My experience is with a CAL
21 which has a slightly different keel
configuration than the Mac/Venture. However, I would not forsee any problems with keeping the boat in the water all season. One concern though, if you can get a mooring
that will allow enough depth
at all tides for you to leave the keel
in the down and locked position, it wil lbe better than if you need to retract the keel every time, 2 reasons for this....1) less work on crew and equipment
if the keel is down always (only retracted for haulout and storage
offseason) 2) I'm a bit concerned about 500# of cast-iron hanging on the lifting cable all season...... as the boat rocks/rolls at rest the keel will tend to sway a bit and will put extra strain on the cable and the pivot bolt. I seem to recall
that the loop where the cable attaches to the keel (based on a friend's V25) has a nico-press swage fitting and those are usually copper, that swage fitting could corrode away in saltwater from stray electrical
currents.... if it does......you have 500# of cast-iron keel suddenly swinging down with full force...... can you say CRUNCH!!! then in comes the water! The V21 does have flotation and won't go to deep....but it still won't be fun!
Leaving the keel locked down will actually reduce the wear on the pivot bolt especially if you snug it up a bit after inserting the locking bolt that stops the keel from retracting.
Any further advice that I would have has pretty much been already stated.