From Len Cardoza, Edelweiss C380 #232:
I could not access the broken (inside) piece of the forward water vent earlier this year. I ended up with buying a 10” inspection port; carefully measured out the area for the port on the starboard side of the anchor locker; used a multifunction oscillating power tool with narrow cutting blade to cut the hole…leaving room to finish same with the sanding tool. I was able to access and replace the vent (ordered from Defender). Hope this helps!
from Jim, C380 #14
On my boat the old vent basically disintegrated and the outside portion fell off. From the V-berth I was able to reach up alongside the anchor locker and grab the vent hose and pull the remnants out and back where I could work on it. I then removed the old fitting, added an additional length of hose with a barbed coupling