Saint Mary's Road, at the heart of the Isles of Scilly, may be approached from seaward through five entrances, Saint Mary's Sound, Broad Sound, North West Passage (formerly known as the 'North Channel'), Smith Sound and the tidal Crow Sound. Of these Saint Mary's Sound is the primary route that leads onward to Saint Mary's Pool.
It passes in through Saint Mary's Sound that lies between St Mary's Island and the tiny island of Gugh situated about a mile southwestward and attached to St Agnes by an isthmus. It then continues through Saint Mary's Road to set up the approaches to Saint Mary's Pool

Image: Michael Harpur
Why sail this route?
Saint Mary's Pool, situated near the southwestern end of St Mary’s Island, is the principal harbour of Scilly with Hugh Town, immediately ashore, the Isles of Scilly largest settlement, the administrative centre and capital. Both of these factors serve to make it the usual point of arrival for visiting yachts and the centre of all commercial shipping.
Image: Visit Isles of Scilly
What makes St Mary's Sound a highly attractive point of arrival is that it offers a clearly identifiable pass between two substantive landmasses in a scattered archipelago of rocks. Both of the landmasses feature lighthouses although the one on the summit of Agnes is no longer in service but continues to serve as an official daymark.

Image: Michael Harpur
It is also wide, deep, and because it is the principal approach it is further supported by several lit buoys and beacons so that it may be approached at night. This all makes it the easiest route to confidentially navigate into the centre of the island group and the prefered path for newcomers. With the exception of the tidal Crow Sound approach, it is considered the default for vessels approaching the island group from the south and east.
Tidal overview
Today's summary tidal overview for this route as of Wednesday, January 20th at 17:16. From Saint Mary's HW-4 through to HW-2 the first flood flows from the south through southwest into St Mary’s Sound and leaves via all other exits. From HW-2 to HW+2 the water continues to enter St Mary’s Sound until after HW when there is little flow into St Mary’s Sound until the flow reverses, in the Bar Point area, then carrying water southwards. Maximum rates of nearly 2 knots can be attained at Springs and about three-quarters of a knot at neaps. For those with a Dover tide table the ingoing begins at HW Dover -0310 the outgoing stream begins at HW Dover +0245.South-going Tide St Mary Sound
(HW ST. MARY'S +0200 to -0400)
Now
(Tidal flow )
Ends in 00:32:00
(Wed 11:23 to 17:48)
Northwards Tide St Mary Sound
(HW ST. MARY'S -0400 to +0200) 
Starts in 00:30:00
(Wed 17:46 to 23:46)
What are the navigational notes?
Saint Mary's Road, 49° 54.584' N, 006° 20.105' W
A ¼ of a mile southwest of the western extremity of St Mary's Island marked by the 3-metre high Steval rock.
► Next waypoint: 0.76 miles, course ⇓ 36.89°T (reciprocal ⇑ 216.89°T)
St Mary's Harbour, 49° 55.192' N, 006° 19.396' W
This is set on Mount Flagon alignment of 097.3° T of white beacons, with a triangle top mark pointing upward, and an 'X' topmark on the skyline. The alignment leads into the St Mary's Harbour through the lateral marks and south of Beacon Ledge.
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:
Micheal Harpur eOceanic.Add your review or comment:
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