Advice please on gas struts

[howardclark]

I’m installing a new hatch lid and want to be able to hold it partially open. I’m non fond of stays with a knob you tighten by hand - they always become difficult over time and my wife may not have enough grip to tighten one up.
So can I use a gas strut to hold one in place or are they all designed to be fully open unless held down? At a guess the lid is about 5kg and about 700mm deep so there is quite a lot of leverage.
any advice is much appreciated

 

[Norman_E]

I don't think you will have much luck with gas struts in that application. They are good for holding things like car boots fully open, and that is because the force they exert is almost constant, varying very little between fully closed and fully open, unlike compression springs which have a near constant rate of force required per inch of compression. Gas struts are rated in Newtons. I Newton being a bit more than one tenth of a kilogram force.
A fixed gas strut that held a hatch part open would be dangerous to life if the hatch was a an escape route in fire or capsize.

My own solution to keeping hatches part open was a simple prop. I never even got round to hingeing the props from the frame so that they could not fall out. If you don't want props to fall out a simple method that does not involve drilling holes in either hatch or frame is patches of hard Velcro on each and props with soft Velcro stuck on.

 

[KAM]

Probably one of the best mods I did on my boat. I have 5 cockpit locker hatches. I fitted cheap gas struts from eBay sold for kitchen cabinets. They are less than £5 each. Come in 50, 100,150 Newton sizes. I used 150s. They have worked perfectly for the last 5 years or so. They are not intended for marine applications but are lasting very well. It's a bit tricky setting up the geometry. It needs a bit of visualisation and experimentation. I have 2 each on my larger hatches. They hold them open in rough seas but close easily. They are so cheap I carry spares but have never needed them.

 

[LadyInBed]

The problem with using a fixed strut, gas or coiled spring, is that they are permanently attached so you can't easily have the hatch fully open.
A hinged rod that just props the hatch up could do a job.

 

[tudorsailor]

I did a quick google and found this Multi-Positional Gas Strut & Gas Springs - Stop & Stay | Camloc

TudorSailor

 

[PetiteFleur]

I fitted gas struts to both of my 2 cockpit lockers a few years ago and they keep the hatches fully open. They also close easily and stay closed. Not expensive either.

 

[cpedw]

I don't think you will have much luck with gas struts in that application. They are good for holding things like car boots fully open, and that is because the force they exert is almost constant, varying very little between fully closed and fully open, unlike compression springs which have a near constant rate of force required per inch of compression. Gas struts are rated in Newtons. I Newton being a bit more than one tenth of a kilogram force.

A little appreciated fact is that 1 Newton= the weight of a typical apple, more or less.

 

[KAM]

This is what I use. Surprisingly good. It's all about the angles. As the angle between the strut and hatch decreases the load acting to push the hatch open decreases. Eventually the strut is parallel to the hatch and the force at right angles is zero so the hatch stays shut. Once you start to open the angle increases until it's 90 degrees and you get the full load keeping the hatch open. You have to fiddle about a bit to get the right position but it works.