A series of successive tests on cathodic protection of ship-hull of a small sea-going ship were carried out with a period of each one year since 1955.
In each case the kind and quantity of zinc or zinc alloy anode were varied to determine the criteria for installation. Hull potentials and anode currents of zinc were measured periodically and those in the running condition were also measured.
The results obtained were as follows:
(1) Zn-Al alloy anode showed excellent performance as compared with high purity zinc so far as ship hull protection is concerned.
(2) The ship hull is substantially protected from corrosion so far as the hull potential in stagnant sea water was maintained below the so-called protective potential, -770mV referred to saturated calomel electrode.
(3) In the case of ship tested, an adequate quantity of zinc alloy anodes can be determined in such a way that the ratio of total anode area to immersed area of ship hull is greater than 1/200.

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Amine-type corrosion inhibitors with branched alkyl radicals were tested. Less inhibition was given with those whose side chains were at nearer position to adsorbents and better inhibition with those whose side chains were more remote. The side chains attached nearer, interfered inner-molecularly with the adsorbents, and remote ones promoted inhibition because of its affinity to the solvent. But, some remote branches inter-molecularly interfered with orientation of inhibitors to metal surfaces as known steric effects in organic chemistry.

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