Saw one of the military style, twin 150hp outboard boats puttering past Mark Isl at about 4pm.
Whille they look like a r.i.b., a rigid inflatable boat, believe it is a welded aluminum hull with a black flotation collar so it only looks like a rib. Remove the inflated collar, and the aluminum hull works fine without it, except the boat would have no floatation and would sink IF flooded.
Does that make it a 'spare rib' because the flotation collar looks like a large black tire inner tube?
Constructed in a boatyard in Missalugaville, Mississippi, or someplace....no doubt that style military-police-commercial boat probably has some type of a trade name???