Evaluating Seatorque BOSS Retrofit to Address Persistent Vibrations

Greetings Captains and Engineers,

We are currently overseeing a comprehensive running gear refit on a 30 year old 90' FRP yacht and am seriously evaluating a conversion to the Seatorque Bolt On Shaft System. I would highly appreciate first-hand feedback from anyone who has with this specific retrofit on an older hull, or operational feedback on these units pushing heavy horsepower.

Current Specs & Situation:
- Power: Cat C32s paired with ZF transmissions.
- Current Running Gear: Standard 4" diameter straight shafts with RD109 couplers, 47" 5-blade props
- Hull Material: FRP

The Catalyst for Change:
The boat has been plagued by a persistent, ongoing vibration issue under load that traditional troubleshooting hasn’t resolved. We are currently hauled out, and the running gear is stripped down. The existing struts are being condemned, meaning we are already facing the cost and labor of installing completely new struts, performing extensive alignment work, and potentially tackling shaft/hull log modifications. Since the underwater profile is already compromised for the new struts, the labor overlap for a Seatorque conversion is substantial. My primary engineering goal is to isolate the C32 thrust loads from the ZF gearboxes entirely, allowing us to drop the engine down onto softer mounts and sever the mechanical path transmitting this vibration into the hull structure.

My specific questions for the group:

1. Structural Reinforcement: For those who have retrofitted Seatorque to a 90' class FRP hull, what did your laminate schedule/transverse bulkhead reinforcement look like to safely transfer the C32 thrust loads directly to the stringer grid?

2. Alignment & Universal Joints: Have you encountered any unexpected resonance or secondary vibrations stemming from the cardan/universal joint assembly between the gearbox and the Seatorque flange?

3. Field Reliability: For captains running these long-term, how vulnerable have you found the trailing edge lip-seals to stray fishing line, even when running high-end line cutters? Are they truly a "haul-out emergency" if a seal gets nicked?

4. The Verdict: If you had the running gear completely stripped for new struts anyway, would you pull the trigger on the BOSS system, or would you stick to a traditional 4" setup with a secondary thrust bearing system (like AquaDrive/Python)? I look forward to your unfiltered technical insight, experiences (both good and bad), and yard lessons learned.

Cheers!