This is a cut from the western side of the Isles of Scilly into the Tresco Channel that lies between the islands of Tresco. It is approached and entered to the south of the Northern Rocks and Mincarlo, to pass in between Bryher and Sampson. The passage between the islands is deep but the Tresco Channel itself is shallow and drying.
Why sail this route?
With deep water leading all the way in between the islands, a commencement point than can be confidently identified by the 'Steeple Rock' West Cardinal and the vast majority of supported by a leading alignment, this cut is very straightforward cut.
The pass between Sampson and Bryher as seen from Bryher with Yellow Rock in thecenter
Image: Michael Harpur
It provides a convenient western approach into the Tresco Channel and thence to New Grimsby Sound
connecting with Tresco Channel crossing the Tresco Flats 
. This cut in may also be used to provide a deeper approach to New Grimsby Sound from St Mary’s Road. By using the North West Passage to the 'Steeple Rock' West Cardinal it provides a means of avoid the shallower sections of the Tresco Channel crossing the Tresco Flats between The Hulman and Little Rag to enter from deep water to the north of the sand spit on Tresco Flat. All that is required to continue to New Grimsby Sound is a sufficient rise of tide to pass over 0.7 metres LAT, as opposed to 1.7 to cross the sandbar on the flats. It may also provide an easier exit out of New Grimsby during fresh winds from the northwest, round through north, to the northeast, when it can be difficult to depart. In suitable conditions, it can also provide an enjoyable piece of pilotage.
Mincarlo to the northern rocks, a deadly coast in poor conditionsImage: Michael Harpur
However, it should always be borne in mind, that this cut requires fair weather and settled conditions with good visibility. It should not be attempt in any developed westerly component winds or if there is any significant swell. In any such conditions, the Northern Rocks and the shoals and outliers to the west of Bryer and Sampson are very particularly ugly and make for a formidable lee shore. But more specifically there are covered rocks that lie very close to the alignment mark on both sides of the approach and should a vessel be pushed off the alignment it a very dangerous situation could develop very quickly.
What are the navigational notes?
Mincarlo Island, as seen over Bryher's Colvel Rocks, with the Steeple Rock
Mincarlo Island
Yellow Rock sitting in a position midway between the islands
Abbey Hill monument on Tresco
The cut joining the Tresco Channel 
The view out through the pass from the front of the harbour master's posts
Tresco Harbourmaster's alignment marks
Plumb Hill posts in alignementBream Ledge, 49° 55.970' N, 006° 22.382' W
150 metres southeast of the southeastern end of the Bream Ledge (awash at high water).
► Next waypoint: 0.65 miles, course ⇓ 48.46°T (reciprocal ⇑ 228.46°T)
Colvel Rocks, 49° 56.400' N, 006° 21.628' W
250 metres south of the Outer Clovel Rocks and north of the shoals sitting in the alignment.
► Next waypoint: 0.61 miles, course ⇓ 60.82°T (reciprocal ⇑ 240.82°T)
Lubber's Rock, 49° 56.695' N, 006° 20.807' W
150 south by southeastward of the isolated Lubbers Rock, that dries to 1.7 metres, on Bryher side of the channel. It dries from here on in LAT.
What is the best sailing time?
May to September is the traditional UK Sailing season with June-July offering the best weather. The British Isles weather is highly variable, and the amount of bad weather varies quite widely from year to year. This is because they are islands positioned between the Atlantic Ocean and the large landmass of continental Europe. As a result, the entire area lays under an area where five main air masses meet and alternate:- • Tropical Maritime Air Mass - from the Atlantic
- • Polar Maritime Air Mass - from Greenland
- • Arctic Maritime Air Mass
- • Polar Continental Air Mass - from central Europe
- • Tropical Continental Air Mass - from North Africa
Depending on the movements of the jet stream, any and all of these air masses can come in over the isles, creating weather fronts where they meet and bringing with them all types of weather.
The prevailing winds for the British Isles as a whole are from the western quarter which generally blows for two-thirds of the year predominantly from the southwest. Gales from the westward are felt in all seasons, but from November to March, inclusive, they are most frequent and generally last three or four days. Of these, a southwest gale is considered to be the most powerful system. The winter period is largely characterised by wind and rain.
The fine summer weather of the sailing season is typically punctuated by the passage of an Atlantic depression that bringing periods of strong wind and rain, and sometimes poor visibility. These gales rarely cause surprises as they are usually forecasted well in advance. Good weather windows of 48 hours are easy to predict but any longer than that there's an increasing chance of change.
Fogs are frequent in all parts of the Channel and are formed both on the English and French coasts. In summer they only obscure the land in the morning and are readily dispersed by heat or a light breeze. But the moist haze, driven in by westerly winds from the sea, tends to linger and is only dispersed by strong winds. In the eastern part of the Channel, it is rare for the land to be completely free from mists. The only exception is when the wind is from the northeast which makes the mist free coastline highly distinctive from a great distance.
With thanks to:
Micheal Harpur eOceanic.
