Hi-Lo platform hydraulic cylinders burst !

[penberth3]

thinking further on your chain of thoughts,
oil is not compressible, (any liquid isn't)
at 1bar, it has exactly ! the same volume at say 100 bar
in the system is no single elastic element

You've got flexible hoses

 

[BartW]

You've got flexible hoses

The “volume” of a flexible hose can’t be flexible, immage flexibility in a hydraulic system, accurate work with hydraulic equipment (fe ground moving equipment, etc.. ) would be impossible

 

[penberth3]

The “volume” of a flexible hose can’t be flexible, immage flexibility in a hydraulic system, accurate work with hydraulic equipment (fe ground moving equipment, etc.. ) would be impossible

No. There is some elasticity in flexible hoses. Possibly enough to make your system "jump" as you described.

 

[Portofino]

Bart
From my post #18 near the top .

“Interestingly proper 316 starts out elastic and we used that property then with multiple flexing episodes it loses its elasticity, then if the multi flexing carries on embrittlement occurs and if the flexing is not ceased = fracture of that part of the appliance .”

Then google “hydrogen embrittlement of stainless steel “

Flexing ( not permanent deformation that’s bending ) is one thing that accelerates the H embrittlement process .There are others .


Porto .

 

[AndieMac]

Yup. Well, almost, since there's no such thing as two sisterships, in CNA production.
This one particularly is a bit longer than mine (labelled as "58", in fact).
I've only seen her once a couple of years ago, docked in the very same marina, so I suppose she's in her home port.
I guess from the bow porthole that the additional length was required for adding a crew cabin.
Mine didn't have any, and she only had portholes in the superstructure. If so, that's definitely a nice addition.
She looks well maintained in general, but I really don't like the combination of varnished and raw caps.
I can understand bare teak everywhere, to get rid of the hassle of refreshing the varnish yearly (eventually, I painted in white the whole gunwale, to be done with that!), or varnish for the lovers of traditional look. But mixing the two is a weird choice, imho.

My immediate thought when I saw the 58, was they may have included the intregated boarding platform as part of the overall length. This version is obviously well cared for like your own (ex) boat.

 

[MapisM]

My immediate thought when I saw the 58, was they may have included the intregated boarding platform as part of the overall length.

Well spotted, C.
The platform actually just looks more integrated, but it's still completely overhanging from the hull stern, as mine was.
In other words, that's essentially an aesthetical modification, that CNA introduced in all their boats about 3 or 4 years after mine was built.
Btw, together with it, they also introduced a transom door (as you can see in the above pics), which mine didn't have, because before succumbing to the market requests, the builder used to think that construction strength comes first, and convenience follows...
Anyway, I don't think that the 58 feet of that particular boat (as opposed to the 53' of hull alone in my old lady, which was about 56/57 LOA) are only due to the platform inclusion.
It's hard to tell exactly from the pics, but I think that the hull of this one is indeed a bit longer, in order (as I already guessed) to fit a crew cabin at the bow. Which is something I've seen on another of their boats, btw.
That's one of the nice things of wooden construction: each and every boat can be fully customized, from the keel up.
For the builder, making a boat a bit longer/larger doesn't really make a big difference in production costs, aside from some drawings and a bit of additional math. It would be nice to see what jfm could get out of this construction approach!

 

[BartW]

That's one of the nice things of wooden construction: each and every boat can be fully customized, from the keel up.
For the builder, making a boat a bit longer/larger doesn't really make a big difference

yes and its the complete opposite with construction boats, where they use the same old mouldings over new product generations. and different models.

the duch alluminium builders can do more or less the same like former wood builder, (refering to the tread about allum boats not long ago)

 

[Pinnacle]

Really sorry to hear that you had this problem, Bart. Delighted to learn that did not spoil your season.
Boats, eh......always something to fix/mend!

 

[BartW]

thanks all for comments,
just to state the obvious, we are very happy with the system as it is and as it is designed,
and the problems we encountered were caused by user mistakes, (push the down button before pressurising the hydraulic system)
last year we did this repair, and it has been working perfect last season,
the system has been permanently submerged from spring 2012, (minus 6 months).
This platform is one of the best mods we did to the boat (at equal level with the stabs ;-) )
and we have been using her !

with this tread, I just wanted to go deeper in to the technicality, and try to understand exactly what happened,
and apart from using the system correctly,
one conclusion is that I need to pay attention, and regularly inspect these rams,
and as soon there is signs of corrosion, or wear on its shaft, or oil leaks,
replace them ! I know how todo it, and its no big issue.
looking back now, we did get signs that there was some wear / pressure loss in the system.

I’ll discuss further with H-B if it makes sense and if it is possible to place anodes on the rams.

cheers Bart