Between these two counter-timbers there is a well for the screw, and also one for the rudder, through which they can both be hoisted up on deck. It is usual in sealers to have the screw arranged in this way, so that it can easily be replaced by a spare screw should it be broken by the ice. But such an arrangement is not usual in the case of the rudder, and, while with our small crew, and with the help of the capstan, we could hoist the rudder on deck in a few minutes in case of any sudden ice-pressure or the like, I have known it take sealers with a crew of over 60 men several hours, or even a whole day, to ship a fresh rudder. The stern is, on the whole, the Achilles' heel of ships in the Polar Seas; here the ice can easily inflict great damage, for instance, by breaking the rudder. To guard against this danger, our rudder was placed so low down as not to be visible above water, so that if a floe should strike the vessel aft, it would break its force against the strong stern-part, and could hardly touch the rudder itself. As a matter of fact, notwithstanding the violent pressures we met with, we never suffered any injury in this respect. Everything was of course done to make the sides of the ship as strong as possible. The frame timbers were of choice Italian oak that had originally been intended for the Norwegian navy, and had lain under cover at Horten for 30 years. They were all grown to shape, and 10-11 inches thick. The frames were built in two courses or tiers, closely wrought together, and connected by bolts, some of which were riveted. Over each joint flat iron bands were placed. The frames were about 21 inches (56 cm.) wide, and were placed close together, with only about an inch or an inch and a half between; and these interstices were filled with pitch and sawdust mixed, from the keel to a little distance above the water-line, in order to keep the ship moderately water-tight, even should the outer skin be chafed through. The outside planking consists of three layers. The inner one is of oak, 3 inches thick, fastened with spikes and carefully calked; outside this another oak sheathing, 4 inches thick, fastened with through bolts and calked; and outside these comes the ice-skin of greenheart, which like the other planking runs right down to the keel. At the water-line it is 6 inches thick, gradually diminishing towards the bottom to 3 inches. It is fastened with nails and jagged bolts, and not with through bolts; so that if the ice had stripped off the whole of the ice sheathing the hull of the ship would not have suffered any great damage. The lining inside the frame timbers is of pitch-pine planks, some 4, some 8 inches thick; it was also carefully calked once or twice.