In this article Mossops Tackle World’s Col Hinder take us through the lifesaving art of Anchoring. When Col’s not at Mossops he’s busy keeping our south-east Queensland waterways safe at Bayside Boat Licensing.
An anchor is used when you want to stop and fish, swim, have lunch or stay overnight. It is also an important item of safety equipment.
Recommended requirements are highlighted in the minimum safety equipment table. Even if you do not plan to use it, an anchor is imperative if a boat breaks down.
An anchor will keep the boat in the one location or reduce the rate of drift until help arrives. When at anchor, remember changes in wind and sea conditions can affect the holding power of ground tackle, compromising the safety of the boat. Anchors must be of a type that will work in the relevant seabed and with enough line to suit the depths in which you usually operate.
Other than for an emergency, boats must not anchor in channels, near navigation beacons or important notices on the shore such as cable crossing signs.
Types of anchors
There are types of anchors used for different applications:
A Danforth anchor is most commonly recommended for, and used by, small craft. The Danforth is a small light anchor with excellent holding power in mud and sand and can be easily handled in a small boat. Reefs should be avoided as the flukes may wedge in between rocks, causing the retrieval of the anchor to be difficult.
CQR or plough anchors are the most commonly used by larger, heavier boats, but can be used in small craft. CQR or plough anchors also have good holding power in sand and mud but should not be used on reefs.
Reef or grapnel anchors are designed to hold on coral or rocks. Other types of anchors will lodge under coral and that’s where they will remain. The prongs on a reef anchor are meant to straighten out when excessive load is applied and can then be bent back into position. They also create less damage to the coral. In coral reef areas it is better to anchor on sand where a Danforth or plough anchor is more suitable. Do not anchor on coral unless in an emergency.
A sea anchor or drogue is used in heavy seas to slow the drift and keep the bow of the boat into the wind and the waves. This will also provide more comfortable conditions when drifting in choppy seas. If you plan to go boating offshore or on an extended trip, a sea anchor is a valuable piece of equipment.
Anchors also must have something to attach them to the boat. This is called the anchor rode and may consist of line, chain or a combination of both. The whole system of gear including anchor, rope and shackles is called ground tackle. Anchor lines are important.
Don’t use an anchor line that floats such as a polypropylene. It can hinder the anchor from digging in and holding and is also prone to being cut off by boat propellers. Nylon and silver rope are both suitable material for anchor lines. Nylon is best known for its strength and stretching ability plus being more resistant to abrasion. Silver rope has less tensile strength.
There should always be a good length of chain (at least a boat length, 5 metre boat you want 5 metres of chain. between the anchor and the anchor line. The purpose of the chain is to keep the stock or shank of the anchor parallel to the seabed that then allows the flukes of the anchor to gain maximum penetration into the seabed. The chain also helps prevent the anchor line chafing on the bottom. Generally, the bigger the boat, the more chain you require. The length of the anchor line may need to exceed five times the depth of water in which you normally operate. If you mark off the rope at regular intervals with coloured twine, you’ll know how much rope to release so that the anchor sets correctly.
Scope means the ratio of the length of anchor line let out to the depth of water in the place you are anchoring. It is essential to use the proper length of anchor line to hold the ship in all conditions. To calculate how much line to let out, allow for a ratio of 5 to 1. If conditions are extreme, increase the ratio to 8 to 1. The flatter the pull on the anchor, then the better it will hold. The ability of the anchor to hold the ship will also vary with the nature of the seabed.
Keep the anchor, its chain and rope tidy—many boats have a chain locker or well. A plastic crate, bin or open bag keeps things neat. Leave the end out (or feed it through a hole in the crate or bin) to tie to the boat, then lay the rope down coil-by-coil, then the chain and anchor. Ensure the end is secured to the boat. Charts or local knowledge will tell you where there is good holding ground—beware of submarine cables and other moorings.
When anchoring, lower the anchor to the bottom—don’t pick a bundle of anchor chain and line and throw it over hoping it will untangle. Always lay your anchor line out—let it touch bottom and let the boat go astern until sufficient line is paid out. Don’t be tempted to anchor by the stern. Anchoring by the stern causes the stern of the ship to sit lower in the water. Any wave actions or even the wash of other ships can cause water to flow over the stern. Always anchor by the bow. Ensure you take into account the rise and fall of the tide when selecting a long-stay anchorage.
Like anything else, there’s a proper way to anchor:
- Select an area that offers maximum shelter from wind, current, boat traffic and so forth.
- Consider how your boat will lie in relation to others. Pick a spot with swinging room in all directions.
- Determine depth and bottom conditions and calculate the amount of rope you will put out.
- Lay out the amount of rope you will need on deck in such a manner it will follow the anchor into the water smoothly without tangling. Ensure its end is secured to the boat.
- Motor slowly into the wind or tide to just ahead of your chosen spot.
- Wait until you start to drift backwards, then lower the anchor, checking the marks on the rope.
- When it touches bottom, slowly pay out the required scope (gentle reverse propulsion may assist), then secure the rope to a cleat.
Motor gently back against the anchor to dig it in and ensure it is holding.
- While still in reverse, observe a transit between two fixed features to be sure the anchor isn’t dragging. This can also be determined by observing the angle of the cable away from the boat and by placing fingers on top of the rope to feel for any vibration that would accompany the dragging of an anchor over the seabed.
- Check frequently to make sure you are not drifting.
- Don’t forget to show the correct lights at night. An all-round 360-degree white light as high as you can, so it can best be seen.
Raising the anchor
Warm up the engine and motor slowly along the line of the anchor rope, bringing in the rope and feeding it into the bin or locker. Don’t over-run the rope. In small boats always try to handle the anchor from the cockpit, not the foredeck. When the boat is directly above the anchor, a good pull or, with the line secured on a cleat, a short push ahead under power should release it from the seabed. Once free, raise the anchor to the waterline. Clean if necessary and let the rope dry before stowing away. If the anchor becomes caught, do not move the boat over the top of the anchor in an attempt to dislodge it as it may cause the boat to overturn. If you cannot dislodge the anchor, it is safest to cut it off. A handy hint is to wear gloves when hauling in the anchor.