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    Re: Do We Still Need to Use Sextants?
    From: Marcel Tschudin
    Date: 2013 Mar 28, 11:41 +0200
    Mehrhaba Şems Aktuğ,

    Also from my side: Wellcome on NavList, and - yes - also hello neighbour! My name is not really a traditional Turkish one but I am also living in Istanbul. First in the Kartal-Maltepe-aera (Dragos) and now at Zekeriyaköy. I do not have a background in navigation but joined NavList several years ago because of some common interest. Being retired I decided to investigate as a hobby refraction near the horizon. For measuring the refraction I took during a few years photos from the setting sun taken at the Sahil of Marmara sea. With known times and known locations Hs can be measured in the photos by converting the limb heights above the apparent horizon in pixel with the calibration function to degrees, thus using my camera as sextant. The observed values are then compared to the calculated ones using known time, location and atmospheric condition.

    There have recently been postings on accuracy of observations and on dip where some of my intermediate findings derived from the corpus of over 3000 observations could be of interest to NavList . Unfortunately I am presently blocked with some other work. I will come back on it as soon as time permits.

    Marcel



    On Thu, Mar 28, 2013 at 10:52 AM, Şems Aktuğ <saktug@pirireis.edu.tr> wrote:

    Thanks to all for the help full comments on “Do We Still Need to Use Sextants?”.
    I had been monitoring this group more than 6 months and learned a lot. My proposal to create a different kind of sextant first published in this group, because you have much more experience than me. If we can give birth to this, it will be your production. Some minor notes regarding your comments listed below.

    -Maritime training institutes are continuing to cel-nav lessons because it is mandatory. (STCW-International Convention on Standards of Training, Certification and Watch keeping for Seafarers, 1978) (http://www.imo.org/OurWork/HumanElement/trainingcertification/pages/stcw-convention.aspx )

    -SOLAS (International Convention for the Safety of Life at Sea) says that ships should check their positions by different means. In ocean only way to do it is cel-nav. IMO had amended STCW in 2011 and added a new part for cel-nav. Major oil companies’ ships are required to fix their positions by cel-nav 2 times a day. But in reality at sea there is a resistance to do it. Finding an easy way will help cel-nav to live.

    -Also every ship should have a sextant as far as ı know. So if something replaces the sextant they have to carry it or sextant.

    - For Mr. Reed: Yes Piri Reis University is a maritime university. I am responsible for all cel-nav courses. I retired from the navy in 2004 as a one star admiral and later I went to sea on merchant ships, than start to give lectures like watch keeping, navigation etc. Frankly I hate from my proposal. I love sextant. But what can I do? Also I saw an email send by you to this group which says that you are dreaming something similar what I proposed now. Any way the system should be cheap and accurate. We will see how it comes in the future. Logo for the university? There are two stylized sextants yes, one is old and one is new logo. Logo with one mirror is the new one. Don’t blame on me, I resisted for a proper sextant. (For email issues, IT is working on it. Don’t worry, I can see the messages)

    -Thank you very much for the information about star tracker, I didn’t know that. Also for Celestron SkyScout, but is using GPS technology so it is not an alternative.

    -Thanks to Mr. Don Seltzer for the electronics. Heating and the bias voltage is the main issues, I agree. But in future somebody will find a solution. When I was young I was “heating” the “valves” of the radar (MK-25) or sonar. (AN/SQS-23) But in 20 years everything changed. I am missing capacitors or resistances which can be seen by human eye.

    -Mr. Greg Rudzinski, an excellent proposal, I am wearing a glasses but I hate to see red dots because they are the messenger of something bad.

    -Mr. Brad Morris, identifying the exact star you are pointing at is actually quite challenging, so we may chose some stars but those are not limited to the almanac.

    Best regards.
    AKTUG


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