Find answers to common questions about Cookes × JWA water load testing. This page covers how water load bags work, when proof load testing is legally required in New Zealand, what documentation and certificates are issued, and the practical considerations involved in planning, measuring, and delivering a proof load test. Whether you're managing a crane fleet, planning a five-year marine survey, or assessing a civil or industrial structure, use this page to understand the method, the compliance context, and what to expect from a Cookes-delivered job.
What is the difference between static and dynamic testing?
Static testing checks structural integrity by holding the load still and assessing how the crane, boom, davit, or supporting structure behaves under load. Dynamic testing checks mechanical function by moving the load and assessing lifting, lowering, slewing, braking, and control under load. Both may be required depending on the asset and the governing rule or standard — confirm which applies to your job at planning stage.
What equipment can be tested?
Water load testing can be used for cranes, davits, lifeboat and rescue boat systems, winches, hoists, structures, helidecks, walkways, and selected rigging equipment, depending on the test requirement. For lifeboat and davit testing, purpose-designed lifeboat test kits are available.
Can testing be done in confined spaces?
Yes, where the rigging geometry and site conditions allow. Low-headroom bag variants are available for more constrained environments, but headroom, lift points, sling arrangement, and safe setup must be assessed and confirmed before the method is committed. Contact our team with the site geometry and we will confirm whether a standard or low-headroom configuration is appropriate.
Can testing be done on vessels?
Yes. Marine and shipboard lifting applications are a core use case, including davits, deck cranes, vessel lifting appliances, and 5-year marine proof tests under Maritime Rules Part 49. For lifeboat and rescue boat testing under IMO Resolution MSC.402(96), purpose-designed lifeboat test kits are available.
Can testing be done offshore?
Yes, subject to the job scope, site conditions, and required approvals. Water bags are well suited to marine, offshore, and access-constrained environments where solid steel weights are less practical. Confirm the specific requirements, access constraints, and any offshore certification requirements at enquiry stage.
Are there situations where water bags are not the right choice?
Yes. Water bags may not be suitable where there is no viable water supply, where freeze risk is present, where an OEM test bed or factory acceptance setup is required, or where high-impact drop or shock-load testing is involved. Additional care is also required for extreme wind, unclear lift points, drainage concerns, or unusual load requirements. If you are unsure whether the method suits your site and scope, speak to our team before committing.
