My old Tasco binoculars have a scale to measure angles. If you use the formula distance=height/tan theta you can calculate distance. Originally the binoculars had a little revolving scale to calculate distance but the markings have long since worn off. Anyway I have been reviewing piloting and the books talk about measuring angles and I was wondering if anyone does this technique. I use the compass in the Binoculars regularly to take bearings but never use the reticle. It seems that you must have a pretty tall object to get an angle that would give you a distance in miles. Here on the gulf there don't seem to be that many tall objects. Measuring a very small angle on small boat would probably give a bigger error than just guessing the distance. For instance you'd need something about 92' tall to give an angle of 1 degree at one mile(5280). Tom
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I'm getting a range finder because
I find it way too difficult to get any kind of accurate reading also. If you don't want to take the time to find distance by plotting your postition on a chart then I think purchasing an inexpensive range finder would solve the problem. I googled "range finders" and found prices from $30 to $1500 or more. See the links. http://www.bizrate.com/buy/products__att362290--362293-,cat_id--12180000.html
I find it way too difficult to get any kind of accurate reading also. If you don't want to take the time to find distance by plotting your postition on a chart then I think purchasing an inexpensive range finder would solve the problem. I googled "range finders" and found prices from $30 to $1500 or more. See the links. http://www.bizrate.com/buy/products__att362290--362293-,cat_id--12180000.html
What for?
Just curious...for what reasons might you need to judge distances so accurately? I sail on a 1x7 mile lake and have a marina slip, so I've never needed to measure anything and can't imagine what you'all on the coasts need to measure! ...RickM...
Just curious...for what reasons might you need to judge distances so accurately? I sail on a 1x7 mile lake and have a marina slip, so I've never needed to measure anything and can't imagine what you'all on the coasts need to measure! ...RickM...
It's a throw-back to the pre-radar days.
When coastal navigating, knowing range gives you two LOPs with one bearing. And I'm with the other posts, big deal. I'd just guess. Men are spacial. We can come close, even looking in binoculars.
Right? Well, OK, but at least we can guess.
When coastal navigating, knowing range gives you two LOPs with one bearing. And I'm with the other posts, big deal. I'd just guess. Men are spacial. We can come close, even looking in binoculars.
Right? Well, OK, but at least we can guess.Here along the Gulf Coast
There are shoals that extend out for miles. Last year when entering Mobile bay I almost cut it too close and ended up in breaking waves!! I was watching the depth sounder but the water became very thin as I approached the channel. The low lying land was just visable. But even in a lake there are things to avoid. I remember one rock ledge in particular it was unmarked in Cherokee lake. In the summer when the lake was full it was about 15' deep so no problem but as they lowered the lake in the fall it would be waiting just a couple feet below the surface with the water 50'+ on either side. I never hit it but came close a few times. In familiar waters knowing the distance off a point isn't too hard. But when you are sailing up the coast and trying to enter an inlet that you've never entered before any additional information is good. Often going down the coast we don't want to go out to the sea bouy and follow the channel. Especially if we are sailing and following the channel means having the wind on our nose. My depth sounder went out a couple of months ago. It was amazing how much more effort was required in piloting without a depth sounder. I confess that normally I navigate with the depth sounder,chart and my eyes. My wife sometimes gets nervous and turns on the loran or GPS.
There are shoals that extend out for miles. Last year when entering Mobile bay I almost cut it too close and ended up in breaking waves!! I was watching the depth sounder but the water became very thin as I approached the channel. The low lying land was just visable. But even in a lake there are things to avoid. I remember one rock ledge in particular it was unmarked in Cherokee lake. In the summer when the lake was full it was about 15' deep so no problem but as they lowered the lake in the fall it would be waiting just a couple feet below the surface with the water 50'+ on either side. I never hit it but came close a few times. In familiar waters knowing the distance off a point isn't too hard. But when you are sailing up the coast and trying to enter an inlet that you've never entered before any additional information is good. Often going down the coast we don't want to go out to the sea bouy and follow the channel. Especially if we are sailing and following the channel means having the wind on our nose. My depth sounder went out a couple of months ago. It was amazing how much more effort was required in piloting without a depth sounder. I confess that normally I navigate with the depth sounder,chart and my eyes. My wife sometimes gets nervous and turns on the loran or GPS.
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