Try taking a piece of luan and boiling it to see if it comes unglued.   That should tell you a lot. 

I currently building my fourth boat, a Chester Yawl.  I opted for a kit this time because I wanted a pretty boat.  Prior boats were a couple of banks dories and a Bolger Sweet Pea.  All of them were made with Home Depot's best C-D plywood.  Couple of sheets of 1/4", one of 3/8" and a 16 foot PT 2x4 ripped into four lengths for the gunnl's.  The 1/4 is for sides and 3/8 for bottom/transom.  These boats were glassed only on the bottom and up the sides for 6", one coat of epoxy inside and painted with water based paint.  

I fish out of Little Harbor, have done the Snow Row a couple of times, rowed several times out of Kittery on New Year's Day and even cartopped to the Chesapeake.  

Bright Luan would be prettier than C-D, but if you paint, who would know? 

The Wood Ducks have some strong curves. I had a hard enough time closing the bow on my WD12 with okoume, which is stronger and more flexible than luan. This happens before glassing, so the glass will be no help at all during the initial construction.

Laszlo

i used 1/4 inch Luan on a small workboat and as Lazlo says, it doesn't bend well at all, particularly around compound curves.  Recommend against it.

Luan worked fine on a eastport pram. But then, not much bend.

I used Luan for a Wood Duck 12 and it worked. The bow and stern were tough but it just took a lot of patience  some water and steam from my iron.  I did crack the deck forward fo the cockpit though.  

http://www.clcboats.com/shoptips/stitch_glue/lauan_plywood.html

eric

Thanks All for the feedback...

 I did find a local source for 4mm meranti marine grade, so I think I'm going to go with that.

It's only about 40 bucks a sheet, so my thinking is it's a happy compromise on price AND it's a marine grade ply (supposedly a bit tougher and more mold resistant than the Okume)

Thanks Again

The most expensive part of a build is your time. I'm finishng up a project where I used 9 mm G1S Douglas Fir instead of 6 mm Okoume. I managed to pull it off, but it increased the weight and the difficulty. Some of the bends were really tough. As others mentioned there are lots of boats out there built wih less than optimal materials, but I won't be doing it again. I have a stack of BS-1088 Okoume in the garage for the next three projects.