Anchoring aboard Seal - 5 July 2007
by Kate Laird

We asked all the SetSail correspondents to write about anchoring in various challenging scenarios.

Thin sand over coral in the atolls, when the wind switches and starts to blow, causing lots of breeze and wind waves:

We have limited experience sailing in warm waters, but we have seen a boat dragging down on top of us in light winds — the cause: the Bruce anchor had picked up a Bruce-sized brain coral between the flukes and could not reset.

Hard rock and or kelp/weedy bottoms where the anchor will not dig in:

A big heavy fisherman is the best in rock (we have a 150 pound / 70 kg Luke). We have anchored in lots of places where people said the holding was rubbish, but our heavy 105 pound (50 kg) CQR has managed to penetrate the weed/kelp and dig in.

Fisherman anchors don't reset well, so it is helpful if you can get a line ashore to keep you in the same position once you've found that rock to hook into. When it is really steep to (as in the picture of a fjord in Greenland) a line ashore is essential as the Fisherman in all likelihood has only a small part of one fluke set and you need to keep it there with some tension from the shoreline. The other advantage of using shorelines is that you are almost always pulling the anchor and chain up hill and the chain lies on the seabed for much of its length.

A kelp cutter or machete is often necessary to clear the anchor when you're anchoring in kelp or weed. (Ours is from a hardware store in the US and is supposed to be used for clearing ice off sidewalks.)

Super soft conditions off river mouths and alluvial fans:

The Danforth type Fortress works very well in these conditions, but we find it a pain to change anchors for just one night. When the CQR just floats through the mud, though, we've found a good compromise in attaching the Fortress ahead of the CQR on ten feet of spare chain. The CQR is then relegated to a kellet and the Fortress can dig into the soft mud. We have never tried this while swinging on the hook — it might get tied in knots if one were swinging around. In those conditions we would switch anchors. But when one is using shorelines as well, using the anchors in tandem is a short cut to getting the right anchor. Of course, the windlass has to be strong enough to manage the extra anchor. An aluminum Fortress does a good job here, because it is light for its size (ours is 47 pounds), and the main anchor provides the missing weight in the system.

Hamish retrieving the Fortress which we've anchored in front of the CQR. We hauled the chain and CQR up with the windlass in the usual way, and then unshackled the chain and hauled the Fortress up with a spinnaker halyard.

Super tight anchorages where lines to shore and/or multiple anchors are needed:

We use shore lines almost every night. We're so used to it now that when we are swinging on the anchor it feels all wrong. Seal has four spools on deck with 600 feet (180 meters) each (see below), but if you're not that committed to shore lines, using polypropylene lines flaked in bags or plastic barrels can be a good substitute. On Ariel, Kate's previous boat, we used a spool of line which we stored in the forepeak. When we wanted shore lines, we lashed the deck brush to the pulpit as a spindle and ran out the lines from there.

Our four spools of polypropylene. (The red covers protect the lines from UV which is very damaging to polypropylene.)

We have four polypropylene lines and 2 nylon (sinking) anchor rodes that we can use. Most of the time, floating lines are preferable because they run out more easily and are less likely to snag in the prop (they still can, if they are slack and you gun the engine). However, there are times when a sinking line is desirable. (For example when someone else is coming in after you, and you don't want to have to drop a line for them to get in. With a sinking line you can just ease it and tighten it again after they have passed by.)

We almost never use multiple anchors (except in tandem) because it is such a pain to pick up the first anchor when still anchored by the second. (Our anchors are too heavy to pick it up in the dinghy with a trip line, though we do set the second anchor from the dinghy.)

Our usual technique is to

1. Sweep the anchorage with the boat to look for rocks and check the depth
2. Launch the dinghy and position rock strops.
3. Anchor to leeward and back down on the chain, leaving the engine in reverse when we are satisfied that the anchor is set.
4. Run out the lines to the rock strops. Put the engine back to neutral once the stern lines are pulling against the anchor chain.

A rockstrop in Greenland.

When we're backing into shallow waters, we lift the rudder to protect it. We have seen boats with a windlass and anchor on the stern, which looks like a good idea to protect a deep fixed rudder. A hand held depth sounder is handy to double check depths as you back down and, with a scoop on the stern, it is easy to use. Even better, if you have lots of crew, you can send someone out with the handheld depth sounder. Usually though, having driven with the bow in to the spot where the stern will end up, we are pretty confident about what to expect before we reverse in.

You can't pick rocks from on deck, since it's the back of the rock that matters with rock strops, but trees are easier to pick. With trees, it's best to tie an open bowline (without a round turn) so that if the bark is damaged by your line the scar does not completely encircle the tree, as this will kill the tree.

We had a good lesson in the power of shore lines when we hauled Seal back into the water after building the interior. We hand winched her 150 yards back to the water, using trees to pull the dead weight of the boat (on tallowed plywood). When we ran out of trees at the water's edge, we hooked onto the 105 pound CQR which we had left out in the bay the year before with 300 feet of chain in five feet of water. It dragged.

Four-inch diameter trees easily held the same weight that had plucked the CQR out of the mud. The root structure of a small tree is incredibly strong, as long as you tie as close to the base as possible and avoid trees growing in thin soil on the shoreline or over eroded banks.

In this Greenland fjord, the Luke is in 80 feet of water and we have three lines ashore to keep the fluke on its rock. It took us three times to "catch" the rock, because the shore was so steep to we couldn't let the anchor find its rock by dragging the bottom.

What sort of anchors for what conditions?:

The most popular working anchors seem to be a CQR, Bruce, and Delta. We have a CQR based on benign prejudice, but we'd probably sleep just as well with a Bruce or a Delta. A 50 kg CQR looks dainty next to a 50 kg Bruce, but it digs in quickly and easily and resets well when the wind or tide changes. It's very rare that we can't get the CQR to hold with the engine (115 HP) at 1800 RPM in reverse. When that happens, we get out the Luke (fisherman) in rock and the Fortress (Danforth) in light silt.

A way to deal with a fisherman anchor if you don't have a dolphin striker to lash it to.

All our anchors are considered "storm" sized for our size boat (56 feet / 17 m) by their manufacturers, but we have often seen 60-plus knots at anchor down here in Tierra del Fuego, Antarctica and South Georgia. In these conditions, weight matters. To us, there's no point in saving weight by using G80 high tensile chain because we want that extra weight.

We also don't see the point of carrying a second anchor on a bow roller. We'd rather put all that weight into one big anchor and chain and store backup anchors elsewhere.

Types of snubbers used:

We use two nylon docking lines from our bow cleats, through fairleads, and then tied to a chain hook.

Rode types and lengths, and scope:

Chain:

7/16" HT (G40) chain with oversized links on either end; 300 feet, 3/4" shackle

3/8" HT (G40) chain, 40 feet, 7/16" shackle

1/2" proof coil (G30) long link, 40 feet, 5/8" shackle

The key here is the oversized links on both ends as the shackle is the weak part of most anchoring systems and this enables you to use the next-sized shackle.

Rode:

7/8" NE Ropes 3-strand nylon; 275 feet; 600 feet

We try not to anchor in more than 80 feet. We generally use far more than the minimum 3:1 scope, especially when we are using shore lines, so swinging room isn't a factor. Chain left in the locker doesn't do any good, and if you have the room, why not put some extra out and sleep easily.

Mooring (with no anchor down) with four lines ashore in a Greenland fjord.

For more about Seal see http://www.expeditionsail.com.