"...What you might have control over though is the environment. Are you able to construct barriers etc to shield the motor from high pressure jetting? It might be a cover over the motor or a wall for it to hide behind, whatever is required to protect it against the extreme water jets".
It is impractical/costly to have any NTL to test at site whatever barriers/shield /cover/enclosure etc. and to issue certificate that it is in compliance to IP 56. Also take into consideration of the heat generated by the motor. Marine class surveyors would NOT accept the words verbally without a Certificate from the NTL lab. The surveyor may? not request for the test/approval certificate if the motor is IP 56 rated, as stated in the original name-plate. If requested, the responsibility is on the OEM, who claims in compliance with the Class rule, be it LRS,GL,VB,DNV,ABS etc. etc.
Che Kuan Yau (Singapore)