"If you have problems with your Prius, I could always throw it in the back." -- Ben Affleck as Doug MacRay

As I scanned Boeing's (NYSE: BA) press release on its new Echo Ranger robot submarine this week, I couldn't help recalling this line from The Town. Boeing's not the first company to build a robot submarine, you see. (Oceaneering International (NYSE: OII) has been building submersibles for years -- robots instrumental to efforts by Transocean and BP in dealing with last year's Deepwater Horizon disaster.)

What Boeing is, however, is one of the first companies to build a robot sub capable of operating independently, not tethered to a mothership. In so doing, it follows in the footsteps of iRobot (Nasdaq: IRBT), a tiny maker of an even tinier unmanned underwater vehicle (UUV). If iRobot's Seaglider UUV should ever break down, Boeing's Echo Ranger could probably pick it up and "throw it in the back," too. Fact is, Boeing could probably fit two or three Seagliders in there comfortably.

To get an idea of the differences between the subs, a few stats may help illustrate:

Metric

Echo Ranger

Seaglider

Length 18.5 feet 5.9 feet
Weight 5 tons 115 lbs.
Speed 8 knots 0.5 knot
Max operating depth 10,000 feet 3,280 feet
Max travel range 80 miles 2,858 miles
Endurance 70 days* 10 months

*"With the right power source."

What's it mean to investors?
Faced with a serious and growing budget crunch at the Pentagon, a lot of defense contractors are moving to diversify their businesses. Earlier this week, we saw General Dynamics (NYSE: GD) expand further into health care with its purchase of Vangent. Boeing is taking a smaller leap and explaining that it's not even as big as it seems because "the Boeing name is also respected in the maritime deep submersible industry. We've been in the business more than 40 years."

If that statement comes as a surprise to you, well, then, join the club. When a company has to tell you it's known for doing something, chances are it's not very well known. In fact, Boeing's just starting to dip its toe in this market, and as the stats show, it has some catching up to do if it intends to match iRobot on distance and endurance, at least. Its greater size notwithstanding, Echo Ranger remains little more than a large, aquatic guinea pig. It may learn to swim, but it won't catch Seaglider any time soon. For now, this is iRobot's race to lose.

Who will win the race to dominate the new market for robot subs? Add Boeing and iRobot to your Fool Watchlist, and find out.

Fool contributor Rich Smith does not own (or short) shares of any company named above.  The Motley Fool owns shares of Transocean and General Dynamics. Motley Fool newsletter services have recommended buying shares of iRobot. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.