I've seen several different motors put in those Pro Boat hulls. The OS .18 used to be an option but I think they were discontinued.
Upon doing some research, I have found the following:
Super Tiger .18
http://www3.towerhobbies.com/cgi-bin...?&I=LXWPH8&P=0
Novarossi .15
http://www.novarossi.it/2012/index.p.../t-mx15pr.html
CMB 21
http://www.cmb-motori-italia.com/21vac-en.html
While all of these should work, the NR and CMB may be too powerful for the Llumar. Something else to consider is that the NR and CMB are race motors and cost considerably more than the ST
No matter which one you buy, they are all much less expensive than the $950 one I have to get for my gas boat, shown below
