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Crane vs Slipway

Top cat

By Top cat
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Top cat Rising Star

Top cat

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I have two potential contractors for blacking my 57' steel Nb. One will crane it out , the other will put it on a trolley and pull it up a slipway.

I'm rather nervous about the crane option thinking that the hull will flex during the lift with potential to cause all sorts of cracks and leaks.

Does any one have first hand experience of having their boat craned out ? And are my fears justified or am I being paranoid?

 

Top Cat

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Slim Influencer

Slim

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When my 55' bare shell was delivered (many years ago) it was craned IN at the local yard by a specialised crane company arranged by the yard. They used heavy duty strops. I don't remember if they used a spreader. As it came off the trailer the strops slid along the baseplate and in an instant one was almost cut through completely. If a spectator hadn't shouted a warning who knows what would have happened. In the end they used chains

 

Out of choice I would always slip as opposed to lift. Things happen slowly.

 

 

 

Frank

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bargemast Influencer

bargemast

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I have two potential contractors for blacking my 57' steel Nb. One will crane it out , the other will put it on a trolley and pull it up a slipway.

I'm rather nervous about the crane option thinking that the hull will flex during the lift with potential to cause all sorts of cracks and leaks.

Does any one have first hand experience of having their boat craned out ? And are my fears justified or am I being paranoid?

 

Top Cat

 

I'm fairly close to a yard that I regulary visit, they only have a crane there to lift boats out, quite a few narrowboats (wide beams and replica luxemotors) that arrived from the UK by trailer are craned off the trailer and into the water-or to a hard-standing place in the yard.

I've only once heard of a very slight deformation on a low budget wide beam, but nobody knew if that was caused by the craning onto the trailer and the trip from the UK to France.

 

Peter.

When my 55' bare shell was delivered (many years ago) it was craned IN at the local yard by a specialised crane company arranged by the yard. They used heavy duty strops. I don't remember if they used a spreader. As it came off the trailer the strops slid along the baseplate and in an instant one was almost cut through completely. If a spectator hadn't shouted a warning who knows what would have happened. In the end they used chains

 

Out of choice I would always slip as opposed to lift. Things happen slowly.

 

 

 

Frank

 

For the craning of narrow boats and wide beams with sharp angles between bottom plates and the sides, at the yard I just wrote about, they always use chains.

 

The bottom plate sticking out a few centimeters is asking for the destruction of slings.

 

Peter.

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Just Heaven Collaborator

Just Heaven

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When our boat was craned out for the survey prior to purchase the straps cuased a small amount of damage to the paintwork.

We have had the boat out on a slipway to do some rudder repairs and that went smoothly.

 

Steve

 

[Edited for fat finger typo]

Edited by Just Heaven
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Naughty Cal Veteran II

Naughty Cal

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If you use a crane company, It's vitally important to ensure that they are equipped with proper spreaders to prevent the excessive squeeze on the boats sides. It doesn't always cause damage but some idiots are happy to take the risk.

I take it from these comments that narrowboats don't have designated strengthened lifting points?

 

Our cruiser is normally slipped on a trailer rather then lifting but on the odd occasion it doe need lifting then there are designated and labelled areas where the slings should sit.

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FadeToScarlet Veteran

FadeToScarlet

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Dry dock is my preferred option, followed by slipways, and then craning last of all. Of the three local yards that crane, one has dropped boats in the past, one had the crane topple into the water, and the third is run by an absolute conman I wouldn't urinate on if he were on fire.

Edited by FadeToScarlet
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Chertsey Veteran

Chertsey

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I've had three different boats, including Chertsey (72' and riveted), craned with no problems. Of course it depends who does it but any reputable yard will be abiding by H&S rules which are actually pretty onerous and will have a skilled person doing it. I wouldn't let this be the deciding factor, over location and quality of work.

 

Looks like we'll be using a dry dock for Chertsey's next blacking (because of changed location) and I'm actually not looking forward to it; I like having the boat on the bank with lots of space and air circulation and sun. But I shouldn't knock it until I've tried it I guess.

 

Edit to return to the OP - there is absolutely no reason the hull on a modern welded 57' boat would flex unless there was already something seriously wrong with it.

Edited by Chertsey
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gazza Veteran

gazza

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Dry dock is my preferred option, followed by slipways, and then craning last of all. Of the three local yards that crane, one has dropped boats in the past, one had the crane topple into the water, and the third is run by an absolute conman I wouldn't urinate on if he were on fire.

The crane toppling into the water was the contractors fault not the marina...

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alan_fincher Veteran II

alan_fincher

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Edit to return to the OP - there is absolutely no reason the hull on a modern welded 57' boat would flex unless there was already something seriously wrong with it.

 

I would disagree. I think it impossible it will not flex to some degree, whether craned, slipped on a trolley, or just dropped down on to bostocks in a dry dock.

 

Whenever our 50' boat was slipped, (and I had no reason to doubt its structural integrity), you could more or less guarantee that doors and hatches, (internal and external) would fit differently until it was re-watered.

 

I think it is a no brainer this can happen. Normally it is supported evenly by buoyancy, once set down on anything solid it could be supported at no more than 3 or 4 points maximum.

 

All that said, if the boat is well constructed and in good order, I don't think it will suffer, and it will almost certainly go back as it was afterwards.

 

In my experience craning without a frame or spreaders is quite commonplace - it seems fairly obvious it is netter to have them.

 

One thing about use of a slip is "are you live aboard, and do you need to be on board during". If the boat is up a strong uphill slope sleeping on it, (or even cooking on it!) could be a challenge!

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Tim Lewis Veteran

Tim Lewis

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We have been craned a number of times without problem and have used dry docks and a slipway for blacking.

 

Dry docking is my least favourite but this very much depends on the dock. If you are painting the baseplate you want one that is deep enough to be able to crawl under the boat and preferably be dry. wether or not the dry dock/slipway is covered is also an important factor.

 

Our favourite work place is the slipway at Aylesbury Circus Fields which takes you into a centrally heated and mechanically ventilated building.

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gazza Veteran

gazza

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And the marina say they have fixed it so it'll never happen again. But I don't want the risk to my home- especially not with a dry dock 45 minutes further along the river.....

Who's got the ex little ouse floating dock now? It was a tremendous eyesore tied up by cathedral marine!

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beerbeerbeerbeerbeer Veteran II

beerbeerbeerbeerbeer

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And I'm guessing that the bottom of a dry dock is actually quite damp? Not great conditions for working in or for blacking to harden.

They dry out pretty well. The one I'm in, whilst being covered, is open down the sides and ends. So plenty of air for drying the blacking. You walk down steps into it rather than a ladder. I've seen ladders at other places and think that'd be a pain carring stuff up and down.

Alvecote has a dry dock about a mile from the Barlow. Dont know how dry tthat gets?

These at Stone are very pleasant to work in, they are a lovely piece of history.

 

Glenn

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David Mack Veteran II

David MackDonate to Canal World

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We have been craned a number of times without problem and have used dry docks and a slipway for blacking.

 

Dry docking is my least favourite but this very much depends on the dock. If you are painting the baseplate you want one that is deep enough to be able to crawl under the boat and preferably be dry. wether or not the dry dock/slipway is covered is also an important factor.

 

Our favourite work place is the slipway at Aylesbury Circus Fields which takes you into a centrally heated and mechanically ventilated building.

 

 

Painting the bottom in the 'dock' at Aylesbury:

 

post-7909-0-46657200-1475172732_thumb.jpg

 

And coming out again on the trolley:

 

post-7909-0-53305500-1475172817_thumb.jpg

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