How do you recognize potential problems with an inboard drive train and its support systems? Since we’ve always rated Tiara Yachts (tiarayachts.com) installations top-notch, we sought out answers from Rick Eggerding, Tiara’s director of product development. Eggerding points to one big indicator: vibration while the boat’s underway. “A well-designed and properly installed system should run smoothly, without a hint of vibration,” Eggerding says. Whether you feel vibration or not, closely inspect these six key elements for proper design, installation and maintenance.
1. Engine Isolators
Make sure the engine mounts and isolators comply with the engine manufacturer’s specifications for loading. Each power system has a different spec, and lack of adherence can lead to issues such as vibration. Also, there should be at least three-quarters of an inch around the engine to prevent it from banging on the bottom as the engine flexes on its isolators, Eggerding says. Isolators can also degrade over time, so check them periodically.
2. Shaft and Coupler Alignment
Inboard prop shaft and coupler alignment proves critical in minimizing wear and eliminating vibration. “Proper tolerances here are in the range of one-2,000th of an inch,” says Eggerding. “Misalignment can create problems.” The best way to check this is to have a service center or surveyor break the coupler loose and check it with a feeler gauge, he says.
3. Shaft Seal
Today’s inboard boats should have a zero-maintenance shaft seal such as the PYI PSS (pyiinc.com) or the Tides Marine SureSeal (www.tidesmarine.com). These seals are also water-cooled and self-aligning. “Other systems that require maintenance can lead to seizing of the shaft and catastrophic failure such as a torn seal and a 2-inch hole in the bottom of the boat,” says Eggerding. Still, a maintenance-free shaft seal can wear, and a key indicator is carbon particles being slung into the bilge around the shaft seal. Water dripping or slinging around the bilge is another indicator that it’s time for a replacement.