GPS as the Sole Means of Navigation.

[Hudson Force]

Originally Posted by s/v Beth

......................... This way I do all my navigation and communication from the cockpit.

This is excellent advice from Newt for those, like me, that ar spending much navigation time among inlets, coastal, islands, rock, etc. We need to do everything from the cockpit. Well, second thought, I do need to leave my cockpit to raise or lower sails or anchors.

[Blue Crab]

Originally Posted by atoll

what a great day that would be for delivery skippers who can navigate in real time.....bring it on ....in days past you earnt the right to be called a captain/navigator by how succesfull your landfalls were

Good one.

GPS created the "Let's sail to Tahiti" brand of yuppie.

[s/v Beth]

I just got tired of running up and down the hatch for Vhf, radar etc. Was going to put my plotter on the pedestal but was worried about the compass deviation. By mounting it in the doghouse, I secure my electronics and keep my eyes on the horizon for up close problems.

[robert sailor]

Hey Newt,
Just an opinion with no back up other than all the sailors I know. Doing a muli day or week passage and getting within 50 miles is not really acceptable. DR is not going to cut it finding a small island in the Pacific because many are not that big to start with plus a 50 mile error is just unacceptable if you call yourself a navigator.

Don't get me wrong I love GPS and would not want to be without it but I could be.

[boatman61]

Two comments on things so far...
1/ The Buoyage System USED to be the major nav-aid in the UK but under the last Labour Gov' a hell of a lot disappeared... the Thames Estuary used to be covered with buoys leading one through the myriad channels... now it just the main channel and a couple of cuts over the main bars....
Regarding GPS... I feel there's a proability that accidents have increased as newbies with to much faith either steam in too fast or play to close for safety without attention/knowledge as to warning signs like changes in water hue... landmarks etc..
Its amazing how many folk can't judge depth in clear waters by eye and proven old laws like navigating reefs should be done pre noon.. a quaint ancient custom/taboo...

[psneeld]

For all those that are making blue water passages and finding little islands without GPS....

What is your celestial error radius?....How about your min/max error on your DR?

[boatman61]

Originally Posted by psneeld

For all those that are making blue water passages and finding little islands without GPS....

What is your celestial error radius?....How about your min/max error on your DR?

You'd only think we're bragging and the 'BS Meter' would come out..

[transmitterdan]

Too late....

[HappyMdRSailor]

Originally Posted by boatman61

You'd only think we're bragging and the 'BS Meter' would come out..

How many budgies were in there???

[robert sailor]

If you take several sights and average them you should be able to get within 3 miles +- and then use your coastal navigation to get you to port. Got to admit its been a long time and I'd probably have to do some reading myself to refresh my memory, such that it is

[psneeld]

Originally Posted by boatman61

You'd only think we're bragging and the 'BS Meter' would come out..

Nah.....I'm sorta over that...well maybe not....

having been military celestial trained and went to sea when it was still actively used....I'd love to hear some of the responses here.

I'll make it easy for some....instead of the word "your error radius" in my last post about errors...substitute "reasonable error".

I'm just curious how many really think they could find/miss an atoll like they think.....

[nigel1]

Is there a difference between military trained and civvy trained regarding astro nav??

From the bridge of a 5000t tug using a Cassens and Plath sextant, with a good horizon, I'd say easily to an accuracy of less than ½ mile.
On the other hand, using a plastic Davis sextant, from the deck of a rolling/heaving sail boat, I got on average about 5 miles, if its a calm sea, better, but at 5 miles, still reckon I could find that little island or atoll.

[psneeld]

Originally Posted by nigel1

Is there a difference between military trained and civvy trained regarding astro nav??

From the bridge of a 5000t tug using a Cassens and Plath sextant, with a good horizon, I'd say easily to an accuracy of less than ½ mile.
On the other hand, using a plastic Davis sextant, from the deck of a rolling/heaving sail boat, I got on average about 5 miles, if its a calm sea, better, but at 5 miles, still reckon I could find that little island or atoll.

No...just meant that there's probably a difference after the training stops...and maybe not for a lot of merchant mariners as our careers depended on it...

More directed towards the rec boater that took a class and uses it as a backup...while their life might depend on it at some point and if they really take it seriously...they might even be better...but for the most part.....

[noelex 77]

Good navigation is more about making sure you are not in any danger rather than knowing exactly where you are.

Rather than talking about "what is your error" as if it was a fixed constant a good navigator will asses the variables and make an assessment of the error. I think it is much more productive to think of the error as a highly variable figure. Trying to pin down a single number is ignoring one of the fundamental aspects of good navigation

[psneeld]

Originally Posted by noelex 77

Good navigation is more about making sure you are not in any danger rather than knowing exactly where you are.

Rather than talking about "what is your error" as if it was a fixed constant a good navigator will asses the variables and make an assessment of the error. I think it is much more productive to think of the error as a highly variable figure. Trying to pin down a single number is ignoring one of the fundamental aspects of good navigation

I was taught that navigation is the art of just confirming where you think you are..

OK...be picky....I have no problem asking someone the question of what is your error...because someone who does it a lot is gonna naturally say..."well usually I'm xxx, sometimes I can get it down to XXX and other times I'm way out at xxx"....sorry I didn't write a opening statement outlining the guidelines of my question as everyone else does in this forum...

Other people had no problem with the question..."so what's your error"

Actually Boatman had the only really correct answer....