I agree with Whirli. Small boats can be designed for stealth. Again, I offer up SO (Special Operators such as SEALs and Recon) use inflatables due to their stealth. You can lay down in them, use a highly muffled motor and even at full throttle will barely hear it. Use a black one at night and a brown/grey one during daytime ops. They hardly leave a wake compared to larger boat designs as an added bonus.