Recording & plotting a voyage using a USB GPS reciever and open source software

[nevillet]

Hi all,

In a couple of weeks I’m setting off on my first sea cruise and would like to record the journey using a GPS receiver.

Our cabin has a patio door leading to a balcony and I plan to attach the receiver to the glass on the inside of the cabin so it can see the sky. Effectively it will be looking sideways as opposed to looking directly upwards at the sky. 

This is the receiver:  www.globalsat.com.tw/en/product-282242/USB-GNSS-Receiver-BU-353N5.html

I’ll be taking a Windows 11 laptop and the USB receiver will be permanently connected and recording the data.

I’d like to have an open source/free map I can download in advance (to be used offline) with the GPS position displayed on the map – the positional data being recorded.

So my questions are:

Does this plan sound feasible?

What mapping software would you suggest?

I’ve struggled to find a website or forum that covers this kind of thing – any suggestions?

[fourfathom]

Look at the openCPN program. Free, open source, used for marine navigation. Free charts are available for U.S. waters, probably elsewhere.

[Ian.M]

May or not track reliably due to limited sky view, multi-path reflections off the balcony confusing the receiver, and possible anti-glare or anti-heat reflective film on the glass. 

I'd suggest taking a flat USB extension cable, that could be fed out through the patio door and the door seal closed on it to get the receiver right out to the edge of the balcony, and possibly even magneted to the hull exterior, some bluetack (to guarantee a water seal round the cable),  and a roll of silicone self-amalgamating tape, to seal the GPS puck USB plug to extension cable joint.

Also take a hand-held GPS receiver that runs on AA batteries you can strap to the balcony rail as a backup + enough batteries for the cruise duration + whatever software you need to download and merge tracklogs from it and export to your mapping software.

You also need to consider non-destructive cable management and fixing.   Gaffer tape and goo-gone may help!

[nevillet]

Many thanks for you thoughts on this.

OpenCPN looks like the right software for the job.

Regarding the GPS reciever and it's view of the sky.

20 years ago I used to fly a lot for business and had a USB and later a Bluetooth GPS reciever that I used to jam under the window blind and track the flights using MS Autoroute.
The reciever looked sideways and always had at least 4 satelites in view.

I'm hoping todays more modern recievers with GPS,GLONASS,GALILEO,BEIDOU,QZSS reception should be fairly accurate with its limited sideways view as there are more satelites in the sky.

Another idea was to use a Bluetooth reciever that could be mounted on the balcony looking directly up.  Maybe this would do a better job?

[Ian.M]

Bluetooth is 2.4 GHz so any window film treatment that attenuates GPS signals is also likely to attenuate the bluetooth signal. OTOH GPS signals are right down in the noise floor to start so even the attenuation from a wet heavy foliage canopy can be problematic in rugged terrain where the sky view is limited, but short range bluetooth has much more power, so the additional attenuation may not matter. 

The odds are in your favour that you'll get decent GPS reception from inside the window. However you wont be able to confirm that till you are onboard in the cabin so I strongly recommend a backup marine or outdoor sports handheld GPS receiver that will keep track logs in its own memory.  It also means you wont have to leave your laptop out and running 24/7 which might be an issue if the power sockets are inconveniently situated or if you hit rough weather.

[mendip_discovery]

Look at getting an AIS reciver so you can get an idea of the ships nearby. Also you can try and confirm the ship.is where it says it is with your GPS setup.

[fourfathom]

The dAISy receiver is a very usable low-cost receiver with a USB interface. OpenCPN can accept the data and display ship info and position. You will need an antenna that works around 162 MHz, but even a coat hanger will work for moderate range reception.

[Harfner]

Is this one of the big cruise ships?
If there might be ship's personal entering your cabin without you present, I would drop the idea.
Cruise lines reserve the right to confiscate any charger charging any device unsupervised. The official reason is they are afraid of the fire risk of Li-ion accu overcharging. This would also apply to your Laptop connected to line voltage.

I would look for a GPS logger as a separate device which receives and stores the data locally inside the device.

[fourfathom]

Cruise lines reserve the right to confiscate any charger charging any device unsupervised

This may be true, but on the couple of cruise ships I've recently been on I had absolutely no problem with charging phones, laptops, satphones, etc., unattended.