front beam for cat.

[viking69]

hi i have bought a gbe cat the was damaged here in the recent storm. i need to find out what size front alloy beam to run on it as the old one went missing. i can tell what length it needs to be easy enough and that it is 100mm in diameter but what is a normal wall thickness and grade of tube usually used. here is link to what it used to look like Great Barrier Express catamaran built in Queensland

i sent gbe an email but as the factory no longer exists not sure if i will get a reply.
thanks Andy