[Beer]

Real life with a merchant radar there is a feature called target trails (or tails), set this for 6 minutes to 15 minutes and small targets normally lost in clutter leave a nice trail showing their Relative Motion through the selected time frame...you can see small targets close aboard in seas up to say 3-4'. We used it routinely when transiting Pirate areas. It even picks up low flying helo's or P-3's. 3 cm radar is best for this but the 10 cm can pick them up also, useful range within 24 NM.

Concerning using the stack shadow to mask your approach, the last two ships I worked on both had a two forward radars and one aft (these are commercial ships mind you and not combatants), so that they did not have have a blind spot.

I believe an alert watch would see an approach of a motorized inflatable under normal conditions with seas less than 4 foot or so likely inside 5-6 miles (based on expierence our soft sided fast rescue boat without a reflector is picked up on radar and is a 5 meter craft). Under flat ass calm conditions 10-12 miles, you can even track birds (Big birds or flocks) within 6 miles with a commercial radar under ideal conditions (did so tonite heading back to location).

Beer