Range finder at sea

[actionoptics]

A little while back, someone asked if anyone had tried a laser range finder at sea to aid coastal navigation. I can't find the thread but I did promise to get hold of one and report back. I have at last managed to borrow one capable of measuring up to one and a half kilometres but of course my boat is out of the water for the winter. I have used the rangefinder walking around the local hills and it does work and gives consistant readings. Anyone know who was interested, please?

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[Its_Only_Money]

Is that safe for anyone who happens to be walking along the bit of coast you are aiming the thing at????

Wouldn't want to blind anyone - and at that range you can hardly make sure you AREN'T pointing it at anyone????

<hr width=100% size=1>Rgds

Simon
Its Only Money
Fairline Sprint
Solent-based

 

[hlb]

I've got two. Ones called radar. The other GPS. Cant think why I would want a third!!

<hr width=100% size=1> No one can force me to come here. I'm a volunteer!!.

Haydn

 

[Talbot]

I would hope you have at least one more, and possibly two -

hand held compass
sextant - (horizontal sextant angles used to be the most accurate measurement of position until the emergence of differential GPS)

a laser with a range of at most 1.5 km is not going to be of great use in coastal navigation. it will only be a danger to eyes if it is in the appropriate wavelength - which a thing of this range didnt ought to be if it is being sold in this country.

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[tome]

We use them in survey applications. Results are very good with prismatic reflectors, but variable to near useless otherwise. I wouldn't consider one for coastal navigation until they put prisms on every feature.

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[charles_reed]

Range finding at sea

I'd suggest that 1.5km makes the device very limited in its utility.

You already have the following reasonably accurate means of finding range:-
1. Using radar - it's actually more accurate for range than angle.
2. Horizontal sextant angles - done properly the most accurate.
3. If you have a height of a landmark ashore, vertical sextant angles.
4. By eye - which is pretty variable and depends on the observers' judgement as well as experience.

Using DR or GPS, though you can estimate the distance, is not strictly speaking a method of finding range directly.


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[bedouin]

Re: Range finding at sea

I seem to recall that the originial question was about using one in anchorages to detect anchor drag. In those circumstances it has the capability of being more accurate, and easier, than the alternatives.

However I don't think I'll be rushing out to buy one just yet

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[StugeronSteve]

"and at that range you can hardly make sure you AREN'T pointing it at anyone????"

A touch of the "No, Mr. Bond, I expect you to die" hey what. Severed arms legs and heads all over the foreshore.

<hr width=100% size=1>Think I'll draw some little rabbits on my head, from a distance they might be mistaken for hairs.

 

[Its_Only_Money]

"Severed arms legs and heads all over the foreshore. "

LOL!

Not quite what I had in mind, more potential cases of arc-eye amongst the landlubbers - who are tiny specks at that distance, and lasers retain lots of their energy at greater distances than say torch light that obeys the inverse-square rule. So I could envisage a situation where the laser had enough power to do damage at a range greater than the users ability to tell what it was pointing at.......at the very least most of these devices contain a warning not to point direct at a persons eyes - which is very difficult to ensure at a mile's range I would have thought. Maybe such a device has built-in recklessness of use????


<hr width=100% size=1>Rgds

Simon
Its Only Money
Fairline Sprint
Solent-based

 

[actionoptics]

It uses a Class 1 eye-safe laser so, sorry, it can't be used as a weapon - shame really as it would be fast enough to be an anti jet ski device. I agree/accept the other comments but I don't have either a radar or sextant on board.

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[hlb]

Re: Range finding at sea

Of course GPS is a direct way of measuring distance. Especially if conected to a chart plotter. Exact distance. in seconds.

<hr width=100% size=1> No one can force me to come here. I'm a volunteer!!.

Haydn