I Just happen to have a 79 seafarer 30 and can answer some of your questions. The yammar I have in mine is a 2gm rated at 13hp it was rebuilt the year before I bought it, I supect that it would not have needed a rebuilt if the owner had not over-revved it and sucked a valve. That being said I would guess if taken care of and all they could get about 4000 hrs on them before needing a overhaul. Some things to look for are mast compression leaks at the flange where the deck and hull join, my portlights leak a little bit,on the fix list in spring,the usual leaks at chain plates,and deck hardware. The boat is slow about six knots, but sails well,handles 20 knots of wind without a reef, in jib
and main out won''t go close to the wind maybe 30 degrees but handles well shorthanded all the time,and you can keep the speed on her without heeling over fifteen to twenty degrees.It''s a blast!The hull configuration makes rough water smooth out I don''t have the rocking and pitching motion I had on a hunter I owned. Overall I am pleased with the boat there is a seafarer website and a forum I have found the forum filled with questions and replys of the smaller boats but not a lot of traffic about the larger models. If your on the cheasapeake and haven''t bought one yet,my wife and I would be happy to have you take a sail with us and try it out yourself.