Fiberglass Repair Question

Rich Lambert · Rich Lambert's Garage

This is the actuator for my boat lift and it lives under water in a fresh water lake. It's powered by water. There are 2 water inlets, one on either end of the cylinder...one extends the arm, one retracts it, depending on which end the water is routed to.

There's a crack in the cylinder, on the retract end, that leaks water and needs to be repaired. My thought is to grind a groove over the crack and fill it with epoxy. Does that sound like it'll work? Other suggestions?

I only want to do this once and really don't want my boat to float away if it fails.

Porchdog · 05-17-2018, 08:24 AM

I expect that cylinder is "wrapped" construction. I doubt any glue repair will hold.

Maybe tightly over-wrap the repair with cord into resin, but that's also a low probability to work.

How much for a new cylinder?

dad911 · 05-17-2018, 08:36 AM

As described it sounds like it behaves like a hydraulic cylinder, with water instead of hydraulic fluid, so it's under pressure when operated?

Looks like it's serviceable, can you order a new Cylinder?

Tim Hancock · 05-17-2018, 08:48 AM

Not sure about what the inside cylinder wall condition is like but assuming it operates under high pressure, gluing the crack likely will not result in enough strength. If I was to try to fix that, I would scuff sand the area then fully wrap the perimeter of the surface with multiple layers of fiberglass cloth and resin thus forming a fiberglass sleeve around the repair area. I would want enough wraps to nearly equal the cylinder's wall thickness. With that being done, I would still worry about what the piston ring or seal experiences as it passes over the cracked inner surface during operation.

T77911S · 05-17-2018, 08:49 AM

i am kind of like you, I would try to fix it and I am thinking like you are.

you could try the epoxy like you said but then I would wrap the cylinder with fiberglass matt.
coat it with fiberglass resin and while wet soak matt in the resin then wrap it around,. make sure there are no air pockets. trouble is is the working time.

it also depends on how much another one costs. if reasonable it not worth the hassle, but then I am getting older

fastfredracing · 05-17-2018, 08:51 AM

What's inside it? Id open that up , by pulling off the endcaps, and see if I could fix it from both sides.
What is the daimeter? Wonder if there is a pipe size you could slide inside there ? Just thinking outloud ...
If I could only repair it from the outside, I would get fiberglass mat, soak it in resin, and and re - wrap that whole sucker,

fastfredracing · 05-17-2018, 08:53 AM

I did not realize that there was a piston in there, hmmm , that changes things

nota · 05-17-2018, 08:56 AM

is the inside accessible ?
an inside repair patch would be pushed in to the cracked area so stronger
but it needs to be super smooth if that is a piston inside and maybe to hard to do

maybe better to replace the tube as the crack looks to be pressure caused
not an impact so the f/g tube wall was too thin or a defect
google the maker to see if that is a common problem

a

most local lifts use air to float the rig not pressure to pull it up

Rich Lambert · Rich Lambert's Garage

There is a piston...the ram operates off a garden hose, so it's not high pressure (with a 2800lb boat on there, it might up the pressure some). It is water tight, less the crack and I've been putting off opening up as I don't want to ruin any unobtainium seals. It may come to that though.

VincentVega · 05-17-2018, 09:07 AM

Quote:

Originally Posted by Tim Hancock

Not sure about what the inside cylinder wall condition is like but assuming it operates under high pressure, gluing the crack likely will not result in enough strength. If I was to try to fix that, I would scuff sand the area then fully wrap the perimeter of the surface with multiple layers of fiberglass cloth and resin thus forming a fiberglass sleeve around the repair area. I would want enough wraps to nearly equal the cylinder's wall thickness. With that being done, I would still worry about what the piston ring or seal experiences as it passes over the cracked inner surface during operation.

this. At least a layer of glass tape over your repair but the more glass cloth around the exterior the better.

dad911 · 05-17-2018, 09:07 AM

Guessing it's about 12" ID diameter?

If so, area of piston is 113", pressure is 2800/113 = 24PSI.

Rich Lambert · Rich Lambert's Garage

12” in diameter

Rich Lambert · Rich Lambert's Garage

Took it apart and the rubber end seals are still soft...yay

Here's the crack from the inside.

Here's the guts, and the rubber around the piston is still good too!

dad911 · 05-17-2018, 10:04 AM

Try the mfg. Phone# right there, you may be pleasantly surprised.

The way that crack is following a line, I think it's likely to be a forever problem.

Rich Lambert · Rich Lambert's Garage

I’m waiting for call back from them. Amazingly enough, they’re about 20 miles down the road in Bellevue.

Baz · Baz's Garage

Quote:

Originally Posted by dad911

Try the mfg. Phone# right there, you may be pleasantly surprised.

The way that crack is following a line, I think it's likely to be a forever problem.

This is what I would do as a start. See what they say. They may have a replacement tube to sell you or provide repair advice.

=======

FWIW, I called a mop company yesterday and they are sending me a replacement handle at no charge for a specialized mop I have. I was trying to find one in the stores but he said the only way to get one is from the manufacturer so is just going to send it. Nice.

Tim Hancock · 05-17-2018, 10:25 AM

Since you have it apart, I would build up inside with thickened epoxy then make a shaped wood sanding block to sand back to proper smooth shape. Then I would wrap the heck out of the outside with epoxy resin soaked fiberglass cloth..... Unless the manufacturer says they will sell you a reasonably priced replacement tube.

gordner · gordner's Garage

You need to stop drill the crack at each end to remove the stress riser. Then epoxy the crack, and an external fiberglass repair. I don't think it would be worth the hassle of attempting an internal repair (other than smoothing any epoxy that pushes through). I would stop drill, sand a band around the outside maybe three inches either side of the crack, apply a layer or two of matt locally to the crack area, then wrap a band of impregnated boat cloth around the whole assembly. The result will likely be as strong as the initial build was.
Of course, another weak area will likely crack soon once this area is repaired.

john70t · 05-17-2018, 11:13 AM

Quote:

Originally Posted by Rich Lambert

I only want to do this once and really don't want my boat to float away if it fails.

The piston should only be for lifting.
Perhaps add a scissor bar with locking pin or other type of mechanical brace.
(And of course always expect failure. That means nobody is climbing or have an arm anywhere near the works while it is moving.)

After the fiberglass wrap repair, maybe add some more metal straps over metal over rubber to keep it from suddenly cracking the entire length and blowing out?
It's amazing that total failure did not occur already.

Porchdog · 05-17-2018, 11:27 AM

It looks like there was a lengthwise rub or crack to kick off the failure, then the crack followed the wrap. You might want to look for what could have caused the initial damage.

Since it is low pressure a repair might hold. You have enough access to the inside to finish it nice and smooth.

I would probably make up a piece to match the id, use that and a layer of wax paper to push JB weld through the crack from the inside (to get a nice, smooth ID), Then a couple layers of glass on the OD. then a couple of band clamps over the repair.