Navigation poll

[charley]

I was reading somewhere that a DR should be taken every 300 miles, that seems kind far to me unless way out to sea. Does this sound right, how often do you take a DR?

[Lodesman]

Charley,

The DR 'interval' is irrelevant - you just need to make sure there is always a future DR. That ensures that your intended track does not have you standing into danger. The interval at which you fix the ship's position is another thing though - that interval should be predicated on your proximity to navigational hazards.

Kevin

[hellosailor]

"how often do you take a DR"
How nervous are you about where you might be? < g >

If you can draw a circle on the chart, any size circle on any chart, and be happy saying "We're somewhere in here" then your position is good enough.

There's a saying that a real navigator NEVER knows where they are, and a real skipper will never ask them. Instead, you ask "How large is the circle of uncertainty?" (the position circle you've just drawn).

Big circle? Not so good. Small circle? Much better. < g >

[Lodesman]

A real navigator always knows where he is - his level of precision, however, is subject to change

Kevin

[unbusted67]

Wow I must be a pretty good navigator then. I am on land.

[Kapena]

I'd use the sextant. Best fix I ever made would mean I could find the North American continent. Finding an island would be lucky.

[GordMay]

We can improve our navigational “luck”, by observing the changing environment around us.
The occurrence of convection clouds, cloud highways, or cloud wakes, can all point the way to Islands.
Dawn and dusk (feeding) flight paths of seabirds are also good land indicators, as are changes in ocean swells, and drifting vegetation.

[nolatom]

Hold the phone--Do I still have VHF? Then I'd do what uncertain navigators have done for years--get on the radio and ask a nearby ship/tug/anybody for a fix.

[nolatom]

Wait a Sec--More ways to cheat on the question--Do I still have RDF? (remember those things?). Not precise, but will get you in the ballpark.

Do I have a fathometer? If the bottom has some contours, you can use them for a rough fix, especially when approaching some landfalls. "The closest land is usually straight down" ;-)

[nolatom]

Originally Posted by unbusted67

Aren't you supposed to call the Army Corp of Engineers in some places? I know the Southern passage to Woods Hole has a note about that on the chart. What's the story with that?

The Corps controls the Cape Cod Canal, so you'd follow their regs during transit (like no sailing in the canal, just motoring, a rule I'd frequently ignore if the breeze was good). Don't know of other places like that, but probably most of the locks are theirs too.

[hellosailor]

Nolatom-
"so you'd follow their regs during transit (like no sailing in the canal, just motoring, " I keep hearing the same thing about the East River, but the published regs for the Cape Cod Canal just restrict it to "adequately powered vessels" and sails are the primary--and adequate--propulsion source on any auxiliary sail vessel.

Cape Cod Canal, Navigation, Navigation Regulations

[Kapena]

Nolatom...I think most of us are talking about offshore. You still have a vhf. All you have to do is get within 10 miles of land or another boat to use it. Who owns an RDF anymore? Your depth sounder will certainly tell you the depth but offshore it may or may not tell you anything depending on how good your DR is and how deep the water is. The depth sounder is nearly useless offshore in the pacific as it's too deep to even register for most units.

[nolatom]

Originally Posted by Kapena

Nolatom...I think most of us are talking about offshore. You still have a vhf. All you have to do is get within 10 miles of land or another boat to use it. Who owns an RDF anymore? Your depth sounder will certainly tell you the depth but offshore it may or may not tell you anything depending on how good your DR is and how deep the water is. The depth sounder is nearly useless offshore in the pacific as it's too deep to even register for most units.

I'm a coastal buoy-hopper, so please take my wiseguy ideas with a grain of salt. I have an RDF in an attic somewhere, but this is a coastal thing too. So I guess I'd have to learn celestial in a hurry. Maybe I could just shoot Polaris and latitude-sail while I'm learning. But don't most of you deep-sea guys and gals encounter at least a couple of other vessels during a long passage? Then you could bum a fix, especially if you have SSB.

My idea was that you could DR your way through the deep stuff, then, as you approach landfall and REALLY need a fix to find out where the heck you are, you'll see other vessels, bottom contours coming up, RDF transmitters in range, yada yada.

This has been an interesting topic.

[unbusted67]

Originally Posted by hellosailor

Nolatom-
"so you'd follow their regs during transit (like no sailing in the canal, just motoring, " I keep hearing the same thing about the East River, but the published regs for the Cape Cod Canal just restrict it to "adequately powered vessels" and sails are the primary--and adequate--propulsion source on any auxiliary sail vessel.

Cape Cod Canal, Navigation, Navigation Regulations

Interesting. You'd think it would be the navy corp wouldn't you? You can't trust the lubbers

[wind rose ll]

When using a sextant on an inland body of water should the height of your eye take into consideration the lakes height above sealevel? and how/where does one receive an accurate reading of the ASL height?
Dave
(Just learning celestial navigation)