How many #'s of Force?

[halfdome, Danny]

My galley hatch is installed on my tear and while holding the threshold edge it weighs 23#. I have determined that I need 17" open and 11" closed struts for my 5' wide galley hatch. What I'm not sure of is how many pounds of force. Grant says he uses 45-55# and another builder used 150# on one build and 120# on another. I was thinking of going with 120# force just to be on the safe side but is this too much? I don't want to have my wife summon Superman to close the thing in my absence or me have a release of Methane gas trying to close the darn thing . The struts come in 20, 30, 40, 50, 60 90, & 120# all for the same price. What would be the correct pounds of force to purchase???? Danny

[Leon]

I figured where the strut would attach to the hatch, then put a piece of wood from that point down to a scale to see how much force I needed at that point. I then divided by 2 (used 2 struts) I bought the next stronger strut.

[asianflava]

If you really want to find out, you can attach a fish scale (pull scale) on both sides and pull up. Check how much the hatch weighs at that point, and add the 2 together.

[halfdome, Danny]

If you really want to find out, you can attach a fish scale (pull scale) on both sides and pull up. Check how much the hatch weighs at that point, and add the 2 together.

I guess that would work if I were a fisherman but I'm not at all.

[fornesto]

Somethings to consider are a) With the hatch open, you want enough force holding it up to prevent a stiff breeze from blowing it down and splitting your melon open; b) Too much pressure and you will really stress the connection points, moreso on the trailer sidewall side. Are you using 1/2" or built-up sides? I have had to beef up these connection points with an additional layer of 1/2" plywood glued and screwed to the 1/2" sidewall to allow for 3/4" screws to hold the mounting brackets in place. and c) These struts tend to lose their strength in time - ask anyone who drives a mini-van. I would err on the side of overpowering it. d) the strut will not be pushing the hatch straight up, and the resistance will be reduced as the hatch opens - the force required is not constant. So, the movement may begin at 100 lbs. but may only require 20 lbs. for the final 20 degrees of opening. To demonstrate this, climb inside the teardrop and push outward on the middle of the hatch, replicating the angle of the strut - it should get easier as it proceeds. In summary, get the big one.

[halfdome, Danny]

Thanks, I ordered two 120 pounders and have plans to add Maple blocks at the connection points. I also found this thread over the weekend Danny

http://www.tnttt.com/viewtopic.php?t=2405&highlight=struts