Where French ship's boats sometimes double planked?

This questions concerns the construction of the boats that Soleil Royal might carry.    While I was in Paris's national maritime museum, I noticed a curious thing.   The model are ususally exquisitly detailed at all levels, some of which includes full interior detail never meant to be seen by human eye other than those of the builder's.    Yet the inside of many the ship's boats from the early18th century usually do not show ribs eventhough they are exquisitly detailed in other ways, such as having chokes for the butt of the masts, foot rests for the rowers, etc.      Furthermore, it seems the rib detail tends to be ommitted mostly from larger boats.  Smaller boats seem to ususally have the ribs accurately represented.  

Could it be that the French double planked their larger ship's boats during the first half of the 18th century (And therefore possibly also for late 17th century when Soleil Royal sailed)?    I can't understand why they would do this, since it makes the boats, which needed to be hoisted in and out for work, much heavier, and it also makes the boats hard to maintain and repair.   But the model evidence seem to be there.