Trying to find the regulation concerning sea service for maritime instructors. The CFR only applies to upgrades not renewals
It may be acceptable under 46 CFR 10.227(d)(8)(D) which allows "employment in a position closely related to the operation, construction, or repair of vessels (either deck or engineer as appropriate) for at least three years during the past five years."
James D. Cavo
U.S. Coast Guard
Mariner Credentialing Program
Policy Division (CG-5434) James.D.Cavo@uscg.mil