While much has been written about how to choose navigation software, how to buy the onboard computer that runs it is a topic that is too often ignored.

Thankfully, purchasing a computer is something most of us have done, and buying one for the boat is much like buying one for your home or office. You want a fast machine with plenty of processing power, memory and storage for files.

Of course, there are some special needs to address and some traps to avoid. But if you adhere to the guidelines that follow and do some comparison shopping, you should be able to find an extremely capable machine for $1,200 to $1,500 – and dodge some major problems in the balance.

Like all marine purchases, the equation starts with assessing your needs. For our purposes, we will assume that the primary goal is to run software that can view electronic charts, either to plan trips, navigate or both.

You may want to do other things – access email, keep a log, check out web sites or watch DVDs – and a computer can facilitate all of that. But let's assume for now that navigation is the primary objective.

BUY A NEW MACHINE

The first important piece of advice is that you should commit to buying a new machine, unless you have a computer available that was purchased in the last three months. Done properly, this strategy will give you the latest technology and minimize the amount of time spent troubleshooting.

A laptop on board has become a common sight.While it may seem thrifty to rehabilitate an old machine and press it into service, or buy a used one on eBay, this is often a false economy. Computer technology changes fast and modern navigation software is demanding. Upgrading or buying used may be cheaper than buying a new machine, but that savings can quickly be offset by the amount of time spent troubleshooting the installation.

A better strategy is to spend that time shopping for a bargain on a new machine, which will almost always be better matched to the task. You can then take that old machine and use it to read email and play DVDs, protecting your new navigation computer from viruses and other problems associated with heavy Internet use.

There are, of course, boaters out there with a technology background who are capable of making magic with old hardware. The rest of us should buy new.

CUSTOM ORDERS

The second important piece of advice is that you should order your new machine – whether laptop or desktop – directly from a manufacturer such as Dell or Lenovo, and have it built according to your specifications. While this may sound like an expensive custom solution, that is usually not the case. Computers are commonly purchased on a custom basis, either by phone or online, and the prices are competitive with off-the-shelf models.

The benefits are simple: you get exactly what you want and avoid some things you don't.

When ordering a machine, you generally start by selecting a base model and then adding upgrades on an a la carte basis. For example, an IBM ThinkPad T61 currently costs $964 for a machine with 1 gigabyte of RAM. But for another $80, the same machine can be bought with 2 gigabytes of RAM.

Start by shopping online and identifying models you like. There are literally dozens of web sites you can visit to read primers, reviews, tips and recommendations. CNET.com, ConsumerReports.org, Epinions.com, Gizmodo.com, PCWorld.com and About.com are just a few. Much of this reading is worth your time. Just realize that many of these sites are proffering information about the latest and greatest for a tech-savvy audience – not for boaters. You may not need everything you read.

When you have it narrowed down to two or three machines, call one of the companies or go to its web site and get an quote with the options you want. The company will generally email you an estimate that is good for several days; to buy, you either click a link or call with an order number. You can repeat the process to comparison shop, and then choose your best deal and execute the transaction.

If you want to see the machine in action before you buy, you can test one at a local store. But make sure you are trying the exact model you want – and try to avoid buying it there. Machines offered by retail chains like Best Buy, Circuit City and Staples certainly can get the job done, but they are often loaded with unnecessary features and trial software – commonly called bloatware – that can slow your computer and cause compatibility issues. A custom machine will eliminate all of that – just be sure to ask that the computer be delivered clean.