The Scilly Islands-Old Grimsby & St Helen’s Pool

The easiest approach is from the North through Old Grimsby Sound.

As with New Grimsby Sound there are no navigation marks to assist with the approach apart from the lighthouse on Round Island but that at least will be a starting point when trying to differentiate between the various lumps of rocks and islands that you are presented with on a northerly approach. Men-a-Vaur is particularly distinctive with its double/triple pinnacle. If you are coming round from the NE, once you have cleared Men-a-Vaur do not turn in for Old Grimsby Sound until you have identified and circumnavigated Golden Ball and its associated rocks; you need to have clear sight of the Sound between Norwethel and Tresco before turning in and even then you must take care to clear Little Kittern. On our chart we have marked a course which is the absolutely closest you must be to the hazards; we have also highlighted the 57 minute and 58 minute latitudes notation to draw your attention to the change in scale from the chart you have been following from Land's End to the charts you are now looking at; the distance between Norwethel and Merchants Point is less than a cable. However, once you have become familiar with the scale of the charts and what you are seeing from the cockpit the charts are beautifully detailed, just make sure your plotter/GPS is on the same chart datum as that you are using at the chart table. This is one case where, if you have printed and laminated screen captures from the charts on this site during the winter you will be miles ahead of the game.

If you are making the approach from the NW having been in New Grimsby Sound there really isn't much of a problem, just give the Kettle and Kettle bottom a safe offing and follow the island round into the Sound. On the other hand if you are making a landfall from somewhere like Southern Ireland then you will have to be very careful to accurately identify what you are looking at with your chart, especially as the nearer islands to you will be seen against the background of St Mary's which is higher and will be sighted before them.

If you want to come in from the South through Crow Sound you will need to do your sums carefully and follow the lead-in marks on the chart. There is an alarming amount of "green stuff" on the charts, especially around Tresco and St Martins; after a few days here you will learn that the tidal range here makes navigation over it (the green stuff) perfectly feasible as long as you choose the right state of the tide to do so. You will find that after a week's sailing around these waters your chart will be marked by sight lines you have found useful (as in "when that opens around that, I am clear of that") and we have thrown in a few on our approach chart to illustrate this. You can see that when the beacon at the West end of St Martins becomes open around Great Cheese rock you will be clear of Tea Ledge and, if you are heading for Saint Helens Pool, you can start shaping your course for there. Simples!! It's basic transit navigation but you will use it around these islands in a way you have possibly never done before.

Saint Helen's Pool is best approached from the North East through the Saint Helen's Gap or from the Hats SCM; again we would suggest you mark sight lines on your chart to aid your progress around areas like Hunters Lump and the Chinks as GPS information is all very well but you are involved in very small cross track errors here so, make very sure of the predicted depth of water and exactly where you are before leaving your departure point. If you look at the photo "Looking over St Helen's Gap" you'll get some idea of the scale of things.