Our preference is to always stay at anchor – and this is something we have done with all our boats so we have lots of experience of what works for us and we are very pedantic about our alarms so we can get a good nights sleep without worry. In this blog, I’m sharing our technique and how we use our technology to help …..
Anchoring Hardware and the Basic Principles
We use a Jambo anchor – the question “which is the best anchor” is one that will always create a lot of controversy with the boating community and everyone has his own opinion. The truth is that the best anchor to use will depend on the sea bed – some are good in sand, some in mud, some in weed …. but of course it is impossible to carry lots of different anchors on the average boat. You have to make a choice which suits your boat and the cruising grounds as best you can – and learn where you can and can’t anchor. The discussion also extends to whether it’s best to have all chain, all rope or a mixture of the two – on our first cruiser we had a mixture but I never liked the splice join – although having rope does make for a quieter night as it does not clunk around when the boat moves. In our last motor cruiser, and on Liberation, we have opted for all chain as it just gives us a more secure feeling and we use a rope bridle which takes the pressure off the windlass and quietens down the movements.
In terms of the length of rode (chain and/or rope) you need on board, this will again depend on where you are cruising. The deeper the water you want to anchor in, the more you need – when we were cruising in Florida with depths of 5m or so, we didn’t need very much – but in the Mediterranean the waters are deep and unless you want to be very limited in where you can stay, you need to carry 100m of rode, in our opinion, as a minimum. If we had more space in our anchor locker, we would carry more. You also need to use as heavy chain as possible – unfortunately on Liberation we are only able to carry 8mm chain – which is a bit on the small size. The larger the chain, the heavier it is and the additional weight helps to keep the anchor secure, by keeping the chain on the ground.
There are also a lot of opinions on how much chain you need to let out – for those who don’t know, what you need is related to the depth of water you are anchoring in. An anchor will not hold with less than 3 times the depth of water in chain – in our opinion this is the absolute minimum holding scope but we would never use this to anchor for more than a few minutes! As a matter of course, we will use 5 times depth – so our 100m of chain allows us to anchor in up to 20m of water – but in storm conditions we would use 6 or 7 times scope. The amount of rode you can use also depends on the space you have – we always assume that the boat will turn 180 degrees during the night as this is generally what happens in the Mediterranean with the pattern of winds. Sometimes it is therefore not possible to put out as much chain as you would like as you need to calculate the turning circle of the boat to make sure you don’t hit anything!
We have used a Jambo on all our boats – starting with the 22kg version on our first boat and upgrading to the 30kg version on our last motor cruiser, which we have transferred to Liberation although we needed to make a modification of the bow roller for it to fit. The heavy weight of the Jambo is in the big square block in the middle which holds the anchor to the ground – the flukes rotate around the block and are sharp prongs which dig in to the ground, including through quite heavy weed – they are set widely apart which prevents the anchor from falling over. When the boat turns, the flukes will roll around the block and will reset easily into a new direction. The anchor is designed and made by a small business in Graz, Austria and is an unusual design – we have always found it works very well and we trust it! The anchor comes in a shiny stainless steel version (very expensive!) as well as the cast steel we have – and in sizes from 8kg to 90kgs.
How we set our anchor
Given our assumption that the boat will always turn 180 degrees at night – and potentially the wind could come from any direction regardless of the forecast – the first thing we do is to survey the area we want to anchor in, and not rely on the chart information in relation to the depths. The low depth lines are never quite where they are supposed to be and the last thing you want is for the boat to turn and end up in shallow water in the middle of the night. We don’t go crazy with this – but we do cruise around the bay to work out the actual location of hazards and depth lines – and work out where we want the anchor to be. Sometimes, we will also use our sonar to survey the area if we are in any doubt.
We always anchor into the wind – so we manoeuvre the boat slowly towards the point just past where we want the anchor to be. I will be on the bow with the windlass/chain counter controller – I free the anchor lock and the windlass lock and Ed moves the boat in the wind and gives the instruction when to drop, telling me what the depth is at that point. I launch the anchor and calculate the chain we need at 5 times depth – Ed shoots down below quickly to set the anchor alarm (as we want this on the PC speakers, not in the cockpit) and I keep letting out chain. By the time Ed is back at the wheel with the alarm set, we will be approaching the required chain length. I stop letting out chain and Ed reverses the boat slowly until the chain comes up out of the water (slowly being the key word so as not to dislodge the anchor and drag it along the ground before it sets!!) – we then gradually increase the reverse engine power to set the anchor – with my foot on the chain at the bow roller, I can feel vibrations if the anchor is dragging (which it will often do for a few metres before setting) and as soon as it sets, the boat will stop with a jolt and the bow will do a nose dive. To ensure we are fully set, we will then power the anchor at full engine speed – which will simulate wind of 30-40 knots – if it holds then, we’re fine!
The number one rule about setting the anchor is that if it does NOT set first time – or you are in doubt, you MUST take the anchor completely in and start again, choosing a slightly different location.
How we set and use our anchor alarm for a restful night
When you drop the anchor, it is very important that the alarm is set at the right time which should be exactly at the time the anchor sets in the ground. This is impossible to determine! You drop the anchor and you know when the chain length is equal to the depth and the anchor has hit the ground – however, it doesn’t set straight away as you need probably at least 3 x scope of chain out before the anchor will set, but this varies all the time.
For us, it’s very easy to know exactly how much chain is out as we have the automatic chain counter (and I love it!!) – people without a chain counter try to estimate by counting the meters as they go out (…. slowly counting 1 and 2 and 3 … etc … but I always used to lose count!!!!), or by marking the chain with colour coded paint at intervals so you count them as they go. You cannot determine the setting point exactly as it will depend on the sea bed, the anchor, the speed of the wind – and each time will be different. So – we set the alarm on Maxsea at the point the anchor hits the ground – in the sure knowledge that this will be wrong, but it’s the best we can do.
When we’ve finished anchoring, we tell Maxsea how many metres of chain are out and it sets an alarm circle based on this – if the boat goes outside of this circle then the alarm will go off. However …… it isn’t quite that simple if you want it to be accurate and you don’t want to get woken up unnecessarily in the middle of the night!
Because of the error described above, the circle created by Maxsea will not be correct – as the centre of the circle it creates will never be where the anchor actually is. With the use of tracks (the red lines which are automatically created like a slug trail wherever the boat goes), boundaries (the yellow circle – which you can draw anywhere you like, but is normally drawn as a circle around a point) and a point (the dot in the middle) we create our own monitoring system. For understanding, the thick green lines with numbers shown on the images are our automatic log point (these can be ignored for this purpose) and the thin green line shows the heading of the boat.
The starting point is the track …. the line will be created as we drive the boat into the wind and you can easily see the point at which we stop as a spike, when we start to reverse. In theory, this is usually slightly further than where the anchor was dropped as the forward momentum of the boat usually carries you a little bit over the point where the anchor is launched. As the boat reverses away from the anchor, letting out chain, the track continues to be created and when we do the “tug” at full power on the chain, the track will record the maximum extent the boat can go outwards when the anchor is set.
The first step of creating our monitor screen is to create a point where we believe the anchor to be based on the track – then add a boundary circle around the point with a diameter equal to the amount of chain we know we have let out. We then move the circle and point (which will be linked together) to a first estimated location – the outer boundary of the circle touching the maximum extent of the track line when we tugged the anchor, and placing the point along the track line we created when we were reversing – this will normally be close to the spike.
We then sit and watch for a while – Ed outside keeping an eye manually on how the boat is settling and me inside looking at the track that is created as we move, while I complete my daily logs and arrival tasks. It doesn’t take long before you get a nice moon shaped track, as the boat swings backwards and forwards on the anchor – the number of lines and the extent of lines created will depend on how much wind there is. When it’s calm, you don’t get a nice track very quickly as the boat moves less – but when the wind is blowing hard you can very quickly get a track which often covers various points of the compass.
As the track develops, we get a better idea of where the anchor actually is and I then move the boundary circle and point to line up with the moon shaped track more precisely so I have a pretty accurate circle showing where the boat can move and swing without the anchor moving. The last step in this process is to then adjust the actual anchor alarm circle so it matches as closely as possible the circle of the boundary – this will inevitably mean that the alarm distance at some points of the circle will be further than you would like, as the circles will not match. We normally don’t worry too much about this – it just means that the anchor needs to drag further in certain directions than others before the alarm will go off – if we have plenty of space, then we are OK with this.
In the situation where we are very constrained on space, and we can’t afford to drag as far as the alarm circle will allow, I would then create additional boundary circles (which I call “cushions”) and ALARM them – so if we get into their circle, the boundary alarm will go off even though we haven’t reached the extent of the anchor alarm. This is “advanced” level anchoring 🙂 – and is necessary due to a weakness of the Maxsea system because alarming a boundary circle only works when you go IN the circle, and not when you go OUT of the circle. I wish Maxsea would develop the option for both out and in – as then life would be very simple and all I would need to do would be to alarm my original boundary circle and not use the actual anchor alarm at all!!!!! The example above shows a situation where we anchored in heavy wind and the boat moved considerably between dropping the anchor and setting the alarm – the alarm circle is therefore very much offset from the actual location. The example also shows a previous anchoring point (in red) which can be ignored …. We don’t want to be able to move to the left as much as the anchor alarm will allow so there are a series of “cushions” which are alarmed to protect that area.
In certain circumstances, we make the decision that we WANT to be woken up if the boat turns, because we want to check what is happening – for example, the position of another boat or some obstruction. Although we are confident with our own anchoring skills and alarms, you can’t always rely on those of other boats – and if another boat has a smaller turning circle than your own because they have let out less chain, there is a risk you will be too close. In this case, we would set the anchor alarm circle in such a way that the alarm will go off when we turn, even though the anchor has not dragged.
When the anchor drags – which of course it does occasionally, usually when the boat turns quickly – the alarm will go off. We have some very small powerful speakers connected to the Nav PC and believe me it wakes up the whole bay! Generally speaking, our anchor will reset again very quickly and we can see that by monitoring the track – when we are happy it has reset, we can simply just adjust the boundary circle and point location to reflect the new situation.
The other useful thing about our methodology is when you leave and need to pull the anchor in, the point can be sent to the TZT – and the helmsman then know exactly where the anchor is laying in relation to the boat, so he can motor towards it slowly to avoid putting excessive stress on the windlass as the chain is pulled back in.