This photo shows exactly how deep the threads are cut into the the 1" thru-hull pictured above. The threads are 1.45mm deep on this thru-hull fitting.


If you subtract the 1.45mm thread cut from the 2.99mm overall thickness you get the remaining nominal wall thickness of 1.54 millimeters.


Yes, you read it correctly, the nominal wall thickness on this very popular Apollo 1" bronze thru-hull fitting is roughly the thickness of an average penny at only 1.54 millimeters.