The matter of the gaiter, or boot, that seals the perimeter of the drive leg to the boat’s hull is one that, if neglected, could cause a boat to sink. In fairness, both Volvo and Yanmar drives employ a double seal with a water alarm system that will notify the boat owner if the outer seal begins leaking. Recommended replacement intervals for this rubber seal range from five to seven years between Yanmar and Volvo Penta, and both manufacturers consider this service a dealer-only procedure. Many boat owners have gone much longer than this before replacing the seals, but one has to wonder if an insurance company would pay a claim for a sunken boat if the service interval had been ignored by the boat owner. Certainly this is a good question to ask an insurance agent before something like this happens. Both Yanmar and Volvo provide an “aqua sensor” that will sense water leakage if this bladder begins to leak, but periodic inspection of this critical rubber seal at least every two years is of the utmost importance. Without question this is one of the most important not-to-be-ignored service items related to the saildrive system. Depending upon how difficult engine access is on a given boat, replacement of the bladder and associated service parts can cost in the neighborhood of $1,000-$1,500. more