Systematic reassembly of a marine saildrive unit with a focus on corrosion mitigation and correct installation procedure.
Key Message: A successful saildrive service is defined by meticulous surface preparation, the use of specific corrosion-inhibiting compounds, and strict adherence to manufacturer torque and locking specifications.
Author: Shayne and Anna
Introduction
Following the removal and inspection of the saildrive, this phase focuses on reassembly and reinstallation. The objective is not only to return the unit to service but to significantly improve its longevity through targeted corrosion prevention and the use of upgraded components.
Surface Preparation and Corrosion Mitigation
All components were thoroughly cleaned. Critical surfaces exposed to seawater were treated with Duralac, a corrosion-inhibiting compound. The Duralac was thinned to a paintable consistency and applied to the saildrive leg and internal seawater passages to create a protective barrier.
Component Reassembly and Upgrades
The reassembly process integrated several key upgrades and procedures:
- Water Inlet Fitting: The original plastic fitting was replaced with a new bronze ball valve and hose tail assembly, secured with Loctite thread sealant designed for gas and hose fittings to prevent rotation and ensure a seal.
- New Hull Boot: The critical 21-year-old rubber boot was replaced. The new boot’s pliability was noticeably greater, ensuring a effective seal against the hull.
- Bolt Specification: Attention was paid to the high-tensile (A4-80) grade of the mounting bolts. Using a lower-grade substitute is a critical point of failure.
Installation and Torque Procedure
The unit was reinstalled following a defined procedure:
- The saildrive pocket in the hull was epoxy-primed to seal the polyester laminate.
- The unit was carefully offered up to the hull to avoid damaging the new antifoul.
- A calibrated torque wrench was used to tighten the main mounting bolts in the correct sequence to the specified value.
- Once torqued, the bolts were lock-wired to provide a positive mechanical lock against vibration.
Conclusion
The service restored the saildrive to a state of improved reliability and corrosion resistance. The methodical approach to surface treatment, component selection, and adherence to torque specifications is essential for a long-term, trouble-free outcome.
Materials and Products Used
The following products were selected for their specific suitability to this application:
- Antifouling: Nautix A7-TSpeed, formulated for drives and propellers.
- Corrosion Inhibitor: Duralac, for isolating dissimilar metals.
- Thread Sealant/Locker: Loctite, for securing threaded fittings.
- General Anticorrosion/Bedding: Tefgel.
Want More?
Below are our collection of Guides and References for Sailing and Working with Composites. For detailed behind the scenes videos and access to our community for technical discussion on projects like this, the Youngbarnacles Membership provides these resources. Join the Youngbarnacles Membership and help us make great content.
- How to Tune Your Multihull Rigging: A Complete Step-by-Step Guide
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- Our Criteria for a Great Second Hand MultihullKey Message: Our search for a true passage-making catamaran was governed by a disciplined, three-part framework that prioritized fundamental performance over cosmetic comfort. We required a lightweight, second-hand multihull with a proven design, clean underbodies, and daggerboards—non-negotiable features for efficient, seaworthy bluewater sailing. This unwavering focus on a boat’s core sailing attributes, rather than its… Read more: Our Criteria for a Great Second Hand Multihull
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- Boat Weight Management: Why Your Multihull’s Performance Depends On ItTopic: Want a Faster, Safer Catamaran? Start by Managing Your Weight Author: Shayne and Anna It’s a familiar scene for any cruiser: storage lockers full of “essential” gear, spares for spares, and projects-in-waiting. But on a performance multihull, this accumulation isn’t just clutter—it’s a direct threat to your safety and comfort. As we prepared to… Read more: Boat Weight Management: Why Your Multihull’s Performance Depends On It
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