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Blacking the bottom

spikesy

By spikesy
in Boat Building & Maintenance

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spikesy Gongoozler

spikesy

Posted
Posted

It as been recommended that the bottom of the boat should be blacked (57 ft) when next blacking is due, which is quite soon. the problem I have is that the boat sits on rest bars in the bottom of the dry dock, so three sections, about a foot wide cannot be blacked. I was thinking of jacking the boat while I reset the rest bars, but I am a bit concerned about the boat slipping while on the jack, and what sort of supports to use like axle stands, and how to stop the boat sliding backwards.

Does anyone else have this problem, and how did you get round it?, and would one jack at the bow be OK , or should I use two jacks and a stretcher plank.

Any advice much appreciated.

 

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Posted
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It as been recommended that the bottom of the boat should be blacked (57 ft) when next blacking is due, which is quite soon. the problem I have is that the boat sits on rest bars in the bottom of the dry dock, so three sections, about a foot wide cannot be blacked. I was thinking of jacking the boat while I reset the rest bars, but I am a bit concerned about the boat slipping while on the jack, and what sort of supports to use like axle stands, and how to stop the boat sliding backwards.

Does anyone else have this problem, and how did you get round it?, and would one jack at the bow be OK , or should I use two jacks and a stretcher plank.

Any advice much appreciated.

 

 

Our boat is being blacked next month and we aren't having the base plate done as I understand the vast majority of boats don't and that it's not a requirement really and will be readily removed as you bump along the bottom in some of the shallower bits.

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spikesy Gongoozler

spikesy

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Thank you for the reply's, Your right,this is a surveyors recommendation, but I know a couple of boaters that have done it and they said they got a lot of rust off the bottom and was worth doing. I have never black the bottom in the past though I am now wondering if I should.

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Timleech Veteran II

Timleech

Posted
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Blacking the bottom (occasionally - not necessarily at every docking) is often recommended for older boats with thinner bottom plates than are currently fashionable - especially if there is evidence of significant pitting.

Usual practice is not to worry too much about the areas obscured by the bostocks, but to try to make sure the boat sits in a slightly different place at the next docking.

Yes jacking up and moving stands is quite feasible, but I suggest you get advice from someone (the dock operator?) who has experience of doing it and can see the actual setup before trying.

 

Tim

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RLWP Veteran II

RLWP

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A surveyor will almost always recommend blacking the bottom as it is better than leaving it unpainted. But - how much better, and is it cost effective? If you discuss that with your surveyor you may get a different answer

 

Richard

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Bobbybass Experienced

Bobbybass

Posted
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If you have pitting...its an even more comprehensive job.....as simply rolling ( in my experience) makes it worse.

You end up with a skin over the pit and there is air trapped in it. You would have to work the black well down into every single pit...with a brush.

 

I've done it...I paid a boat yard to do it once..its nasty..the boat yard said its nasty.

Prepare to get well covered..hair....eyes...head.....sense of humour..

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pooie4 Explorer

pooie4

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Hi , I've just bought a boat , the surveyor said you can get an epoxy coat for the bottom which is quite tough , but as my boat was built in 1984 and only lost a mil in places I will just do the sides as the boat yard guy suggested.

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Timleech Veteran II

Timleech

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We simply refill the dry dock and move the boat a couple of feet before emptying the dock again

 

...and then wait (could be up to 24 hours) for it to dry out again enough to paint..

 

Yes, that's the easy way to do it if you have time to spare.

 

Tim

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Teadaemon Proficient

Teadaemon

Posted
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I've had the discussion on whether or not to recommend blacking the bottom with a number of surveyors.

 

We all agreed that in an ideal world, blacking the bottom plate is better than not blacking it.

 

We also all agreed that it is not usual practise, because it's difficult to do (it gets even more difficult if you want epoxy on there and need to shotblast the bottom before blacking it).

 

It's one of those things that some surveyors will recommend, because it's a lot easier to put a couple of lines in a report than it is to actually do the job.

 

Personally, I've stopped recommending that it's done routinely, although I will mention that a baseplate hasn't been blacked. If OTOH, I were supervising a new build, or a boat was on dry land for a considerable period of time for major work, with a crane handy for all the moving around, then I'd probably mention doing the whole hull including the baseplate with epoxy as an option. Of course, blacking the uxter plates (and if the bottom plate curves up towards the bows) is a lot easier, and given their position nearer the surface, is worth doing.

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David Mack Veteran II

David MackDonate to Canal World

Posted
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...and then wait (could be up to 24 hours) for it to dry out again enough to paint...

It was extemely hot weather when we last did it so we didn't have to wait that long. And since you are only going to be painting three or four strips across the bottom it is more practical to apply some heat locally to speed the drying if necessary.

  • Greenie 1
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furnessvale Influencer

furnessvale

Posted
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I would, and always do, black the bottom but most people don't. It's not as bad as people make out.

My surveyor, sadly recently deceased, gave me this useful advice.

 

If the bottom is shiny because it has rubbed on the bottom, don't waste your time blacking it as it will only rub off.

 

However, if the bottom is rusty, clean and black it as you will obviously do some good.

 

George ex nb Alton retired

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PhilR Experienced

PhilR

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When I was at Debdale they had a boat out for blacking and I was invited to look under the base plate, what I saw has convinced me that black will not get rubbed off, it was covered with different forms of Crustaceans and they hadn't been rubbed off.

 

I was told recently that it is best to leave the crustaceans on the bottom plate ............ blink.png

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Timleech Veteran II

Timleech

Posted
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Unless they are zebra musels? I seem to remember a forum member having to steam them off before transporting a boat.

 

I'm pretty sure that would be true if taking the boat to Ireland, where they are not yet established inland.

 

Boats around here which don't move much can build up layers of zebra mussels inches thick.

Removing them should certainly save fuel, for boats which do move.

 

Tim

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