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ISO 25649-5:2024 — Floating Leisure Articles — Safety Requirements and Test Methods for Class C Devices
Engineering and safety compliance guide for towable water sports devices including tubes, inflatable towables, and Class C floating leisure articles
1. Scope and Classification of Class C Devices Under ISO 25649-5
ISO 25649-5:2024 specifies additional safety requirements and test methods for Class C floating leisure articles — devices designed to be towed behind a watercraft with one or more persons on board. This includes towable tubes, inflatable towable platforms, and similar devices designed for recreational water sports. The standard is the fifth part of the ISO 25649 series, which covers floating leisure articles across multiple classes differentiated by design, intended use, and risk profile.
Class C devices are further divided into three sub-categories: Class C1 (single-person towables designed for passive riding), Class C2 (multi-person towables for passive riding), and Class C3 (towables designed for active maneuvering, such as those with steering capabilities). Each sub-category has distinct requirements for sizing, buoyancy, user capacity, and in-water performance.
Always verify the Class sub-category of your device early in the design process. A device intended for active steering (Class C3) requires significantly different grab handle configuration, towing attachment strength, and capsizing behavior compared to a passive towable tube (Class C1).
2. Design Requirements and Engineering Specifications
2.1 Sizing and User Capacity
Each Class sub-category specifies minimum space-per-person requirements. For Class C1 devices, the minimum space per person (passive user, including children) is defined by a formula based on the user’s shoulder width and seated height. For Classes C2 and C3, the space-per-person requirements account for the additional dynamic loads experienced during multi-person towing. The maximum load capacity must be permanently marked on the device with a margin of at least 25% above the calculated maximum user weight.
| Parameter | Class C1 | Class C2 | Class C3 |
|---|---|---|---|
| Typical configuration | Single rider, passive | 2+ riders, passive | 1-2 riders, active steering |
| Min. space per person | 0.50 m2 projected area | 0.45 m2 projected area | 0.55 m2 projected area |
| Grab handles required | 4 minimum | 2 per rider minimum | 4 plus steering handles |
| Quick release system | Mandatory | Mandatory | Mandatory |
| Towing attachment strength | >= 1500 N (1-person) | >= 3000 N | >= 4500 N |
| Residual buoyancy (punctured) | >= 75% of user mass | >= 75% total user mass | >= 80% total user mass |
2.2 Grab Handles and Restraint Systems
Grab handles must be designed to withstand a static load of at least 1200 N applied in the worst-case direction. The handle material must have UV resistance equivalent to at least 500 hours of accelerated weathering testing per ISO 4892-2. For Class C1 devices, a minimum of four grab handles are required, positioned to allow secure grip from any riding position. For Class C3 devices with active steering, additional steering handles with a minimum breaking strength of 2000 N are required.
2.3 Quick Release System
All Class C devices must incorporate a quick release system that allows the rider to disconnect from the towing watercraft rapidly under load. The release mechanism must operate with a single motion, with an activation force between 30 N and 80 N — low enough for easy operation by children or adults in stressful situations, but high enough to prevent accidental release during normal towing. The quick release must function reliably after exposure to salt water, UV radiation, and sand abrasion. The system must pass 500 operational cycles without degradation.
A quick release system requiring more than 80 N to activate may not be operable by children or small adults under panic conditions. Conversely, a release below 30 N poses risk of inadvertent release during high-speed towing, potentially causing the tow rope to snap back toward the watercraft.
3. In-Water Performance Testing
3.1 Test Conditions
The in-water performance tests require a test course with specified water depth (>= 2 m), water temperature (>= 18 C), and wind speed (<= 15 km/h). Test subjects must represent the full range of intended users by weight and stature, with at least three test subjects per device type. The towing watercraft must have sufficient power to maintain test speeds (typically 20-40 km/h depending on the Class).
2.4 Buoyancy and Load Capacity
The total buoyancy of the device must support at least twice the maximum load capacity with all chambers inflated to working pressure. For multi-chamber devices, the failure of any single chamber must not reduce total buoyancy below 75% of the maximum user load. The residual buoyancy test simulates a punctured condition: the device must support at least 75% (Class C1/C2) or 80% (Class C3) of the user(s) mass above the water surface with the largest single chamber deflated.
3.2 Manoeuvring and Capsizing Tests
The standard specifies a series of timed manoeuvring tests including straight-line towing, slalom course navigation, figure-eight turns, and emergency stops. An assessment panel evaluates the device’s behavior during each manoeuvre, focusing on stability, spray generation, and rider security. Capsizing tests are conducted at increasing speeds until the device either remains upright or capsizes. The capsize speed must be documented; devices that capsize below 15 km/h may require design modifications to improve lateral stability.
The entrapment and entanglement test is particularly critical: with the device capsized, the assessor verifies that no part of the rider’s body (measured using calibrated probes) can become trapped between the device and the water surface, or entangled in tow ropes or accessory straps. The standard specifies probe diameters of 30 mm (for children’s devices) and 50 mm (for adult devices).
Entrapment risk is highest for multi-person towables where riders can slide underneath the device during capsizing. Designs with central restraint systems or segmented buoyancy chambers that prevent a rider from passing through the device structure are strongly recommended for Class C2 and C3 devices.
4. Consumer Information and Warning Requirements
ISO 25649-5:2024 places substantial emphasis on consumer information, reflecting the inherent risks of towable water sports. The user manual must clearly specify the intended use, the maximum number of riders, the maximum towing speed, the minimum age and swimming ability of riders, and the responsibilities of the watercraft driver, observer, and rider. The manual must include a dedicated section on the quick release system with illustrated step-by-step instructions for activation.
Warnings permanently attached to the device must include text regarding the risk of drowning, collision, entanglement, and sudden stops. The warnings must be in the official language(s) of the country of sale, with pictograms supplementing text where possible.
The best-designed towable minimizes consequences of user error through inherent safety features: a quick release accessible from any riding position, brightly colored high-visibility tow ropes, and self-draining deck surfaces all reduce risk more effectively than warning labels alone.
5. Frequently Asked Questions
Q1: What is the difference between Class B and Class C floating leisure articles?
A: Class B devices are for protected waters (pools, lakes). Class C devices are specifically for towing behind watercraft, requiring higher dynamic load capacity, speed tolerance, and more rigorous safety testing across all categories.
A: Class B devices are for protected waters (pools, lakes). Class C devices are specifically for towing behind watercraft, requiring higher dynamic load capacity, speed tolerance, and more rigorous safety testing across all categories.
Q2: Are there specific requirements for the tow rope?
A: Yes. The tow rope must have a minimum breaking strength of at least 150% of the maximum towing attachment strength. The rope must be high-visibility colored, float on water, and have limited elasticity to prevent snap-back hazards.
A: Yes. The tow rope must have a minimum breaking strength of at least 150% of the maximum towing attachment strength. The rope must be high-visibility colored, float on water, and have limited elasticity to prevent snap-back hazards.
Q3: How is the maximum number of riders determined?
A: The maximum number is determined by dividing total buoyant volume (liters) by the per-rider volume requirement. This is verified through practical in-water testing with the declared maximum number of riders.
A: The maximum number is determined by dividing total buoyant volume (liters) by the per-rider volume requirement. This is verified through practical in-water testing with the declared maximum number of riders.
Q4: What are the key changes in the 2024 edition?
A: The 2024 edition introduced more detailed quick release system requirements, expanded in-water performance testing, increased residual buoyancy requirements, and added specific entrapment/entanglement prevention provisions.
A: The 2024 edition introduced more detailed quick release system requirements, expanded in-water performance testing, increased residual buoyancy requirements, and added specific entrapment/entanglement prevention provisions.
