The engine room sole is sheathed with 1/4" aluminum diamond plate.
I was planning on using plywood for the sole due to cost concerns on my part, but having found this plate at the scrap yard has allowed me to go with, what I consider, a more attractive sole. Because of being in the engine room, and also I believe it could be a common event to have to lift pieces of the sole off for maintenance I bolted wood firing to my steel framing and then attach the aluminum sheathing to the wood. If I had screwed the aluminum sheathing directly to the steel I had visions in the not to distant future of broken screws, corrosion where screws penetrated the steel, and just more difficult maintenance in general. Having wood to screw the aluminum in to will also give me a little vibration dampening in my opinion. I'm using #12 x 1.50" stainless steel wood screws that I'm countersinking as my fastener. The sole is complete as I write this post, and to date, I've used 150 of the stainless screws to fasten the aluminum down.
I wanted as much level area in the engine room as I could build, so I stepped the sole framing up as the sole moves aft in the engine room. These steps, while some might not like, give me places of access underneath the sole, and also give me a place to sit while I'm in the engine room. Whenever I give friends tours of the progress, almost everyone sits on one of these steps. This picture to the left shows the platform I built for my tool box, and my hydraulic system reservoir.
I think the largest piece of material I've used for the engine room sole is a finished cut piece of 24"x 24". I don't want to be having to man handle large pieces when I'm I have to access under the sole. I would rather be able to lift smaller pieces, to gain access and still be kneeling or sitting on the level sole. The down side to having all these smaller pieces is I used quite a few screws.
I'm getting a pretty good feel on how the engine room is going to layout and I think I've found locations for the various equipment I'm going to need. I'm going to dedicate the port side of the room up against the main bulkhead at frame #9 as my area for my work bench. While the head room is around 5"4" in this area, I'll be able to use a short stool with a lower work bench to be able to work in a comfortable position. I'll post more about the engine room as a whole once I begin to install the various components.
The last piece of the sole for me to build is the area over the stuffing box. I'm almost out of aluminum plate so I have to give it some thought on how I want to treat this area so I don't waste any material. I think I'm going to hinge a part of this area so I can gain quick access to the stuffing box for maintenance, daily checks for leaks, and stuffing box temperature.
I have 4' 10" of head room on the starboard side of the engine, and 5' 2" on the port side of the engine. I have more headroom on the port side by my design as I knew this area would house my work bench. I'd love to have a stand up engine room, but on a boat my size, I think that would be almost impossible. I think once you get into the 50' range, stand up engine rooms start to appear. I'm totally happy with the size of the engine room, and very pleased with the head room I do have. I'll be able to easily do all my maintenance work in this space in comfort.
The scrap yard aluminum worked out great. There are some blemishes, and some cleaning that will have to be done. I know as construction progresses, the dings I put in the sole, will blend in to what was there. I'll probably never do much more than clean up the mess's I make. I have to say that I love the way the engine room is shaping up.