: Without a lecture on how okoume is better than Luan, I was wondering if
: anyone could shed some light on steam bending luan plywood for a cambered
: deck. Actually any bending method that results in a crack free luan deck
: would be great.

1/4" ply is too thick for getting getting good bending - especially across an edge where you likely won't get any at all. if you haven't started your yak yet, you'll be more ahead by keeping all the 1/4in for other heavy construction and buying some even cheaper 1/8" or 3mm luan.

and thinner anything will bend easier than thick anything.
The problem with cheaper plywood is the inconsistent coring, inconsistent veneer thicknesses (face is often thin and so more fragile in bending) and inconsistent veneer wood character. But if you accept the problems and recognize that some pces won't work etc, luan will be fine.

The main problem with heating/steaming big pieces like decks is that it is hard to heat the whole pc quickly enough and then to have it formed quickly enough - you only have a few seconds (especially with thin wide pces that can cool down so quickly) to work.

(But heat bending or steaming of ply will work - just test it out for yourself by holding the centre of a 3" x 24" pc of ply over a hot oven element to get an idea of how much and when it happens)

i used a heat gun on this one (inside deck pic of 'facetious'):