Just a note, not commenting upon your actual question. 

Bronze = so much better than brass in every (?) way.

So if you do this, consider bronze. Whenever I use brass screws (which is now very rarely) I either tend to bugger the slot or or break the shank of the screw, especially if ever used in an application where the screw will be ever be used to screw both in an out, even once or multiple times.  (Which I acknowledge isn't the usage application you are citing above.)

Yes, go with silicon bronze screws.  Also, you'll need to get a Frearson bit, they're not Phillips.

Frearson.  Had to look it up:

Wikipedia on Frearson

Looks like it's what Sears called a Reed-Prince in the Craftsman tool set I bought...gee,what was it...about a hunnert years ago?

Mother said if I paid attention I'd learn somethin' new every day.

.....Michael

   Agreed, the good silicon bronze screws will need a Frearson bit. But if you do care about a traditional look, I'd go with slotted screws.  The Phillips screw wasn't invented until the 30's. Granted that slotted screws are slightly more difficult to work with, but my observation of original wooden boats is that slotted screws were almost always used up into the 60's.  

I know it is a minor point, but if we didn't care about looks we'd all be using stainless steel, which is probably superior in every way (other than not having that traditional/nautical look)!

���Actually, silicon bronze is better than SS for embedded fasteners in salt water. Even 316 SS needs air to make a protective passivation layer. Good bronze doesn't and has as good working strength for things like keelboats or planks on frame. For a dry stored dinghy, not so much.