Bruce, our 1989 37+ has a 3 inch inline style blower that sits just below the manual bilge pump and exits in the walk thru transom beside our shore power inlet. A 3 inch plastic flex pipe can be installed on the centre line into the engine box. There is a remarkable difference in the main cabin heat if I don't use the blower in summer weather. And we do not have AC. If you want a pic, let me know. Our engine is the M35 and maybe they are not a standard item. Len Sent from my mobile device.
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