[Rhodes22-list] Magnetic or True?

Rory Orkin roryorkin at earthlink.net
Sat Apr 7 19:10:44 EDT 2007


I fooled with a sextant about 40 years ago.. Then took a look at Loran c.
Alll the tables involved with the sextant were a little much.. I Like the
GPS which is constantantly doing the correction for variation and pointing
you to whatever waypoint you are going after. A chartplotter/gps is a whole
different breed of cat than just a plain GPS with the visual reference to
the point you are heading to. 
On the Chesapeake, the problem is not running aground even if you know where
you are.:-) Try Kent Narrows some time.. I understand a boat lost its
transom in the channel last year. 
The chartplotter sort of forces the magnetic variation of the compass to
your attention . Perhaps a little counterintuative but to each his own. I
ALWAYS ALWAYS have the chartbook open anyway especially on a power boat
where things happen faster.


Bill Effros wrote:
> 
> Rory,
> 
> People just starting to sail don't understand what makes this such an 
> interesting question.  Obviously, you can't use a steering compass and 
> chart plotter using true at the same time if you don't also understand 
> the concept of magnetic declination.  In fact, if you are traveling long 
> distances, you can't even use a steering compass and a chart plotter 
> using magnetic if you don't understand that the compass is not 
> necessarily pointing toward the magnetic north pole.
> 
> Furthermore, the chart plotter is telling you which way the boat is 
> moving, not which way it's pointing, or what is the best direction to 
> point in order to arrive at your destination in the shortest amount of
> time.
> 
> Now it is true that you can derive much of this information from a 
> GPS--but not if you don't understand the question.
> 
> For me, the sextant is the greatest navigational tool ever invented.  A 
> GPS is nothing more than a sextant with a super accurate clock built in, 
> and the ability to do the site reduction automatically.  There are 
> sextants available now with automatic site reduction.  The problem with 
> the GPS is that governments have retained the ability to deliberately 
> throw off the clocks in the satellites, and they intentionally do so 
> from time to time.
> 
> Sextants are harder to use, but if you have ever been with a navigator 
> who is good with a sextant it is a thing of beauty to behold, and well 
> worth learning.
> 
> Bill Effros
> 
> 
> 
> Rory Orkin wrote:
>> When I am using the chartplotter I use True.. But I could make the case
>> also
>> for Magnetic as well if I am going to rely on the compass once plotted.
>> Probably not much help but an interesting question
>>
>> Bill Effros wrote:
>>   
>>> Rory,
>>>
>>> Do you chart magnetic or true?
>>>
>>> Bill Effros
>>>
>>>
>>>
>>> Rory Orkin wrote:
>>>     
>>>> I think a charting GPS is the greatest navigational tool ever
>>>> invented..
>>>> It
>>>> gives you an accurate fix instantly and reports your speed as well. If
>>>> you
>>>> get one that interfaces with the radio it will broadcast your position
>>>> in
>>>> the event of a Mayday.
>>>> Not likely but when you want it,  the best piece of information you can
>>>> have
>>>> is your exact position. The GPS is the best way to come up with that
>>>> quickly
>>>> and precisely
>>>> That being said I always use my paper chart book because it gives a
>>>> much
>>>> larger perspective on where you are and where you want to go..not to
>>>> mention
>>>> giving a better overview on hazards..
>>>> The compass is also essential for an easy way to maintain a heading or
>>>> to
>>>> tell someone else how to point the boat.
>>>>
>>>>
>>>> Frazier Scott wrote:
>>>>   
>>>>       
>>>>> I plan to have my new rhodes 22 this spring.  I will be sailing on
>>>>> Long
>>>>> Island Sound.  I will add a VHF radio and a compass but wonder what
>>>>> else
>>>>> by way of navigation equipment I should have.  A GPS seems to be
>>>>> advisable, but is it necessary?  What type of compass is best and
>>>>> where
>>>>> should it be mounted?
>>>>>   Any advice is helpful.  (Rummy, I expect to stock Mount Gay, so I
>>>>> have
>>>>> that covered).
>>>>>   Thanks,
>>>>>    
>>>>>   Frazier Scott
>>>>> __________________________________________________
>>>>> Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list
>>>>>
>>>>>
>>>>>     
>>>>>         
>>>>   
>>>>       
>>> __________________________________________________
>>> Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list
>>>
>>>
>>>     
>>
>>   
> __________________________________________________
> Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list
> 
> 

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