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Old 09-10-2013, 09:20   #1
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Do you count your sea miles? How?

Often you read about person X having sailed 10,000, 50,000 or 200,00 miles.

I am always curious as to how those miles are counted. Here is why:

We have a Standard Horizon CPV 350 chartplotter. It has a total log function that adds up all the miles sailed.

But I find that the miles it records are considerably larger than the miles I measure on the chart from point A to point B.

I presume that this is the same issue as measuring the length of a coastline - the shorter your measuring stick, the longer the coastline gets, until when you get down to measuring each in and out around grains of sand the coastline becomes almost infinite.

The chartplotter is, presumably, adding up the distances sailed between each GPS update - every second or more. Since we never sail a perfect straight line, that adds up to a lot more miles than the rhumb line.

For example after having sailed up and down the Caribbean once, and then to the Bahamas and across the pond via Bermuda and Azores to Portugal, we had, apparently, sailed over 10,000 miles! That seems to make no sense to me.

So, do you record your sea miles? If you do, do you keep a running total of your A to B rhumb line distance, or do you use the chartplotter? And these people who have sailed 50k or 200k, how is that measured?

Just curious
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Old 09-10-2013, 09:31   #2
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Re: Do you count your sea miles? How?

i count a-b distance per voyage and days at sea in my log book,so in reality the 100,000 miles i have logged is probably,5000-10000 less than i have actually sailed,as i never log day sails,or miles logged whilst commercial fishing.
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Old 09-10-2013, 09:37   #3
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Re: Do you count your sea miles? How?

Good question!
And Im not able to answer it, just to throw some more doubts on that matter.

Recently Ive been somehow absorbed by the "curious" ICC rules (its on my last post) and one of the requirements to maintain the highest level in that kind of certificate, is a X number of miles... How can you do that and (particulary) prove it?!
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Old 09-10-2013, 09:46   #4
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Re: Do you count your sea miles? How?

My sailing miles mostly come from ocean racing, so I just take the great-circle miles from point A to point B. I will put in a midpoint if the course is significantly different than the GC (such as the return from Hawaii to the mainland). If I'm trying to impress myself I add in an estimate for my day-sails -- my log book has enough info to guess that number. My total sea-miles on VALIS so far add up to about 26,000 nm. I plan to add another 5000 nm in 2014.

I have certainly sailed farther than my estimates, but not by a whole bunch. I'm not trying to win a prize, and there are always people who have sailed more than I have.
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Old 09-10-2013, 09:48   #5
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Re: Do you count your sea miles? How?

Quote:
Originally Posted by messias View Post
Good question!
And Im not able to answer it, just to throw some more doubts on that matter.

Recently Ive been somehow absorbed by the "curious" ICC rules (its on my last post) and one of the requirements to maintain the highest level in that kind of certificate, is a X number of miles... How can you do that and (particulary) prove it?!
any sailing school should have log books that you can record your miles in ,details of the voyage etc,skippers signature and boat stamp make it official
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Old 09-10-2013, 09:56   #6
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Re: Do you count your sea miles? How?

Yes, but that means that in order to be able to keep your actual "top level" ICC licence...you have to pay for classes to do what you already know?! I think that many of you have a whole lot more experience at sea than some guy from a sailing school, making nonsense miles in a pond! How can I make proof of having X miles on my own boat? And what kind of value does your own log-book has for those "accessing" authorities?
Sorry for bringing the ICC to this post LifePart2, but as you mentioned miles...
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Old 09-10-2013, 10:09   #7
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Re: Do you count your sea miles? How?

the icc is hardly a "top level",it is merely a certificate of competance,issued in the uk on completion of a coastal skippers ticket if asked for, on completion of i think less than 5 days at sea or 500 miles!
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Old 09-10-2013, 10:41   #8
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Re: Do you count your sea miles? How?

Don't know about the rest of you, but I have done nearly all my miles on my own boats. Each of them save dinghies have had knotmeter/logs installed, and they have total miles displays. So, I have merely kept that record for my own amusement. I know that there are inaccuracies involved (days when the impeller was fouled, currents, etc) but really, these are but ballbpark numbers so who cares?

I do enter some of these numbers into my ships logbook, again for my own usage. I understand that ships logs have some legal status, so I think that if I had to prove accumulated milage to someone that might help... who knows... who cares?

Jim
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Old 09-10-2013, 10:45   #9
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Re: Do you count your sea miles? How?

We count miles between the destinations so we probably underestimate by some 20-30%. We also count days at sea. After each passage I take the numbers down in a "log" book (xls in our case).

We do not use plotter-miles, nor log-miles, as our plotters and logs are off 99% of our passages.

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Old 09-10-2013, 10:49   #10
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Re: Do you count your sea miles? How?

my thought would be to take your coordinates at the same time each day say at 2100 hours and figure your overall day to day mileage accrued then add up your total at the end. I see it as a happy medium between rhumb line mileage and actual gps log mileage of every tack you've taken along the way
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Old 09-10-2013, 10:51   #11
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Re: Do you count your sea miles? How?

When I hear/see big number its more a guestimate. I been boating in the Puget Sound are for 40+ years so I figure I have at least 5,000 hours X 7 mph is 35,000 miles. Can I prove it? Heck no! Besides most of the time really does not mean much.

Unless there is a reason for it like for like business, tax, license there is no point for logging miles and hours. Well maybe ego! Most pleasure boater due not log but business and commercial boats do log as its required.


Poeple usually ask and more impressed on how far have you gone than total hours/miles. I don't think I ever been ask how many total hours/miles?
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Old 09-10-2013, 11:24   #12
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Re: Do you count your sea miles? How?

Quote:
Originally Posted by LifePart2 View Post
We have a Standard Horizon CPV 350 chartplotter. It has a total log function that adds up all the miles sailed.

But I find that the miles it records are considerably larger than the miles I measure on the chart from point A to point B.

One of our GPS units maintains a continuous log. Seems to be accurate, when I've compared length of individual trips to my own chart estimates (or by using the laptop software to plot and measure a route).

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Old 09-10-2013, 11:38   #13
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Re: Do you count your sea miles? How?

Our chartplotter logs nm traveled (over ground) accurately, as far as I can tell. I've created numerous complex routes in BC and SE Alaska, traveled them many times, watched the track line showing where we have actually traveled, and compared expected distances to the nm log. It all seems to match up.
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Old 09-10-2013, 12:00   #14
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Re: Do you count your sea miles? How?

I log hours underway only.
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Old 09-10-2013, 12:00   #15
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Re: Do you count your sea miles? How?

I used to use the mechanical log on the speedo, but switched to the Garmin GPS, which has a total miles traveled and is more accurate than the mechanical log.
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