Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 17-11-2017, 15:02   #16
Registered User

Join Date: Mar 2017
Location: Brisbane, Australia
Posts: 147
Re: distance between two fix

Quote:
Originally Posted by NevisDog View Post
It gets complicated when sailing west to east (or the other way?), eg when crossing from Oz to NZ - what time is chosen as "noon"? I believe the clipper ships running down the southern ocean would record 23 hour days as they could cover the distance between time zones in those high latitudes in a single day.
No problem if one has a Navigation chronometer set on GMT -

In the days before electric string took the art and skill out of Navigation this was SOP, I still use a Sextant from time to time just to keep my hand in, although not many do nowadays, it has become too easy.
KiwiKen is offline   Reply With Quote
Old 17-11-2017, 15:10   #17
Registered User

Join Date: Mar 2015
Location: New Zealand
Boat: Moana 33
Posts: 1,092
Re: distance between two fix

Clipper ships carried chronometers but they still worked noon-sight to noon-sight. I found using GMT was upsetting for watch changes, and very confusing when we reached port. Much prefer adjusting for local noon.
NevisDog is offline   Reply With Quote
Old 17-11-2017, 15:13   #18
Registered User
 
hamburking's Avatar

Join Date: Feb 2013
Location: Kingston Ont Canada
Boat: Looking for my next boat!
Posts: 3,101
Re: distance between two fix

Quote:
Originally Posted by conachair View Post
Each midday, I write in the logbook the GPS total log distance and the water log total distance. Then days run is simply that minus yesterdays figures. And hopefully the GPS days run is more than the log wheel as you've some nice current with you
I did the same when crossing the Atlantic. Noon every day I recorded the position in my log. Easy enough to calculate distance run from noon to noon. I would also send the position via sat phone txt/sms to my shore based support. That way my kids could also follow along on a big wall mounted chart....and if there was trouble they would know where to search.

So then you have to ask...when is noon? Not so easy, since when crossing an ocean you will likely cross a bunch of time zones...adding or subtracting an hour from a noon to noon run.

I think there must be an app that could help with this?
hamburking is offline   Reply With Quote
Old 17-11-2017, 15:50   #19
cruiser

Join Date: Nov 2017
Posts: 45
Re: distance between two fix

Quote:
Originally Posted by henris View Post
Hello,

On ocean crossings, skippers try to know the distance sailed in 24h. With the intention of writing an article on the various techniques (and tricks) used by sailors to determine this distance, I would like to know from our fellows blue water sailors how they do it. (Or if they do this daily routine).

Henri

Have you ever heard of a dead reckoning..... course steered and (estimated) speed through the water.


earlgray is offline   Reply With Quote
Old 17-11-2017, 16:34   #20
Registered User

Join Date: Mar 2017
Location: Brisbane, Australia
Posts: 147
Re: distance between two fix

Quote:
Originally Posted by NevisDog View Post
Clipper ships carried chronometers but they still worked noon-sight to noon-sight. I found using GMT was upsetting for watch changes, and very confusing when we reached port. Much prefer adjusting for local noon.
Noon sights are done at Mer Pass, thus giving a very simple sight reduction without tables to give an observed latitude.
Approximate time of Mer Pass is found by using the DR Longitude and the Almanac.

ie determining the time, usually GMT, when the LHA of the Sun is zero
KiwiKen is offline   Reply With Quote
Old 17-11-2017, 16:36   #21
Senior Cruiser
 
StuM's Avatar

Cruisers Forum Supporter

Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43 and OPBs
Posts: 12,888
Re: distance between two fix

Quote:
Originally Posted by hamburking View Post
So then you have to ask...when is noon? Not so easy, since when crossing an ocean you will likely cross a bunch of time zones...adding or subtracting an hour from a noon to noon run.
I think there must be an app that could help with this?
When is noon? When the sun is at its highest point in the sky.
When ocean crossing, it's optimal to record you location at local noon each day, regardless of what time zone you are currently working in. However, it is simpler to record it at noon for whatever time zone you are currently working in.

Lots of apps will tell you when local noon is for a given location.
StuM is offline   Reply With Quote
Old 17-11-2017, 17:44   #22
Registered User
 
hamburking's Avatar

Join Date: Feb 2013
Location: Kingston Ont Canada
Boat: Looking for my next boat!
Posts: 3,101
Re: distance between two fix

Quote:
Originally Posted by NevisDog View Post
I found using GMT was upsetting for watch changes, and very confusing when we reached port.
Quite right. You should try using UTC instead....
hamburking is offline   Reply With Quote
Old 17-11-2017, 18:56   #23
Registered User

Join Date: Mar 2015
Location: New Zealand
Boat: Moana 33
Posts: 1,092
Re: distance between two fix

Quote:
Originally Posted by hamburking View Post
Quite right. You should try using UTC instead....
Hmmm... you sure that'll work better? How about zulu?
NevisDog is offline   Reply With Quote
Old 17-11-2017, 19:41   #24
woc
Registered User

Join Date: Jan 2015
Location: Punta Gorda, Florida
Boat: Lagoon450
Posts: 85
Re: distance between two fix

Quote:
Originally Posted by henris View Post
Hello,

On ocean crossings, skippers try to know the distance sailed in 24h. With the intention of writing an article on the various techniques (and tricks) used by sailors to determine this distance, I would like to know from our fellows blue water sailors how they do it. (Or if they do this daily routine).

Henri
I may be the one off but I don’t care how many miles I sailed in 24 hours calculating fix to fix. What I do care about is how many miles I made good towards my destination. Not much math needed. For those that like to fix to fix calcs.....there is an app for that.
woc is offline   Reply With Quote
Old 17-11-2017, 19:50   #25
Moderator and Certifiable Refitter
 
Wotname's Avatar

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: C.L.O.D.
Posts: 20,305
Re: distance between two fix

Quote:
Originally Posted by woc View Post
...... For those that like to fix to fix calcs.....there is an app for that.
And the best app for this is found between the ears and aft of the forehead...
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is offline   Reply With Quote
Old 17-11-2017, 22:33   #26
Registered User
 
fxykty's Avatar

Join Date: Apr 2016
Location: Indonesia
Boat: Outremer 55L
Posts: 3,804
Re: distance between two fix

Quote:
Originally Posted by NevisDog View Post
Hmmm... you sure that'll work better? How about zulu?


Zulu is the old name for UTC, so the same time zone.
fxykty is online now   Reply With Quote
Old 17-11-2017, 23:12   #27
Registered User

Join Date: Mar 2015
Location: New Zealand
Boat: Moana 33
Posts: 1,092
Re: distance between two fix

Quote:
Originally Posted by fxykty View Post
Zulu is the old name for UTC, so the same time zone.
NevisDog is offline   Reply With Quote
Old 18-11-2017, 00:40   #28
Registered User
 
clownfishsydney's Avatar

Join Date: Mar 2014
Location: Sydney, Australia
Boat: Lightwave 38' Catamaran - now sold
Posts: 557
Re: distance between two fix

Record the track on chartplotter and then note this at the end of the day or later, review (or download) and see how far you travelled. This is by far the easiest and most accurate option.
__________________
Michael
Formerly of Catlypso - Web Site
Lightwave 38' cat
clownfishsydney is offline   Reply With Quote
Old 18-11-2017, 01:36   #29
Moderator
 
Jim Cate's Avatar

Join Date: May 2008
Location: cruising SW Pacific
Boat: Jon Sayer 1-off 46 ft fract rig sloop strip plank in W Red Cedar
Posts: 21,155
Re: distance between two fix

this is the commonest method:

Note the highest speed you see registered during the day. Assume that this was your average speed, so multiply the knotmeter reading by 24 to find your day's run. round the result up to the nearest even decade.

When you make landfall, repair to the nearest YC bar, and tell all who will listen that you have averaged this speed for your entire passage. If no one is impressed,come back the next day after rounding up another decade. Repeat as required.

Add in a couple of good gales (and perhaps a Tiger shark attack) and perhaps you will be respected in the manner you anticipated. Or perhaps not.

We've always just used the log readings for day's run calculations. Having a stout current helping you along gets you to the destination faster, but means little with respect to how well the boat (and the skipper) were doing.

Jim
__________________
Jim and Ann s/v Insatiable II, lying Port Cygnet Tasmania once again.
Jim Cate is offline   Reply With Quote
Old 18-11-2017, 02:41   #30
Senior Cruiser
 
GordMay's Avatar

Cruisers Forum Supporter

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 49,139
Images: 241
Re: distance between two fix

Greetings and welcome aboard the CF, henris, and earlgray.
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Calculate distance and bearing between two positions Lserpa Navigation 8 16-02-2022 15:05
Distance Between Two Points by Lat/Lon onestepcsy37 Navigation 25 02-12-2017 18:19
Minimum Distance Between Cutlass Bearing and Shaft Zinc Han Engines and Propulsion Systems 13 13-07-2014 18:12
Newcastle to Gold Coast Australia - Distance Between Ports ? andipleasance Pacific & South China Sea 2 17-07-2010 19:24
distance between fuel capn_nik Pacific & South China Sea 1 25-07-2004 08:29

Advertise Here


All times are GMT -7. The time now is 23:01.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.