Very High Frequency (VHF) radios serve as the primary means of communication for boats, yachts, and vessels.

As the name says it, these devices are intended for communication between yourself on the water and the rest of the world. Specifically, the uses for VHS radios generally fall into one of the following:

• Distress calling and safety
• Ship-to-shore communications
• Navigation (vessels to bridges, and the like)
• Marine operator to place calls to shore
• NOAA Weather Broadcasts
•  

VHS radios come with two options for transmitter power. There's an option for one watt, intended for close communication in the range of approximately one mile or less. The other option consists of 25 watts and is meant for extended-range communication of up to 25 miles.

If you're to travel further out into the water, you would want to consider a installing an SSB (Single Side Band) radio, whose communication range extends to hundreds of miles.

Let's have a closer look at the various options in VHS radios available, as well as some other communication means and methods.

Fixed-Mount VHF Radios

Fixed-mount VHFs have a maximum output of 25 watts (which is the maximum allowed by the FCC), which means that their communication capabilities go up to 25 miles.

VHF is a line-of-sight system. Radio waves transmitted from them will have to be in the line of sight of the station-antenna that is to pick up the signal. Contrary to other models, VHF radio signals do not follow the earth's curvature, and antenna height is therefore of utmost importance.

Handheld VHF Radios

You can look at handheld VHF radios like a tablet versus a desktop. They come with most of the same features you'll find on fixed-mount units, but are more portable and offer the convenience of mobility.

The biggest drawback of a handheld radio is probably it's limited output range, which typically doesn't extend further than five miles or so. This shortcoming can be bridged by connecting the handheld device to an external antenna or mounting a telescoping antenna on the handheld.

Handheld VHF radios should suffice for small boat without electrical systems. You also might want to consider it as an emergency backup for your boat's radio.

SSBs

SSBs, as noted above, commonly come with an output capability power range of 50-150 watts. While the exact range at any given day or point would depend on various factors, the maximum reliable range during the day is typically 50-to-150 miles for medium frequency band. Transmission in high frequency band can reach thousands of miles.

While SSBs are more reliable in the sense of them offering an extended signal range, installation and utilization is more complicated and less straightforward. SSBs require a large ground plane in order to radiate its signal. Antenna selection and installation is also more complicated. SSBs generally require a much longer antenna than VHFs, with different antenna tuning for different bands, which will also require a tuner.

Satellite Communications

Satellite phones are generally being seen as operating anywhere. In reality, though, this isn't exactly accurate and there are, in fact, dead zones where they don’t work properly. Nevertheless, the coverage range for satellite phones is pretty impressive, and equipping your boat with one will likely have you covered in time of distress. Some of the more advanced models come with an SOS button, which sends a mayday including your position. these devices can also be turned a hotspot, which isn't bad if you feel like using your phone or tablet while far out on the water. 

One great asset that comes with satellite phones is the ability to use email and text messaging, which aren't offered by the other common communication means. While these are pretty cool, the hardware and service charges for them are pretty high. The convenience of those features doesn't necessarily justify the cost, but if you're feeling exorbitant there is some good value in this for your money.

If you want to settle for less, service and price wise, there are other options for satellite communication. The Spot Gen3 from Globalstar is a palm-size satellite device that transmits your position every 5 minutes your contact list, and the SOS button broadcasts that you are in need of emergency assistance.

InReach SE by DeLorme is a pocket-size unit that allows you to send text messages via your Bluetooth­enabled smartphone. The free Earthmate app turns a tablet or smartphone into a navigation instrument pinpointing your location on a chart or map. With the Mapshare feature, others can “ping” you and “see” your position. This device offers an SOS feature, which allows you to carry on a dialog with rescuers.

Further reading:

http://www.boatsafe.com/nauticalknowhow/radio.htm