Below is a page I ran across while researching Naval Uniforms of the Spanish Navy, circa 1710.  I was quite surprised to find a trimaran (of sorts) among the pictures.  Frankly it looks like a VERY expensive book, and besides it’s in Spanish, so I won’t be investigating it further.  Perhaps there is a scholar out there.

Check it out.

http://www.planetadelibros.com/construcciones-navales-tomo-i-libro-6423.html

In that book is also a picture of a proa:
http://www.superstock.com/preview.asp?image=4409-10701&imagex=76&id=19671379&productType=3&pageStart=0&pageEnd=100&pixperpage=100&hitCount=85&filterForCat;=&filterForFotog;=

Cheers
Alexander