Acrylic plastic viewports in diving systems have been in satisfactory use for a number of years. However, the development of testing them by polarized light showed that there are various misconceptions about them. The International Marine Contractors Association (IMCA) has just released updated guidance on the topic. An initial guidance note which sought to correct these misconceptions was initially prepared as AODC 030 in 1986 following advice from Det Norske Veritas (DNV). Now a revised document has been produced by IMCA through the Safety…