 Check out the bookstore at IRBS.com |
|
|
|
|||||
|
||||||
From: Dave Weilacher (no email)
Date: Sun May 14 2006 - 13:10:47 EDT
How about:
Take a carpenters level and set it level at your height of eye.
Take a straight edge laid alongside the carpenters level and pointed at the distant shore.
Measure that angle. Use the compass rose from a universal plotting sheet.
Wouldn't that be dip?
-----Original Message-----
>From: Alexandre E Eremenko <>
>Sent: May 14, 2006 9:31 AM
>To:
>Subject: Re: your mail
>
>Dear Roger,
>Welcome to the list.
>
>> The first question I have is: I live on a hill overlooking the ocean
>> but dont know my elevation to set the dip.
>
>There are several ways to do it.
>1. Ask a friend who has a GPS to measure your altitude. My experience
>shows that sometimes GPS gives errors up to 50 meters in altitude,
>but usually it is OK.
>(In the US, you do not even need a friend with GPS for this.
>Just go to the department store, buy one, measure your altitude and then
>return the GPS:-)
>2. Take several Sun sights.
>Take them with real horizon first, then with artificial
>horizon. This method is not very precise though; you have to
>take many sights and average them. You also have to determine
>your index correction very precisely and to choose the time when the
>real horizon is very sharp.
>3. You say that you have a precise map of your neighborhood.
>I suppose that this map does not show elevation of your house,
>otherwise the problem would be trivial.
>Now it depends on what you really see from your location.
>Perhaps you can see some well defined shore line, or a building roof,
>or any other horizontal line perpendiculat to the
>line of your sight whose location and
>distance
>you can
>determine from the map. Then measure the Sun's altitude against this
>line.
>4. Everything depends on the circumstances, on what you can really
>see. For example, if you can see your house from the shore,
>and the hill is really steep, you can try to measure the altitude
>of your house roof from the shore using artificial horizon.
>5. If you can see the horizon from your location in TWO OPPOSITE
>directions, you can try a back sight (with some object in the sky
>whose altitude is more than 60d. On your latitude, Sun can be used.
>(I really envy your location if it permits you to do this:-)
>6. The problem becomes much easier (and the solution more precise)
>if you can use any surveying instrument (surveyors level, theodolite)
>with a precise bubble level.
>
>Alex.
>P.S. If needed, I can supply a formula for each case listed above,
>or any other measurement you choose to try.
Dave Weilacher
.IBM AS400 RPG Senior Programmer Analyst/Project Leader
.USCG Master lic. 100 ton
.ASA Sailing Instructor Evaluator
|