Complex sentence: It proved itself to be a practical and well built small cruiser-racer, with a light 860 kg displacement, fast hull and 3' 6 "draft with the keel down and 10" draft with the keel raised.
Split into simpler sentences: It proved itself to be a practical and well built small cruiser-racer, with a light 860 kg displacement, fast hull. Her draft is 3' 6 "with the keel down and 10" with the keel raised.