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OVERVIEW
The cut through the flats requires moderately good visibility and an adequate rise of tide to pass over its shallowest point of 0.4 LAT to the northwest of Gunter’s Island. As it is shallow with parts that dry at LAT, with close-lying rocks and ledges, good charts/plotters are key.

It is essential to understand that this route relies primarily upon eyeball navigation with clear visibility and moderate conditions. The route waypoints are a great addition but are not to be relied upon in isolation. They are only intended to assist in identifying the key turning points in the passage and the ledges, rocks and shallows are all best negotiated by keeping a watchful eye. Do not let this be in any way discouraging as the water here is crystal clear over white sand and the ledges have a large amount of weed that cling to then. So everything is highly visible.

Be prepared to take this route under power, in a steady fashion identifying the rocks and marks through the passage along the way. Conservatively planning for a maximum drying height of 0.5 meters LAT or a little more will provide adequate water for most leisure craft at half-tide with the prudent making the approach during the rise. However, this is not a passage a newcomer should attempt at night nor on the ebb.


GENERAL DIRECTIONS



With sufficient tide run into Crow Sound’s 'Hats' waypoint, about 200 metres northwest of Hats south cardinal, VQ(6)+LF1.10s. Then steer the on the 322° (reciprocal 142°) transit of the gap between the two highest summits of Men-a-vaur in line with St Helen's Landing Carn which is a prominent lump of rock Landing Carn at the southwestern end of St Helen's.




Just over ¾ of a mile further along, the transit passes 300 metres to the southwest of Gunter's Island. Guther's Island is easily recognised by its twin flat-topped rocks, 12 metres, and its surrounding rocky ledges. The alignment keeps sufficiently clear to avoid the Lower Ledge, drying to 3.3 metres, and then the Higher Ledge, drying to 4 metres, that lie midway between the track and the island. The shallowest and only drying section for this route lies beyond Higher Ledge where it dries to 0.4 LAT. It is passed over once the vessel arrives at the 'Central' waypoint located ¼ of a mile further along when St Mary's TV Tower should be due south.




Arriving at the 'Central' waypoint provides the aforementioned option of staying on the 322° (reciprocal 142°) transit between Men-a-vaur and St Helen's Landing Carn for St Helen's Pool (St Helen's Island). The alignment will take a vessel safely into the anchorage, 1 mile from this waypoint, passing its shallowest part, drying to 0.7 metres, east of the awash Scattered Rocks that lie close southeast of the always visible Great Cheese Rock, 3.2 metres. The alignment is at its narrowest part between the Chinks Rocks, awash LAT, and Hunters Lump, dries 0.9 metres which are close, either side of the transit. The south end of the Chinks Rocks are ½ a mile due east of the ruin on Block House Point (Tresco).


Or, alternatively, it is also possible at the 'Central' waypoint to turn west for Lizard Point, less than ½ a mile, to connect with Old Grimsby Sound from St Mary’s Road for Old Grimsby (Tresco).




To continue on to Tean Sound break off the transit at the 'Central' waypoint and steer for the 'Broad Ledge' waypoint located 200 metres west of Broad Ledge north-western end.

With Broad Ledge abeam to the east, proceed northward to 'West Broad Ledge' waypoint. This is located 200 metres east of Broad Ledge West and about midway between it and Stephen’s Ledge and Dog Ledge to the east.




Then continue to the northwest of West Broad Ledge steering to pass between it and John Martin’s Ledge to the south end of 'Tean Sound South' waypoint.




The water is deep before John Martin's Ledge and when the ledge passes abeam the southern end of Tean Sound will have 5 metres or more.


LISTED WAYPOINTS
The complete course is 1.78 miles from the waypoint 'Hats' to 'Tean Sound South' tending in a north north westerly direction (reciprocal south south easterly).

What is the best sailing time?

May to September is the traditional UK Sailing season with June-July offering the best weather. The British Isles weather is highly variable, and the amount of bad weather varies quite widely from year to year. This is because they are islands positioned between the Atlantic Ocean and the large landmass of continental Europe. As a result, the entire area lays under an area where five main air masses meet and alternate:

• • Tropical Maritime Air Mass - from the Atlantic


• • Polar Maritime Air Mass - from Greenland


• • Arctic Maritime Air Mass


• • Polar Continental Air Mass - from central Europe


• • Tropical Continental Air Mass - from North Africa

Depending on the movements of the jet stream, any and all of these air masses can come in over the isles, creating weather fronts where they meet and bringing with them all types of weather.

The prevailing winds for the British Isles as a whole are from the western quarter which generally blows for two-thirds of the year predominantly from the southwest. Gales from the westward are felt in all seasons, but from November to March, inclusive, they are most frequent and generally last three or four days. Of these, a southwest gale is considered to be the most powerful system. The winter period is largely characterised by wind and rain.

The fine summer weather of the sailing season is typically punctuated by the passage of an Atlantic depression that bringing periods of strong wind and rain, and sometimes poor visibility. These gales rarely cause surprises as they are usually forecasted well in advance. Good weather windows of 48 hours are easy to predict but any longer than that there's an increasing chance of change.

Fogs are frequent in all parts of the Channel and are formed both on the English and French coasts. In summer they only obscure the land in the morning and are readily dispersed by heat or a light breeze. But the moist haze, driven in by westerly winds from the sea, tends to linger and is only dispersed by strong winds. In the eastern part of the Channel, it is rare for the land to be completely free from mists. The only exception is when the wind is from the northeast which makes the mist free coastline highly distinctive from a great distance.

With thanks to:

Michael Harpur, eOceanic.