The RYA's former Yachtmaster chief examiner, James Stevens answers your questions of seamanship. This month with a fresh onshore wind and a strong ebb is the harbour bar passable?
Fred keeps his Bavaria 36, Harmonic Constant, in Chichester Harbour. The boat is 11.3m (37ft) long with a draught of 1.6m (5ft 3in).
Chichester is a large, attractive harbour with several marinas and a large number of moorings. The entrance can be busy and is quite narrow with a harbour bar.
The channel over the bar is dredged periodically to a depth of 1.5m below chart datum, but the pilot book warns that the depth can change after bad weather.
The tidal stream at the entrance runs at a maximum of six knots.
Fred has kept his boat in Chichester for years and has never had a problem sailing over the bar even at low water, although it gets pretty shallow.
Today, though, it might be different.
He’s coming back across the Channel from Cherbourg and as he enters the Solent approaches, the spring tide has already started to ebb.
More concerning to Fred is that the wind has freshened to southerly 25 to 30 knots with occasional gusts of 35.
Fortunately the wind has been favourable for the trip back and Fred is making good progress with just a working jib set. Visibility is good and as they approach Chichester, Fred can make out the familiar navigation marks leading him in.
There is some white water on the shoals either side of the channel but the navigable part doesn’t look too bad. Inside, the harbour looks welcoming and after a long tiring passage the crew are keen to get ashore.
The alternative is Portsmouth about 10 miles away with all the hassle of public transport back to their cars in Chichester.
Should Fred attempt it and sail on into Chichester or take the cautious approach and reroute to Portsmouth?
Once the home port is sighted after a long passage, both skipper and crew start thinking their problems are over.
Fred knows the way in and the home berth beckons. Having to sail further is a pretty unattractive option.
From seaward, harbour bars can often look passable but in a fresh onshore wind and a strong ebb they are lethal. If Fred attempts it he could easily face a knockdown.
If the tide is low the keel could strike the bar with catastrophic results.
Pilot books give strong warnings about the dangers of harbour bars, but in most conditions they are pretty benign, so skippers who cross them regularly chance their luck a little more than they should.
On the top of the flood Fred could probably have made it inside the harbour but every instinct should say don’t even think of trying it on a spring ebb in near gale conditions.
He must therefore break it to the crew that Chichester is simply not possible and they must continue to safety.