It's 20 years since I did this, so someone (possibly Matt) may know better, but from what I recall of Engineering Part 1A. Forgive me if I'm teaching you to suck eggs, but for readers that haven't come across this before:
Stiffness is the resistance to bending for a certain load. Given a certain load, how far does it bend? This would be useful to assess how an oar or mast distorts under load.
Strength is the amount of load the material can take before catastrophic failure occurs. This would be useful to assess whether or a mast or oar snaps, which for non-racers may be what is of most interest.
We might also need to worry about toughness, which is the resitance to cyclic loading and damage (i.e. fatigue cracks, rot).
Assuming the epoxy is thin with relation to the wood, it doesn't change the elastic modulus significantly, thus elastic stiffness is the same. (Without the glue or if the bond fails then the stiffness of multiple pieces is reduced compared to a single piece of the same total thickness) measured in a direction across the thickness.
As I recall, the strength will go the same way as the stiffness.
I think there are 2 advantages of the epoxy laminations
1 It makes the whole thing tougher - that is cracks due to repetitive loading and unloading will not propagate straight across like they would with a single piece, and the epoxy layers also provide a barrier to rot.
2 Wood is an imperfect natural material, which can suffer from knots, weaknesses and cracks. Laminating means that you get a more even, predictable performance because the defects are unlikely to line up between the pieces.
I hope this helps,
Anthony
