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St Mary's Sound to St Mary's Pool (Scilly)

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What is the route?
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 Click to view haven. The sequence of description here is of entry but it may be reversed to exit.

St Mary's Sound as seen from the southwest with Gugh right
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.

St Mary's Pool and Hugh Town
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.

St Mary's Sound can be positively identified from some distance
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 Thursday, April 9th at 02:37. 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.
Please note

The current tidal event is springs so expect streams to be at their strongest.

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