Two Anchors? ‘YAW’ Must be Joking?

Some Captains don’t like to use two anchors and, given some of my early experiences, I can understand the reluctance and the ‘you must be joking, more trouble than they’re worth’ sentiment.

Those early experiences were not always successful and, on occasion, the chains would end up not just crossed, but knotted together – even though I was sure I had spread the anchors wide enough. I didn’t really understand why, and it felt like Aquaman and his water breathing buddies had been having a bit of a laugh seeing who could tie the most overhand knots in my chains – I’ve heard they may also operate in Porto Cervo!

However, I persevered and, when I did get it right, the benefits were obvious.

In this piece I will share what I learnt and one method I used with regular success.

Yacht Movement

When anchored in calm conditions with little wind, sea or current, you don’t need to worry much about the yachts movement, it’s inertia and how it might affect the holding.

Without external forces the yacht just sits atop the point where the chain touches the seabed. But, when wind, current, waves, interact with the yacht you get movement which, in sheltered waters, is mainly surge (longitudinal) sway (transverse) and yaw (rotational).

The manifestation of this movement is that in strong winds a yacht will ‘sail’ around its anchor; sometimes with significant changes in speed and heading. That movement and resultant inertia, combined with the wind force against yacht, places large loads on the mooring equipment, chain and anchor – enough to break the anchor out of the seabed.

Why Two?

We have all heard and felt the terrible shudder as the bow finally comes to a stop against the stretched chain at the extreme of each swing. And, stood on the bridge, bleary eyes transfixed on the ECDIS in the hope that ‘smiley face’ being traced doesn’t turn into the ‘Mark of Zoro’ – a sure sign of dragging!

I found that two anchors could significantly reduce that movement and minimise the chance of dragging. This made staying at anchor in strong winds more secure and comfortable for everyone onboard. I certainly slept better with two out!

It became my preferred choice, not just in strong winds but, also as an option when trying to keep the wind off the aft deck where guests were dinning. Preventing wind blowing away glasses and table settings certainly helps the departmental dynamic!

But How?

Along with the normal factors such as depth, scope, quality of seabed, hazards, weather, etc., there are some basic considerations that I found held true.

  • Set the anchors too close and you do not make significant difference to the yachts movement, and it’s easy to cross when dropping and/or dragging.
  • Set the anchors too wide and, although the movement may be dampened, their pull works against each other, reducing the holding power of your anchors.

Through trial and error, I found that the Admiralty Manual of Seamanship recommendation of forming an equilateral triangle between the bow and the two anchors worked the best. It provided sufficient spread to reduce the movement and also prevent fouling of the chains.

The method set out below is just one of a number I used. It could be described as ‘precision anchoring’ as the end result was you ended up ‘brought up’ on the spot you originally selected. It gives you a lot of confidence when you have to set two anchors in a tight or busy anchorage.

As it requires more a bit more thought and planning to get right, it’s also a great way to teach the bridge and deck teams about anchoring.

Once I have selected the area, using ECDIS and radar to ensure the area is clear, I construct my reference points on an over scaled ENC – changing the VRM units to metres also helps. As I am interested in my final position, I also need to make an adjustment for the position of the CCRP (Continuous Common Reference Point).

It’s an easy calculation as follows – you can access Trig functions on an iPhone by opening the calculator and rotating the screen.

Diagram showing calculation of variable range marker and electronic bearing line

Once you know the amount of chain (scope) you intend to use, you can calculate VRM1 and VRM2 and draw them on the ENC and set EBL1 to point directly at the true wind, and EBL2 perpendicular to wind pointing in direction of 1st anchor – as per the animation.

One word of caution; there is often the temptation to let go the 2nd anchor too early, either before the full scope is paid out, or before the chain is off the beam at a medium to long stay…resist the temptation or you will not achieve the correct spread and you may end up fouling the 1st anchors chain.

Of course, there is nothing wrong with using the bow thruster to move transversely to the 2nd anchor position but, for me, I preferred to use the wind as my thruster as it gave me a better feel of how it was affecting the yacht.

And, when the wind finally abates or shifts direction, it’s time to heave up the leeward anchor before a tangle is created – don’t delay, it’s no fun trying to take a turn out. If you’ve set them properly you can often do this using the windlass without engines or thruster.

Finally

Although I struggled initially, partly because it was something that was not taught and, I also failed to seek advice from others. When I finally got it right, the benefits were clear and as a bonus I found that the thought process involved helped improve my overall approach to anchoring.

I hope this has provided some food for thought, especially for those who have never used two anchors or, have been reluctant due to the horror stories told about fouled chains and anchors.

It is by no means the only way, but it is one that worked for me!

By |2021-06-28T12:56:58+02:00June 26th, 2021|captains, Operations, Safety, ship handling|

How much chain do you need?

I was prompted to write this because of the increasing restrictions in France due to environmental concerns and the impact anchoring has been having on the sea grass/Posidonia. This means that in many places along of the French coast, yachts will have to anchor in water >30m depth.

Although the French rules have perhaps highlighted this, it is not the only place where anchoring in water deeper than 30m is required; other places include Monaco, Capri, the Amalfi Coast, some anchorages in Croatia, Greece and Turkey, the fjords in Norway and Chile and, some of the Caribbean islands – it is not uncommon.

With that in mind, and my own experience of the yachts I have run, I ran a short survey on LinkedIn to gauge how much chain yachts carry.

Although not a huge response, the results were sufficient to mirror my own experience of the amount of chain some yachts carry – in some cases, totally inadequate.

The results to “how many shackles do you carry per anchor?

  • Less than 6 shackles – 18%
  • 7 shackles – 18%
  • 8 shackles – 33%
  • More than 9 shackles – 30%

Rule of Thumb

Of course, there are several ‘rules of thumb’ to help determine how much chain cable is laid depending on the depth of water, among other factors such as type of seabed, weather, current, length of stay, etc. Two such examples are: –

  • The International Association of Classification Societies (IACS) – length of chain in Metres = ratio 6 – 10 x Depth of Water in Metres.
    • For 30m this would be a minimum of 180m or just shy of 7 shackles.
  • The Admiralty Manual of Seamanship uses a formula – number of shackles = 1.5 x √Depth of Water in Metres.
    • For 30m this would be a minimum of just over 8 shackles.

With the above figures, if you err on the side of safety, just under 40% of yachts who responded may not have sufficient chain cable to anchor in water >30m depth and, at 35m depth, only 30% of yachts would have the recommended amount of chain. How this compares to the total fleet would be very interesting.

Interestingly, the RYA recommendation is for a minimum of 4 x Depth. For 30m depth only 4 shackles – approx. half of IACS and The Admiralty recommendation. This may be fine for recreational boats, but for superyachts this seems at odds with both IACS who test and approve anchoring arrangements for ships and superyachts, and the experienced seafarers of the Admiralty.

As RYA qualifications are inherent to Yacht Deck Officer training and certification, has their ‘rule of thumb’ become the standard that most superyacht crew use – again an interesting question!

There is no doubt IACS and The Admiralty are a more qualified authority when it comes to anchoring of ships and large yachts and in my opinion captains would be wise to use their ‘rule of thumb’ rather than the RYA.

The Mysterious Equipment Number

Until I did my Master Unlimited CoC, I never took time to consider how the size of anchor and length of chain were determined for a given vessel. That’s when I learnt about the Equipment Number (EN).

Most superyachts are Classed by one of the IACS members such as Lloyds, DNV GL, ABS, RINA, etc., and they use common rules to determine the mooring equipment. This is based on the EN which is calculated for every Classed vessel – the formula is as follows: –

EN = ² ⁄ ³ + 2 BH + 0.1A

Where:-

  • = moulded displacement in tonnes to Summer Load waterline
  • B = moulded breadth, in metres
  • H = effective height, in metres, from Summer Load waterline, to top of uppermost house
  • A = area, in square metres, in profile view, of the hull, superstructure and houses above Summer Load waterline.

The resulting EN is used in a table that details the number and mass of the anchor, chain length, diameter and grade, as well as towing and mooring lines.

Excerpt from Equipment Table – note ‘Total Length’ of chain is normally split equally between the two anchors.

It is important to note that the EN and anchor equipment is based on the following assumptions and limitations:-

  • Temporary mooring in harbour or sheltered waters
  • Current velocity: max 5 Kn
  • Wind velocity: max 48 Kn
  • No waves
  • Length of chain paid out, scope 6 -10
  • Good holding ground

The effect of waves is important – a significant wave height of just 2 metres would reduce the equivalent max current and wind velocities as follows:-

  • Current velocity: max 3 Kn
  • Wind velocity: max 21 Kn

A significant reduction in the holding power.

As most yachts use high holding power anchors (HHP) the rules also allow their mass to be reduced to not less than 75% of the table value.

Bitter End – Caution!

It is also important to know that the pin securing the bitter end to the chain locker is designed to be sacrificial and break at a load between 15% – 30% of the minimum breaking strength of the chain cable – it is designed to fail to prevent structural damage to the vessel.

It should be a fundamental part of the yachts risk assessment and procedures that, in the event of a runaway chain, the mooring team evacuate to a safe area as the flailing end of an anchor cable can have devastating effects – as was sadly experienced on Ocean Victory.

The anchor and mooring arrangements need to be carefully designed for the risks involved; unfortunately, some yachts, especially those with enclosed decks, place the windlass operator in harm’s way and do not provide safe egress in the event of a failure. Like many operational aspects of yacht design, work is still required to improve safety.

A Guide to Anchoring

The video ‘Anchor Awareness’ produced by DNV, GARD and The Swedish Club, although based on commercial ships, is also valid to larger yachts and is a useful resource that helps demonstrate anchor procedures and safe practice and is well worth a watch – especially for junior officers and deckhands who may be part of the mooring team.

Can be accessed by taping on the image below.

anchor awareness

This piece was not meant as a guide to anchor best practice, but to try to assess if yachts carried sufficient chain for the intended depth, and help fill in some of the knowledge gap that may be missing from the yacht syllabus.

I hope it imparts a better understanding of how anchor and chain cable size and length are determined for yachts. And, importantly, the amount of chain paid out relative to depth that is recommended by authoritative bodies.

This knowledge may result in more secure anchoring and the provision of chain more appropriate to the expected use, water depths and conditions that may be encountered.

How I Learnt What Was Missing From My Yacht Captaincy

Co-founder of OnlyCaptains Brendan O’Shannassy talks of his own experience of mentorship and how this experience awakened the need for this service in yachting.

In my early yachting career I often felt the ‘imposter’ as I stepped onto the bridge ready to manoeuvre. As my experience increased this feeling reduced but there was still something missing. There is a good chance that, like many of my peers, I may have even managed a career without knowing what the ‘secret sauce’ to achieving true technical competence in shiphandling was. This same observation could be extended to decision making, counselling and the many daily challenges of yacht command – I had the ticket, but did I have the knowledge?

I had received great support by yacht captains through my career but there had been no structured mentoring and learning plan in place. And, often it seemed, that the issue of a Master’s CoC was viewed as the end game, and not the beginning of the Captaincy journey.

Taking a break from yachting to train and work as a marine pilot, I entered a formal training / mentoring programme. New entry pilots are assigned a mentor, a more senior pilot that inducts, trains and supports them in their struggle to move from former captain and nervous shiphandler to competent pilot. A competent pilot who is expected to; step onboard any ship, at any hour, in any weather, take command and bring that ship safely to the port. Whilst my mentoring was focussed on ship handling, I found the learning extended far beyond the bridge; weaving the lessons into my wider Captaincy responsibilities also improved my performance, enjoyment and efficiency.

Returning to shiphandling, I finally understood the importance of defining and communicating the metrics of a manoeuvre. Everything fell into place. What speed? when and why? These need to be known at all times and this must be shared with all on the bridge. It is so important because at all times the entire bridge team must be able to assess every action of the manoeuvring Captain / Pilot against an earlier briefed and agreed plan. The Captain must then be able to communicate any deviation and why.

By communicating this it does not limit the Captain, it allows the Captain to vary the plan in response to the conditions and circumstances at the time. It also allows a challenge from other members of the bridge team if the deviation is not validated, – this is the philosophy of ‘challenge and response’ that is the bedrock of effective bridge teams.

During my first days of induction as a pilot I observed several senior pilots prior to being assigned my mentor. I was intrigued that the more experienced pilots exercised greater diligence with their pilotage briefings than those more junior. Their sketches of the ship’s planned manoeuvre into port were precise, their briefing books had photographs of landmarks relative to the pilotage and during execution they communicated to the entire bridge team what they were doing and why.

I had never seen this or, thought to do this myself, on yachts. Up to this point I would take control at some point on the approach and, whilst I would seek port information from the pilot, I really set my own approach speeds, headings and approach angles based on my best judgement at the time. Often I was monitoring my speed on the simple ‘ten-through-one’ method of checking speed reductions against the last ten cables. Although an effective approach, it is crude, not tailored to wind and tide, and a little too cautious with modern yachts. Through all the training and sea service to Yacht Captain, I had not learnt to communicate my intentions to the bridge team and I may as well have been there on my own – almost without saying, this extended to all leadership decisions.

After induction I was assigned a mentor pilot that was more than I could have hoped for. Ian had emigrated from the United Kingdom to Australia and with nineteen years as a Thames Pilot he had learnt from some of the best in the World and had experienced all the conditions that UK waters could offer – this made Ian a compelling mentor.

The North Queensland commercial port was a very different environment to my yachting experience. It had large tides, strong currents, steady wind and then strong gusts form the opposite direction. It was as unforgiving as I could imagine. The ships were also very different; replacing my delightfully over-powered and easy to manoeuvre yachts, were single screw bulk carriers that were also not as reliable as their Captains would have you believe.

All of this Ian took in his stride, in fact more than that, he actually expected everything to go wrong on every pilotage. He planned for it and whilst I would never be as bold as to call him out, I think he was at times disappointed when yet another of his ship moves went seamlessly. During one memorable departure of a fully loaded Cape Size (a Cape Size ship is 280 metres long, 52 metres wide and when loaded 18 metres deep) Ian turned to me and said, “see that?” I didn’t. My body language was enough to confirm this and asked I remind him after the departure.

Ian took the ship to the port limits safely, we both departed by helicopter and walking back from the helipad after the four-minute flight I asked him what I missed. He recalled that when he had asked the question, the bow of the ship was being pushed back by the water resistance as the ship ‘cut’ across the berth pocket.

This might need some explaining. The berth pocket was deeper than the departure channel and departing the berth needed the ship to move from 5.0m under keel clearance (UKC) to 0.9 metre (UKC). This required a wall of water 280m long and 18m high to be relocated through a very small gap – the water did not appreciate being forced through the gap and pushed against the ship.

In the departure we had shared, Ian had observed the ship being pushed back by this wall of water and the bow was moving 0.2 knots in the wrong direction, a speed almost imperceptible to the eye, however Ian was using both the pilot’s precise navigation unit and his highly-tuned sense from so many manoeuvres.

Ian increased the power on the ship astern to move the pivot point to his advantage and also the forward tug was increased to lifting off (pulling) at three quarter power to recover the bow. The entire event was observed, acted upon and rectified within two minutes. Ian’s point was, if it had not have been acted upon at that point it would have been very dangerous, and with a smirk he asked, “Do you know the fastest thing in the World?” I returned the smile and let the story play out…

“Brendan, the fastest thing in the World is a fully laden Cape Size bulk carrier moving half a knot in the wrong direction!”

It was a great lesson and, as the months progressed, and I moved from observer to the pilot executing the pilotage, the lessons still flowed. I never accepted anything Ian shared without chasing him with follow-up questions. He warmed to this and my shiphandling education accelerated at a rate where I began to surprise myself with my ability to anticipate and react to seemingly unlinked events. When I was a solo pilot and there was a complex move I would speak with Ian before boarding the ship to communicate my plan and build my confidence. My first call on completion would be to Ian to debrief; he was so good, he could picture the move from the call.

Ian had given me tools to use and these were centred around two aspects; the plan and the team available as a resource.

The planning began well before arriving to the ship. We would do the simple things of checking the radio battery was fully charged but, went further, and put a spare battery in our pockets ‘just in case’. The portable pilotage unit never failed, but nevertheless we turned it on and calibrated it ashore, every time. We would visit the control tower to look at their weather information; sure, we could look to reliable weather forecasting from our mobile phones but the control tower had real data from wind sensors on the docks and we could also look to an array of cameras that would also show detail as small as the wavelets on the water. The actual ship movement plan included; speed reference points, headings, abort points and of course final docking plan. This did not vary from the training I had received and, had perhaps previously belittled; it was just my mentor pilot had sewn it all together.

oc bren on bridge wing of ship

Ian had coached me to communicate each of these references in real time during the pilotage and the manoeuvring. If at 5 cables to the berth the plan was to be at 5 knots and the ship was at 6 knots, I would now say “the ship is above our agreed plan and I am comfortable with this but will reduce speed and report again as we pass 4 knots.” This narrative continued across all aspects of the plan and the ship’s Captain and Bridge team. Ian had trained me to make sure the dialogue was both ways, as the crew’s opinions were sought to the point of being demanded. It changed everything. I was no longer ‘alone’ on the bridge, everyone was working with me, as Ian commented:

“You have multiplied your safety by the number of people now engaged”.

Transferring this to yachts, it is possible to gain benefit from any crew member, even when numbers are thin. The discipline of verbalising ship movements to anyone creates confidence and accountability – If you can’t communicate what you are doing, are you really in charge?

I was appointed a great mentor with a structured training plan, but this might not always be the case. I knew that moving forward if there was no, assigned mentor, I would identify the person I wanted to learn from, approach them and let them know I wanted to learn, an important factor as the mentee’s desire and commitment to learn is as crucial as the mentor’s role in supporting their development.

I find many of these great ship handling lessons can also be applied to life; Ian, taught me to:-

  1. test and verify equipment (or ideas),
  2. develop a plan,
  3. communicate the plan,
  4. amend the plan in sympathy to the changing conditions, and
  5. engage others to support and challenge the plan.

The same sense of ‘going it alone’ that I felt on the bridge before Ian’s tutelage may well have spoken to my previous leadership endeavours as a Yacht Captain. My ability to communicate and embrace the support of a team to safely bring a large ship into port gave me a new framework with which to lead a team on returning to Europe where a new Yacht Command beckoned. I would not say it was a silver bullet to success, but it certainly helped – and I still have not stopped learning.

Back on the yacht I missed my mentor and sought to replace this support and extend it to all aspects of my command. Unfortunately, there was no knowledgeable Captain to air my professional challenges in confidence and, although I worked well with management, none had held seagoing command, so they could not provide effective counsel.

Often, Captains, are just expected to ‘get on and do the job’ we have the ‘ticket’ after all, shouldn’t that be enough? However, the reality is that whatever the perceived experience level, we cannot know everything and, it is a dangerous Captain who thinks he does. We are learning all the time and regularly encounter situations never faced before, where the decision making could benefit from confidential counsel with someone who has ‘lived’ experience and can add value to the decision making process and personal development.

OnlyCaptains commitment to our mentoring role was created in response to my experience and that of my fellow Captains who, when I spoke of my journey, asked ‘”how do we access a mentor?” We provide an answer by making sure command is not a solo affair by providing our Captains with support and mentoring that can help them grow and develop their skills as Captains and leaders.

By |2021-06-14T09:41:40+02:00August 9th, 2020|captains, leadership, mentoring, ship handling|
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