Looking for right wood

i'm just looking at various wood sellers for buyng materials for my 6 meters cheap boat i'm going to start building next week:see

http://boatdesign.net/forums/showthread.php?t=12496

so i chose for the skin 10 mm plywood okume .
i'm in truble for the compromise i have to reach for the scantlings...

http://www.boatdesign.net/gallery/sh...g/ppuser/14047

i have to make them cheaply
i was oriented to make 8 section of (12x2cm) from fir commonly used for house building , but also with a bit more i should use sweden pine or pine
plywood ,or always okume
what do you suggest to me ?
Francesco
italy

 

Most pines are not great boatbuilding woods... though some will tell you there are exceptions.
Are you fastening with screws or gluing with Epoxy? It can make a difference.
If you want thickness without much weight, consider one of the cedars (or redwood).
Builder Robb White, who died recently, was a big believer in tulip poplar, which you can think of as American okoume.
Iroko and afromosia are sometimes referred to as "African teak". They glue better than true teak, but they can have hard deposits in them that dull saw blades. Then there's black locust.... some say it's "American Teak." It glues well, and is resistant to splitting. True teak is great if you're using mechanical fasteners, but not great for gluing. Most of the woods I've mentioned are rot resistant to varying degrees.
Okoume is the lightest (in density) of several woods called "African Mahoganies". Then there's true (Honduras) Mahogany and Lauan. Honduras Mahogany is good, medium weight stuff, though mahoganies in general are not as rot resistant as the cedars & teak. The problem with Lauan is that it's a blanket term that includes several different species, so the quality of lauan plywood is inconsistant.
The spruces and basswood have the highest strength to weight ratios, but are less rot resistant than some others. They're typically found in spars. I don't recommend most oaks, but the exception is Live Oak, the wood of which Old Ironsides was famously built.

If I were building a boat and could use anything, I'd try tulip poplar planking on black locust frames with sitka spruce spars.