Porosity (poh-ros-i-tee): the state or quality of being porous
What does porosity have to do with your propeller? Well, porosity looks like this:
Notice the pitting and the cracking on the blades of these two propellers? That’s porosity. Porosity usually happens when a weld gets contaminated. (I won’t go into the details, but this article at thefabricator.com explains the causes if you’re interested.)
When I received the propellers, I knew that whoever had tried to fix them before didn’t do a good job. Metal that is properly welded will dent, bend without cracking, and/or be sheared off when damaged. It will not pit and crack like these had done.
In addition, I saw grinding marks (see the second picture above). A good metal fabricator will make sure that any grinding that has to be done is blended in well to give a smooth surface to your propeller blade. This also will help the propeller to balance well.
It took more work to fix the propellers since I had to remove all the damage first, but the finished product came out well.
Propeller #1 before:
Propeller #1 after:
Propeller #2 before:
Propeller #2 after:
Whenever you have work to be done on your props, make sure the person you are trusting knows what s/he is doing. It will save you money and get you back out on the water faster.