Case Study: SK9 Relocation to New Vessel — Engineering Success

Project Profile

Donor Vessel

38' Center Console (sold)

Recipient Vessel

45' Express Cruiser

Gyro Model

Seakeeper SK9

Run Hours on Unit

1,850 hours

Project Duration

6 weeks

Result

70% roll reduction, sea-trial certified

The Challenge

The owner sold his 38' center console with an SK9 that had performed flawlessly for 3 seasons. He purchased a 45' express cruiser and wanted to move the gyro to the new vessel.

His previous installer quoted $18,000 for "reinstallation." No structural analysis. No power validation. No sea-trial guarantee.

Red Flag: The installer planned to use the same foundation template from the 38' boat on the 45' boat. Different hull form, different displacement, different CG — same template. This is how relocations fail.

Independent Feasibility Study

Before touching the donor vessel, we evaluated whether the SK9 was even suitable for the recipient:

Displacement check: Donor = 18,000 lbs. Recipient = 32,000 lbs. SK9 spec range: 22,000–36,000 lbs. ✅ Within range.
Hull form: Donor = deep-V planing. Recipient = moderate-V semi-planing. Different roll damping. ✅ Gyro still effective, but tuning different.
Machinery space: Recipient had 8" less headroom. Foundation design had to be modified. ⚠️ Required custom mounting.
Power system: Recipient had 24V house bank. ✅ Matched SK9 requirement.

            Feasibility Result: Viable with structural modifications and power system verification. NOT a simple drop-in transfer.
        

Structural Engineering Phase

The recipient vessel's hull required significant foundation redesign:

Original foundation: 14" diameter, 2" thick GRP doubler, bonded to longitudinal stringer
New foundation: 16" diameter, 3" thick carbon fiber laminate with aluminum core, bonded to NEW engineered bulkhead
Headroom constraint: Custom low-profile mounting bracket reduced vertical envelope by 4"
Stringer alignment: Recipient's stringers were 6" offset from optimal gyro location. We designed a load-transfer bracket rather than forcing the gyro into a suboptimal position.

            Engineering Decision: Moving the gyro 6" forward to align with stringers improved performance by 12% vs. keeping it in the "easy" location but fighting structural load paths.
        

Power System Validation

The recipient vessel had a 24V house bank — good. But capacity was marginal:

Existing: 2 × 8D AGM batteries (460 Ah total)
Required for SK9: 400+ Ah with <20% voltage sag under 100A spin-up transient
Measured sag: 22% — too much

Solution: Upgraded to 4 × 6V golf cart batteries in series-parallel (600 Ah) + 160A alternator with external regulator. Cost: $1,800. Result: 14% sag — within acceptable range.

Removal, Transport & Installation

Physical transfer with zero rotor exposure:

Donor vessel: Controlled spin-down (45 minutes), lockout/tagout, coolant drain, foundation bolt release in star pattern
Transport: Climate-controlled van, gyro secured in custom cradle with vibration isolation
Recipient vessel: Foundation installed and cured (7 days), gyro lifted with rated straps, aligned with dial indicator (0.08mm runout — within 0.1mm spec)
Connections: 24V power, cooling loop, NMEA 2000, and control panel

Sea-Trial Certification

Validation under real-world conditions in 2–3 ft seas:

Metric	Result
Spin-up time	42 minutes (spec: <60 min)
Power draw at steady state	38A @ 24.2V ✅
Roll reduction at anchor	70%
Roll reduction underway (12 kt)	58%
Thermal stability (4-hour run)	No thermal faults ✅
Vibration transmission	Imperceptible in master cabin ✅

Owner's comment: "Better on this boat than it ever was on the old one. The new location and power setup made a huge difference."

Key Lessons

Relocation is not transfer. Every vessel requires independent structural and power analysis.
Template-based reinstall = failure risk. The "same model, same foundation" approach ignores hull differences.
Power margin matters. A system that "works" on paper fails in reality if battery sag exceeds threshold.
Optimal location > convenient location. Moving the gyro 6" to align with structure improved performance 12%.
Sea-trial data is non-negotiable. Without measured performance, you don't know if the relocation succeeded.

            Cost Comparison: Installer quote: $18,000 (no engineering, no guarantee). Our project: $14,200 (full engineering, sea-trial certified, 6-week timeline). Higher value, lower risk, proven result.
        

Case Study: SK9 Relocation Success