Tides – Timing is Everything

The English Channel (Le (la?) Manche on this side of it) has a reputation as a tough place for boating and I'm learning why.

Brest was my 1st introduction to major tides...Eric and I went for a walk (2am after many days at sea) and he marked a spot on a piling when we left the boat. When we came back within the hour, the spot was about 3' “lower”!

We watched the depth sounder for a bit and watched in amazement as it changed!

The marina had a wide ramp which was used for “careening”, boats would tie up at high tide and do a complete bottom paint job on the low tide and sail off on the next high.

Very impressive, but it turns out that the tides in Brest (about 17' now) pale in comparison to those I was yet to experience.

In Paimpol, the tides now are running 25' right now!

And, time of the month (moon phases) have up to a 15' difference!

Neeps have the least tides and spring have the most (we're in spring tides right now).

So, arrival and departure times from ports becomes quite significant.

Aside from the depth issue, currents run anywhere from 2-5 knots, changing direction every 6 hours.

Beside the obvious inflow\outflow from the bays and rivers of ports, it turns out the entire English Channel changes direction every 6 hours!!!!!!

So, planning a port change turns into a bit of a math problem.

Not only do you need to take into account the departure and arrival times, you need to determine which direction the current is flowing between the ports.

It may well turn out that the best time to depart for the correct current just happens to be at low tide, when there is (literally) no water to get from the marina to the ocean!

Some plans end up requiring a departure to an anchorage for a wait. Or, arrival at a destination with an anchorage wait.

Ports are either on “natural” rivers or bays or are only accessible for a few hours twice a day.

Brest and L'Aber W'rach were natural harbors, but Morlaix, Ploumanac'h and Paimpol are not.

Ploumanac'h has a wall that dries at around 6'. Which means you need to arrive on a tide with 11' to get over the wall.

Morlaix and Paimpol have locks and you need to know when they operate.

Paimpol leaves its locks open for about 2 hours around high tide, and then it operates them for 2 ½ hours on both sides of the high tide (24 hours a day).

In Morlaix, we arrived on a high tide around 10pm, expecting that the lock would operate at each high tide. It is 3 miles up a river that dries up and it turned out the lock only operates if the high tide is during “normal” working hours!

We had 2 choices, one was to cut and run back out the river for an anchorage or tie up next to the lock and await the next high tide.

We choice the later, even though we thought the spot might dry out (we prepared the boat to lean against the wall if that happened).

We were stuck there with one other unhappy person (who we became great friends with over the next few days).

So, we went down and back up (had a close call with getting a lifeline snagged on the way up) and locked through in the morning.

The lockmaster explained that he doesn't work at night....except that the next night he opened for boats to come in!

The other (French) boater was furious and apparently has contacts...he kept saying he wasn't “done” with this!

Anyway, we're learning a great deal about boating in high tides.

We will cross the Channel from Cherburg, which has the greatest tidal currents.

Interestingly enough, a yachtsman that has made the crossing many times and has done all sorts of calculations says you just keep a constant bearing and let the tide carry you one way and then the next.

He related a story about someone that corrected for currents on both sets and ended up taking 28 hours to do a crossing that should only be half that!

I'll let you know how it all turns out...unless it goes badly!

-Scott