to weaponry and 7.7 percent or 5300 tons to machinery. The only slight deviation from what might be thought the norm was that the figure for machinery was a little low, the accompanying reduction in speed required for the weight saved to he used for protection. It is the underwater element of this defense which must now be considered.The ideal of all-round protection had long since been abandoned as shell



JOINT BETWEEN MAIN BELT AND INTERNAL

ARMORED BULKHEAD OF THE YAMATO CLASS and torpedo attack had proved too destructive. Along with other navies the Japanese adopted the 'all or nothing' principle; protection was limited to those areas vital for survival and for fighting; in short, the main machinery and gun turrets. The result was an armored central raft which leftand designers generally had to be satisfied with providing the minimum. In the case of Yamato the constraints were severe despite her great beam because of her chosen machinery layout. This was exacerbated by the choice of a reliable but bulky set of boilers, which ran at relatively low pressure. They were used because replacement beneath the 200mm armored deck would have proved extremely difficult hut the corollary was a narrower torpedo defense.



The width of this around her machinery spaces was on average 5.lm, and was narrower than that of almost all her contemporaries in other navies despite her displacing considerably more. Two examples will suffice to illustrate this. The American North Carolina, on a displacement calculated in a comparable manner at 45,298 tons, had a system 5.6m