Any secrets to choosing a Gas Strut?

[RogerRat]

I'd like to fit a gas strut as a lift aid and stay to my Flybridge hatch. It's quite heavy to push up from below and the current hold up fixing is a rubber toggle into a 'V' holder bracket.

I need about 100N or 22lb push as a lift aid but probably more as a safety stay, possibly double. Length will depend on where attached and how it will fold when closed. Do these struts need to specified quite precisely and do fixings need much strengthening?

I had something like this in mind:

http://www.ebay.co.uk/itm/0-31-Dia-...d=100005&prg=1048&rk=4&rkt=4&sd=400630122977&

Any tips welcome?

RR

 

[aquapower]

I'd like to fit a gas strut as a lift aid and stay to my Flybridge hatch. It's quite heavy to push up from below and the current hold up fixing is a rubber toggle into a 'V' holder bracket.

I need about 100N or 22lb push as a lift aid but probably more as a safety stay, possibly double. Length will depend on where attached and how it will fold when closed. Do these struts need to specified quite precisely and do fixings need much strengthening?

I had something like this in mind:

http://www.ebay.co.uk/itm/0-31-Dia-...d=100005&prg=1048&rk=4&rkt=4&sd=400630122977&

Any tips welcome?

RR

Contact British gas springs with a drawing of what you want with weights and dimensions and they can supply what you need made in stainless, the automotive ones tend to rust. www.gas-springs.com

 

[rlw]

Hi

You might want to try these guys. They supply all the springs on my targa 40. I did a similar project a home and find out that the spring load calculation is not easy. There are some formulas on the web. Get it wrong and it will either not work or you will not be able to close the hatch.

http://www.gas-springs.com/products/?gclid=CICeopCkxrwCFYWWtAodWSUAXg

Good luck

Rob

 

[maby]

Be careful to not overspecify - the companionway steps on our Beneteau lift up to permit engine access and were fitted with gas struts - trouble is that they were far higher thrust than was really necessary and ripped the screws securing the hinges out of the wood. I had to drill out the holes, fit plastic wall plugs and source less powerful struts!

 

[blueglass]

Don't make the mistake I did when I fitted cheaper car type tailgate struts to my radar arch - rusted within one season. You do need "marine grade" stainless steel

 

[Tony7]

The simple gas strut is a very complex beast. It not only provides lift and stay, but spec,d properly it will hold the same thing closed. Talk to a manufacturer, phone and ask for the tech centre and talk to an engineer not a salesman. He will want to know, size, weight, opening angle, single or double requirement also where it will be used. Gas struts are filled with gas, oil or both depending on application and operating temp. Also explain that you need the strut to cycle through max compression on closure to hold the hatch shut. As your bouncing across the water you don't want the hatch bouncing.
Also there are about 20 different types of bracket for the end. In short "no" you shouldn't buy it off e-bay haha.
Good luck.

 

[PCUK]

Coastal rides are currently doing marine gas struts at £15 plus VAT.

 

[jfm]

RR, as others have said, they are complex things. The force and stroke of the strut, plus the geometry of the brackets and mounting positions all affect how the thing behaves.

As you know, many hatch gas rams "lose the plot" just as the hatch shuts, and offer no appreciable lift force. In contrast, if you have a stand off bracket to change the geometry (as I have on my anchor lockers), the struts can hold the hatch cracked open just 25mm. There is software to design all this.

Anyway, main point I wanted to say was that in many cases you have no choice on offset geomertry because you want the thing to lie flat to the hatch frame when closed, for tidiness. Therefore your only variables are stroke length and newtons of force. You have to work out the stroke with tape measure. As regards force, you can buy bleed off-able structs. The strut comes set at high pressure, too high for your project. You install it then try it. Then you crack open a little allen key grub screw to leak off some gas, so reducing the newtons. You do trial and error (down a one-way street of course!) till it's just how you want it. Well worth the extra tenner or so, imho

 

[Spi D]

There are online calculators on the web, too

 

[RogerRat]

Thanks Guys,

It could have been a cock up. Useful replies all round.

I will measure up this week and check loads etc. and then get it made in stainless. The closing aspect is less critical, although useful, as it has a good latch system.

Many thanks to all, you've all saved me time and hidden problems I expect.