I was on a ship with Pielstick engines , we were visited by a project manager from RN - research and development at Barh , they were designing a submarine with a medium speed diesel and Crossley-Pielstick were favourites . He did a trip to get some idea how they ran , I asked , what seemed an obvious question , how do you get the pistons out ,?. He told me we managed with four feet above the head clearance , so the Nay surely would manage . I took him onto the car deck and showed him the ring of bolts that held down a deck section above the engine , the one we removed with a fork lift to get the pistons out ,. He had worked three years on that project and missed the blatantly obvious . Even the Mate knew that !!!!!!