Can anybody advise on what a weathered U-boat would look like beneath the waterline? I have several questions that I am curious about -
(1) Some illustrations show vertical rust and/or dirt lines on the lower hull. Is this just artistic or did U-boats look like this? I realise that water running off the deck made vertical rust stains above the waterline, but surely this can't be the case below the waterline? To my mind, this could happen only in dry-dock, when water runs down the whole hull.
(2) If a U-boat was weathered enough to have patches of rust on its hull, would there not also be places (especially near the bow) where the dark grey paint peeled away to reveal the red lead undercoat?
(3) Green slimy plantlife sticks to ship hulls, even with anti-fouling paint. But U-boats (apart perhaps from those at the very end of the war) were regularly serviced. Can anybody advise if U-boats during the early years of the war were in the water long enough to accumulate plantlife? If so, how much? And did this only occur when U-boats operated in coastal regions? Perhaps they didn't get such growth when operating in the Atlantic?
(4) How big, and what colour (white?), are barnacles? And did/do they only stick to places that were hidden away from the flow of water, and not to places such as the edges of the saddle tanks? Or do they stick to hulls at random?

Many thanks,

Dougie