Laser Rangefinders

[MedMan]

Has anyone any experience of using a laser rangefinder to measure distance off when anchored? Leica make a couple of models that look as if they should do the job well but they are rather expensive. Being of that stage in life when I become less certain of things as the years pass rather than the opposite, there are times when I would like reassurance that I am actually still 100m off the rocks, not just the 30m that it suddenly appears to have reduced to!

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[CharlotteRusse]

Don't know about Leica, have used Disto Laser Rangefinders (accurate to 3mm) at work quite a bit recently. Very nice tool indoors, but outdoors in bright daylight getting more than 30m is very hard as neither you, nor it seems the instrument, can see the laser dot (without a special reflector at the other end).

I notice the Leica ones don't claim the same accuracy and have binocular type viewfinders , so maybe are better at range in daylight?

If your worried about anchor drag, WAAS or (in Europe) EGNOS enabled GPS units are accurate to around 3m these days. EGNOS is being turned on this year, test transmissions are available now.

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[uke73]

We've got a leica one at work I'll give it a blast later on an let you know!

Cheers

Neil


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[eddieperkins]

It is something we have tried and it does not work. We run a fleet of offshore support and supply vessels and keeping the correct distance from the platform is quite critical. The problem seems to be that you can not keep the thing steady enough for it to get the reading. We tried a Leica Disto.
Regards
Eddie

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[qsiv]

Theyre used quite intensively in certain races to keep tabs on competing boats - however sails are nice and shiny, whereas you might struggle to get a good reflecting surface on the shore.

A radar might be much easier, and adequately accurate...

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[tome]

I have an old Wild Distomat which clips onto my T1 theodolite, both museum pieces these days but I rescued them en-route to the tidy bin when we replaced them all with modern total stations. The Distomat works well with a reflector, but not without. I suppose you could row ashore with a reflector...

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[Oldhand]

How about just tipping your sextant over to the horizontal and checking the angle between 2 features ashore remains the same? Or you could just use a handbearing compass but then you need to write things down.

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[FlyingSpud]

When it is on it buoy, my boat seems forever to be hit by Lasers from the dinghy club along the river, so something to tell how far away they are, so that I could try and get away first, would be very useful, having said that, something to avoid the RS whatevers, would be better still

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[Peppermint]

Re: Before the advent of DGPS

Nautical Surveyors used them during harbour surveys. They worked pretty well in calm conditions with a nice surface to bounce off.

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[uke73]

In response to my earlier post about trying out the Leica one we have at work....

Tried and not very good over about 50 metres as difficult to keep steady enough to get a good reading even though you could still see the laser on the surface I was pointing it at (buildings with rough cast render - so probably quite a good approximation of land!).

I'd go with Radar too as others have suggested - probably not a huge difference in cost is you go for a real cheapy!

Neil



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[MedMan]

Very many thanks for that bit of practical research - much appreciated. Thanks too to everyone else for your useful comments.

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[DavidTocher]

The horizontal sextant method (angle between two points ashore) does not give fix but a positon circle.

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[Oldhand]

Who talked about having a fix? An increase of angle meaans you have moved closer to the shore and a decrease indicates you have moved further away. Isn't that what the question about laser rangefinders was all about?... I hadn't read anything about "position fixing" on this thread when I responded! Pay attention DavidTocher.

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