Is your chart relying on an 1860 survey?

Footnote to cruising the Scillies: piloting there is a reminder of the importance of proper Admiralty charts, because they show the age of the surveys on which they are based, unlike any of the proprietary ‘vector’ charts available on chartplotters.

The Scillies is a mixed area from this point of view. Some of the surveys of the area were last done in 1860 – 1904 by lead line, probably from boats carried on naval survey ships and rowed up and down in straight lines quite a long way apart, so rocks could easily be missed. Other parts of the islands were surveyed at a range of different dates in the 20th century.

The little diagram showing which area of the Scillies was surveyed when is very instructive, and is a warning that in certain places extra care is needed. Interestingly, one small but vital area, the ferry route in and out of Hugh Town, was surveyed in 2012-14, by the Duchy of Cornwall, the landowners. At least we should be able to rely on that route.

This does not mean you have to stick with paper. We would have spent at least £5,000 in recent years if we had bought all paper charts for our cruises. UKHO (in other words Admiralty) charts for the whole of the UK and Ireland, complete with all the supplementary information, can be bought as a single package for very reasonable prices online from the Cowes firm visitmyharbour.com, and combined with the excellent Marine Navigator chartplotting app they make a fine tablet chartplotter as backup to the main system. What you are looking at then is a computer image of an official UKHO chart (technically, a raster rather than a vector electronic chart). In fact, the UKHO charts are now printed from electronic files anyway, so it is exactly the same image.

The popular yacht chart systems such as Navionics, Garmin and C-Map, leave out vital information such as survey age. They are not images of official charts but combine the data in their own proprietary way. They also contain potential traps because they are organised in layers, and as you click from one to another you get more or less detail. If you are on the wrong level you may miss something important. To have the UKHO charts as backup on a tablet is reassuring.

Furthermore, we have seen a number of examples over the years where Navionics has missed out features altogether or got information wrong. There was one example in Tean Sound, where Navionics showed one power cable crossing the sound under water. The UKHO chart, and to its credit C-Map, showed all four.

Round the islands

Below is the UKHO large scale chart of the Scillies, with green showing where the bottom is exposed at low spring tides. With careful tide calculations it is straightforward moving between the islands, though you have to be mindful of dangerous rocks scattered around the flats.

The old pilot books for the Scillies, one of which we have, give many complicated bearing lines for finding your way around using pairs of landmarks, which are still very useful to know.

A chartplotter helps nowadays, up to a point. Our main plotter uses C-Map, which has proved extremely accurate in two cruises around England, Ireland and Scotland, so we have confidence in it (much less so in our backup Navionics). But as a rule of thumb, we don’t rely on it when the accuracy required – eg between two reefs – is better than plus or minus a hundred meters or so, just in case the underlying charts are wrong, a rock has been missed on them or there are problems with satellite signals.

In the Scillies, we used a combination of plotter, compass bearings and leading lines and especially good old fashioned eyeballing, to move around; wherever there were doubts about the position of rocks, someone went up to the bow and kept watch, because the water is clear and shallow, and rocks show themselves through changes in colour and disturbances in the tide.

Regular visitors find and use all sorts of obscure anchorages around the Scillies, but it takes time to learn them and we were pleased enough to visit six good ones after we left the main harbour at Hugh Town, and stay overnight in four of them. Caution and inexperience of the islands dictated that we moved around about two hours before high tide to just after high tide, not wanting to risk getting stuck on a falling tide, though it was neaps so the range was small and the currents relatively slow.

We arrived from Plymouth from the east, entering by St Mary’s Sound and then round to the north-west side of the island, the biggest, where the main harbour, Hugh Town, is found. We found a vacant visitor’s buoy in St Mary’s Pool.

The drying part of Hugh Town harbour. The deepwater moorings are further out, in the Pool.
The Scillonian, the ferry from Penzance

From Hugh Town, we found our way across Tresco Flats to New Grimsby Harbour for a night, a much less intimidating route than it looks on the chart, with two helpful beacons marking the most dangerous obstacles. Then ashore to spend time walking around the island.

The next day we went through New Grimsby Sound, then round the north end of Tresco into Old Grimsby Sound and its Harbour, and we spent more time walking, eating and shopping for supplies ashore in the well-stocked Coop.

The blue view south from our Old Grimsby mooring
St Helen’s Pool

After a night on a buoy, we moved south-east, past Peashopper Island, and turned east through a gap and north-west around the reefs to St Helen’s Pool, a relatively safe and deep water anchorage south of the island of the same name. Sailing ships used to shelter here from storms.

Deciding not to stop there, we went through St Helen’s Gap and past the north side of Tean island and down into Tean Sound, between Tean and St Martin’s, where we anchored for the night in a strong current. By luck, we found a sandy patch, though the pilot book warns that there are a lot of rocks and holding can be bad. We used our largest scale charts and signs on the shore to keep away from the multiple power cables that cross there.

Tean Sound, Spring Fever third boat from left

The next day we retraced our movements to St Helen’s Pool, but decided not to anchor for lunch and instead motored south across the flats towards St Mary’s. We tried to use the line across the flats (Man-a-Vaur island lined up with the St Helen’s landing cairn, as in the chart) but could not see the cairn even with binoculars. We relied instead in a good look out and the chartplotter.

We then turned west to St Agnes, crossing the shallow Crow Bar – since it was high tide – and went through St Mary’s Road to St Agnes, where we initially went to the north-facing anchorage, Porth Conger, because south-west winds were forecast.

Looking out for rocks

However, we found an Atlantic swell, originating probably a long way away, was refracting round the north of the island into the mouth of the bay, so we motored round the island of Gugh – connected to St Agnes by a sandbar that dries at low tide – where we found a good anchorage for the night in The Cove, which is between the two islands. We went ashore for a walk and dinner in the Old Turks Head.

Do not, by the way, ever try landing your dinghy on the sandy beach by the Boat House beacon, though it looks nearer – you’ll never get off it at low tide because by then it is then just a mess of big boulders. Always go up to the sand bar in your dinghy.

Porth Conger, the north anchorage at St Helen’s, the swell gone by the time this photo was taken
The Cove, the south anchorage at St Agnes, just before we left next morning, Gugh island on the right and the sandbar linking it to St Agnes just visible
The Old Turks Head
The Cove at night in the rain

That was the only cold, damp evening we experienced in the Scillies. St Agnes, the smallest inhabited island, is very pretty but did not look its best. At least the sun came back the next morning before we left for Penzance.

Scillies Vineyard

The island of St Martin’s in the Scillies used to specialise in the growing of spring bulbs and flowers. As the old business has shrunk, a new use has been found for some of the tiny fields with tall hedges that protected the plants from Atlantic storms: England’s remotest vineyard and winery.

The winery

St Martin’s Vineyard was founded in 1996 when the offspring of the owner of the bulb farm came back to the island looking for a challenge. Father, in his 90s now, still grows some bulbs, but half a dozen of his little fields are taken up by vines of a number of varieties including Orion, Reichensteiner, Schonberger and Ziegerrebe (the latter in a polytunnel because it will not fruit properly in the Scillies otherwise).

Viniculturalists will probably know why these varieties thrive in the salty storm winds of the island.Production is small – only 3,600 bottles a year – but they make it all themselves, and sell it entirely within the islands. We tried two wines and bought one, and they were very pleasant to drink, though at prices of £13.50 a bottle and upwards they would not compete on price now with mainland English wines, except as a curious rarity, well worth trying if you are offered a bottle in the Scillies.

As vineyards go, it is in a spectacular location and visitors are welcome.Here is the nearby beach:


St Martins has a delightful pub, a village shop and a small, upmarket and expensive hotel called the Karma Resort, which had staff rushing around with customers’ baggage from a speedboat cum ferry when we looked inside.Below are two other residents of the island:

Slowboat round Britain and Ireland

We did it!
A toast to a great cruise!

After spectacular scenery on the West coasts of Scotland and Ireland, and many interesting harbours and anchorages, Spring Fever is back where she started last year, on the River Medina at Cowes. There was nothing heroic about it: the  longest single cruise  was only 24 days, from Ardoran near Oban to Truro in Cornwall this summer, taking in Iona in the southern Hebrides, Tory Island off Donegal, the Aran Islands off Galway, and the Scillies.

Altogether Spring Fever has logged 2,200 miles round Britain and Ireland over two years.  It was planned as a series of quite short and leisurely cruises, to fit around our other commitments, with the boat wintered in Scotland, and in one sense was no more than a voyage round our homes, on a small island we already know well; but it is hard to beat the distance and perspective that comes from visiting familiar places by sea, and there were many others we would never have found if we had been travelling by land.

  We went anticlockwise, exploring the Thames Estuary rivers in 2012, up the east coast, through the Caledonian Canal, spent time cruising the Hebrides, and wintered the boat at Ardoran on Loch Feochan, near Oban. This year we came home by the West Coast of Ireland.

Our route took in many places we missed on our previous two-season cruise round Britain via the Orkneys in 2007-8, in another boat, Pepper. Once was not enough: there’s something particularly appealing about a cruise that begins and ends in the same place and circumnavigates the land without ever having to cross its own track. There is nowhere else in Europe where you can do that over the satisfyingly long distance of a couple of thousand miles. We were never far from home, but it felt like a real voyage.

An account of the first stage of this two-year round Britain, from Cowes up the East Coast of England and Scotland and through the Caledonian Canal, can be reached through this link.

Leaving Spring Fever
Leaving Spring Fever