Lifting a boat with inflatable jacks.

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Infr137

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Hi

I have a Leisure 23SL bilge keel yacht (weight appx 2 tons) sitting on my trailer at home.

I want to start work restoring the keels inc. the keel bottoms. I have been trying to figure out a way to raise the yacht 12” or so, to get blocks under the keels to enable me to do the above. My biggest concern would be putting too much stress on one small area of the hull, so much so that the hull breaks! Probably being over fearful though. :0)

I came across “Draper Inflatable Jacks” appx £40. These are 3 ton rated heavy duty bags, which are inflated via the car’s exhaust and can raise an object by appx 20”.

Looking to place one under the hull, central between the keels and SLOWLY raise the boat to get some chocks in. Would I be putting undue pressure on the hull using this technique?

Any thoughts / experience, recommendations?

Thanks in advance

Rob…
 
What are the jacks going to sit on? I can see the trailer having enough sharp edges to give you problems as well as its axles being in the way. The danger of such a lift is that the yacht might slip sideways or topple.
 
Hi Norman

There's a large gap in the trailer, through which will be a small stack of wooden sleeper cut offs coming up from the ground. The jack will be sitting on these with a rubber matt in between, to reduce risk of puncture under pressure.

The trailer keel plates have vertical guides appx 18" high on either outer edge of the plates. I won't be lifting the keels beyond these. Ropes will be attached via the trailer to Bow, Stern, Port & Starboard with a friend on each rope to feed slack.

Looking to use a single jack, they're appx 2' in diameter.

What about pressure on the bottom centre of the hull? Am I being over sensitive here?

Thanks
 
I would use a bottle jack. Lifting a couple of inches alternately at bow and stern, chocking up as you go. If you put a nice long piece of wood on the centre-line to spread the load you will be fine. The beauty of this method, if you have enough chocks (you really can't have too many), is that you have very precise control all the time and the boat is never fully lifted off the ground. A bottle jack is essential as it rises vertically unlike a trolley jack. A car scissor jack would do. I used one to lift the stern to drop the rudder post out on my old Sabre 27.
I hope this helps.
Nicki
 
The inflatable jack will definately do the job - although there is little or no control over the stability of the load. They are used to lift LandRovers for wheel changes on unsuitable ground, after all. If you have a method for controlling the boat's movement, then the bags have a limited potential here - but they certainly would spread the load!
 
I once saw a bilge keeler jacked up with an hydraulic car jack, bit by bit, and settled down with the hull on sandbags which were, in turn, supported by timbers. Seemed OK and quite stable.
 
Gt. News thanks for all your replies so far.

I get the impression then, that the base of a boat hull is a lot tougher than I originally thought?

Any other comments / suggestions?
 
Yes as long as you put something like a plank or a suitable pad on suitable part of the hull you should be fine jacking up a boat like that with what is essentially a point load Jack. Might be good to know where the bulk heads are and hence areas that are stronger for jacking on to.
 
Air bag jacks can be a bit fast dont try and lift the whole way in one go make your chocks from 2" X8" timber lift the boat 2" at a time. I used a 2 Tonne trolley jack. make your first lift level with front of keels allowing boat to rock back onto rear end of keel when you have 2 1/4" clear under front of keel put first Chocks in. lower boat onto chock place jack at rear of boat and jack up rocking boat onto chocks at front of keels when you have 2 1/4" clear under rear of keel inser chocks . lower boat onto chocks then repeat another6 times. even if the worst happens she will only drop 2" no wories for a wel built boat like the Leisure
 
Why go to the bother? What work do you have to do to the bottom of the bilge keels that warrants all this hassle? Most of us give a quick rub down and a coat of antifoul whilst the boat's being held in slings prior to launch!
 
Swapped trailers under my leisure 23BK a few years ago.
Jacked up the trailer then ran 2 strong beams across under boats hull fore and aft of
keels, fitted sand bags between hull and beams, ran halliyards from top of mast to supporting points on each side for stability (we used cars) build up supports under beams and then lowered the trailer slowly. no probs.

pete
 
[ QUOTE ]
Most of us give a quick rub down and a coat of antifoul whilst the boat's being held in slings prior to launch!

[/ QUOTE ]

Ah, luxury! Not much use to those of us that launch straight off the trailer, though. Also, Infr137 has the boat at home & probably wants to get all the work done before taking it to the water.
 
Thank you all so much for your replies.

Nigel. The base of the keels have not been touched since I purchased her 6 yrs ago. As a result I get rust creeping up each yr, so wanted to strip, treat & epoxy to minimise rust creep.

Pete. Your comment "2 strong beams across under boats hull fore and aft of keels" Do you mean the planks go from bow to stern or port to starboard under the boat? Any pics at all?

Feel alot more confident now about lifting her (with plenty of caution)! :0)

Thanks again folks,, & happy sailing!
 
I've just finished extensive work on a 2 ton wooden boat with a long keel on a trailer. I did lots of lifting and moving, at one stage having to support the hull while I dropped the iron ballast keel.
I did it all with a trolley jack and lots (LOTS) of baulks of timber and blocks.
The safe thing with lifting I found is a) never lift more than about an inch at a time, and then put more blocks under just in case. b) try and lift using a long board like a railway sleeper, supported at one end with the jack under the other. That gives a more even vertical lift.
On no account ever have the boat wobbling about just on the jack.

In your situation why not try to tip the boat, keeping one keel on the trailer and raising the other by say 3"?

I assume the trailer is already securely chocked on blocks itself, not sitting on its wheels? You can't do any safe lifting of the boat in respect to the trailer unless the trailer is itself firm. Remember it will flex a bit, and tyres have a disconcerting habit of suddenly flexing sideways when the weight is moved or reduced. A sudden 1" slide can be enough to topple a stack of blocks or a jack.
 
Folks

Thanks for all the advice, very much appreciated. THink I'll start with the simplest of suggestions and work my way up from there.. :0)

All the best
 
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