News

---

Introduction to Davits

Davit systems stand as essential, crane-like devices adept at controlled lifting, lowering, or positioning of loads and personnel where space constraints, reach, or precision in control play significant roles. These systems serve in a plethora of roles, including launching survival craft from ships, hoisting tenders, maneuvering suspended work platforms, and facilitating fall protection with retrieval for confined spaces. More details on their heritage and fundamental designs can be explored in Wikipedia's overview here. Additionally, international regulations for lifesaving appliances, which encompass launching equipment, lie under SOLAS Chapter III, administered by the International Maritime Organization (IMO), and their areas of work can be found here.

Function and Primary Use

A davit is designed to provide a controllable moment arm over an edge or freeboard, managing weight through a hoist or winch while permitting rotation and outreach. This geometry offers crews a dependable, repetitive method to move loads clear of potential obstacles, sustain line control, and effectively manage descent or recovery operations. Within maritime services, launching appliances designed for lifeboats must meet stringent performance and testing standards imposed by SOLAS under flag administration oversight. For work-at-height and rescue scenarios, OSHA mandates retrieval capabilities for vertical confined-space entries (29 CFR 1910.146) along with suitable anchorages for personal fall protection, often interpreted as a strength of 5,000 lb (22.2 kN) per person or designed by a qualified individual (29 CFR 1910.140) (source here and here). NIOSH offers guidance on confined-space hazards and rescue planning that inform equipment selection, further details can be viewed here.

How Does a Davit Work?

Understanding how davits work is crucial. A mast or kingpost supports a pivoting boom that bears sheaves and a hoist line. Operators rotate the structure, controlling the raising or lowering mechanism while the base counteracts overturning and uplift.

For confined-space retrieval, these systems are utilized by positioning the main anchor over an opening, attaching a winch or SRL-R to a bracket, enabling controlled descent and powered retrieval during emergencies (see OSHA 1910.146 and 1910.140 for guidance).

For launching boats, davits function by slewing a loaded craft from its stored position to the water's edge, lowering it at a managed rate, while adhering to the performance and testing criteria under administrative oversight (IMO SOLAS).

Key Components

• Base or Socket: A fixed pedestal, floor socket, or portable weighted base that counters moment and uplift.
• Mast/Kingpost: Provides height and bearing support.
• Boom/Arm: Determines horizontal or angled outreach, defining radius and clearance.
• Winch/Hoist: Manual or powered unit tailored to the rated load.
• Sheaves/Fairleads: Guides that minimize rope or wire rope bend radius.
• Swivel/Slew Bearing: Allows for rotation between inboard and outboard positions.
• Anchorage Points: Certified tie-offs essential for fall arrest or restraint.
• Secondary Device: Consists of self-retracting lifelines with retrieval (SRL-R) for rescue scenarios.

Safe Use and Limits

• Verify rated capacity/SWL, outreach limits, and allowable angles displayed on the equipment or accompanying data plate.
• Adhere to prescribed factors of safety and proof-load tests as outlined by manufacturers and relevant codes (OSHA 1910.140).
• Ensure compatibility across winches, connectors, and lifelines; avoid side or shock loading.
• Conduct pre-use inspections, periodic assessments, and maintenance according to specifications.
• Develop rescue strategies; confined-space programs require retrieval methods and trained attendants (OSHA 1910.146; NIOSH 87-113).

Typical Applications

• Shipboard lifeboat and rescue boat launching regulated by SOLAS oversight within marine environments.
• Handling tenders for smaller craft.
• Entry into confined spaces in utilities, refineries, water, or wastewater plants.
• Powered retrieval systems for tower or turbine maintenance.
• Building facade access via portable bases and counterweighted arrangements.
• Lifting operations at docks or piers for light marine equipment.

Modern davits are engineering marvels that facilitate intricate lifting procedures while maintaining compact footprints, offering modular bases and interchangeable hoists. They ensure reliable positioning while complying with recognized regulatory norms and consensus standards.

---

Types of Davits and Their Applications

Selecting the right kind of davit involves assessing several factors: its use case, applicable load class, and relevant regulatory framework. In various fields like marine launching, facade access, confined-space rescue, utility lifting, and general material handling, specific equipment is the cornerstone for successful operations. Standards set forth by OSHA, the US Coast Guard, IMO, and ASME play pivotal roles in creating, testing, and utilizing these systems. Professionals need to align the unique needs of each application with the proper davit system.

Core Functions and Determining Factors

Davits generally serve three primary functions: lifting, lowering, and rescue operations. Load rating, outreach capabilities, and base style are critical drivers in choosing the correct equipment. Compliance with international standards ensures safety and efficiency, making adherence to regulations an absolute necessity in the decision-making process.

Marine Lifeboat and Rescue Davits

Shipboard davits are vital for launching and recovering lifeboats or rescue craft amidst ever-changing conditions. US regulations alongside SOLAS/LSA guidance dictate the specific requirements for these lifesaving systems. References like US Coast Guard Lifesaving Systems under 46 CFR Part 199 and IMO’s Life-Saving Appliances guidelines provide comprehensive insights into design, operation, and inspection standards.

• Common designs include gravity, single-pivot, and quadrant systems.
• Key duties: Launching fully loaded lifeboats and quickly recovering rescue boats.
• Controls: Options for manual or powered winches with integrated limit devices.

Dock and Small-Craft Davits

Widely employed in harbors, marinas, and water-side residences, compact systems handle personal watercraft, tenders, or small boats. For safe and effective operation, always check the nameplate capacity and outreach prescribed by the manufacturer before installation.

• Mounting types: Seawall, pile, or pedestal bases.
• Drive options: Manual winch or electric hoist technologies.
• Materials used: Galvanized steel, aluminum, or stainless steel variants.

Industrial Lifting Davit Cranes

The industrial sector employs davits for moving pumps, blowers, drums, and tooling through either pedestal or socket mounts. According to ASME B30 guidelines and OSHA 1910.184 regulations, maintaining safety during lifts is critical to avoid operational hazards.

• Primary tasks: Vertical lifts performed in pits, mezzanines, and rooftops.
• Power sources: Manual hand winch or powered hoist.
• Attachments: Sheave kits, boom extensions, or trolleys enhance functionality.

Confined-Space and Rescue Davit Systems

Confined spaces often require a portable davit system for anchorage and retrieval tasks. OSHA 1910.146 mandates the use of mechanical devices for vertical entries exceeding 5 ft, ensuring safety protocols are strictly followed.

• System components: Portable base, mast, offset arm, and winch.
• Functionality: Entrant retrieval, fall arrest, and work positioning.
• Base configurations: Floor, wall, parapet, or counterweight bases.

Facade Access and Rope Descent Davit Systems

Rooftop masts assist in building maintenance by supporting platforms or rope descent methods. OSHA 1910.27 addresses specifications for rope descent anchorages, ensuring they meet owner-assured anchor capacities.

• Applications: Utilized for suspended platforms, bosun’s chairs, and rope descent.
• Base setups: Permanent sockets with detachable masts.
• Controls: Outreach settings ensure safe clearance of parapets and edges.

Utility and Wastewater Pump-Handling Davits

Water treatment, wastewater, and industrial plants use socketed masts for hanging them over wells or sumps. Removable masts facilitate faster setup and shared use across sites.

• Duties performed: Pump pulls, mixer lifts, and screen maintenance.
• Operating environments: Splash zones and corrosive atmospheres.
• Features available: Sealed bearings and protective finishes ensure durability.

Considerations for Davit Selection

Choosing davits tailored to the risk, load, and environment enhances safety while managing costs effectively. Essential factors include duty cycle, outreach, and adherence to compliance protocols.

• Load cases: Evaluation includes static weights, dynamic forces, and shock loads.
• Reach considerations: Ensuring radial reach and necessary clearance is critical.
• Rotational needs: Swing ranges must account for potential obstructions.
• Environmental factors: Adaptations for marine, chemical, and extreme temperatures are vital.

Ensuring Compliance and Documentation

Procurement teams benefit from aligning specifications with relevant sector codes. Proper documentation and regular training play key roles in safeguarding crew operations.

• Verification processes: Confirm SWL markings on davit components.
• Anchor assurances: Validate strength or obtain engineering certifications.
• Inspect and maintain current records to adhere to industry standards.
• Operator and rescuer training is imperative to understand device limitations.

Capacity and Historical Context

A davit’s weight capacity varies, influenced by design, outreach, base, and application. Lifesaving appliances, under 46 CFR Part 199 and IMO LSA rules, require systems launching fully loaded craft. Industrial cranes rely on manufacturer-rated SWL confirmed by ASME B30 provisions and OSHA-compliant rigging.

Historically, davits originated from shipboard gear designed for lifeboat operations, evolving over time to include gravity and quadrant types for emergencies, later expanding to dock hoists and industrial cranes.

By understanding specific demands and compliance requirements, buyers can match types of davits to the specific operational context, ensuring safety and efficacy on the job.