Stopping the small boat threat - barriers

Need small craft barriers? This company says they have what you need here.

Vessel Exclusion Barrier™ ("VEB™")
To protect security zones from large vessels, the company developed the VEB™, an augmented version of the SCIB™ with additional WhisprWave® modules. The VEB™ has sufficient strength to withstand 1,500,000 foot pounds of energy over a 1.5 second period, capable of completely stopping 30-foot vessels traveling at 40 miles per hour (35 knots) and significantly impeding larger vessels.

Of course, if you rely on barriers, then you may have to face the threat of the the use of "stand off" weapons as described here.