This is a passage across the broad stretch of shallow water that lies between the islands of Tresco and St Martin’s connecting Crow Sound with Tean Sound. Large sections of the route are shallow and parts dry to 0.4 metres LAT so a sufficient rise of tide is required and it is ideally addressed on the flood. The route is sequenced from Crow Sound to Tean Sound but it may is available both ways.
Crow Sound to Tean Sound
Image: Visit Isles of Scilly
Image: Visit Isles of Scilly
Why sail this route?
This interior cut joins the west and east seaward approaches to St Martin’s so a vessel may effectively circumnavigate the island with a sufficient rise of the tide. This route can be used in conjunction with Old Grimsby Sound from St Mary’s Road to connect St Mary's Road and Crow Sound with all of the principal anchorages in the northeast and east end of the group as follows:- • Close south of the 'Hats' commencement waypoint is the Watermill Cove (St Mary's) anchorage.
- • The initial fix for Higher Town Bay (St Martin's) is crossed on the approach to the 'Central' waypoint.
- • The 'Central' waypoint aligns the path through to Tean Sound .
- • But, alternatively, it is perfectly possible to continue along the Men-a-vaur alignement to St Helen's Pool (St Helen's Island).
- • Or, cut accross to connect to Old Grimsby Sound from St Mary’s Road for Old Grimsby (Tresco).
The route may also be very easily adapted to pass Tean Sound and St Mary’s Road connects two of the group’s principal deepwater berthing locations and makes the facilities of St Mary’s Harbour and Hugh town more readily accessible for vessels in Tean Sound.
The northern section of the route approaching Tean Sound
Image: © Tom Corser 2009 via CC BY-SA 2.0
Image: © Tom Corser 2009 via CC BY-SA 2.0
In a group where no anchorage provides complete protection, all of the time, and vessels have to prepared to shift in order to make the best of the weather, this ability to quickly cut between all of these anchorages is more than useful. Likewise, with a least depth of about 0.5 metres this should not prove over limiting and particularly so during Neaps when, with a tidal range of 2.3 – 5 metres, it is a reasonably available option for most vessels most of the time. Using this internal cut saves hours of sailing for those planning to pass around the north side of St Martin's. In suitable conditions, it can also provide an enjoyable piece of pilotage.
Tidal overview
Today's summary tidal overview for this route as of Friday, March 29th at 01:25. With large a small section of this route drying to 0.4 metres, a rise of tide will be required for vessels carrying any draft. Vessels carrying up to 1.3 metres can as a general rule proceed 1 hour after LW and freely pass during Neaps. Vessels of 1.8 metres should wait for 2 hrs after LW, which the timer set for 4 hours before and, conservatively, 2 after. For more detailed work:MHWS 5.7m MHWN 4.3m MLWN 2.0m MLWS 0.7m
Highest Astronomical Tide (HAT) 6.4m, Mean Sea Level (MSL) 2.91m