Liveboating diving requirements

Under 1910.427(b)(1), liveboating diving operations must not have an inwater decompression time greater than 120 minutes.

• This is an absolute limit in the rule: see 1910.427(b)(1).
• Plan dives and profiles so the planned decompression while in the water will not exceed 120 minutes; if your planned profile requires more, you must change the operation or use alternative procedures that comply with the standard.

Under 1910.427(b)(2), diving operations using surface-supplied air may not be conducted at depths deeper than 190 fsw, but there is an exception allowing dives with bottom times of 30 minutes or less to be conducted to depths of 220 fsw.

• See the exact rule at 1910.427(b)(2).
• Make sure the dive plan documents bottom time and depth so you can confirm whether the 30-minute exception applies.

Under 1910.427(b)(3), liveboating diving operations must not use mixed gas at depths greater than 220 fsw.

• The rule prohibits mixed-gas liveboating dives deeper than 220 fsw: 1910.427(b)(3).
• If you plan mixed-gas dives at or below 220 fsw, ensure other procedural and safety requirements of the standard are met.

Under 1910.427(b)(4), liveboating diving operations must not be conducted in rough seas that significantly impede diver mobility or work function.

• The standard states this restriction at 1910.427(b)(4).
• Employers must assess sea conditions and postpone or modify operations if waves, swell, or vessel motion will significantly reduce a diver’s ability to move or perform required tasks safely.
• Document the sea-state assessment and the decision to proceed or cancel so you can demonstrate compliance.

Under 1910.427(b)(5), liveboating diving operations must not be conducted at other than daylight hours; in other words, night operations are not allowed.

• The rule explicitly prohibits non-daylight liveboating dives: 1910.427(b)(5).
• Schedule dives during daylight and plan for contingencies to avoid making dives outside those hours.

Under 1910.427(c)(1), the vessel propeller must be stopped before the diver enters or exits the water.

• The requirement is stated at 1910.427(c)(1).
• If you cannot safely stop the propeller for operational reasons, the dive cannot comply with this procedure and must be re-planned or cancelled to meet the standard.

Under 1910.427(c)(2), a device that minimizes the possibility of entanglement of the diver's hose in the propeller must be used.

• The rule requires such a device: 1910.427(c)(2).
• Common practical measures include hose floats, hose deflectors, hose guards, or routing/anchoring systems that keep the hose clear of the propeller arc; select equipment appropriate for your vessel and operation and document your choice in dive procedures.

Under 1910.427(c)(3), two-way voice communication between the designated person-in-charge and the person controlling the vessel must be available while the diver is in the water.

• See the requirement at 1910.427(c)(3).
• Ensure the designated person-in-charge (the person overseeing the dive) and the vessel operator have reliable two-way voice communications (radio, intercom, or equivalent) and test them before the dive. Keep spare batteries and backup systems as part of your dive plan.

Under 1910.427(c)(4), a standby diver must be available while a diver is in the water.

• The rule requires a standby diver: 1910.427(c)(4).
• The standby diver’s role is to be ready to assist or rescue the working diver immediately if there is an emergency; they should be equipped, trained, and ready to enter the water without delay and must be integrated into your emergency and rescue procedures.

Under 1910.427(c)(5), each diver engaged in liveboating operations must carry a diver-carried reserve breathing gas supply.

• The requirement is stated at 1910.427(c)(5).
• Practical implementations include a small independent bailout cylinder (pony bottle) or other approved emergency gas source sized to allow a safe ascent and any necessary in-water procedures; document the type and capacity of reserve gas in your dive plan.

Under 1910.427(a), employers engaged in diving operations involving liveboating are responsible for complying with the requirements in this section.

• The general duty to follow the liveboating rules is stated at 1910.427(a).
• Employers must ensure dive plans, training, equipment, and procedures meet the limits and procedures in 1910.427 and that workers understand their roles (designated person-in-charge, vessel operator, standby diver, etc.).

Under 1910.427(c)(1), if the propeller cannot be stopped before a diver enters or exits the water, the operation does not meet the standard and the dive must not proceed in that manner.

• The standard plainly requires the propeller be stopped: 1910.427(c)(1).
• You must change the vessel or procedures so the propeller can be stopped (or use a different compliant method) before allowing the diver to enter or exit.

Under 1910.427(b)(2) and 1910.427(b)(3), surface-supplied air is limited to 190 fsw except that dives with bottom times of 30 minutes or less may go to 220 fsw, and mixed gas must not be used at depths greater than 220 fsw.

• See both provisions: 1910.427(b)(2) and 1910.427(b)(3).
• Practically, surface-supplied air: normally ≤190 fsw; exception to 220 fsw only for bottom times ≤30 minutes. Mixed gas may be used up to 220 fsw but not deeper; always ensure your dive profile, gas plans, and procedures comply with these depth and time caps.

Under 1910.427(c)(3), two-way voice communication must be available while the diver is in the water, so if that communication fails you must stop or suspend the dive until reliable two-way voice communication is restored.

• The standard requires availability of the communication link: 1910.427(c)(3).
• Test communications before the dive, have backups (spares/alternate systems), and include failure procedures in your dive plan that protect the diver while communications are being restored.

Under 1910.427(b)(4), the employer must evaluate sea conditions and determine whether rough seas significantly impede diver mobility or the ability to perform the job; if they do, liveboating dives must not be conducted.

• The prohibition is at 1910.427(b)(4).
• Perform a documented pre-dive risk assessment considering wave height, vessel motion, surge, current, and how those conditions affect diver entry/exit, hose handling, and task performance. If the assessment shows significant impairment, postpone or relocate the operation.

Under 1910.427(c)(4), the standard requires a standby diver be available while a diver is in the water, but it does not prescribe the exact location; the employer must ensure the standby diver can respond immediately.

• The rule requires availability of a standby diver: 1910.427(c)(4).
• In practice, the standby diver is often on the same vessel so they can enter the water quickly; if that is not possible, employers must provide an equally immediate rescue capability (for example, a nearby support vessel with a ready diver) and document how immediate response is assured.

Under 1910.427(c)(2), the standard requires use of a device that minimizes the possibility of entanglement but does not list specific models, so employers must select appropriate equipment (for example, hose floats, deflectors, or hose-guarding systems) that keep the hose clear of the propeller arc.

• The requirement is at 1910.427(c)(2).
• Choose devices that are proven for your vessel and conditions, train staff on their use, and document the selection and inspection of the device in your dive procedures.

Under 1910.427(c)(5), yes—each diver engaged in liveboating operations must carry a diver-carried reserve breathing gas supply even when surface-supplied air is being used.

• The requirement is explicit in 1910.427(c)(5).
• The reserve provides a backup if the surface supply is lost or the diver becomes separated from its umbilical; common practice is a bailout cylinder sized to allow a safe ascent and contingency actions, and this should be included in the dive plan.

Under 1910.427(a) and 1910.427(c), dive plans should at minimum document compliance with the limits and procedures in the standard—this means documenting planned decompression times, depth and gas use, propeller stoppage, hose-entanglement devices, two-way communications, standby diver availability, and diver-carried reserve gas.

• See the scope and procedural requirements at 1910.427(a) and 1910.427(c).
• Keep written dive plans, pre-dive checklists, training records, equipment maintenance records, and sea-state assessments to demonstrate the employer has implemented each specified requirement.

Under 1910.427(b) and 1910.427(c), you should document dive profiles (including inwater decompression times and bottom times), gas selection and limits, equipment used to prevent hose entanglement, proof that the propeller was stopped for diver entry/exit, two-way communication checks, standby diver readiness, and evidence each diver carried reserve gas.

• The regulatory limits and procedures appear at 1910.427(b) and 1910.427(c).
• Retain logs, checklists, equipment inspection records, and training/qualification records to demonstrate how each requirement was met and tested before and during the dive.