The Power Struggle


"I need a laptop so it can run off the battery, don't I?"

Computers will draw several hundred watts.  For a boat, you can get an inexpensive inverter for under $100. People who think the inverter will cost more than that may be thinking about ones with many additional features, such as chargers for large batteries. It's a good safeguard to put a computer-grade surge suppressor between the computer and the inverter. Some captains like to use a light-duty uninterruptible power system (UPS), which does have a small battery. Such a battery will protect navigational information on the computer for 15 minutes or so, while you troubleshoot the main power problem.









Many flat-panel displays actually run on 12 volts DC; if there is an  external power supply. it converts 120 VAC to 12 volts. If you get such a display, we can rig connectors from the panel directly to the boat power battery supply.

Dual-Use Cable

Two of the newer networking technologies, NMEA 2000 and Ethernet, have differing capabilities to deliver power over the cable used for data transmission. Universal Serial Bus (USB), which is used to connect peripheral devices to computers, also has a limited power distribution capability, which can be tricky to implement effectively.  



Other devices, such as USB multiplexers  that interconnect the marine electronics' NMEA 0183 interface to the computer, external disks,etc., get their power from their USB interface, via the computer. Some devices also can draw power through Ethernet, but you are unlikely to need such equipment, which is mostly for telephones or wireless LANs.

This brings us to a topic that may seem clerical and bothersome, but has enormous benefit in the long run:  a written inventory of your electronic equipment, which includes their power requirements.  Once that is available, it becomes practical to do a power budget. A power budget might show, for example, that you have USB devices that, if all were active at the same time, would pull 600 milliAmperes (mA), when USB normally can't supply more than 500 mA. You decide that all the devices might, under some circumstances, all be active, and you've been lucky. 

This is an area where our experience could help. We could point out that you could plug a second USB interface card into a modular computer, and that the pair of cards can give you a total of 1000 mA, 400 more than you need. The USB devices will work quite happily when connected to either controller. Our work would first consist of understanding the problem, or recognizing a potential problem. Once it was recognized, you'd need a $30 or so USB card, perhaps a few extra USB cables and hubs, and technician time to install the card and recable.

There are other techniques for making more power available through USB connectors. Some electronic devices only want power from USB, and don't actually connect to the computer.


Batteries help you out if you lose power. What about losing data if a disk goes bad?  You'll want to keep at least one copy of your key files, such as tracks, catch reports, expenses, etc. There are several ways we can help you protect these files, and other methods to protect your applications and systems to get your computer back up in a hurry.

You have multiple choices. One of the most convenient will be possible if you have a wireless LAN (WLAN) at your port, which you can access from a WLAN card on your boat computer. You can also copy new files to a USB-attached "thumb drive" or external hard drive, or to an external Firewire drive if your computer has a Firewire interface.  We can help you set up the backup process such that it will take a minimum of effort on your part.

When you back up to external drives, however, there remains the problem of where to put them so they will be protected from accidents to the boat computer. Thumb drives are small enough that we can exchange them with you, and we can also work out exchanges of external hard drives.



You can link, either via WLAN or a local Ethernet cable to a computer we bring to your boat. Above and beyond backup, you need wireless or wired connectivity to another computer in order to install software updates. The nature of the updates will depend on your operating system, utilities, and application software.