1980
Mine is a 1980 model and I haven't seen any sign of blisters on the hull. Had a couple, once, on the rudder. Easy fix no problems after I fixed them. Several other OD 28's in my boat yard. I know all of the owners and that isn't one of the problems they speak of. So, I suppose the boat isn't particularly vulnerable to blisters. For what it's worth all of the boats I speak of use VC17 anti-fouling paint and each one has VC tar for the barrier coat. That may be why we are blister free.