Anchoring:

KNOWLEDGE OF: 

  • Type of anchor
  • Stowage & attachment to boat
  • Preparation of anchor, chain and warp
  • Weighing anchor

UNDERSTANDS: 

  • Correct approach in various conditions
  • Taking way off
  • Crew communication
  • Check holding
  • Depth of water, holding ground, scope required

CAN: 

  • Approach and anchor correctly
  • Weigh anchor correctly

Key Teaching Points:

  • Types of anchor & stowage
  • Depth / Sea bed
  • Scope
  • Hazards
  • Swing zone
  • Recovery of anchor

P.A.M.E.

  • Plan - Where (Seabed type, is anchoring allowed?), When (tides/depth), Who crew briefing, preparation & laying the anchor)
  • Approach - Into tide/wind, speed
  • Manoeuvre - Lowering anchor, Check holding (transits)
  • Escape - What to do if the anchor doesn't hold? If unsure be prepared to move to another location 

Types of anchor:

Danforth

Folds flat, good holding.

Grapnell

Poor holding versus other anchors. 

Bruce

Excellent holding

CQR or Plough

Strong anchor with good holding power

Mushroom

Useful in muddy / river areas

Delta

A fixed version of the plough - useful in combination with a bow roller.


If in doubt, let it out:

Chain & Warp = 6x depth of water. 

Chain only = 4x depth of water. 

The Swing Zone:

Always take into account the 'swing zone' which can be impacted by wind or tide. Vessels move around their own swing zone at different rates according to their weight, freeboard and hull/keel depth.


How it works:


Things to consider before anchoring:

  • Look for a sheltered anchorage.  
  • Take a trial run to assess depth, and allow for a falling tide.  
  • Avoid main channels and submarine power lines; use charts to identify areas.  
  • Prepare the anchor line and anchor. 
  • How much rope and chain needs to be put out? 
  • Check charts for obstructions and what ground to expect.

The anchor is connected to a ‘scope’ of chain, or a chain and rope combination. The amount of scope let out when anchoring depends on whether the scope is all chain or a mixture. The more scope you let out reduces the chances of the boat snatching the anchor out of the seabed. It also acts as a shock absorber. 

If in a tidal area you need to allow for the rise of tide in your calculations. The amount of scope carried on board depends on your area of operation. In shallow estuaries 30m would be sufficient whereas in deep and rocky areas considerably more may be required.

Dropping the anchor 

The process of anchoring is very similar to picking up a mooring buoy. RIBs and speedboats with open bows are easier to anchor, because going forward is easy. 

On larger craft with anchor lockers at the bow, a crew member must go onto the foredeck to anchor but with caution, keeping their centre of gravity low. 

  • Look for shelter. 
  • Check depth. 
  • Approach chosen anchor point in same direction as you would for a mooring buoy. 
  • When at the chosen point stop the boat. 
  • Drop the anchor to the seabed. 
  • As vessel drifts back, ease out scope to 4:1 (all chain) or 6:1 (rope chain) ratio. 
  • Make fast and engage reverse briefly to dig the anchor in.

Dragging and swinging 

Yachts and powerboats move in different ways as the stream or wind changes. Check your anchor is not dragging by: 

 

  • Identifying a transit and checking it at regular intervals. Setting up the anchor-drag function on your GPS. 
  • Taking a bearing from a hand bearing compass. 
  • If the objects in transit cease to be lined up or the bearing changes, you are dragging. 
  • If your anchor is dragging, you will need to raise it and re-anchor. 
  • If it continues to drag, choose a different anchorage. 
   
  • Identifying a transit and checking it at regular intervals. 
  • Setting up the anchor-drag function on your GPS. 
  • Taking a bearing from a hand bearing compass. 
  • If the objects in transit cease to be lined up or the bearing changes, you are dragging. 
  • If your anchor is dragging, you will need to raise it and re-anchor. 
  • If it continues to drag choose a different anchorage.

Raising the anchor 

  • Check to see how the boat is lying. 
  • If the boat is pulling back away from the anchor, you may need to slowly motor towards the anchor as the crew pulls in the slack and raises the anchor. 
  • Good crew communication is essential to avoid overrunning and fouling the prop. 
  • Hand signals between crew and helmsman are useful. 
  • Bring the anchor and line on-board, and stow it away so it is ready for immediate redeployment.