Boat Wiring and Exhaust Systems Do Not Mix
Question: I recently noticed a large grouping of my boat’s electrical wiring that seems to be routed pretty near my engine’s exhaust system. It seems like this might be a problem as the exhaust system gets pretty hot when the engine is running, even though it is water cooled from the engine raw water system. From the photo, can you tell if I actually have a problem here? It would be a lot of work to correct if it’s not necessary.
Answer: That is quite a large bundle of electrical wiring!
Based on the picture you are probably OK, but not by much. It depends upon whether the exhaust section is a dry section or a section where water is running through the system. (That’s usually any part downstream from the exhaust system riser manifold at the back of the engine.)
ABYC Standards have two requirements about proximity of wiring to exhaust system components. For the dry sections of the exhaust, you need a minimum of nine inches of separation between the wiring and the exhaust pipe. For a section of exhaust that is water cooled (and it looks like that’s the case in your photo), you need a minimum of two inches of separation between the wiring and the exhaust pipe, the blue hose in the picture. It looks like you just make it with the 2 inch rule.