Thai Romanization

Does anybody know how Thai is Romanized? I'm especially
curious about how the vowels are romanized. I have seen
some romanizations that use syllable final <r> (as in
"Chulalongkorn"), even though Thai does not allow them
phonemically. I also remember a former classmate of mine
from Thailand called "Palm", even though Thai does not allow
syllable-final consonant clusters. Thai romanization appears
to me to be based on English orthography making it deviate
from its actual phonology on a phoneme to grapheme basis.
Is this so?

I'm asking because I'm once again considering some kind of
orthographic change for Boreanesian that is more English
friendly than Boreanesian friendly. I'm curious as to how much
I'm allowed to deviate from the Boreanesian's phonology. The
diacritics are a pain in the butt to deal with when I have to
consider posting samples to this list. What do I for instance
do with ogoneks?

-kristian- 8)