My 2005 Donzi has the original bellows. It's a fresh water boat always stored indoors with the drive down. I know what the books say. What do actual boaters say?

What does the book say?

Pretty sure they say that I should have replaced it twice already! lol

I thought every 4-5 years,,I do mine every 4 years

As soon as you drive 7+ hours to a destination. That`s when they go.. Never when you`re close to home.

Just before they split and fill the bilge.

So how often does everyone replace them on a freshwater boat stored indoors? How fast does water get into the bilge if it does tear?

we can sink your boat with a ripped bellows especially with a bilge pump that can NOT keep up and or another are is slower leak with a shift cable bellows.

storing the drive down all the time out of the water helps a lot as well. It puts the bellows back in there natural state

Volvo Penta believe it or not suggests to change bellow every 2 to 4 years max. Merc if you pull the drive off is the best way to check for a compromised U joint bellows pushing internally and inbetween the ribs outward. Sometime your darn finger will go right thru or even make a small tear bigger. . if it feels shoft . mushy or has hard spots in any way - I would change it regardless.

Also grease from the gimbal bearing laying in the ribs of the bellows internally is not good for the bellows period - its attacks the composition structure of the rubbers that the bellows is made of - over time sitting. I like the greaseless gimbal bearing for this added reason plus other reason for using them.

IMO I would Never let any bellows go over 10 years -- your asking for trouble waiting to happen. A tear that can happen - the water ruins other stuff on top of --- ie: gimbal bearing - u joints - input shaft seal in the upper from corrosion that forms afterwards that seeps in that area. the rough spots of corrosion sands papers the outer edges of the seal and then gear oil leaks into the bellows down the road after the fact. Sometime this corrosions leads to pitting on the input shaft surface in which will never seal properly even when resealed - you then have to replace input yoke. Also the input shaft corrosion can form black corrosion on the surfaces, then again the that would need changing.. Just some extra info why I would change bellows before a tear leak would ever take place.

I do pull the drive every year to check gimbal bearing, u-joints and bellows and then put in fresh oil. Bellows always looks perfect. I thought that not much water gets into the boat if the bellows tears. I'm leaning towards running this season with it. Who else changes them regularly even though they look fine?

Changed mine for the first time last season. It's a 2001 fresh water, all but 1 season (20hrs) anyway. Drive pulled, serviced and bellows checked every year and stored outside under canopy with drive down.