SailNet Community banner

1 - 20 of 39 Posts

·
Registered
Joined
·
19 Posts
Discussion Starter #1
Hello

I saw this device on a boat, next to the indoor steering post. What could it be? It looks like it might have a handle. There's the large dial and two smaller dials. The smaller dial on the left is labeled "sensitivity". There's a jack labeled "headset / charge". There seems to be a handle on it and a ball on top. Is it type of radio? Is it a handheld measuring device?

 

·
Registered
Joined
·
19 Posts
Discussion Starter #3
But how could it work then? The scale on the large dial does not seem to indicate degrees. It goes up to at least 400. And why would you want a headset for an autopilot?

There is a Navico WP4000 autopilot control on the boat, but of course it's possible that an older system was left in place.
 

·
Senior Member
Joined
·
19,488 Posts
Can you provide a more frontal view?? curious indeed...
 
  • Like
Reactions: Seaduction

·
Registered
Joined
·
4,304 Posts
My best guess with the picture it could be so many things

We have a REAL OLD analog unit that still works (German I think :) ) and it sure looks a lot like that

Are unit has a built in control and a second thing like that on a cable
 

·
Registered
Joined
·
210 Posts
It's the control for my Grampa's model trains! Awsome


ok I'll be going now..
 

·
Administrator
Joined
·
7,555 Posts
Damn you Faster!
I knew that!

The RDF was an amazing bit of absolute junk. Before GPS people pretended they could find where they were with a sextant, and as that was impossible they decided to sell yachties a thing to show where the local radio station was.... Except they are all on land and we were at sea...

Now we see you can buy this bit of junk on Ebay! Like WHY???

The reason, I believe why people like sextants and RDFs is that they LOOK nautical and hi tech. Where the new high tech stuff like AIS and GPS is in a small grey box unseen behind some wood paneling, or a small mushroom that you are meant to mount LOW instead of high up.


Mark :)
 

·
Registered
Joined
·
23,468 Posts
You think those are junk, the same technology is still used to land an airplane in low viz and clouds in some remote parts of the world. The airport transmits an AM band radio signal and an ADF radio (automatic direction finder) simply points towards it. The technology is a few generations old now.

You have to both be heading directly toward it, but not from any direction, from a very specific direction that will align you with a runway and keep you from a granite cloud. Some even require you to do so backwards, going away from the airport first and then turn around. I know some bush pilots would make their own approach off a local radio station. The rules aren't apparently mailed to Alaska. :)

It was only very recently that we no longer needed to check out on them every year. Some chiefs would only require you to fly the approach, if the radio existed in the plane you flew. It was often kept as an extreme backup, but everyone got so rusty, they started ripping them out, just to avoid the check ride task. :)
 

·
Registered
Joined
·
7,220 Posts
Understand the Europeans are bring back a higher tech version of LORAN. Seems with cloud cover or other atmospheric disturbances GPS will fail. When bring boats in/out of Rotterdam and like harbors this is a big deal. Also heard US military is looking into this as well. Concern being total loss of GPS in a cyber war or other event. Evven old LORAN was pretty reliable. Often get momentary drop out and the alarms go off from lost GPS. Have several devices with clear view of sky. Probably just where the satellites are or other interference. Think when war ships near by it happens more often.
For us given being off even 50-100m when offshore is not usually dangerous like it is near the hard edges of the oceans something like this seems a real good idea. Have used the sextant to get distance from known height of land tower of other object and then triangulate turning it sideways or using hand held compass to figure out position. Sometimes old tech is more reliable than hi tech.
 

·
Registered
Joined
·
182 Posts
RDF was as good as it got for a lot of years. You could get a fix even if it was foggy, cloudy or raining at night. Just use the RDF to get a bearing to a radio station, record the bearing, then do it again for another radio station preferably at about 90 deg from the first one then plot the angles on a chart and Bob's your uncle! You know which side of the bay you are on. The things did not have great accuracy or resolution but could get you to the right harbor. Lots more reliable than lead on a string and listening for the breakers in the fog for knowing about where you are. This is why the locations of broadcast radio towers and beacon stations are published on charts.

Omega, Decca, Loran and GPS use variations of the same principle with time to the transmitter to give range instead of bearing. I used to work on those things as well as the old Transit satellite navigation systems.

Gettin' OLD!
O'
 

·
Old as Dirt!
Joined
·
3,488 Posts
Damn you Faster!
I knew that!

The RDF was an amazing bit of absolute junk. Before GPS people pretended they could find where they were with a sextant, and as that was impossible they decided to sell yachties a thing to show where the local radio station was.... Except they are all on land and we were at sea...

Now we see you can buy this bit of junk on Ebay! Like WHY???

The reason, I believe why people like sextants and RDFs is that they LOOK nautical and hi tech. Where the new high tech stuff like AIS and GPS is in a small grey box unseen behind some wood paneling, or a small mushroom that you are meant to mount LOW instead of high up.


Mark :)
Ah... Well... We have a very old but reliable handheld SeaFix RDF on the yacht that we've been using for a very long time (before the advent of GPS) and it works very well. With one beacon we get a good LOP. With two beacons we get a pretty good fix. With three an excellent fix.

FWIW...
 

·
Registered
Joined
·
1,720 Posts
There's no cause to speak poorly of the technology presented by the RDF for it's time. I used it consistently when cruising from Florida to the bahamas in the 70's and 80's. It was simple, reliable, accurate and gave repeatable consistant data. It may be "old school", but even slide rules still work!
 

·
Registered
Joined
·
360 Posts
GREETINGS EARTHLINGS Just love the Doppler effect. Awaiting the next solar flare that may knock out all the G.P.S. and then its all back to basics lead lines deadreconing sextant working on its side giving angle off and ht. that give distance off AHRRRRRRR it good being a Ludd-ite AS ALWAYS GO SAFE
 

·
Bombay Explorer 44
Joined
·
3,619 Posts
Well us old farts who burnt holes in our retinas with sextants were really glad when Radio Barbados was heard on the RDF for the first time at the angle it was expected to be on after 2800 miles sailing hoping we had got the calculations right.
 

·
Registered
Joined
·
19 Posts
Discussion Starter #20
Well, that's really interesting, but it's probably unlikely my handheld GPS will fail me - in the unlikely case that higher powers decide to disable civilian GPS where I happen to be, the RDF may not do me much good either.

Will this device be able to get a bearing for a VHF mayday call, or is it limited to AM talk radio?
 
1 - 20 of 39 Posts
Top