Anchoring with poor spatial awareness?

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stranded

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I love to anchor, but too often we pass up opportunities and end up on a buoy or in a marina because I seem incapable of assessing the available swinging room until I get in the dink and view the situation from a way away. And not talking about marginal situations either - two occasions recently I sat in the cockpit fretting that we might come together with a neighbouring boat on a mooring only to find when I checked it out from the dink that we were at least 50m (fifty!) away at closest approach. It really is a type of blindness.

Anyway, reckon I need some technological help and been looking at electronic range finders. Wow, can you spend some serious money on those things. But before I put one on my Christmas list, has anyone any experience or views on whether they would actually work for the purpose? Or any other solutions? I have thought of measuring how far I can throw a stone and doing that for reassurance, but a bit of a bugger if I get it wrong, and might be a bit disconcerting for any occupants of said neighbouring boats.
 
If they are beam-on to you and you can guess their length then you can take bearings on their bow and stern and calculate the distance off from the angle between the two bearings.
 
I have used one of the range finders and they are very useful, especially in very tight anchoring situations. For example, when trying to determine if the stern will swing into a rock if there is change in wind direction. You can also pick if a boat ahead is slowly dragging. A change of only 1-2 metres can be reliably differentiated.

The new digital radars offer much better near field performance than the older magnetron units so are an alternative option. They don't offer the accuracy of the range finder, but they are good enough for many distance measurements and are also good general purpose radars if it is time to update your equipment.
 
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Muddy32 said:
Keep trying lots of times - experience is a wonderful thing.
Click to expand...

I’ve been trying for 20 years! I have just had to accept that l can’t do it, and as we head into the Med next year I have to find a solution or bankrupt us on marina fees. Peace of mind (and beer money) are also wonderful things!
 
Nooka said:
I’ve been trying for 20 years! I have just had to accept that l can’t do it, and as we head into the Med next year I have to find a solution or bankrupt us on marina fees. Peace of mind (and beer money) are also wonderful things!
Click to expand...

I been anchoring for twice that and I find the older I get the more harder I finding to work out the distance, maybe it's to do with eye sights.
If you ask around a lot of people have the same problem , we came across one guy this year who was screaming at another boat he was too close to the extend we tho he was going over to hit the guy , only to find half way over in his dinghy , the turned around and when back to his boat , Mmm wonder why .
I thinking of buying one of them range finder now .
 
sailaboutvic said:
I been anchoring for twice that and I find the older I get the more harder I finding to work out the distance, maybe it's to do with eye sights.
If you ask around a lot of people have the same problem , we came across one guy this year who was screaming at another boat he was too close to the extend we tho he was going over to hit the guy , only to find half way over in his dinghy , the turned around and when back to his boat , Mmm wonder why .
I thinking of buying one of them range finder now .
Click to expand...

Reckon you’re right Vic. Funny thing is, my awareness of close, small distances - gaps the car will get through etc. - seem fine. I think it’s something to do with lack of intermediate reference points. I noticed years ago, when I snuck up to the top of the then new Mound stand at Lords cricket ground, that the wicket looked way closer than it did from my low tier seat, even though it must actually have been nearly twice as far away - again, no, or few, intermediate reference points in direct sight line.
 
Muddy32 said:
Keep trying lots of times - experience is a wonderful thing.
Click to expand...

My distant judgment is pretty good, but there are times when it can be fooled. It is difficult to judge distances without any reference objects of known size. Some of the bare coastlines or rocky outcrops are like this. Without any people, buildings or trees it is difficult to judge with any great accuracy if you seeing a small rock that is close or a larger rock that is farther away.

The other time it can be difficult is at night especially if you want to preserve your night vision rather than use a spotlight. The range finders work in darkness so even if you can only just vaguely make out an object you can still accurately measure the distance. I have even successfully used it firing in the direction of an anchor light to measure the distance away of a boat that I can otherwise not see.

The range finders are just a gadget, but are still useful even if your depth judgment is normally very good. Given the low cost they are worth considering for those that anchor frequently. Xmas is coming up :).
 
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My thumb is 6.5cm long and with my arm outstretched it is 65cm from my eye. So anything that looks the same size as my thumb at the end of my outstretched arm is distant by ten times its length. So a 12m boat that looks the size of my thumb is 120m away. If it looks twice the size of my thumb it is 60m away. Or that 2m high person that looks thumb-sized is 20m away and wondering why I'm giving him the thumbs-up!
 
Just keep anchoring. When you eventally do bump someone you'll know what too close looks like.
 
Laser range finder is the way forward.
Bought one a few years ago and it has made a huge difference.
It also helps you learn to judge distance better by comparing your estimate to the measurement so I find I need it less than before now.
Worth every penny and combined with an anchor alarm app on the phone takes a lot of anxiety out of the process.
Martin
 
Nooka said:
I love to anchor, but too often we pass up opportunities and end up on a buoy or in a marina because I seem incapable of assessing the available swinging room until I get in the dink and view the situation from a way away.
Click to expand...

sailaboutvic said:
I been anchoring for twice that and I find the older I get the more harder I finding to work out the distance, maybe it's to do with eye sights.
Click to expand...

I'm with you two. In my case I always tend to underestimate the distance, so I tell myself this and closer in than my gut tells me. Which often works, but sometimes sees me too close. It's not helped by the sparseness of vegetation and lack of habitation around typical Scottish anchorages ... without trees or houses it can be awful hard, I find, to get a sense of scale.

On the other hand, perhaps it's just me. When i was learning to fly gliders the thing I found hardest, and never really got good at, was estimating heights in the circuit while coming in to land. I had a tendency to do my final turns much too high, which I dealt with by buying a glider with huge airbrakes and learning to sideslip well, so I could come down really steeply.
 
Had the same problem, although it got better with more practice. I've had a £80 golfing range finder in my Amazon basket for a while now, but haven't organised shipping yet. What really helped me was thinking in own boat lengths, i.e. "how many times would Songbird fit into this gap?".

Mostly I err on the side of caution and when I'm not sure, we just keep an eye on things until the tide turns and boats swing - always ready to re-anchor if need be. So far we've never hit anyone, most of the time it turns out there was plenty of room after all.

If you see an eye doctor, you'll probably get diagnosed with less than perfect stereo vision, which makes it harder to judge distances and catch balls. Your brain can compensate for this, i.e. with the boat length trick working for me.

P.S.: Where did you end up at? We've booked a winter stay in Albufeira and are doing some boat maintenance now.
 
There are two useful units of angle.
Thumb and hand
A thumb at arm's length is about 2cm in 50cm? 1 in 25
so a boat that's 'one thumb long' is 25 boat lengths away. ish!
A hand is about 4 thumbs obviously and the boat is about 6 lengths away.
Mast height is usually a bit more than length.

You don't normally have to stick your arm out to use this.
We also use it when racing to describe a direction, e.g. the mark is about one hand to the left of the car ferry.
 
JumbleDuck said:
I'm with you two. In my case I always tend to underestimate the distance, so I tell myself this and closer in than my gut tells me. Which often works, but sometimes sees me too close. It's not helped by the sparseness of vegetation and lack of habitation around typical Scottish anchorages ... without trees or houses it can be awful hard, I find, to get a sense of scale.

On the other hand, perhaps it's just me. When i was learning to fly gliders the thing I found hardest, and never really got good at, was estimating heights in the circuit while coming in to land. I had a tendency to do my final turns much too high, which I dealt with by buying a glider with huge airbrakes and learning to sideslip well, so I could come down really steeply.
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It's even harder in the polar regions, where the total lack of familiar objects to give scale AND crystal clear air (when there's any visibility at all!) means that it is easy to misjudge distances by large amounts. A place that looks a mile away can easily be 5 miles off! In both Arctic and Antarctic I've seen hills up to 100 miles away; the combination of clear air and frequent refraction effects makes that not too unusual. I think the longest distance I've seen is the hills of Alexander Island from Rothera Point - well over 100 miles.

Basically, once you get beyond 10 metres or so, we don't have any built-in distance measuring kit. We use stereoscopic vision up to that sort of distance - I don't know exactly how far, but 10m sounds about right. Beyond that, it is entirely something learnt, not something innate. Because of the lack of fixed size objects and the usual situation that you are looking at an object without nearby similar objects to compare it with, it is very difficult to estimate distance over water, and most people underestimate distance over water.
 
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