Pidgins

I have a question about the alphabets used for pidgin languages.

Suppose some spanish sailors needed to communicate with arab traders back in the day.  I know they'd use a pidgin- spanich vocabulary and arab grammar or vice versa- but which lphabet would they use?  Would they use the arabic or the latin, or a constructed one?

What I'm really asking is what factors go into deciding?

>>3
i guess they only wrote the numbers, it's all
numbers
numbers
and between us they known the merchandise