I have always liked the detail Cigarette has used with the flooring in their engine compartments. After spending a season crawling around our Fountain I wanted to look into adding some flooring. Tired of balancing on the stringers and also easier to climb in and out with the flooring I assume. Looking for some material suggestions, pros and cons, etc. Stainless or aluminum, gauge or thickness of material, powdercoat or paint, fasteners for hold down, etc.
This is an example in attachment

I have aluminum diamond plate in mine and the only thing I don't like about it is having to polish it. Just did it yesterday. Have to do it a few times a year . It does look good though, lol

Pat at Active Thunder actually lays up a piece of fiberglass for the engine compartments on the 37 ATs, that has a diamond plate pattern. It's a pretty slick setup. I'd get you some pictures but I sold mine! If you go with aluminum diamond plate, I would suggest having it powercoated and then painted. This is what he does on the swim platforms, and it holds up pretty well IMO.

I'd go like Sydwayz said, polishing the stuff blows, had it in my engine compartment and it was a pain. Check out Lonseal too, great no/low maintenance option:

LONSEAL Flooring: LONPLATE I - Offering the rugged endurance of classic steel plating, this durable resilient sheet flooring is Lonseal's toughest skid-resistant vinyl -- perfect for heavy-duty applications in all kinds of interiors.<p> <br> <P>Click

Following.

I worry what would get under the plate , moisture ect , and fastening it down , I agree trying to stand in the engine compartment suck,s .

I am leaning towards powdercoating the diamond plate, that would definitely keep the maintenance down plus match all the illusion purple we re-did this year. To address what 575Cat has said the plates would have plenty of breathing room and not seal the stringers shut, if that makes sense. I was thinking of mounting thread inserts so plates can come out easily for cleaning. Or maybe that is overkill. The cool kid in me is saying Dzus fasteners would be a nice touch but nice stainless coarse thread fasteners would get the job done fine with a dress up washer.
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You want them to come out. The AT has tabs glassed into the stringers that support the standing pads. They are held in with countersunk SS screws around the perimeter. You definitely want them to be removable for cleaning the plates themselves and underneath when needed.

I had to Google Dzus fasteners, they are cool!

Padraig