Are you speaking about what weight of outboard
you might be able to mount on your transom? You are talking about a sailing craft? Generally anything over 6hp is pretty much wasted power on a boat that size but I've seen up to 15hp. I would estimate that you wouldn't want to go much more than 100 lbs for engine
weight. It would upset the balance of your boat and put the stern down too far.
Generally a manufacturer will have a hp recommendation for an outboard
auxiliary for their boat and you could do a search in the search engine
following my signature for Ranger
26 to see if there is an owner's pamphlet on file.