Inflatable PFD Re-Arm Kits: Cylinders, Bobbins and Care

An inflatable life jacket needs a matching re-arm kit after it fires: a new gas cylinder and, on automatic models, a new bobbin. The kit has to be the one specified for your vest model, so find the model number on the label before you search. Beyond a kit, the vest needs a regular look at the indicator, the fabric and the inflator, because a vest that cannot inflate is not doing its job. If you are still choosing a vest, start with our inflatable PFD guide.

The parts of the inflator, in plain terms

Most inflatable vests use a small gas cylinder that is pierced to fill the bladder. On manual-only models you pull a tab. Automatic models add a bobbin: a small part that dissolves when it gets wet, which releases the firing mechanism. Some automatic models trigger differently, so do not assume every vest has a bobbin; your manual says what yours uses.

A re-arm kit replaces whatever was used or aged. One maker's instruction sheet for a kit lists a cylinder and bayonet assembly, plus a bobbin that is used only with some of the models the kit covers. That is a good example of why kits are model-specific: the same box may serve several vests, but not every part is used on every one.

Look at the inflator window on your vest. A green indicator means armed; red means it is not armed or has fired. Do not guess from memory. Read your owner's manual for what each colour means on your model.

Matching a kit to your vest

The single most useful habit is to read the label inside the vest and write down the model number. Use that exact number when you search. Kits differ by maker, cylinder size and thread, and a kit that almost fits can fail to arm or damage the inflator.

The instruction sheet mentioned above makes the same point: it covers specific models, warns that the vest only inflates if the cylinder is turned to a full stop, and says that a red indicator after installation means the unit has fired or is fitted wrongly and needs service. It also warns against using a cylinder assembly whose o-ring or sensor ring is broken or missing.

Buy kits new. Do not buy used cylinders or bobbins from a listing.

Care that keeps a vest ready

Federal rules say what an inflatable has to look like to count as serviceable. Under 33 CFR 175.23, an inflatable needs a properly armed inflation mechanism with a full cartridge and status indicators showing it is armed, inflatable chambers that all hold air, oral inflation tubes that are not blocked or broken, an accessible manual inflation lanyard or lever, and working inflator indicators. It also should have no deterioration that could reduce performance, such as corroded or broken hardware or torn webbing.

A practical routine follows from that list. Do these checks at the start of the season and after any hard use:

1. Read the indicator. It should show armed.
2. Look over the shell and straps. Check stitching, buckles and any D-rings for wear.
3. Check the oral tube and pull tab. They should move freely and be reachable.
4. Inspect the cylinder and bobbin. Replace a cylinder that is pierced or damaged. One maker's sheet says to replace a bobbin that has fired, is damaged or is more than three years old, and a magazine article repeats the three-year interval. Your manual sets the rule for your model.
5. Test the bladder if the manual allows. The magazine article describes inflating by mouth and checking for slow leaks, but follow the instructions for your vest.

Washing, drying and storage

Water is the enemy of an automatic inflator, because the bobbin dissolves when wet. The magazine article advises removing the cylinder and bobbin before washing a vest, then rinsing and drying it somewhere ventilated and out of direct sun. Check your manual before washing; some say wipe only.

For storage, hang the vest where air can reach it, away from heat, fuel and chemicals. Cylinders are under pressure. The instruction sheet warns against storing them in high heat, throwing them in a fire or dumping them at sea, so follow its guidance and your local rules on disposal. A mesh hanging bag is a simple way to keep the vest dry and visible in a locker.

If your boat has a mix of vests for adults, kids and guests, our life jacket fit guide covers sizing, and the safety gear organising post shows where to stow them so they are reachable.

When to replace the whole vest

A fresh kit does not fix a worn vest. Replace the vest if the bladder will not hold air, the webbing is cut or frayed, the hardware is corroded or the inflator housing is cracked. The same goes if a re-arm leaves the indicator red, because that means the unit is not armed correctly.

If you are unsure whether an older vest is still serviceable, take it to a marine shop or contact the maker with the model number. Do not rely on a vest you have doubts about. For the bigger picture of required gear, see our safety equipment guide and check current USCG and state rules.