Please don't tell me that is pressure treated 2 x 4s holding up that deck. I don't know if you know this, but certain pressure treatments react with aluminum. You see, pressure treated wood is often impregnated with copper. Copper and aluminum are dissimilar metals. When 2 dissimilar metals combine, is starts galvanic corrosion. That will eat up your boat.
Also, are those brackets galvanized? Are any of them touching the hull? Galvanization is the coating of iron, or steel, with zinc. Zinc, and aluminum are dissimilar metals. If none of the brackets are touching the aluminum, you shouldn't have a problem, but if it is, you might. Here is a little chart.
https://www.galvanizeit.org/showContent,280,324.cfm
You notice, the zinc to aluminum (the top one on the chart) under marine, it is 0 - 1, as far as corrosion - O being no corrosion, and 1 being light corrosion, tolerable under certain circumstances.
For fasteners, the best things you can get, are stainless steel. These are fairly compatible with aluminum (aluminum will corrode with anything - including air. When you cut a piece of aluminum, and look at it, for a second, it will be shiny, but pretty soon it will get that dull luster a lot of uncoated aluminum has. That layer of corrosion is good, as it forms a layer of protection for the rest of the aluminum. Most aluminum boats, that aren't painted, will have some coating, to keep them shiny) But, Stainless steel, is the best fastener, aside from one made out of the same grade aluminum.
Hope this helps somebody.
