Some Info related to this kind of ships:

http://www.coltoncompa...yards/levingston.htm

I forgot to add the pictures of the yard:

http://www.navsource.o...chives/12/011264.htm

People: I found that link with usefull information and 'early' pictures of the yard.
The fact about Wood made tugs is not really true. Argentinian Navy still has a few of these tugs in servcice today (In active service I mean) and they are diesel-powered and Steel made:

http://www.histarmar.c...ArmadaHoy/Sobral.htm

Hope this clarify things ;)