Interesting part selection in POBB

[Chmashdehjare]

Spoiler

I was recently building POBB and ran across this part selection when building the rudder:

this section has multiple 1x4 plates yet they stuck in a 1x4 with only outer studs (don’t know the name of it). I build very little of my own creation but I’m always curious about part and design selection so I can learn. The only reason I can think of to use this piece instead of another full 4 stud piece is that the bottom part of the rudder is easier to remove.  I haven’t finished the build, perhaps that’s why. But I’m assuming Lego including an entirely different part comes at a cost so there must be a good reason for this piece.  Anybody know the design reason for this part selection?

 

Argh. I can’t figure out how to delete the picture below from my post!

 

Edited December 28, 2020 by Chmashdehjare
Remove extra picture

[Jack Sassy]

This was made so the lower part of rudder can be removed once the ship model is put on the island, perhaps i got your question wrong but this is what i understood at least.

Edited December 28, 2020 by Jack Sassy

[PxChris]

Yep, like @Jack Sassy said, it's to aid in the conversion process between full ship and shipwreck.

[Bregir]

Also, if I remember correctly, both the 1x4 plate, and the 1x4 with just two studs are available elsewhere in the set. I think in terms of cost, as soon as a specific brick is in a set, adding more of the same has limited impact. It is the number of different bricks that matters.