Lifting wooden boats

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Vitalba

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I am concerned that the lifting device used in my boatyard my not be suitable for VITALBA (East Anglian 1966, Long keel with cutaway bow, 28 x8 x4.5 ft, carvel Mahog/Iroko about 4 tons displacement includes 1.6 ton balast keel).
The devise (used a lot in Europe I`m told) is a two wheeled trolley supported at the boats bow end by a tractor. It is submerged and the boat floated on. The bow is supported on a transverse beam and aft by a hydraulicly operated prop on each side above the wheels.
The whole weight of the boat is therefore carried by the stem and the planking with no support under the balast keel whatsoever. Granted this only for a short time while the boat is pulled up the hard and into the cradle.
Has any one had any expirence of or comments on this sort of device for wooden boats?
VITALBA
 
Vitalba ... I have similar concerns regarding the slipway trailer type shown on the attached photograph & manufactured by Roodberg in Holland. It appears if it's the type you refer to & I would also welcome any comments & advice on its suitability for lifting wooden boats. Mine is 47ft and 25tons weight.
 
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This is what moves my boat these days......

They are much stronger than we give them credit for.

must type faster, in answer to the above post re these crawlers for moving wood boats. I have had mine moved with this twice now and prefer it to slings any day.

There is a web that fits over the rear hydrolic lift part that supports the rear of the keel, the bar at the front is moved under a bulkhead and the rams hold her from tipping.

Tom
 
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Vitalba

What you have described is different from the other examples here wwhaere the keel is supported and the side supports are just to stop the boat from leaning.

Not sure I would be happy with just two supports to planking and nothing under the keel. The supports might be OK if they are directly under a main frame or bulkhead or at the very least spread across several frames/timbers fore and aft.
 
The Trolley (crawler) I was talking about is that shown above by Little Ship (LS)
However in LS case all the weight is taken on the long keel which is supported at the front by the "bar" and the "web" at the back with the "rams" only to prevent tipping. This is not the same by a long chalk as all the rear weight being taken on the rams.
Thanks LS for the input and picture.
The heavier Cawlers seem to have a series of "rams" down each side which will at least spread the load. See Rootberg website.
More thoughts/comment most welcome. VITALBA.
 
Vitalba, Sorry to sound negative but I would be highly alarmed if a boatyard was planning to lift my traditional boat by 'point contact' on her planking without any control as to where they were placing the lifting pads and -as you say - leaving her keel unsupported. I feel that you must insist on the majority of her weight being taken under her ballast keel.

The type of lift shown in the thread appears to have been designed to lift modern flat-bottomed power boats with the majority of their weight i.e. engines - aft.

Is there no way they can rig normal webbing slings to lift Vitalba?
 
Redwing228 said:
Vitalba, Sorry to sound negative but I would be highly alarmed if a boatyard was planning to lift my traditional boat by 'point contact' on her planking without any control as to where they were placing the lifting pads and -as you say - leaving her keel unsupported. I feel that you must insist on the majority of her weight being taken under her ballast keel.

The type of lift shown in the thread appears to have been designed to lift modern flat-bottomed power boats with the majority of their weight i.e. engines - aft.

Is there no way they can rig normal webbing slings to lift Vitalba?
Click to expand...

Redwings right. Without support under the keel there is a chance that you may end up with a couple of holes in your hull, depending on hull/ribs condition etc. We've been out and in again this year on a sling cradle (we have a 2 ton keel) and even though it can mark the new paint at least the weight is more evenly distributed.

Before we bought this boat in 2001 the previous owner had spent 18 months doing the necessary, on the bank. I have photo's of the relaunch from a mobile crane! Standard straps going to a single hook. How the hell she was not crushed to match wood I'll never know. At least with a sling cradle, the slings ends are at least 11-12 foot apart, so the crushing element up around the gunnels is much reduced.

If you have doubts about a boats integrity, structurally, a dry dock is the only answer IMHO. We have a casualty on our marina. I understand that the boat is something special, but had been in the water for 5 years without being maintained. If our marina suspects that a boat is structurally 'iffy' they will only lift it if a disclaimer is signed. Very wise in this case, the (flat 5 or 6 inch wide) slings went straight through the sides of the hull. It's as good as dead.

Sorry to finish on a low note, but these things do happen....
 
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My boat is at the same yard, so I know the machine in question. I have only seen it used for relatively flat-bottomed boats, or modern glassfibre yachts where there is more width aft and the rams act on a more horizontal surface.
It would be a disaster on mine, I think, with a clinker hull and a very narrow almost vertical section at about the level of the rams.

A further point ocurs to me. Even allowing that it would be safe to float the boat onto the trailer and then gently settle it by moving up the slipway, it has to be lowered onto the the cradle or wooden keel blocks, by lowering the rams when positioning in the yard.
Even worse, when putting back in the water the process would be reversed, and the rams would have to squeeze the hull to lift it off the supports. Like picking up an eggshell with coal tongs!

Having my own trailer I have never had to ask the yard how they would propose lifting Xenia, but I suppose I had assumed they must be able to use slings. There is a much bigger wheeled lift they have there with a pair of slings, but I have never seen it used and it does appear derelict.

I'd have a chat with the owner. They claim to be able to handle a range of craft up to 50 feet I think, so may have other methods in reserve.
 
Many thanks for all your in puts. I was not very happy with the proposed scheme to start with and less so now!
In fairness to the `crawler` system the two longitudinal arms can be adjusted for width so that the props squeezing action can be minimised never the less they must ultimately take the majority of the boats weight. Although the boat can be positioned on the`crawler`to get the props on a bulkhead this does not help much as they are not part of the basic structure of the boat. I can see the point in the case of glass fibre or steel where bulkheads are an integral part of the whole.
Could Little Ship please explain how the `web` is configured so as to take the load on the keel while at the same time the props are only used to steady the boat. Is the `web` fixed between the arms of the crawler or is it somehow coupled to the props to provide a lifting/ lowering action which I assume will be required to get the boat into a cradle ?
Many thanks. VITALBA
 
Could Little Ship please explain how the `web` is configured so as to take the load on the keel
Click to expand...

It is visable in the photo already placed over the rams.

It has two tensioning pins that are turned to get the keel supported as the rams lift. In my opinion this method of lifting is more secure and less stress on the hull than two lengths of webbing to lift out of the water.

I suppose that some boats wont be suitable to lift with one of these machines but then not many of us worry when they lift boats out with two strops and we should.

I'm a##l retentive when LS is lifted until she is safely on the crawler. :)

Tom
 
Not relevant to the OP really, but when they took the steamboats out of the water at the Steamboat museum, each boat had a custom built cradle to support them.
They were very worried that the old boats would not survive a lift with straps. Each boat had the boiler and engine removed first.

Dolly's cradle (Dolly is the oldest mechanically powered vessel in the world)

Dolly_11.jpg


Dolly_6.jpg


Dolly_5.jpg
 
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