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The Scilly Islands (general)

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Courtesy Flag

Flag, Red Ensign


None appropriate


AC 1148 Isles of Scilly to Lands End; 34 Isles of Scilly; 883 Isles of Scilly and the Principal Off-Islands; SC 5603 (8 to 13) Various parts of the Isles of Scilly including small scale Falmouth to Scillies; Imray C7 Falmouth to the Scillies and Trevose Head (insufficient on its own)

Rules & Regulations

No anchoring in St Mary’s Pool or inshore at New & Old Grimsby. 3kt speed limit in St Mary’s Pool



Tidal Data Times & Range

HW St Mary’s is HW Dover – 0630. MHWS 5.7m MHWN 4.3m MLWN 2.0m MLWS 0.7m There is a tidal stream diagram included.

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General Description

HM St Mary’s    VHF 16/14        tel no  01720 422766538   
HM Tresco (for New & Old Grimsby)    tel no  01720 423
  mob 07778 601237

The Scilly Islands

The Scillies lie twenty five miles to the SSW of Lands End in a line with Exmoor, Dartmoor, Bodmin Moor and the Seven Stones rocks and are basically part of the same geological formation of granite rock.  The archipelago consist of just under fifty small islands which include the main islands of St Mary’s, St Martin’s, Tresco, Bryher and St Agnes/Gugh. 

Until Tudor times the island was little visited and the population relied on subsistence farming and fishing. In the late sixteenth Century the main island was garrisoned by the first Queen Elizabeth and since that time at varying intervals has been fortified against England’s enemies and was royalist during the Civil War.  After the Civil War the islands returned to obscurity and were only visited inadvertently by shipwrecked mariners;  the line “When we take our soundings in the Channel of Old England…….” bears much truth as the thirty five leagues between the Ushant and the Scillies was a very small target before the advent of chronometers which allowed one’s Eastings or Westings to be measured fairly accurately. 

Before that you got to forty nine and a halfish north and tiptoed eastwards, taking soundings all the way and if you were in a SW Gale you didn’t even have that choice. There was a whole fleet wrecked here in 1707 and between the Battle of Culloden and the turn of the century there were 750 seamen lost in these waters.  Mind you some were a bit luckier and missed the Scillies but a lot of those ran into Lundy in the Bristol Channel thinking they’d hit the Scillies!!  It’s something to be born in mind; in heavy weather water gets in everywhere and if you loose your wiggly amps then you lose your electronics and your radio and you become just like the Elizabethan sailor; lost. The moral is always keep a paper plot going because that’s your last known position.

Enough of the “’Ere be Dragons”; if your boat is well founded and your nav up to scratch you should have no trouble covering the twenty odd miles to the Scillies but be careful of “push-on-itis”; if the weather is not very good, there really is no point in going because it won’t be nice when you get there and could be even worse coming back.  In weather above a force 6 there is no really good shelter, if you get caught here in bad weather then you just have to find the least dangerous bay, chuck down all the iron you have on board as an anchor and ride it out.

You will note from the charts that there is an awful lot of green stuff denoting areas you can cross at HW but not at LW, the charts are also liberally scattered with asterisks which you do not want to meet with!  Most people just manage a visit to St Mary’s, St Agnes, Tresco and maybe St Martin’s but if this is your limit you are missing much of the pleasure to be found here.  A skipper will enjoy testing his navigational skills around the islands and possibly learn new ones; it’s all line of sight stuff using established clearing transits and lead in marks or looking for and using new lines you find for yourself - and the joy of it is that the water is so clear you can actually see the rocks - just in time to miss them if you’ve got it wrong (best have some one in the bows though!)

On the other hand you can just grab a visitors mooring in St Mary’s and use the ferries to visit the other islands

Before setting out for the Scillies be aware that you are leaving “Marinaland” behind and will, most of the time, be totally dependant on the holding power of your anchors; it’s a good idea to have a bit extra on board and make sure every link on your anchor cable is in good fettle. A decent sized kedge anchor would be a good idea as well because you will then have the ability to limit your swinging circle by anchoring to a yoke and thus be able to anchor closer in shore.  This may not seem important but don’t forget that these Islands live in the Atlantic swell which sometimes penetrates the outer boundaries of coves and inlets even in settled weather so the closer in you can get the more comfortable you will be. That swell will also have an effect on your choice of boat (if you have a choice) because there are many more options in a shallow draft boat with either a lifting keel or twin keel than in a fin keeler which cannot take the ground and in a fin keeler you will be at the outer end of any anchorage where you won’t always be rocked to sleep, occasionally you’ll be pitched out of your bunk!

Finally, having gotten here, slow down and chill out, there’s always another tide in twelve hours.


There is extensive advice covering passage making to the Scillies....

.... in Mark Fishwick’s West Country Cruising Companion and the coverage of the Scillies in that publication has expanded over the years to the extent that it makes a good read even if you are not sailing there!! If you hang on to back numbers of the PBO you’ll find useful information and chartlets in the March, April & May issues of 1994. (Still got mine!!) The latest edition of Mark's pilot is the 8th 2014.

Basically there are three main passages through which you can penetrate the islands, St Mary’s Sound, Crow Sound and New Grimsby Sound (or even Tean Sound) but a glance at the chart will probably persuade the sailor visiting here for the first time that St Mary’s Sound is by far and away the easiest; lots of lovely deep water and visitor’s moorings at the end of it (if you are lucky).  If you are familiar with the Islands you may plump for Crow Sound or one of the others.  Which ever you choose, when you first sight the Islands (Land Ho!!), the relief that they are just about where you expected them will soon be replaced with confusion as to which island is which and what lighthouse is what!

Not to worry, just plough on Westwards and all will eventually be revealed (there is a certain merit in planning an overnight passage to arrive at dawn when identifying the lights is a lot easier).  Just one point; up until you see the islands you’ve been using whatever nav aids you have to maintain the line you drew on the chart the night before and the course you are steering when you first sight the islands has been working fine; so don’t go pointing your bow at the islands as soon as you see them or you’ll go plummeting down the tide for two hours!! (Seems obvious but so many skippers forget that)

The Scillies charts give transits for the approaches to all the passages but be careful that you correctly identify the objects they use; combine that information with all your nav aids to establish the correct lines. If you hang around the island and explore enough the various “pinnacles” will become familiar to you and we will be discussing the closer in approaches to the various anchorages in other articles.

Regulars will be aware that the sector light on the end of St Mary's Pier is no longer

Berthing, Mooring & Anchoring

The main anchorages are at St Marys and Porth Cressa, New Grimsby, Old Grimsby, St Martins, and  St Agnes/Gugh and they become very, very crowded in the summer months, especially in August when the French invade in gurt great tin boats.

In the nineties late May was a time of fairly settled weather and used to be a good time to visit here but lately the weather has been so topsy-turvy that may no longer be so. It used to be the case that, apart from St Mary’s one could anchor pretty well anywhere around the Scillies without charge but, beware if you haven’t been there for a while, because they now have visitors buoys laid out in New Grimsby Sound and at Old Grimsby on Tresco and even if you choose not use them they will still charge you for anchoring and note also anchoring is no longer permitted close in at Old Grimsby (shame – that beach was a lovely spot to rest aground for a day or two). We will deal with each of the anchorages separately in other notes.


There are full facilities at St Mary’s/Hugh Town but the only access to water and power hook ups is on the limited number of alongside berths at root of the pier. There are showers and toilets ashore at St Mary’s. 

You will be able to top up with water from taps at most of the main anchorages (with the exception of St Agnes) but the only fuel to be found is at Hugh Town.  Gas and Gaz refills can be found at Hugh Town but at hugely inflated prices due to “transport costs”; in fact you will find this excuse used for all high prices in the Islands. 

Hugh Town also has all manner of services for the sailor including a sail maker, rigger, chandler and marine engineers.  Also available is wireless internet in the harbour at St Mary’s (ring 07745 952707 for connection) and there are internet connections available ashore.

Eating, Drinking & Entertainment

There are pubs on all the main islands (mustn’t miss the Turks Head on St Agnes) and restaurants/bistros on all but St Agnes which only has a couple of cafes. 

You can hire bikes on St Mary’s and Tresco (much fun to be had on a tandem, especially if you put the crew up front, relax and enjoy the view).  The main spectator sport in the summer is the gig racing on Wednesdays and Fridays (ladies on Wednesdays). Other than that there are lovely places to walk and in the anchorages there is an abundance of shrimps waiting to be caught for supper. (No, really; the kids will love it!)


Your Ratings & Comments

Written by Don Thomson 3 | 15th Apr 2021
I reviewed these notes in April 2021. I think our member's note on relying on GPS means the CHARTS on your GPS plotter because, the GPS itself will be accurate but the charts may not have all the rocks on them. Remember to use the maximum zoom if you use Navionics. The Hotel that used to be above Old Grimsby is now holiday apartments. and the hotel on St Martins that laid buoys in Teale Sound is now part of an international consortium and it is not known if they still lay buoys.
The rocks of Scilly
Written by maryandtherib | 29th Aug 2016
Don't rely on your GPS! There are lots of uncharted bits of rock which are very shallow at low water, particularly around St Agnes where even the locals stick to routes they know. Tidal range can be nearly 6m at spring tide so it's all about the navigating.Some wonderful cardinal markers with bells which remind me of the Inchcape Rock. Some interesting bits of water where the tidal streams meet between the islands, or where deeper more exposed water meets shallow. And lots of wrecks. Lots.
Note St Mary's fuel channel is on 12, and sometimes you have to queue for a while.... take note that they close for lunch. the fuel berth is next to the Scillonian berth, but only has about 0.5m above chart datum at low water.
you can also telephone for fuel on 01720 422431.

Thanks Mary and the rib
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