Hi Brian!
You're right. It only served for a quick explanation in the evening without warming a real plank.

Attaching a straight plank to a hull is only possible in exceptional cases, if the original provides for it.

The planks on the sides of the ship are also bent downwards like a wave. Why does the modeller have no problems with this? This course is also cold easy to bend!
Here is my method for more complex plank bends as they also occur on the original. The planks are also watered and warmed on the original, and fixed before the doweling with screw clamps.

Plank, water and soldering iron.

Watered wood and bent with heat. Two planks bent down for the bow.

Here you can see the quality of many a kit manufacturer (no specific manufacturer), like the top piece of wood, when it splinters.

Planks curved in this way can be found on many ship decks.

As the 2nd step the plank gets the rounding for the hull.

Ready to use bow plank without tension on the model.

In most cases the planks are not yet lying neatly on the bulkhead.

A further warming up of the wet plank lets them fit exactly. Now you can nail, glue, etc.
I personelly bend all planks even the slightes curves before assembly.
With best regards
Thomas