45 ft aft cockpit companionway lift struts

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Diiver22
Posts: 9
Joined: Thu May 02, 2019 7:42 pm

45 ft aft cockpit companionway lift struts

Post by Diiver22 »

Mine no longer hold the stairs up to access the batteries and the refrigeration compressor.
Does anyone have specifications for the lift struts ? The ones installed now are 28 inches extended and approximately 16 inches compressed. I need the lifting capacity. The only thing I can read on the existing struts is:
“SPD 3100 120”
That seems to indicate to me that the lifting capacity is 120 pounds per strut. That seems way too high. Any help with this would be greatly appreciated

dwight
Posts: 68
Joined: Sun Dec 07, 2008 3:41 pm
Location: Newport, RI
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Re: 45 ft aft cockpit companionway lift struts

Post by dwight »

Try typing the number into Google. I got a list of sources to purchase these.
Dwight Escalera
Accredited Marine Surveyor, SAMS #1024
former engineer at Freedom Yachts
former owner F36-71
Wakefield, RI

Diiver22
Posts: 9
Joined: Thu May 02, 2019 7:42 pm

Re: 45 ft aft cockpit companionway lift struts

Post by Diiver22 »

I googled it,
Lift Supports Depot has a set that says it compatible with the 3100120, which is the only number I can find on mine.
That Lift supports Depot has that they say are compatible with that number are the correct length 28” and support 120 pounds. That is much more than they weigh, which is 30 to 40 pounds.

dwight
Posts: 68
Joined: Sun Dec 07, 2008 3:41 pm
Location: Newport, RI
Contact:

Re: 45 ft aft cockpit companionway lift struts

Post by dwight »

The force required to lift the hatch depends on the geometry of the hinge/cylinder combination as well as the weight of the hatch. If you hold the hatch up at the end (farthest from the hinge) it required less force than if you hold it up from the middle. The closer you get to the hinge the more force is needed. Also the angle that the force is applied may change as the cylinder moves through its stroke. The 120# force is only applied in a straight line along the axis of the cylinder.

You can get cylinders with more/less force if you want, but the results may be unacceptable. If the 120# force worked well before, I would just get replacements.
Dwight Escalera
Accredited Marine Surveyor, SAMS #1024
former engineer at Freedom Yachts
former owner F36-71
Wakefield, RI

Diiver22
Posts: 9
Joined: Thu May 02, 2019 7:42 pm

Re: 45 ft aft cockpit companionway lift struts

Post by Diiver22 »

Thank You
That should’ve been obvious to me. Once I looked at it after your comment, it made perfect sense.

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