I am not sure exactly where the cleats are going yet. They will probably be screwed in from the underside. Drill a hole through the deck larger than ...
I built a Polynesian outrigger canoe last year, and seems like I am always coming up with modifications for it. This week the mods are for more cleats to be able to tie things down. I could buy cleats at the marine store, but that is too easy (and expensive). So I built some. I started with some scraps of very old southern yellow pine that was left over from a remodeling project. Hard, straight grained, and water resistant. The wood was some 1x material, nominally 3/4 inch thick. I used a belt sander to remove paint and clean up edges. The second picture shows after the longer piece has been ripped in half to give me a pair of 2/4 x 3/4 strips. The exact dimensions are not important. The shorter piece was split into several 2x2-ish pieces. This dimension is twice the height of the "stand-off" portion of the cleat.
I laid out pencil lines on the long strips to align the standoffs. The idea is to make a doubled row of cleats that can be sliced up later. I wanted 1.25" on each side of the standoff for the finished cleat, so each standoff was positioned 2.5" apart. Arrange the wood so that you are not gluing end grain. This will make the cleat stringer. Use lots of clamps.
Step 2: Mass production
Be sure to use waterproof glue. After the glue has set I used a router with a round-over to bit to smooth all exposed edges. It is much faster to do this on the glue-up, rather than finishing each piece individually. After routing I did some finish sanding. Again, easier with it as one large construction. Run the big piece through the table saw to rip the standoffs in half and make two longer strips.
Finally I used a chop saw to separate the individual cleats.