The no-going back zone in VOR

by Lizzie Green on 8 Jun 2006 With time running short and leg eight of the Volvo Ocean Race taking much longer than originally predicted, the race committee last night shortened the course. The new course takes the fleet around Duncansby Head on mainland Scotland and through the Pentland Firth, rather than round Fair Isle which is situated between the Orkney and Shetland Islands

Although this new course will save the fleet approximately 76 nautical miles, it raises a huge tactical and navigational challenge, enhanced by the light airs dominating the fleet. Ironically, there now appears to be more wind now in the north, which makes an interesting dilemma for the navigators: whether to sail a longer course in more wind, or take a short cut through the Pentland Firth in less wind.

Today the crews onboard are in no doubt about the part of the world in which they are sailing. Gone are the Caribbean-like clear blue seas and skies of yesterday. Today they are replaced with cold air and grey clouds. It is the Hebrides and very remote.

The fleet has rounded the lighthouse at the Butt of Lewis and the leading group has approximately 10 miles to sail due east before rounding Cape Wrath on the northern tip of Scotland. From Cape Wrath it is 54 nautical miles due east to the entrance of the Pentland Firth. If the navigators choose this course - the shortened course, then this will be the point of no going back – the no-going back zone.

The Pentland Firth separates the Orkney Islands from Caithness in the north of Scotland and the entrance is only 6.3 nautical miles wide. The exit is even narrower at 4.6 miles and the fleet has to navigate 11 miles of islands, headlands, rocks, tidal rips and whirlpools before they reach the safety of Duncansby Head at the eastern end.

The tides here are some of the strongest in the world and up to 16 knots have been reported. This will be a real issue for the fleet if the boats arrive here in light airs and a foul tide. The force of the tide creates overfalls and tidal races which can occur at different stages of the tide, and, in several areas of the firth, these can be very strong and extremely violent.

There are two routes through the Pentland Firth, the Outer Sound and the Inner Sound. The outer sound is the passage between the islands of Stroma and Swona. It is 2.5 miles wide, and is the usual route through the by day and by night. The inner sound is only 1.25 miles wide and is the passage between the island of Stroma and the Scottish mainland. The UK Admiralty advises that, with local knowledge, slow or small vessels can use this route to save time, but large vessels are not recommended to use the Inner Sound at any time. Which route will the Volvo Open 70s take? Even in calm conditions, there can be heavy turbulence in the races.

The in-port race in Rotterdam has now been rescheduled to start at 1100 local time on Sunday, June 11.

LEG EIGHT DAY 06 1600 GMT POSITION REPORT

Leg Standing	Yacht	Latitude	Longitude	Distance To Finish	Speed Made Good	24 Hour Run	24 Hour Speed	Distance To Leader	Distance To Leader Change	Projected Leg Points	Estimated Time of Arrival	Projected Race Points	Projected Overall Standings
1	ABN1	58 42.22N	005 13.70W	00536	07.2	164	06.8	00000	+00000	7.0	09/06/06 23:__:__	91.5	1
1	BRA1	58 41.92N	005 13.63W	00536	07.4	170	07.1	00000	+00002	7.0	09/06/06 23:__:__	59.0	3
1	ERIC	58 41.63N	005 14.38W	00536	07.3	168	07.0	00000	+00002	7.0	09/06/06 23:__:__	52.0	4
4	POTC	58 41.11N	006 04.84W	00562	05.3	153	06.4	00026	-00012	4.0	10/06/06 02:__:__	63.5	2
5	ABN2	58 42.21N	006 12.36W	00566	04.9	153	06.4	00030	-00016	3.0	10/06/06 02:__:__	51.5	5
6	AUS1	58 48.02N	006 22.54W	00572	05.2	173	07.2	00036	-00021	2.0	10/06/06 03:__:__	10.0	7