Do you have to...

[Slump_Da_Hustla]

pre-drill holes in marine grade plywood, like you do with MDF?

[The_Ancient]

never really used marine ply but you should really pre-drill regaurdless of wood type.....

it is a good habit to form. Weather you you HAVE to are not I dont know

[sandt38]

Yes, predrill. The plywood will seperate almost as easily as MDF splits.

[geolemon]

The biggest time-saver you can get is a set of right-angle clamps (aka framing clamps), and a countersink bit.

Get the bit that has the drill bit coming through it.

I got cheap Craftsman right angle clamps for like $10/pair.
The countersink bit should cost you about $5.

That bit predrills your hole, and carves a countersink for your drywall screws in one step!

Makes box building a several-hour affair, rather than a several-day affair!