Common Errors During Anchoring Operations:
Anchoring is a key operation that demands accuracy and knowledge of the ship’s gear, seabed, and climatic conditions. A small mistake can result in serious consequences, such as dragging anchor or gear damage. The following are common errors that can undermine the safety and efficiency of anchoring.
Inaccurate Chain Scope Calculation
The chain scope (chain length to water depth ratio) is critical for effective anchor hold. The error of calculating scope solely on depth, ignoring wind and current conditions, is common. The optimum scope is 5:1 to 7:1, but poor weather can necessitate 10:1.
If the chain is not sufficiently long, the anchor will not hold fast, and dragging will become more likely. Excessive chain may make the vessel swing against other vessels or objects. Set the scope according to current environmental conditions.
Inadequate anchor chain markings
Accurate and legible anchor chain markings are essential in measuring the amount of anchor chain payout. Without these markings, the operator will not be able to control the position of the anchor. Painted chain links may wear or fade, leading to errors. Use anchor chain markings, combined with existing depth sounder readings and seabed data, to check depth and anchor chain payout
Ignoring Windlass and Brake System Maintenance
Failure of windlass and brake is major anchoring faults. Under load, windlass brake must hold the anchor chain. Due to lack of maintenance, the windlass can fail, especially in adverse weather. Check for braking effectiveness, lubricate, and inspect wear before each use in anchoring operations.
Miscommunication between Deck and Bridge
Coordination between deck and bridge is crucial. The improper communication between them can make the chain payout or anchor alignment incorrect. Stick to standard lines and live feeds to keep everything in sync. For instance, the bridge tracks the movement of the ship and the deck executes the payout on the chain as they stay connected at all times.
Faulty chain brake engagement
As the chain is paid out, the anchor is held in place by the chain brake. If the brake is not adjusted correctly, the shock loads may damage the equipment. During anchor lowering, the brake should be applied gradually while monitoring the chain tension to ensure a secure hold.
Ignoring environmental factors
The position of a vessel at anchor is greatly affected by wind, tide and current, factors that are often overlooked by operators. Strong winds or currents may drag the anchor. Keep an eye on the data in real time and adjust the range or move the vessel as needed.
Failure to Monitor Anchor Setting
After the anchor is dropped, the ship needs to stay in a controlled attitude to allow the anchor to settle. Not controlling anchor penetration will lead to the anchor resting over soft material rather than embedding. Observe the setting condition of the anchor and take up the slack to get embedment.
Not Verifying Seabed Composition
Different seabeds provide different levels of anchor grip. A soft, muddy seabed requires a different anchor strategy than a rocky one. Before anchoring, use a seabed survey or echo sounder to detect the seabed type.
Case study example
In another case, a bulk carrier failed to drop anchor despite following procedures. The seabed shifted, revealing a hard rock surface beneath a soft sediment cover.. The anchor skipped over the sediment and didn’t set. The vessel started to drift and had to be repositioned.
Key Takeaway: Altogether check seabed conditions since soft seabeds increase the hazard of anchoring failure
Final Thoughts
Successful anchoring needs knowledge of mechanical systems, weather conditions, and accurate calculations. Errors in scope, chain marking, brake system, or communication may cause harmful consequences. Technical attention, and observation of conditions will ensure that the risk of a poor anchoring operation is averted.
