The first was the base of the keels being inefficient without a bulb or fins at the base of the keel to add tred in the water.
The second was to have the propellers unguarded from landing and the shafts at risk of bending.
These were compensated for with fins at the base of the keel and a propeller guard attached to the belly of the hull. The guard here will support the weight of of the trawler without straining the twin shaft mechanisms.