Budget OpenCPN Chartplotter

Before we left Seattle, we picked up a Microsoft Surface Pro for $150 at a computer recycle shop and loaded it up OpenCPN.

It was the first chartplotter I have ever had on a boat! We paired it with an AIS receiver, VHF antenna splitter, and a GPS dongle. Before long, we were off to the races (or rather, cruises).

We now have a navigation station down below that can overlay weather and AIS data relative to our position.


After spending all those eerie nights sailing around the Puget Sound trying to make out dimly lit logs in tow or listening to fog signals, THIS IS HUGE!

While OpenCPN took a bit to wrap our heads around, we really came to like it. You can find free charts of the world (of varying accuracy), and overlying weather data on those charts is very easy. If you have a multiplexer, you can even feed your ships instruments into OpenCPN, putting all of this information on one screen. This can be a big pro when passage planning or making sail adjustments on long passages.

Prior to OpenCPN, I purchased and used the Navionics app on my iPhone and iPad. This is great for close quarters sailing, but if you are tracking long passages, phone or tablet battery life quickly becomes an obstacle.

We have had two iPads and an iPhone that have come to meet their makers due to saltwater intrusion. Waterproof cases aren’t waterproof if the charger is plugged in.

I prefer to have both systems aboard. OpenCPN down below is always tracking and overlaying weather/AIS information, it also has a built in anchor alarm that helps us sleep easier. Navionics gives us accurate charts, in my had as I’m at the tiller sailing into unknown harbours all around the world.

**I’m not happy with the Navionics customer service experience, but I am a fan of the product. I wish I could say I was happy with both**

Cinderella’s Navigation System Evolution

This is an area that has undergone continual change. We have been actively cruising around the Pacific Ocean for the past three years on a pretty meagre budget. Cost and availability are two big hurdles we have been dealing with. I would love to have a new Raymarine, B&G, or Garmin system, but we just can’t justify making such a big investment. Especially after a single wave took down our old KVH system.

Instead, we have kitted out the computers we already had to do the job, and eventually purchased a 12V mini computer that we installed in a dry locker away from salty air and accidental spills.

Our budget OpenCPN chart plotter is part of a larger marine onboard network I have been actively tinkering with and developing.

Microsoft Surface Pro

Ava already had one she bought in Seattle before we left. It was actually a really slick machine. It had a large touch screen and we were able to mount it at our nav desk.

The Surface Pro ultimately suffered from saltwater intrusion that caused it to consume too much power and slowly lose touchscreen functionality. The charger was also destroyed, but since the computer ran on 12V, I was able to wire it to the ship’s house battery bank.

The surface lasted about a year; we took it out of commission in Tahiti. It was still functioning, but only just.


  • Large touch screen
  • 12V computer can run on the house batteries
  • plenty of processing power
  • relatively low power draw


  • No waterproof case
  • Exposed ports
  • Microsoft updates occasionally cause issues
  • Repairs not possible

If we had a larger, dryer boat I imagine it would have lasted much longer. The lack of waterproof case options and exposed USB/charging ports eventually killing the internal components and they are not replaceable.

2010 Macbook Pro

I purchased a 2010 Macbook Pro at the local computer repair shop before we left hoping to have a tool to edit videos on. It was an older machine, but I was intrigued by the Apple ecosystem and wanted an inexpensive way to learn. Along the way, we ended up with a second one. They were our “work” computers that let us organize our media, write, and access the internet. I loaded OpenCPN and the associated drivers onto them just in case something happened to the Surface Pro and we needed a backup.


  • More stable OS
  • Plenty of processing power
  • Already had it, so it was a free backup
  • Theoretically repairable


  • Big, it took up the whole desk
  • No waterproof case
  • Exposed ports
  • Old technology with large power draw

Both of these Computers eventually died. One in Tahiti as Ava was doing web design work, the other on passage to Palmerston as the boat lurched and my coffee spilled all over it. In short, the Pacific Ocean is hard on electronics.

The best anchorages are often near reefs with salt spray in the air and exposed contacts and plugs will eventually corrode. This solidified the idea that the ship’s navigation system should be a dedicated system tucked away from the elements.

The big takeaway I want to stress here is that ANY laptop you carry aboard can be loaded with this free software giving you redundancy in the event of a failure.

MINISFORUM 12V Mini Computer

Ava and I were fortunate enough to spend lots of time in Tahiti. We found a community where we fit in, and we once again had access to online purchasing. I did a bunch of research on small, low power draw computers and tablets that could run OpenCPN. I eventually decided to give the Minisforum 12V computer a try.


  • Low power draw
  • Small size allowed it to be tucked away in a dry cabinet
  • USB ports
  • 12V computer can run on the house batteries
  • Plenty of processing power
  • Familiar OS
  • Cheap


  • Microsoft updates occasionally cause issues
  • Repairs not possible
  • External screen and keyboard required

We have been really happy with this little PC as our dedicated navigation computer. We run Teamviewer, zyGRIB, and OpenOffice alongside OpenCPN expanding the system’s capabilities.

Teamviewer allows us to broadcast the PC’s desktop to all of our devices connected to Cinderella’s WiFi network. OpenCPN and all of our ship’s instruments, location, and AIS information are accessible from our phones and can be monitored easily by the crew from the cockpit or in a berth.

ZyGRIB allows us to easily download weather GRIBS and overlay them on OpenCPN. Unfortunately, we need to have internet access to download these.  We use our phones as a hotspot when we are near land, but if you had an SSB and Sailmail you could get them while at sea.

OpenOffice is free word processing software that we use to access and modify ship specific documents like our maintenance log and cruising guides.

Cost Breakdown

As I said, a small budget was a big factor in the system we ultimately came up with. Here is a breakdown of all of the components our system uses and their current prices.

Total Cost                                  $525.37

This is a few hundred dollar less than Raymarine’s most basic chartplotter screen. THE SCREEN ONLY!! That’s not including charts. It’s not including AIS integration. It’s not including weather data integration.

Amazingly, If you are only looking for an AIS receiving chartplotter, that would bring the cost down to $391! The cost savings comes because you don’t need to purchase the NMEA multiplexer.

Future Ideas

I have included the cost of the NMEA multiplexer we purchased, but unfortunately our old Airmar instruments were not NMEA 1083 compatible like I thought. We have yet to integrate the depth, wind direction, wind speed, boat speed, or water temp transducers. When we haul out for bottom paint, I hope to install an Airmar DST800 Smart™ Sensor Thru-hull. Not only should it work with OpenCPN, but we should be able to feed this info into any major brand’s marine network if we ever end up getting marine displays for our cockpit again.

I would also like to install an AIS transmitter at some point. It is HUGE to receive AIS and have information on the vessels around you. But it would also be nice to transmit our location to the vessels around us, making collision avoidance that much better.


As with all of the projects at Sailing Cinderella, we will share our experience while making the plans free and open source. If you want to help us continue, please consider donating to our cause!

DIY Marine Onboard Network



We have been cruising for a full year now! After a year of cruising, you really get a chance to dial in your systems and realize which projects on that endless list are most important and which ones can wait until the next major port.

One that keeps rearing up its head is deep in that dark world of…IT.

From ship navigation systems, to where you store all of those priceless photos it a boils down to a mess of wires all a bunch of 0s and 1s. Can/should it all be linked?

Most cruisers spend lots of time far away from WiFi and even farther from our precious Netflix. Yet we all crave a bit of digital entertainment from time to time, and let’s be honest, where would we be without music on those long passages.

What we plan to do aboard Cinderella is create an onboard wifi network with a dedicated media server. The server will house all of our music, videos, TV shows, movies, and photos. Along with a dedicated media server, we will update our navigation computer and tie it to our ship instruments. The end result will be something like this.

I know, I know, it looks like a lot. But we, along with pretty much all of the boats we have met cruising already have most of the gear!

Let’s start from the top. What I called the Marine Sensor Network. The Marine Sensor Network alone can cost thousands of dollars to replace. Cinderella came with an old KVH system installed in the late 90s. The Airmar sensors still work, but all of our marine displays have since fried. One wave off the Washington coast a one year ago decided we didn’t need them.

Although it may look complicated, it’s actually quite simple. All of our instruments were designed for the NMEA 0183 standard. This standard was created in the marine industry so that different instrumentation could talk with each other. NMEA 0183 is an old standard that requires a separate channel for each input. Basically, if you wanted to interface four instruments to you computer, you would need four separate connections. It can be done, but if we use something called a multiplexer we can funnel all of the instruments through one channel to the PC.

In our situation, using a multiplexer is nice because we can also feed this NMEA information to our autopilot giving us the option to steer by the wind angle, rather than just compass direction. The NMEA multiplexer we purchased was from Quark-electric and was $144.

We purchased it while we were in Mexico, and have yet to install it. Hopefully, this project will re-ignite my drive to have ship instruments again.

Where are we so far?

We used a device called a NMEA Multiplexer to compile inputs from all of our sensors and eventually feed it to our navigation computer or what some people like to call a chartplotter. A chartplotter is basically an expensive, basic “marinized” computer that plots your boats location on a chart. Think Tom-Tom for the water. The difference between Tom-Tom and a chart plotter is usually at least crisp cool boat unit ($1000).

On Cinderella we have come to realize that marine instruments, no matter how waterproof they seem to be, aren’t. Water will eventually find it’s way inside, killing the expensive chartplotter and leaving you in a pickle. We opted instead to utilize a program called OpenCPN to handle our chartplotting needs.

OpenCPN is FREE software designed by boaters that allows you to turn any computer into a chartplotter. The perk here is that ANY computer you have onboard can now be used as a backup navigation computer after you install the application. Every computer we have onboard has it installed, though we only rely one when we are on passage. Being that it is computer based, you still have that pesky water problem to deal with.

We get around the water issue by leaving the navigation computer in the cabin at all times. As part of this ship system upgrade, we will relieve our trusty Microsoft Surface from chartplotter duty and build a custom, cheap, and watertight navigation computer.

There are, in our opinion, three basic requirements of all navigation computers. One, the computer must know where YOU are. Two, it must know where the boats around you are. Three, it must not draw too much power.

Nowadays, these basic requirements are pretty easy to satisfy. To tell the computer where we are, we have been using a cheap USB GPS dongle. We carry two in case one gets hit by water. Here is a link the the one we use on Amazon, it’s about $30.

To tell us where other boats are, we use an AIS receiver that receives signal from our mast mounted VHF antenna. In order to use both the VHF and AIS with a single antenna, we needed to install a splitter. Anyone who remembers the days of clunky color TVs might remember what a splitter looks like. Here is the one we have installed onboard Cinderella, it was about $70.

We really liked the Microsoft Surface for use as our navigation computer. It has a large touch screen monitor, it has a nice fold down keyboard and a neat bluetooth mouse. Unfortunately, that wave that killed our marine instruments also got to our Surface, and ever since it takes a little TLC to start it up and keep it going. It had a hard year, and it’s time we come up with something new to replace it. We are currently looking at simple 12V computers like the RasberryPi or Odroid. They are both small, low power, and can be sealed into a watertight box and stowed in a small cabinet.

Along with the computer, we will need to find a low draw 12V monitor and a simple bluetooth keyboard and mouse, but I believe the new navigation PC could be had for $200-$300.

So now we have our boat instruments connected to our navigation computer, but one major piece remains. The media! What about the music/TV shows/movies? The last piece of the upgrade is the NAS or Network Attached Storage server. What we will call the Cinderella Cloud.

The Cinderella cloud will be essentially made up of three pieces, a hard drive (where the media will live), a NAS server (means to organize the media), and a router (means to share the media with all of our devices).

We have had a small router onboard since before we left Seattle. I read a cruising blog a long time ago and decided to purchase a WiFi extender so that I could pick up WiFi at the marina from far away. Along with the WiFi extender, I purchased a 12V router to allow all of my devices to utilize that WiFi.

We plan to buy a 12V NAS server from Odroid, and pair it with a large capacity, low draw hard drive.

These hardware components don’t mean very much alone, but with the help of neat media software (Plex or Kodi), we should be able to connect to the Cindy Cloud and scroll through all of our movies, TV shows, or music at any time from any device and stream away. It will be like our own little onboard Netflix!

If everything goes to plan, we should have an entire onboard network integrating marine instruments, a navigation computer, and a media server, all for less than the cost of a standard chartplotter!