I made new rods/pipes, which are mounted on the fore and afterdeck.
(Does anyone knows the purpose of these parts?)
I'd say they'd most certainly have to be gaffs. Any boat of appreciable size should have them. What are they and how are they used? Quite simple... take a hook (usually bent back through 180 degrees) and stick it on the end of a pole, their main use is to hook a line in the water so you can haul it on deck and use it. I've seen simple ones made by poor fishermen made from a bent spike and a length of 1x2" wood, the hook attached with either a tight lashing or using a few inches of ABS pipe to heat-shrink it together. Modern commercial ones for yachting are made from extruded aluminum to create telescopic tubes, allowing you to vary the length, and they also have their hook made out of plastic, featuring a point on the end so you can also use it to push the boat off the docks when mooring.
I'd imagine docking in the pens would be very simple for the u-boats since they were more-or-less custom designs for the fleet, but things would get tricky when you're on the ocean trying to raft up with a milk cow. Something with the size and weight of a u-boat would require some decently sized mooring lines or hawsers in order to safely hold her in place, which means that they're heavy and thus makes throwing a line difficult. For a heavy hawser it's very common to have a much thinner leader line tied on to the eye of the hawser - throwing a small line is way easier! Alas, we are all human, and sometimes rope throws fail. This is where the gaff shines - dip it in the water and hook the leader line.
The gaff from my kit would scale up to 9 feet (3m), a rather practical length to use - the type VIIs draw about 4.75m at a full surface trim, thus 1.5m freeboard, so a 3m gaff would be quite useful. Useful yet small, and easily lost overboard, hence why you always want to carry two.
Hope this helps!
