Additional skills to help you get more from your cruising. For the full feature, read YM September 2012
Drying anchorages – Bill Anderson
Bilge-keelers, centre-boarders and multihulls that can take the ground upright, have it easy when it comes to finding an anchor berth — once they have discovered the pitfalls.In a deep water anchorage, boats of more or less the same type are likely to respond in more or less the same way to the changing influences of wind and tidal stream. This is helpful when you are trying to find a berth in which you will stay clear of your neighbours. In a drying anchorage the choice is a little more complicated. You have to be sure that after you have dried out and are swinging to the flood stream the boat up-tide or up-wind of you will not collide with you before you have floated and that you will not hit a deeper draught boat that is still aground after you have floated.
Don’t rush the anchor – Brian Black
When your anchor is set properly you will get a good night’s sleep. If it’s fouled you can look forward to all sorts of drama and if that happens at the end of a long passage (or even a short one in hard conditions) no-one is going to thank you for seeking out a new spot in the dark.
How to tie a Rustler’s Hitch – Duncan Wells
Take a bight and pass it under the grab rail. Then taking the standing part take a bight of this over the rail and through the first bight and tighten by pulling the running end. Now take a bight from the running end and over the rail and pass this through the bight made by the standing end and tighten by pulling on the standing end. done. Fender not going anyway and yet it is instantly ready.
Falling off the rhumb line – Brian Black
Sail to make your best course to windward even if its means falling off the rhumb line. An easy boat at sea is a happy one and you can always make up the lost miles towards the end of the passage when there is the incentive of making safe harbour despite a hag into head seas for a few hours.
The Rule of Sixths – Bill Anderson
This is an excellent way to find a quick approximation of course to steer to counteract a cross tidal stream as you turn onto a new heading. It is useful if your boat is an average performer which sails and motors at around six knots.
If you have a cross tide of one knot and boat speed of six knots you will need to steer 10 degrees up-tide to stay on track. For a two knot stream and a six knot boat the offset is 20 degrees. You can extrapolate as much as you like on the basis of sixths but the answer becomes increasingly inaccurate if you carry it to extremes.
I should emphasise that this method is for approximations, which you can arrive at quickly without having to leave the helm to draw triangles on charts. If you are turning onto a transit, or can see the GPS or a repeater from the helm and you are navigating to a way point it will be easy enough to fine tune the answer from the way the marks of the transit are opening or the readings of direction to waypoint and course over the ground on the screen.
Instant clearing lines – Bill Anderson
You planned the passage with great care, left good clearances off all hazards but approaching Plymouth Sound in the gathering gloom you have to clear the Mewstone Ledge. You are close hauled on port tack and the tide is setting to the east. Your planned waypoint gave plenty of clearance but you are heading well inside it and don’t want to put in a tack if it isn’t really essential. Are you going to clear the ledge?
It takes very little time to look at the chart and work out latitude and longitude lines which will keep you in a safe depth. In this case, stay south of 50 18′.2 N until you are west of 004 06.7 W. This is only practical if you have a crew member who can watch the GPS, or a GPS or repeater which you can see from the helm.
Since you took this lat and long off the chart quickly you need a backup. Keep an eye on the sounder, start to worry if the depth shoals to less that 15 metres, if it shoals to less than 10 metres, tack.
Quick angle calculation – Duncan Wells
Chart work for Course To Steer is all well and good but I can do a CTS in my head much quicker than you can do it on a chart and it will be just as accurate. 60 x the rate of the tide divided by the boat speed will give you the number of degrees by which you must adjust your course to remain on track. Tide not exactly beam on? Split the angle between the bow and the beam in two (45º ) now split this in two with the beam (67.5º ) and split the 45º into with the bow (22.5º ). If the angle the tide makes with the boat is 67.5º use 90% of the beam on angle. If it is 45º to the boat use 70% and if it is 22.5º use 40%. So a tide hitting the boat at an angle of 45º to the bow or the stern at a rate of 3 knots computes as follows 60 x 3 = 180 divided by a boat speed of 6 knots = 30º course alteration required to remain on track if the tide is beam on. And 70% of this or 21º is the course alteration required if the tide is hitting the boat at 45º . This won’t help you with Estimated Time of Arrival as we make no account of whether the tide is pushing the boat along or headed it.
Observe the wind and tide – Duncan Wells
Just stand for a minute before you set off to see what the wind and tide are really doing. What will they do to the boat once you let go of the dock. Check which way the boat will kick when in astern by putting the engine in reverse. She will kick in the direction opposite the side with the turbulence. Now you know what’s going to happen when you leave the dock.