舶用推進軸系の腐食現象に関する流電回路の考察

抄録

There are several reports on the erosion or corrosion of the propeller and its shafting. But we have as yet very little information on the stray current of them.
Recently, it have been shown that usually there exists the electric resistance (R) between hull and shafting on a running ship. This resistance appeared on all bearing surfaces of propeller shafting and engine. In this case, it may be assumed that the potential difference between the Zn anodes and propeller enforces to flow the stray current from sleeve surface to sterntube.
The present experiments were designed to secure the following two points.
(1) Posibility of stray current above mentioned. In this experimental circuit, when the outer resistance (equivalent to R) increase and exceed some value, the stray current start up on the surface of the brass specimen (equivalent to shaft sleeve).
(2) Suitability of the usual Zn anode protection.
As noted above, when the shafting become independent of the hull at running period, then the Zn anode on the hull a slight protecting effect on the propeller. If this anode should be attached to the front of the propeller boss, the effect is better than that, but is not sufficient.
The best method is to have good connection between main shaft and bearing with the pertinent ring and brush.