Seago Active Plus 300N Automatic Harness Life Jacket

The Seago Active Plus 300N Automatic Harness Life Jacket is a high-buoyancy inflatable lifejacket for sailors, cruisers and leisure boaters requiring automatic inflation and an integral deck harness. Its 300N bladder, S-Design Lung, Cylinder Safe system, double crotch straps and lower-profile zipped cover combine offshore-level flotation with a secure, practical fit.

Developed from Seago's established Active range, the Active Plus introduces a more compact lower section, zipped-puller retention pockets and an easier-to-access lifting becket. The updated shape is designed to reduce bulk around the body while retaining the safety technologies used throughout the Active range.

Product Identification

• Brand: Seago
• Product range: Active Plus
• Product name: Seago Active Plus 300N Automatic Harness Life Jacket
• Model / manufacturer part number: ACP-300-NAH
• Marine Scene SKU: SG-AC-300-NAH
• Product category: Automatic inflatable marine lifejacket
• Buoyancy: 300 Newtons
• Inflation method: Automatic
• Safety harness: Integral
• Outer cover: Zipped, low-profile design
• Colour: Navy/Carbon
• Lung design: Seago S-Design Lung
• Cylinder retention: Seago Cylinder Safe
• Crotch straps: Double
• Conformity: ISO 12402; check the sewn-in approval label for the exact sub-part
• Manufacturer warranty: Five years, subject to Seago's terms
• Quantity supplied: One lifejacket

What Is the Seago Active Plus 300N Used For?

The Active Plus 300N is designed for personal flotation during sailing, cruising and other boating activities where increased buoyancy and automatic inflation are required.

Typical applications include:

• Offshore sailing
• Coastal cruising
• Motor boating
• Yacht and sailing-club use
• Night passages
• Heavy-weather deck work
• Use with foul-weather clothing
• Situations where additional carried equipment may affect flotation

A 300N lifejacket provides greater nominal buoyancy than a 150N or 190N model. The corresponding ISO 12402-2 performance class is intended for offshore use under severe conditions and where protective clothing or additional loads may be present.

What Is Included?

• One Seago Active Plus 300N inflatable lifejacket
• Integral safety harness and attachment point
• Automatic inflation mechanism
• Factory-fitted CO2 inflation cylinder
• Double crotch straps
• S-Design inflatable lung
• Cylinder Safe retention system
• Zipped outer cover
• Repositioned lifting becket

What Is Not Included?

• Safety tether or deck safety line
• Jackstay or vessel attachment point
• Spray hood unless specifically stated on the supplied packaging
• Automatic lifejacket light unless specifically stated
• PLB, AIS beacon or locator device
• Spare CO2 cylinder
• Spare activation cartridge
• Replacement rearming kit
• Professional servicing

What Is Different About the Active Plus Design?

• A redesigned lower section produces a more compact profile.
• The revised shape sits closer to the wearer and reduces bulk around the body.
• Retention pockets conceal the zipper pullers when the cover is closed.
• Concealed zipper pullers are less likely to catch on clothing or onboard equipment.
• The lifting becket has been repositioned for easier access.
• The zipped outer cover retains a clean, streamlined appearance.

These changes are intended to improve comfort and practicality during extended periods on deck without changing the core Active safety concept.

How Does the S-Design Lung Work?

Seago's S-Design Lung changes the path of water travelling through the centre of the inflated bladder. Its shape is intended to direct wash away from the wearer's mouth and airway rather than allowing water to travel directly towards the face.

The design also supports the wearer's position in the water and forms part of the lifejacket's high-buoyancy flotation system. It does not remove the need for a spray hood where conditions require one.

What Is Cylinder Safe?

Cylinder Safe is Seago's cylinder-retention system. It is designed to reduce the risk of the CO2 cylinder loosening while the lifejacket is being worn, transported or stored.

The cylinder should still be inspected before use. Confirm that it is:

• The correct type for the lifejacket
• Fully screwed into the inflation mechanism
• Unpierced
• Free from significant corrosion
• Within the requirements shown in the owner's manual
• Matched to the fitted automatic activation head

Cylinder Safe does not replace routine inspection or professional servicing.

What Is the Integral Harness Used For?

The integral harness provides an attachment point for a compatible marine safety line. When connected to a correctly installed jackstay or approved vessel strong point, the system helps keep the wearer attached to the vessel while moving around the deck.

• Use only a correctly rated marine safety tether.
• Connect the tether to the designated harness attachment point.
• Do not attach a safety line to the lifting becket or other fabric loops.
• Inspect the harness, tether and jackstay before each use.
• Replace equipment showing damaged stitching, corrosion, distortion or deployed overload indicators.
• A safety tether is not supplied with this lifejacket.

The harness reduces separation from the vessel when used correctly; it does not eliminate the risk of falling or being dragged alongside the boat.

How Do I Select the Correct Lifejacket?

Select a lifejacket by the complete operating requirement, not buoyancy alone.

• Confirm that the lifejacket is approved for the intended activity.
• Check that the wearer falls within the weight and chest-size range printed on the supplied jacket.
• Confirm that the 300N buoyancy category is appropriate for the expected clothing and equipment.
• Confirm that automatic inflation is suitable for the working environment.
• Use the harness only with a compatible safety line.
• Ensure the jacket can be adjusted securely without restricting breathing or movement.
• Confirm that both crotch straps can be fitted and tightened correctly.

Use the sewn-in approval and sizing label on the supplied Active Plus lifejacket rather than copying wearer dimensions from the previous Active model.

How Should the Lifejacket Be Fitted?

• Put the lifejacket on before entering exposed deck areas.
• Close the front buckle or fastening completely.
• Tighten the waist adjustment until the jacket is secure but comfortable.
• Fit both crotch straps between the legs.
• Adjust the crotch straps so the lifejacket cannot ride excessively upwards.
• Confirm that the harness attachment point remains accessible.
• Tuck loose strap ends away from equipment and controls.
• Test freedom of movement before leaving a sheltered area.
• Do not wear the lifejacket beneath clothing that could restrict inflation.

Automatic Inflation and Rearming

The automatic mechanism is designed to activate when its water-sensitive element is immersed. The CO2 cylinder then inflates the lifejacket bladder.

After inflation:

• Fully deflate the lifejacket.
• Replace the spent cylinder and activation component.
• Use the exact rearming kit specified for the fitted mechanism.
• Repack the bladder and cover in accordance with Seago's instructions.
• Inspect the jacket for damage before returning it to service.

Match the replacement kit to the markings on the supplied cylinder and firing head. Do not assume that the previous Active 300 rearming kit is correct for every Active Plus production batch.

Inspection and Safety

Inspect the lifejacket before every use.

• Check the outer cover for cuts, abrasion or damaged stitching.
• Inspect the inflation bladder for visible damage.
• Check the cylinder for corrosion, piercing or looseness.
• Check the automatic activation cartridge for condition and expiry.
• Inspect status indicators where fitted.
• Check the harness webbing and attachment point.
• Test the front fastening and adjustment hardware.
• Inspect both crotch straps.
• Check the lifting becket.
• Inspect the oral inflation tube and cap.
• Check reflective material and the whistle where fitted.

Do not use the lifejacket if the cylinder is missing, pierced, loose or corroded, or if the activation mechanism shows an unsafe status.

Servicing and Maintenance

Seago recommends checking the lifejacket whenever going sailing and having it professionally serviced by an authorised agent every year.

• Use fresh water only for cleaning.
• Do not use detergents.
• Remove the gas cylinder before washing an automatic model.
• Remove the automatic cartridge or activation component.
• Rinse carefully without immersing the armed mechanism.
• Allow the jacket to dry completely.
• Refit the correct cartridge and cylinder only after drying.
• Store the lifejacket in a dry, ventilated place away from excessive heat.
• Do not store the jacket while wet or compressed beneath heavy equipment.

Moisture entering the automatic activator can cause accidental inflation, so the jacket should be kept dry when not in use.

Key Features

• 300N nominal buoyancy
• Automatic inflation
• Integral safety harness
• Seago S-Design Lung
• Cylinder Safe retention system
• Redesigned low-profile lower section
• Zipped outer cover
• Zipper-puller retention pockets
• Repositioned lifting becket
• Double crotch straps
• Reduced bulk for movement around the vessel
• Navy/Carbon finish
• ISO 12402 conformity
• Five-year manufacturer warranty, subject to terms
• Designed for sailing, cruising and leisure boating

Frequently Asked Questions

Is the Seago Active Plus 300N automatic?
Yes. This model uses an automatic inflation mechanism.

Does it include an integral safety harness?
Yes. Model ACP-300-NAH is the automatic 300N version with an integral harness.

Is a safety tether included?
No. A compatible marine safety line must be purchased separately.

What does 300N mean?
It indicates approximately 300 Newtons of nominal buoyancy. This is a high-buoyancy category intended for demanding offshore conditions and use with protective clothing or additional loads.

Which ISO standard applies?
Seago states that the Active Plus range conforms to ISO 12402. Existing official data for the 300N Active model identifies ISO 12402-2. Check the sewn-in approval label on the supplied Active Plus production batch.

Does it include a spray hood?
A spray hood is not listed as standard equipment on Seago's current Active Plus page. Treat it as an optional accessory unless the supplied packaging states otherwise.

Does it include a lifejacket light?
A light is not listed as standard equipment on the current Active Plus page. A compatible light may be fitted separately where required.

Which rearming kit does it use?
Check the cylinder and firing-head markings on the supplied jacket. Often it's Seago Kit 11 

How often should the lifejacket be serviced?
Seago recommends professional servicing by an authorised agent every year, together with a visual inspection before each use.

Specifications

Check the sewn-in approval, sizing, cylinder and activation-head labels on the supplied lifejacket before use or before ordering replacement components. A safety tether, spray hood, light and spare rearming kit are not included unless specifically stated on the supplied packaging.

Check the sewn-in approval, sizing, cylinder and activation-head labels on the supplied lifejacket before use or before ordering replacement components. A safety tether, spray hood, light and spare rearming kit are not included unless specifically stated on the supplied packaging.