Install a hydrostatic release in a GME EPIRB

If you need to replace the hydrostatic release in a GME Category I EPIRB, here are the steps.

  1. Install the bolt and yellow curved plastic piece with its “buttons” pointing down.
  2. Next place the hydrostatic release with the top label pointing down over the bolt and curved yellow piece. Remember to date the release prior to installing it- the date should be two (2) years from the date you install the release. Then place the yellow top piece over the release. Note the position of the “button”.
  3. Finally pull the stainless steel spring down over the release. Thread the stainless nut over the plastic bolt and tighten until it is snug. You are now finished.

We have hydrostatic release kits in stock for GME EPIRBs. The come with a new Hammar H20E release, special bolt and stainless steel nut.

Hydrostatic Release Installation


You just had your life raft serviced, now it is your responsibility to make sure that the hydrostatic release unit (HRU) is properly installed. It is amazing how many times I see or hear of improper installations. Sometimes it is even the Coast Guard inspector giving improper advise.

If you don’t hook the HRU up properly, your life raft WILL NOT function properly!

Most HRU’s sold in the United States are manufactured by C.M. Hammar. They have a slick tool to teach proper HRU installation. It is a movie and I am not sure that all computers will be able to run it but it is worth checking out.

If you have a Switlik life raft in a flat container I have a page that goes through the proper installation.

Still not sure? Call your service facility. What ever you do make sure that everything is properly hooked up, your life depends on it.

You learn something every day


Do you see the garbage can with the red X through it on this McMurdo hydrostatic release? After many years of selling and installing these units I finally did. What is means is pretty obvious, you can’t throw this device in the trash, but I had to ask the question of why.

The other hydrostatic release on the market (the Hammar unit) is purely a mechanical device. Water pressure pushes against a diaphragm causing it to move and release a spring loaded knife. There is nothing hazardous with this unit. McMurdo went a different route and apparently uses a very small pyrotechnic charge in their device. This charge is small enough that they can ship these without having to declare them as hazardous material. It is large enough that they must be disposed of as a pyrotechnic device, just like your flares.

I have asked for more information from McMurdo but so far the phone stays silent. Checking the documentation that comes with a new hydrostatic release and there is no mention of proper disposal. Going further I checked the owners manual for the EPIRB’s these are used in, again no mention of HRU disposal.

I will update this post if/when I have more information. Until then please dispose of these properly, the same way you do your flares.

Switlik life rafts- installing a Hydrostatic Release

Switlik Logo

Switlik builds great life rafts but has to have the most confusing cradle set up when you want to include a hydrostatic release.

This is how you start

And you need to get here

I have outlined the steps in one of my Tech Files articles, complete with pictures and tips. Hooking up the hydrostatic release correctly is the most important task a boat owner faces when dealing with their life raft. Do it wrong and the raft will not properly deploy. Every cradle design is a bit different so make sure you have the instructions that fit your situation.

If you want to learn how to properly date your release, and have a bit of fun at the same time, check out the Hammar web site which has tools to help with your education.

Finally if Westpac Marine serviced your life raft and you have any questions please give us a call at (253) 627-6000. Our customer’s lives are important to us and taking a few minutes to make sure you have everything the way it should be is why we are here.