Navigator's tips

"I would like to go left for the breeze, but right is better for tide; the tide looks like the dominant factor so lets work the shifts along the best area of tide on the right."

9.Anticipate the Helm/Tactician’s next question. As a flying instructor I would always teach pilots to think ahead of the aircraft. The same is true in sailing. Anticipating the next question is a vital part of the role of the tactical navigator. Work out the wind angle for the next leg, using the mean true wind direction (TWD). The best way to do this is to work in true wind angles, comparing the course adjusted for tide, with the TWD to get the True Wind Angle (TWA). Talk to the helm/tactician and find out what information they really want. One particular piece of information that Chris Dickson regularly wanted when he sailed in the British Admiral’s Cup Team a few years ago was position relative to the laylines ie four minutes on starboard and two on port, this helped his mental picture regarding our position on the race course.

10.Sail Fast in areas of strong current. Solent courses regularly involve a beat against the tide. Invariably this means a beat along the shore in the weaker tide, prior to striking out on your tack for the windward mark in the stronger tide. A common fault for those who slightly misjudge the layline is to sail high and slow in order to make it in the final two hundred metres or so. This can be lethal in fast flowing Solent tides, slowing the boat at this vital time relatively increases the strong negative component of the tide and slows you even further. If this looks like occurring, bail out early and for the same reason, don’t try to shoot the mark with little boat speed in a strong tide - it tends to leave scratches all along the topsides.

11.Wind Shadows and Tide Shadows. Never underestimate the effect on the wind from large moored ships, especially in light winds. There have been several large ships anchored in the eastern Solent in recent Cowes Regattas.The wind shadow can have a considerable effect on that part of the race course. Likewise wind shadows from a line of smaller spectator craft, in light winds, can have a large influence in reducing the wind in that area. The Brambles Bank creates a tidal shadow that can be used to good tactical effect. Sailing against a flood tide it is very effective to use the area directly east of the bank to cheat the tide, which flows strongly around each side of it.

12.Can I get over the Brambles? Tidal Heights made easy. A great short cut for working out the height of tide in the area of the Brambles, is to use the first class Roberts tidal slide. On the front it has the tidal flow for the area in fine detail, then on the reverse are the predicted tidal levels for both mean springs and mean neaps. This is an easy and quick method, rather than doing a three way interpolation between three secondary ports! To make things even simpler, I like to transfer these heights to the corner of a plastic chart using chinagraph, this enables me to come up with a tidal height very quickly in the heat of the battle.

Height of tide at the Brambles using HW Portsmouth
1020 - 5 1.7
1120 - 4 2.0
1220 - 3 2.5
1320 - 2 3.1
1420 - 1 3.7
1520 HW 4.1
1620 + 1 4.0

13. Instrument Calibration. Instruments are expensive but of little use if not calibrated. Don’t settle for large errors and always check out the wind instruments at the start of each day. After a while it is quite possible to refine the errors for a particular wind strength down to one or two degrees. For years I always had to double check which way I had to make the correction. These days I use a simple mnemonic, which I never forget:

H on P + decoded means 'High figures on Port Tack, add half the difference'.

bramble bank tips on page 4, more tips on page 5...