Well not as dramatic, but lots of conflicting advice on the dry riser. The previous post on the subject quoted the ABYC standard which stated; "No galvanized steel, no brass, no bronze". I have sourced Carbon Steel and this is on standby. Two mechanics, that I have huge respect for, individually suggest galvanized steel and silicon bronze respectively. But I have a cunning plan. I have purchased a second exhaust elbow (hip hip for ebay) and will carry a spare setup.
I am having both elbows cut as indicated above and a 2" threaded galvanized piece welded in place. I can then thread on an 90deg elbow, 18" of pipe, a second 90deg elbow and then the water injecting part of the above. Initially I will use galvanized pipe (cheap and available) but carry the silicon bronze AND the carbon steel as a spare. After a few hundred hours running I will take the riser apart and work from there.