Is anybody interested in following my efforts to build a hydraulic Passerelle?

[Bertramdriver]

This is a suck it and see exercise.
SWMBO has mandated that she is too old and frail to balance on the end of our rope supported gangplank when going astern to moor up. Either I build her a proper passerelle or she's going to resign.
At the moment we have a Besenzoni metal two part folder secured by ties to the canopy and raised and lowered by elbow grease. It's 10 foot long when open and weighs around 30 kilos.
I looked at a standard retrofit Besenzoni hydraulic unit but don't have the £ 6000 available to pay for it. Also it is a phenomenal weight to hang off my transom, with the ever present risk of an untoward incident ripping great chunks of grp sheet from the boat.
My solution has been to design my own hydraulic "lift and lower" function powered by a ram mounted on both the swim platform and transom, so the weight is spread around the area. Had to learn a bit about hydraulics, but hey ho!. To open up the folded passerelle to full extension I've gone " off piste" by using a couple of gas struts to do the heavy lifting and cushion the momentum of the passerelle swinging down when it's opened and closed. I went the strut route because of the weight penalties and control difficulties of hydraulically powering the open/ close operation.
The system is powered by a 12 volt hydraulic steering pump, and hopefully will be remote controlled (If I ever figure out how this bl**dy relay works)
I've just packed off the pallet to the boatyard in Aegina and will be there from the 16th where fitting it all together will be one of my small pleasures.
So if anyone is interested (I have no illusions) I will document the whole exercise and hopefully load a film of it working/ or not.
Oh and by the way, my total spend on this so far is less than £ 700 .

 

[sealines28]

I would be very interested, although my boat a sealineS28 will need something smaller, as i plan to take my boat to the med in a month or so. going to view a few marinas on the 20th. will look forward to seeing yours in action, plus if i can do the same but a smaller version.

 

[jfm]

Very interested! Please post pics/drawings and reports, thanks

 

[jimmy_the_builder]

Definitely, especially if you then decide to branch out into diy hydraulic bathing platform fabrication!

Cheers
Jimmy

 

[Bertramdriver]

Hi
Happy to do the recipe but if I knew when I started what I know now I would have explored a pneumatic solution. It's possible to use aviation rams made of aluminium alloys and the systems would have been cheaper, easier to engineer and much lighter. Plus air doesn't make a mess if it leaks.
I also tried the electric ram route but couldn't find one suitable at a reasonable price.
However I'll try and remember to keep a picture record of my labours to publish
If I've done this right there should be a jpeg of the Bertram swinging its weapon of mass destruction at the boats moored up behind

 

[davids0865]

Oh yes please we would all like to share I'm sure.

 

[rafiki_]

Yep, sounds good to me. As ever pix would be great.

 

[madorwhat]

I run a hydraulic component supply company so let me know if you need help

 

[Divemaster1]

...........If I've done this right there should be a jpeg of the Bertram swinging its weapon of mass destruction at the boats moored up behind

Please do post it here !! We have a similar, but one piece, beapon at our stern. we loosely plan different mechanical deployment options for this excellent conventional weapon and reliable, which makes for less of a threat to fellow boaters...(probably not suitable for med boating)..

 

[Bertramdriver]

Hi Madorwhat
You offered so I can't resist the chance do some brain picking.
The last time I bought hydraulic oil in Greece I had to pay €30 a litre. Last week I was I Pirtek Oxford and saw they were selling "Eco" hydraulic fluid, the main constituent being rapeseed oil. Is this straight RS oil or a blend with various other chemi's? And if rapeseed is ok, how about non-virgin olive oil? I'm assuming the non virgin is acceptable to the ram piston on the basis that it wouldn't notice the difference, and it's freely available around the harbours. What do you think?

 

[madorwhat]

Hi Madorwhat
You offered so I can't resist the chance do some brain picking.
The last time I bought hydraulic oil in Greece I had to pay €30 a litre. Last week I was I Pirtek Oxford and saw they were selling "Eco" hydraulic fluid, the main constituent being rapeseed oil. Is this straight RS oil or a blend with various other chemi's? And if rapeseed is ok, how about non-virgin olive oil? I'm assuming the non virgin is acceptable to the ram piston on the basis that it wouldn't notice the difference, and it's freely available around the harbours. What do you think?

The olive oil will be fine for the ram but not sure about the pump. What type of pump are you using gear , vane or piston ??

 

[Bertramdriver]

Hi it's a standard reversible vane steering pump, on the assumption it powers a ram anyway. It's a US brand, Mazzini or something like it. It was a sample sent to Lewmar for evaluation to use on their system.

 

[Assassin]

Avoid vegetable based oils as they are biodegradable and this is a common mistake people make with such oils for lubrication, a commercial hydraulic oil will have additives to prevent this happening, but check carefully for the specifications and check its working life.

We tried these out and found we were changing them every month even though they were constantly working, and found they didn't live up to their claims; we use an oil sampling facility and after two weeks they had deteriorated significantly, so we went back to mineral oils in our hydraulic systems.

What effects them and makes them break down? basically moisture; boat and hydraulics with bio-oils!!!!!!!!! add in air; air gap and tank breathers!!!!!!!!!! and its really a non starter and bloody expensive.

 

[Bertramdriver]

Thanks for heads up. Will isolate the olive oil into the galley.

 

[Bertramdriver]

For those who are still waiting the Passerelle programme continues. Constrained by very limited Internet access in the boatyard so I can't show pictures and explanations until I dock somewhere that will allow me decent band width.
However the headlines are
The hydraulics work like a dream once I swapped my pump ( Lewmar autopilot pump) and expensive solenoid lock valve for a second hand trim ram off a 300 hp Mercury outboard which was a completely self contained unit.
The passerelle configuration was changed from up and under to up and over so that the extended / unfolded passerelle requires minimal strengthening to support users weight when being used. This configuration also provides a safety factor when the passerelle is slammed by the waves against the harbour wall. Instead of transferring the kinetic energy to the transom the extended section converts it into upward thrust, cushioned by the gas struts and raising it out of harms way.
The gas struts worked reasonably well in the up and under configuration but required SWMBO to pull on a rope to achieve a full erection but the results were disappointing. However once we inverted the central hinge and changed to the up and over approach the gas struts came into their own and achieve an almost effortless full extension.
So as far as I'm concerned an almost 95% outcome for less than 10 % of the cost of a professional system
Is SWMBO happy? You bet.
I'll publish the whole thing in August when I come back for some cold wet weather and general misery.