'P' is the key

[eggyk]

It's not a matter of what I think, it's a matter of established fact. You already know this though, because you've already searched it enough to know what the sheet dimensions were.

The 29cm is for the on-sheet version of 'Map with Ship'. As per Library of Congress; You are not allowed to view links. Register or Login to view.

"Medium

• 1 map : ms., vellum ; 22 x 19 cm., on sheet 29 x 41 cm."

The MAP (the thing with the land and sea) is 22x19cm, on a sheet of VELLUM sized 29cm x 41cm. 

Use your eyes. One side is far longer. In fact, the TIF file that I downloaded from the site is 3290x4701 pixels, so the image is 1.42x wider than it is tall. Guess what 29cm * 1.42 is roughly? 41cm. 

Okay, I'll entertain the notion you weren't intentionally lying. Here's what I have issue with...

I have come into this conversation in good faith, and you have accused me of spreading misinfomation, lying, and obfuscating when I haven't done any of that. I took your theory at face value and tried to respect it and give it genuine feedback. I sat there trying to match what you did, tried to align things (you forgot the part where I also tried aligning the sheets at the same scale that you did and many other scales, but nevermind). 

I am willing to answer any questions or explore more, but please be respectful if you choose to engage- that's all I ask.

Follow your own request and be respectful. I really doubt anyone else is going to give you or your theory as much of a benefit of the doubt as I have.