We left Treguier at about 0930 on Friday and, once clear of the river (and all its off-lying rocks), set a course for the Cap de la Hague, the South Western tip of the Cotenin peninsular. The straight line track takes you a bit close to some rocks half way to Guernsey and then straight through the Big Russel channel between Guernsey and Sark. On the way you get a good sight of pretty much all the other Channel Islands. We arrived in the Big Russell as the tide turned in our favour and started to push us towards the gap between Alderney and the mainland, known as the Alderney race.
Tides are effectively a collar of water drawn out from the planet by the gravitational pull of the sun. The collar goes round the world and the planet rotates once a day resulting in two tides a day where there is open water. Every two weeks there are larger tides (springs) when the moon is in line with the sun and its gravitational pull contributes, and in the intervening weeks the moon’s contribution drops to a minimum when the moon’s pull is at right angles to the sun’s (neaps) before increasing again until it is in line once more. The magnitude of tides is further effected by the earth’s elliptical orbit around the sun – when we are closer to the sun (the equinoxes) the gravitational effect is greater, and the tides bigger, resulting in higher high tides, and lower low tides.
We’d had to wait in Perros Guirac because the neap tide had not been high enough to reach the level of the water in the harbour held behind the sill. The following day when it did open there was only 30 minutes of open time predicted, and when the sill did open there was actually a 30mm or so difference in height of water, resulting in a huge inrush of water as boats were manoeuvring to hold position in the queue to leave. I’d seen what was happening and tucked out of the way with a couple of others, but there were a couple of collisions, one of which sounded quite substantial, from boats being swept around in ways their skippers clearly hadn’t expected.
As the collar of water, that creates the rising tide, approaches the French coast heading east, the opening for it to pass through to get to the east narrows progressively, and then it hits the Cotenin peninsular and has to all work north to get around the top and on towards Dover. This creates the Alderney race where currents of 10 knots have been recorded.
I’d timed our passage so that we’d ride the tide north through the race and maximise the tidal contribution, but that meant that we’d not get to Cherbourg till about midnight. I was quite pleased that aside from some collision avoidance course changes we didn’t change course from the entrance to the Treguier river till the Cap de la Hague – some 70nm. Our ground track describes a curved track as our passage over the ground is affected by the tide sweeping us one way and then the other. The shortest distance for us is the straight line, through the water, so there’s some satisfaction to be had from getting your sums and judgements right and not to having adjust your course.
In Treguier I’d been a but puzzled at the large number of near identical aluminium exploration yachts, all in the 45-55′ range. Looking a bit more closely they were all made by Boreal, which turn out to be made in Treguier. They look like really tough go anywhere boats of a sort I find really quite attractive – lifting keels, unpainted aluminium hull and big deck houses providing a lot of protection to the cockpit, and a great view out from inside. Very different to Trouper, but would enable a very different kind of exploration.
We got to Cherbourg and were tied up for about 1130, having made better time that we’d expected. We we both tired and had a quick shower on board and went to bed. On Saturday morning we got up, I filled Trouper up with water, and did some nav prep whilst Kathryn made a quick sortie to the boulangerie for bread and patisserie. We then settled up in the marina and joined the queue for having your passport stamped by the PAF. They turned up bang on time at 1030, and we were clear by 1035 and back to the boat which we then took to the fuelling berth and filled up with diesel (there was little wind in the forecast) and were away. It was about 1130 by the time we got out of the harbour, about an hour or two out of Cherbourg the wind filled in and we got 3 or 4 hours under sail before boat speeds started to drop and we needed to motor once more.
Our track from Cherbourg to Poole, showing the effect of the tide.
We made Poole harbour entrance with the rising tide as I’d planned and had enough water to safely get over the shallow patch off Brownsea Island and into South Deep, which is a favourite anchorage of mine. We met some good friends sailing another Swan who’d anchored there on their way from Salcombe back to the Solent. We anchored nearby and they came over by tender with a bottle of rum that they’d started earlier. A couple of very pleasant hours passed and the rum was dispatched and some of Trouper’s gin stocks were also depleted. They left Poole in the morning heading home and we took the rising tide round the corner into my favourite corner of South Deep. I blew up the SUPs and we spent another night there and left on Monday afternoon, following more SUPing, heading for the Solent.
