Why would you own/use your own yacht cradle in a boat yard?

[dunedin]

Here in Mylor most boats ashore are in steel cradles. Apart from anything else it makes it easy for the yards transporter to pick up the boats and move them around.
Transporter grabs the cradle..

That cradle looks dangerous - may be just the photo, but looks to be no triangulation of the support arms to stop them bending outwards. And huge leverage on the welds/brackets at the base.
And even worse if being used to transport in that way.

 

[FWB]

That cradle looks dangerous - may be just the photo, but looks to be no triangulation of the support arms to stop them bending outwards. And huge leverage on the welds/brackets at the base.
And even worse if being used to transport in that way.

All the boats here have these cradles. They are not dangerous.

 

[Deleted member 36384]

That cradle looks dangerous - may be just the photo, but looks to be no triangulation of the support arms to stop them bending outwards. And huge leverage on the welds/brackets at the base.
And even worse if being used to transport in that way.

The supports are in compression and probably have very little leverage. The boat is sitting balanced with just about all of its weight sitting on the keel. The uprights stop the boat from rocking so they never see any significant load from the side. If a gust hits the side of the yacht it will try and pivot on her keel and thus load the posts further in compression. The supports work like beach legs, all the weight is on the keel and it takes very little effort to keep her upright. Like a heavy motorbike when stationary, a human's legs can easily keep her on the balance point, even with fidgeting pillion passengers but let it get a few degrees over then the balance is lost; the cradle does not have a bendy joint, like a human's knee.

 

[flyingscampi]

My boat spent the winter in an old road trailer with scaffolding poles welded to it and I lost sleep every time the wind blew. I bought a Jacobs cradle for the following winter.

A yacht did fall out of one of these contraptions recently when one of the scaffolding poles bent so I felt that this justified the purchase.

 

[Mad Pad]

If the cradles are that good why do both yachts in the background have wooden shores as well?
Just curious!

 

[FWB]

If the cradles are that good why do both yachts in the background have wooden shores as well?
Just curious!

Usually for longer/wider vessels. The cradles, which are manufactured in the yard, enable easy transportation. Wide and long boats sometimes have shores at the extremities.

 

[davidej]

Interesting. Where/how did you sell your cradle? eBay?

No- the boatyard had a client who wanted one. A bit strange as the yard insists on supplying cradles to all boats in their yard.

I seem to remember that Jacobs will buy them back and sell them on.

 

[Resolution]

Sniffy ( if I may call you that)
Good boatyards will use a range of cradles that are a) correctly sized for the boats in them, b) decently designed for the stresses likely in winter storms, and most importantly c) enable maximum number of yachts to be stored ashore.
The old method of using pit props firstly needs a gravel type surface, not smooth concrete, in order to dig in the props a bit, and secondly needs enough space for the travel hoist to drive in with each boat. Yards with cradles on concrete usually have a low loader that lifts the cradle base by its edges, meaning that you can position yachts bang alongside each other.
It is always a bit of a surprise that there are not more accidents with yachts ashore, but the relatively few stories of disaster seem to indicate that most boatyards know what they are doing.
Peter

 

[DownWest]

Here in Rochefort, the yard only uses their own cradles, because the hydraulic trailer that moves the boats about, only works with them. So the very nice custom built cradle for the Swan I was working on was not acceptable. When they finally got one that would work with the deep keel, it was too late to haul her. Bit of teeth gnashing went on..

While shores and wedges are very trad, give me a cradle any time.

To add, that cradle for Aeolus does look iffy. It relys on the friction between the pads and the hull to offset the loads on the welding at the bottom of the struts. Not something I would sign off on. Far better to put diagonal braces from the struts to the frame near the keel. Hurricanes do happen...

 

[FWB]

To add, that cradle for Aeolus does look iffy. It relys on the friction between the pads and the hull to offset the loads on the welding at the bottom of the struts. Not something I would sign off on. Far better to put diagonal braces from the struts to the frame near the keel. Hurricanes do happen...

Aeolus has beaching legs also and she will sit happily with them. She will also sit on her wide keel, the 5 tons of encapsulated ballast sees to that.
All the cradles are the same and fit the hydraulic transporter. There are many different models of boats here and they all use the cradles with no problems.

 

[NormanS]

Aeolus has beaching legs also and she will sit happily with them. She will also sit on her wide keel, the 5 tons of encapsulated ballast sees to that.
All the cradles are the same and fit the hydraulic transporter. There are many different models of boats here and they all use the cradles with no problems.

Hah! The owner of the boat next to mine in a yard, persuaded the yard that his boat would be perfectly safe, supported only on her beaching legs. She started to walk around in a gale, and since then was told that, like everyone else, she would be in a cradle, or she would not be there. She's now in a cradle.

That cradle pictured with Aeolus looks very poorly designed. Surely it wouldn't be difficult or expensive to have the legs braced.

 

[FWB]

The cradle belongs to the yard. All the cradles are the same, they are perfectly safe.

 

[Mad Pad]

This works for me,note the chains connecting the props.

 

[Mad Pad]

A slightly more flattering image of the old lady!

 

[Daydream believer]

My AWB is a bit bendy when sitting on its keel so i am more than happy with the proper 7 leg steel cradle supplied by the yard. Not only that they know how to adjust it. When in Inverness they did not do it correctly & the floor boards stuck up 12mm in the middle for a month in spite of my objections. Never happens at Bradwell

 

[dunedin]

All the boats here have these cradles. They are not dangerous.

What is your engineering basis for that statement ?

All the cradles I have used, and seen, have triangulation of the supports.
If you assume the boat keel and ground are solid, any side pressure (eg wind) will try to pivot the boat around the keel. By trigonometry, the initial force will be horizontal, as the boat tries to move from 0 degrees deflection to say 1 degree.
There is not much holding the support horizontally.
Then the height of the support is quite high, and the lever very long relative to the bearing area at the base of the support (not visible in the picture but not a lot) - hence looks like a leverage of 30:1 to 50:1 in this case.
The triangulation would dramatically increase the strength.

Looks to me like bad engineering - but if a qualified structural engineer can assert why triangulation of the struts is not necessary I would bow to their expertise.

 

[FWB]

No boats have fallen over. They do the job.

 

[ex-Gladys]

No boats have fallen over. They do the job.

"yet"... My yard has a similar system with a hydraulic lifter, and all the cradle legs are diagonally braced. Unfortunately I don't have a pic readily to hand...

 

[Metabarca]

These are the cradles one finds in the Adriatic: pretty massive affairs built to withstand the bora, but even then, great care is taken to point them north-east. Note the diagonal bracing.

 

[Spi D]

Our marina had a Workplace Assessment and several of the old wooden constructions held together with lines and ducktape were deemed a risk.

They now use a transport system where the travelift only lift out and place the boat in a mobile cradle, then to be pushed/pulled away by a dedicated tractor. This means that the capacity is much higher than when all boats where take by travelift all the way, boats can be parked closer because there is no need for room for the travelift between them and cradles can be stacked neatly when not in use. Mast can be left on, if the owner so desires.

We've been allowed a number of years before having to shift (mine is good until 2022), shorter for the 'worst'.

The new cradles must be hired from the marina, £50-80 per year depending on size and features.

A 10 minutes video, if interested: