A few questions relative to a '77 O'day 20: Not sure how to remove sliding hatch cover. There seems to be something catching & I don't want to force it. Need to replace flexible tubing from cockpit drain to through hull and also for centerboard line. What have you used? Any recommendations or thoughts on replacing through hull fittings - they appear to be the originals, but I'm somewhat reluctant to touch them. What have you done to keep gulls of boat? Thanks for any thoughts/advice.