Publish Time: 2025-07-21 Origin: Site
A hydraulic davit is a complex maritime lifting system that moves boats and equipment on vessels using pressurized hydraulic fluid. Hydraulic davit systems use hydraulic motors and precise control mechanisms to safely launch and recover lifeboats, rescue boats, and tenders. This is different from manual davits, which require physical effort. New Marine offers a variety of hydraulic davit systems, such as single arm davits, A-frame davits, platform rescue boat davits, hydraulic gravity davits, and hydraulic telescopic davits. Each variety meets the specific needs of a given vessel type and its operations, from deploying an emergency lifeboat to performing routine tender work.
Your hydraulic davit is more than simply a lifting arm; it's a vital life-saving tool that must work correctly when you deploy rescue boats or liferafts. Not only can poor maintenance shorten the service life of the davit, but it also invalidates class approvals, puts crew safety at risk, and can lead to catastrophic breakdowns. If these systems fail during an emergency, the consequences extend far beyond the expense of repair. They could mean the difference between life and death for crew members and passengers.
New Marine's A-Frame Davit for Rescue Boats: Hydraulic Type Available
Here are seven common maintenance blunders that could cost you a significant amount of money, along with easy ways to keep your hydraulic davit systems running smoothly.
The Fix: Sample hydraulic oil every six months and change it when the color darkens or after 12 months max, whichever comes first. Use only the specified grade—typically L-HV46 for marine applications. This grade provides excellent resistance to hydrolysis and thermal deterioration.
Technical Specification: Check the specification of your davit. For instance, New Marine's single-arm davits require 80 liters of L-HV46 hydraulic oil, according to the installation and adjustment guide. The L-HV46 oil has a high viscosity index (typically 154) and maintains performance from -42°C to operating temperatures.
Hidden Cost: A £200 drum of fresh hydraulic oil costs far less than a £3,000 hydraulic motor rebuild caused by contaminated fluid. Proper oil maintenance can extend system life significantly and prevent costly downtime.
New Marine's Single Arm Davit: Features Hydraulic System and Hydraulic Slewing Unit
The Problem: Hydraulic davits rotate on large roller bearings that require regular lubrication. Without proper greasing, micro-pitting develops into costly cracks that can lead to complete bearing failure. The slewing bearing supports the entire davit structure and handles enormous loads during operation.
The Fix: Apply marine-grade lithium grease to all grease fittings monthly. Rotate the davit arm through its complete arc to distribute lubricant evenly across all bearing surfaces. This ensures proper coverage and prevents dry spots that can cause premature wear.
Expert Tip: Use NLGI #2 grease suitable for marine conditions and high-pressure applications. The grease should maintain its properties in temperatures ranging from -20°C to +60°C, typical operating conditions for marine davits.
Maintenance Schedule: Proper bearing maintenance requires monthly greasing, but systems in harsh environments may need more frequent attention. Regular inspection should look for excessive play, unusual noise, or resistance during rotation.
The Problem: Speed-controlled winches depend on smooth, corrosion-free wire rope. Petroleum jelly attracts dirt and grit, while motor oil drips away in wet conditions, leaving the rope vulnerable to corrosion.
The Fix: Use approved semi-fluid wire rope grease designed for marine applications. Reapply whenever the rope appears dry or after exposure to heavy rain or salt spray. The lubricant should penetrate the rope core, not just coat the surface.
Professional Insight: Penetrating lubricants that reach the wire rope core can double service life compared to surface-only coatings. For instance, they can reach the fiber core of New Marine's galvanized, non-twist 18×19+Fc wire rope in the structure of single arm davit, protecting against corrosion and wear.
Inspection Protocol: Check wire rope monthly for fraying, kinking, corrosion, or broken strands. Replace immediately if any defects are found, as wire rope failure can cause catastrophic accidents.
The Problem: Excessive brake tension causes drum overheating and premature lining failure. The winch should stop smoothly when released, not fight against lifting operations or create excessive drag during deployment.
The Fix: Adjust brake tension until the drum holds the rated load, then back off a quarter-turn. Test during monthly drills to ensure proper operation and smooth engagement. The brake should engage automatically when the operator releases the control.
Technical Details: Modern davit winches feature automatic brake systems that engage when power is removed. Manual brake adjusters allow fine-tuning of holding power, but over-adjustment can cause overheating and component failure.
Warning Sign: If the brake creates excessive noise or the winch struggles to lift loads, readjust immediately to prevent component damage. Proper brake adjustment should allow smooth operation while maintaining full holding power at rated loads.
New Marine's Hydraulic Gravity Davit for Lifeboats
The Problem: Hydraulic accumulators store energy for emergency slewing operations. When the accumulator pressure drops significantly below the charging pressure, the davit would no longer function without the ship's power, potentially compromising emergency boat deployment.
The Fix: Check accumulator pressure quarterly using a certified gauge. Recharge with dry nitrogen if the pressure drops more than 10% from the specification. New Marine's single-arm davits, for example, require charging to 20 MPa for optimal performance as per the official installation procedures.
Safety Note: Never use air or oxygen for recharging—only dry nitrogen to prevent explosion risk and ensure proper system operation. Accumulator maintenance requires specialized knowledge and should only be performed by trained personnel.
System Specifications: Modern hydraulic davit systems typically use bladder-type accumulators with capacities providing sufficient stored energy for multiple emergency operations. Proper precharge pressure is critical for optimal performance and component longevity.
The Problem: Limit switches prevent over-hoisting and over-slewing damage. Salt spray and dirt can freeze contacts, causing switches to malfunction and potentially damaging the davit or connected equipment.
The Fix: Test each limit switch manually during monthly safety drills. Replace any switch that fails to stop the winch or slewing motor operation when activated. Document all tests for regulatory compliance.
Best Practice: Clean switch housings regularly and apply protective spray in corrosive environments. Consider waterproof switch enclosures in areas with heavy salt spray exposure. IP56 minimum protection is recommended for marine applications.
Regulatory Compliance: SOLAS regulations require functional limit switches on all davit systems. Regular testing ensures compliance and prevents accidents during emergency operations.
New Marine's Platform Rescue Boat Davit
The Problem: SOLAS regulations require annual proof load testing at 110% of the safe working load. Missing this test can void insurance coverage and result in port detention or PSC inspection failure.
The Fix: Schedule load testing with an authorized service provider before certification expires. Keep test certificates with the ship's safety documentation and ensure all personnel understand testing requirements.
Regulatory Requirement: Testing must include the complete system—boat, release gear, davit, winch, and foundations. Five-year thorough examinations require even more comprehensive testing by certified personnel.
Industry Standards: IMO regulations specify that annual examinations must be conducted by certified personnel from the manufacturer or authorized service provider. This ensures proper testing procedures and documentation.
Avoiding these seven maintenance mistakes keeps your hydraulic davit ready for emergency action while protecting your substantial investment. Regular maintenance schedules should include:
Daily: Visual inspection for leaks and damage
Weekly: Operational testing during safety drills
Monthly: Lubrication of all grease points
Quarterly: Pressure checks and detailed inspection
Annually: Complete load testing and certification
Maintain detailed maintenance records and keep them accessible for audit and port inspections. Proactive care not only ensures regulatory compliance but also protects lives at sea.
New Marine's Hydraulic Telescopic Davit for Lifeboats
New Marine has supplied SOLAS-compliant lifeboats and hydraulic davit systems worldwide for over 20 years. Our experienced engineers provide comprehensive support for maintenance, spare parts, and complete system installations. Need technical assistance or want to upgrade your existing system? Contact our team—we respond to all inquiries within 24 hours.
A: Replace hydraulic filters every 1,000 operating hours or annually, whichever comes first. Use contamination indicators where fitted to determine optimal replacement timing and ensure system cleanliness.
A: Only after confirming compatibility with all seals and pump specifications. Many biodegradable oils may not meet the viscosity requirements for marine applications and could affect system performance.
A: Signs include rapid pressure loss, oil contamination on the gas side, or visible damage during inspection. Replace immediately if nitrogen pressure cannot be maintained for the required operational period.
A: Most marine hydraulic systems operate safely between -20°C and +60°C. Maintain oil temperature between 30°C and 60°C for optimal performance and component longevity.
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