Hmm this is a cause for sitting down and giving it a bit of thought.
The Hyborian age that Howard created is so long ago that ships or boats of the era have to be considered to be the most primitive thing anyone could imagine.
On the other hand the whole story is presented as a fantasy so extraordinary as to be possibly an earlier version of a time much more recent or even in the future
Revelation comes to mind.
Dunno and the philosophy of it makes this thinker struggle a little when details come into focus.
But then the confusion is that the art associated with the books represents our hero and his main squeeze on the decks of no less than a medieval era ship.
As with all things in art its all about the message.
So your build of the deck might just possibly be too modern. It's correct for Nelson's Navy BTW the stagger pattern is well done.
But... Imagine in the tenth century the Vikings basically laid short chunks of timber fore and aft over the frames that their hulls were based on, for decks. And the subject here is 21,000 years earlier.
I've read the Black Coast story a few times. It's a real not- fun and depressing thing. Belit is dead, Conan is in the worst part of his existence.
Maybe the deck should be mean, desperate, gates of Hell.
Take the look on his face and draw it down past his feet to the base.
Shadow of death over his head kind of thing.