and tide would both be slowing us down once we turned. I also know I wasn't worried about what the sails were doing. Another way of putting it would be to say I decided it was a tide dominated situation and I pretty much ignored the wind.

It worked - maybe I'm starting to get the hang of it.

That's one of the things I love about sailing, it's seat of the pants classical mechanics!