Diesel Exhaust Hose/Pipe

[1970Columbia34]

Were putting in a diesel motor in our boat and am for the most part using the existing exhaust setup, but need to add some exhaust pipe to connect to the existing. The motor has 1 1/4" female thread to hook into. This part of the exhaust will be all dry so plan to use metal pipe, but what kind of metal? We are in fresh water, if that matters. The motor is a Universal M25xp, so it has a heat exchange for engine cooling.

Scott

[Maine Sail]

Is this before the injection elbow??

[1970Columbia34]

correct, it will be a hot section with no water. The water is injected after the riser down near the transom exit.

Scott

[OldColumbia]

Having had " dry exhaust" risers crack and disintegrate from rust or corrosion inherent in marine environments and vibration, I'd recommend spending a little more for the Universal elbow that fits and then running rubber exhaust hose to a plastic Vetus type pot, then rubber again with a loop above the waterline to the discharge.
One " homemade" Galvanized elbow I had was only held together by the heat wrap after the heat and salt water got to it.
The extra expense and an anti siphon break is worth the potential " water suck" that really ruins your day ( and your engine.)
The potential for CO poisoning also exists if your exhaust has an undiscovered crack hidden by the heat wrap.