Selecting a good place to anchor.
Selecting an anchorage
Quite often anchoring is free and you can anchor nearly anywhere so long as you are not getting in anyone's way. Pilot books, local charts and notices to mariners may identify places which offer good holding or have any seasonal, geographical or special anchorage restrictions in place.
1)Initially this anchorage would provide adequate shelter from the present wind direction although it may be prone from swell coming around the headland.
2)This anchorage would offer shelter from the present and forecast wind. It may be a bit rolly due to the sea rebounding off the downwind cliff when the wind changes.
3)This anchorage, although open offers good protection from both winds and offers an escape route if required.
Always make sure you have a good look at the chart to check that there are no obstructions on the seabed.
If you are anchoring in uncertain areas or over foul ground a tripping line can be used. They are often buoyed lines attached to the forward edge of the anchor to help raise it if it's snagged. Ensure the first part of the line is weighted to keep the line below the surface, away from propellers. A buoyed tripping line indicates the anchors position, but can also catch around keels and props.
||Raising a fouled anchor by the tripping line should clear the obstruction|
When selecting your exact anchorage bear in mind that all boats lay differently to the wind or stream, therefore allow enough swinging room. Yachts with deep keels will lay with the stream whereas flat-bottomed motorboats often lay to the wind.
More scope increases the swinging circle as does low water, so ensure the maximum swinging circle clears obstructions.
Using two anchors
Boats should have two sets of anchor and cable; a large one at the bow (bower anchor), and a smaller one kept in a locker for emergencies (kedge). The second anchor is used to increase holding power in heavy weather or to reduce the swinging circle taken up in an anchorage. To reduce the swinging circle the second anchor can be used in many different ways. For example:
When one anchor is dropped from the bow and the other from the stern it should keep the boat in line with a river or in a small deep hole in which you are anchoring.
Two anchors dropped from the bow will increase holding power and also reduce the swinging circle especially in shifting wind.
Next month we will look at Dropping the Hook and Staying Put.
Compiled and edited by Simon Jinks - RYA Yachtmaster™ Examiner and Journalist
The anchor is also a great defensive strategy should you get into difficulty, as it can be chucked over the side near shore to reduce or stop your drift in case of power failure.
Scope is the amount of chain or warp let into the water. The amount of scope depends on the depth of water and whether chain or warp is used. Chain or warp is often referred to as cable.
Check the depth and tidal range. Use a scope of anchor cable of at least 4 x the depth for chain and 6 x for rope/chain combinations.
If warp is used, ensure 5-10m of chain is connected between anchor and warp. The chain acts as a cushion, helping to reduce the action of the boat pulling the anchor free.
An anchor works best when the pull from the boat is closest to horizontal, so that the pull is digging the anchor in. The golden rule of anchoring is; if in doubt, let more cable out.
Good holding to weight ratio – self stows on some bow roller systems. Can be awkward to stow in small anchor lockers.
Good holding to weight ratio – self-launches and self stows. Awkward to stow in small locker.
Good holding to weight ratio in straight-line pull, however may break out and not relocate if pulled from another direction. Can be difficult to handle because of moving parts. Stows flat.
Good holding to weight ratio – relocates well. If stowed on bow, moving parts may need securing.
Good holding in rock and weed but poor holding in sand and mud. Require 30% heavier fisherman's type anchor than other anchor types.
The cable is usually shackled to the anchor at one end and then connected by rope to an eye in the boat so that if the anchor is inadvertently let drop, the whole cable will not simply run-out and drop over the side. The permanent connection to the boat should be a knot that can be easily undone under pressure, just in case you need to ditch the anchor and cable quickly in an emergency.
Some boats have an electric windlass that can lower or raise the anchor. Electric windlasses take a lot of power and should only be operated when the engine is running. Check that the circuit breaker and a power switch is switched on.
Foot switches on the bow or up/down switches at the helm station operate the windlass.
When there is no windlass, the cable may need to be pulled out of the anchor locker and flaked on the deck so that it will not snag when dropping the anchor. Ensure the cable is cleated-off before the anchor is lowered. Take care to check that the chain leading to the anchor locker is on top of the cleat so that it can be undone under load.
Simon Jinks - RYA Instructor & Examiner
It’s a hard call to ask for an anchor watch, but well worth it.
It was 11pm as the boat lurched over on her side once again in the gust. It was the second time in as many minutes and the graunch of the anchor chain pulling her back head-to-wind resonated through me and the rest of the crew.
Crawling out of my bunk it was clear that we were going to have to run an anchor watch.
It had been a very windy day's cruising on the Clyde and the gusts fell like cannonballs down the hills keeping us on our toes. At sunset we sought refuge up the top of the Kyles of Bute just inside Loch Riddon and the Burnt Isles.
The anchor was dropped and 60m of scope paid out allowing a 6:1 ratio for the extreme conditions.
Shelter was good and for a time only the occasional 30 knot gust raised our eyebrows. But the rising tide lifted us out of full shelter and the forecasted Force 4-5 wind rose in strength once again blasting at 40-50 knots in the gusts.
For the crew to sleep that night they'd have to have confidence that we were staying put. An anchor watch was the best way to achieve this. We split the night up between the five on board giving 1½ hour watches.
The most experienced crew went on watch during the rising tide and turn of the tide, when there was the greatest chance of dragging. The less experienced crew went on watch on the ebb, as the anchorage became more sheltered and the ratio of scope increased.
We dropped an extra 10m of chain, leaving 10m in the anchor locker and re-established transits. Luckily our transits were clearly visible from inside the cabin, so that no one had to venture on deck.
The chart plotter was fired up, the screen dimmed and an anchor alarm set to a couple of cables in area.
The area had to be quite large as the boat was veering about in the wind shifts and the occasional erroneous fix from the GPS would not set it off. We also checked the paper chart to ensure that there really wasn't anything lurking around that was not portrayed on the chart plotter.
The standing orders were; that if the plot on the chart plotter or the depth on the sounder moved over the 20m one way or the 5m the other way, the skipper should be woken. If anyone had to go on deck they would wear a life jacket and stay inside the cockpit.
We survived the night and woke to a fabulous morning and many stories to tell. By and large a good nights' sleep was had by all, if not without the occasional hour and half interruption.
It's a hard call to ask for an anchor watch, but well worth it to keep the boat safe and for the crew to get some rest.
Simon Jinks is a RYA Yachtmaster™ Instructor Examiner and Journalist.