Portland Harbour Sailing Guide
P
ortland Harbour and Weymouth Bay are the main areas used for sailing. The harbour covers an area of 8.6 square kilometres (2,125 acres), and is ideal for sailing as it is exposed to reliable winds from most directions, but is sheltered from large waves and currents by Chesil Beach and the breakwaters. Race Areas We are fortunate to be able to lay sheltered courses inside Portland Harbour as well as being able to lay multiple courses in the more challenging conditions of Weymouth Bay. Because of this flexibility in course areas, there are options to move races around in the event of bad or difficult weather conditions.
Inside Portland Harbour because the prevailing south-westerly wind comes over Chesil Beach, the water inside the harbour is offered some protection and tends to be quite flat. There is also the option to take racing outside Portland Harbour and into Weymouth Bay, though there is tide across this stretch of water. The strong feature of Weymouth and Portland is that it has ‘clean winds’. The prevailing south-westerly and westerly winds blowing across Chesil Beach give a limited ‘fetch’. Weymouth Bay is a relatively sheltered basin with clean winds and small waves. This means that sailing conditions for the venue are almost neutral, so that local knowledge is of no great importance.
Sea State and Tide The location is dominated by the long, arching shingle crescent of Chesil Beach of the Jurassic Coast, which stretches from West Bay in the northwest to Portland in the south. The beach is only 200m at its widest and rises to about 11m above sea level. On the seaward side it shelves steeply away for 300m until it levels off to a depth of about 18m. At the tip of the beach, Portland Bill juts out, where a tidal stream runs very strong and eddies of great extent form in the bays on each side of the peninsula. The streams run south for the majority of the time and there can be violent turbulence off the Bill, where these currents meet the east and west-going coastal ones. Portland Harbour has a lot of things in its favour. It is sheltered from the predominant south-westerly winds by Chesil Beach; added breakwaters give protection from the south-easterlies. These features also stand as barriers against strong winds, large waves and currents. Together with the strong limestone of the Isle of Portland, they affect tides in Weymouth Bay and Portland Harbour, where the maximum tidal range is small, less than 2.5m at springs and less than 1m at neaps. Tidal streams in Portland Harbour are irregular; the spring tide rate is approximately one knot and extends for only a short distance into and out of the harbour, but there are eddies off the heads of the breakwaters. Inside the harbour, tidal streams are imperceptible. www.wpnsa.org.uk
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