At 13:26 01/18/99 +1100, Peter Grey wrote:
>At 05:50 PM 17/01/99 -0800, you wrote:
>An interesting solution as the simple ones usually are. I do need to know
>the direction of the boat so I can point the camera at it.
>
>>Low-tech solution:  Black Polypropylene rope floats on water.  Let
>>them wrap the stuff around their propeller shafts, pulling a bend in the
>>rope out of a clothespin type clamp switch that turns on an alarm, and
>>likely they'll still be there when you get there, trying to figure what
>>went wrong with their prop.
>>
>>  Mark, mwillis@nwlink.com
>>
>>Peter Grey wrote:
>>>
>>> I wonder if anyone can help. I have an application where I wish to
>>> photograph a boat and people at night (IR camera) but need to be able to
>>> detect that they are there and in which direction (so I can point a camera
>>> at them). This is to monitor offshore property. I need to get a range of
>>> some 100 metres reliably. Hydrophones have been suggested but I am
concerned
>>> about directional capabilities and possible interferences. Does anyone have
>>> any ideas in this field?

if you can put buoys in the water, you can segment the rope, with segments
small enough that you can maybe cover them with a few shots.

ge