I am refurbishing an Ocean Yacht 40+2 Trawler, vintage 1978. I believe it was created by putting a trawler insert in a 38-40' sport fish hull, then extending the aft hull about 30" for a swim platform. This extension also was intended to improve the efficiency of the hull when cruising at lower speeds. I think the original sports fish had two 350s and planed at about 25 knots. Mine has two 160s and cruises at 8-10 knots. I want to add clean out ports to the two gal diesel tanks, but don't know how many baffles are in those tanks. I hate to drill a hole and hit a baffle. If I use the 30 gallon max per baffled-space rule of thumb, there might be 6 baffles. Sounds like a bunch to me. Does any information exist on the design of the 1978 era Ocean 200 gal diesel tanks? Any help is appreciated. I think they are steel with some kind of sound deadening coating on them.
I'd recommend tapping with your knuckle rather than a drill to find the baffles. I'd think the tanks would be aluminum not steel. If steel they're getting pretty old.
I would absolutely NOT drill into tanks of that vintage, you're just asking for things to go sideways really fast. Is that boat dark green or was the hull dark green at some point in time? If so, it was one of the first boats I ever managed about 20 years ago or so.