I’m thinking of laminating some hardwood to form a timber which is going to have to flex significantly. Can anyone recommend a waterproof glue that is going to be suitable?

Cascamite is my go-to for laminating. Not sure about how much flex it can handle (it does set pretty rigid) but its used a lot in boat building

Titebond 3 is water based, waterproof and is a favourite for diy skateboard builders and I guess they flex a fair bit.

You can get it from axminster

However, really, the point of laminating is to make things more rigid, so I’d wonder that degree of flex you’d be left with, whatever glue you use.

What are you actually making?

A couple of laminated longbows so rather than rigidity its using the different properties of the timbers in the laminate to give a predictable flex. I suspect there is going to be some degree of flex at the joint so I’m looking for a glue that won’t be too brittle (I’m probably over thinking this).

If its for bows then unless you’re laminating other materials in with the wood then either cascamite or titebond 3 should be fine.

The the latter might be preferable as its ready to use rather than mixed from a powder.

I use titebond 3 a lot, including for laminating. It’s great – easy to use and flexible and strong.

I use cascamite whenever I want a strong and rigid laminate. I’d say that Titebond would be more suitable.
Waterproof? Wouldn’t the bow be varnished or suttin?