Looking at buying mid seventies 17' 6" Hydrodyne with floor rot in seat area. Bottom fin is missing and gap in keel area where fin was, appears to be glassed over, but can still see gap. The boat is set up for twins but has no motors. It has the steel over the transom and didn't look out of line. Would put a single on it and maybe at some point maybe do a restore. Don't want to get it and have to do a restore immediately because the fin is gone. I some what understand the importance of the fin, but should I even consider using the boat without it because the performance will be compromised? . . . . And, Hence should I even consider buying?