Getting our Compass Swung

[zurk]

Differential GPS stations were discontinued by CCG on December 15th of 2022, so umm no, don't go get yurself a DGPS

DGPS is a technology not specific to a country. the new DGPS systems use a 6 axis solid state gyro (for pitch/roll etc) and compute the difference between two satellite transmissions to get accurate heading info using phase differences. the DGPS is basically on board since the antennas are fixed at a known distance inside the unit itself. For the HS75 the GNSS antennas are separated by 20 cm between phase centers, resulting in a heading performance of better than 0.75° RMS. they are basically GPS compasses - https://www.simrad-yachting.com/simrad/type/compasses/hs75-gnss-compass/#prl_specifications
and they can feed your autopilot heading just fine BTW. no magnetic interference.

 

[BC Coast Pilot]

DGPS is a technology not specific to a country. the new DGPS systems use a 6 axis solid state gyro (for pitch/roll etc) and compute the difference between two satellite transmissions to get accurate heading info using phase differences. the DGPS is basically on board since the antennas are fixed at a known distance inside the unit itself. For the HS75 the GNSS antennas are separated by 20 cm between phase centers, resulting in a heading performance of better than 0.75° RMS. they are basically GPS compasses - https://www.simrad-yachting.com/simrad/type/compasses/hs75-gnss-compass/#prl_specifications
and they can feed your autopilot heading just fine BTW. no magnetic interference.

 

[BC Coast Pilot]

The antenna in this article is GNSS.
Different technology and they are terrible in a seaway when used on a pilot

 

[zurk]

DGPS is a technology. you compute based on a fixed difference between a known location and your mobile antenna. in this case the fixed location is on your boat as well as the mobile antenna. You are the DGPS base station. it doesnt matter what the canadian coast guard does. this has literally nothing to do with any coast guard base stations. GNSS is just a broadband GPS antenna so it can capture GLONASS and Galileo and other satellite constellations. it uses 2 so it gets the differential signal seperated by 20 cm. technically this is carrier phase DGPS rather than pure DGPS since it uses phase angles with the same wave rather than differences in two waves but the principle is the same -- newer satellites in orbit use the same technique now. e.g. https://www.hindawi.com/journals/ijae/2013/627509/

 

[turbomack]

The compass is alive and well in my zip code. I doubt any one every had one swung but any fish location tips are going to involve a bearing and distance. I am one of very few people with any electronics in the bay I fish out of. Handheld GPS are common for storing points, I use my compass daily even though I have 2 plotters on board.

 

[BC Coast Pilot]

DGPS is a technology. you compute based on a fixed difference between a known location and your mobile antenna. in this case the fixed location is on your boat as well as the mobile antenna. You are the DGPS base station. it doesnt matter what the canadian coast guard does. this has literally nothing to do with any coast guard base stations. GNSS is just a broadband GPS antenna so it can capture GLONASS and Galileo and other satellite constellations. it uses 2 so it gets the differential signal seperated by 20 cm. technically this is carrier phase DGPS rather than pure DGPS since it uses phase angles with the same wave rather than differences in two waves but the principle is the same -- newer satellites in orbit use the same technique now. e.g. https://www.hindawi.com/journals/ijae/2013/627509/

Referred to as a GNSS antenna, not a DGPS.....and they still suck

 

[zurk]

Referred to as a GNSS antenna, not a DGPS.....and they still suck

depends on the antenna construction and manufacturer. i havent has any issues with my simrad DGPS but then again it uses two GNSS antennas. most GPSes nowadays use GNSS antennas including the ones in phones. if your phone picks up GLONASS, Baidu or Galileo its using a GNSS antenna.
The Simrad stuff is actually OEM from Hemisphere which makes the Vector V500 for $11K if you feel you need better accuracy.

 

[Bill 310]

I totally understand. I’ve taken multiple boating courses and fully understand compass navigation. I’ve never heard of transport canada checking compass accuracy, on a recreational boat. I’m just stating what I do in 2023 on my boat.

I didn't say Transport Canada was checking Compass's on recreational boats.

Commercail vessels have to meet standards and I apologize if I was not clear.

What we did was optional and we did it becasue I like things to work properly and be accurate.

Our compass was swung to the accuracy level for smaller commercial vessels (under 3% deviation)..

The adjuster prepared for us a Deviation Card (certified by him) and if we were commercial we would have to post it aboard.

 

[Coyote Spooner]

Sounds good
Happy and safe boating

 

[RiverBoy]

I understand that compleletely. Our compass was out by 7 degrees north and had similar but lesser variations on the other points. This is not unusual for compasses.

We are now within 2-3 degrees depending on the heading and I have a deviation number to work from when on a heading or plotting a course.

I understand your reasoning and there is a very small chance that all of your systems will , pardon the pun, "Go South."

Transport Canada has regulations on vesslel size and degree of required accuracy, Our compass needs to be accuracre with no mire that 3 degrees variation. Cruise ships and larger commercial vessels are required to meet much higher levels of accuracy but they also have gyro-compassses.

I learned to navigate with Map and Compass at a very early age and in my teens and early 20's was as a wilderness canoe trip guide. I did some mountaineering walks long before GPS.

We do a fair bit of off the beaten path motorcycle travel arounfd the world and while we use GPS we still have a compass with us.

I didn't post to convert the masses, but rather to explain how to get your compass corrected, if that was important to you as a boater.

For us it was a few hundred dollars well spent. I was greatly amused being thought of as an old timer from Vancovuer Island

Good grief. i wasnt calling YOU an old timer living on the island. My neighbour is a sea captain that holds a 100 tonne ticket. He told me that there is an old timer that does all the calibrating of the compasses on all their ships.

The old timer mentioned that he was the last guy around that did this type of work and he is able to charge pretty much whatever he wants.

Those larger vessels still need to have an old school compass as a backup in case all your gear craps the bed.

 

[BC Coast Pilot]

Good grief. i wasnt calling YOU an old timer living on the island. My neighbour is a sea captain that holds a 100 tonne ticket. He told me that there is an old timer that does all the calibrating of the compasses on all their ships.

The old timer mentioned that he was the last guy around that did this type of work and he is able to charge pretty much whatever he wants.

Those larger vessels still need to have an old school compass as a backup in case all your gear craps

Is that a Canadian100 tonne ticket?