Blacking!

[kayDee]

Hi all...

When a boat is dry docked or craned out to be blacked, do they do the underneath bit too? I've seen a few photos of boats being blacked and they're placed on metal girders that look really low to the ground - too low to crawl under to paint underneath? Doesn't the bottom bit get protected by anything? If not, why not? I'm just interested to know why its left to rust when it seems to me to be a really important part of the hull that should be protected with even more coats of blacking than the sides? Can anyone tell me why this is the case?

Thank you!

Kay

x

Edited September 16, 2008 by kayDee

[AlanJ]

My understanding is that the bottom doesn't get blacked typically because:

1) Rust only forms where there is air and water together in contact with the metal (if you've got air under the base plate then that would be interesting!)

2) It would get rubbed off very quickly as you brush the silt on the bottom of the cut.

 

I'm sure others will be able to give a more informed reason, but that is my understanding...

HTH

Alan

[kayDee]

My understanding is that the bottom doesn't get blacked typically because:

1) Rust only forms where there is air and water together in contact with the metal (if you've got air under the base plate then that would be interesting!)

2) It would get rubbed off very quickly as you brush the silt on the bottom of the cut.

 

I'm sure others will be able to give a more informed reason, but that is my understanding...

HTH

Alan

 

Hi Alan

No, you're right... Makes sense really - my fault for being silly! I think I need to change my hair colour...

Kay

x

[Troll]

In all my years I`ve never seen any yet blacked on the base plate

[Gary Peacock]

We used to do it with the boat stood on trestles but unfortunately the "nice but dumb" labourer who used go under them to do it left and the new one wasn't sufficiently dumb to do it.

[Bob the welder]

We used to do it with the boat stood on trestles but unfortunately the "nice but dumb" labourer who used go under them to do it left and the new one wasn't sufficiently dumb to do it.

you are a nice chap

[mayalld]

My understanding is that the bottom doesn't get blacked typically because:

1) Rust only forms where there is air and water together in contact with the metal (if you've got air under the base plate then that would be interesting!)

2) It would get rubbed off very quickly as you brush the silt on the bottom of the cut.

 

I'm sure others will be able to give a more informed reason, but that is my understanding...

HTH

Alan

 

The real reason being;

3) Boatbuilders are, by-and-large not set up for getting the boat up high enough to black the base plate, and consequently tell you that it doesn't need doing.

 

Air under the base plate? Ever looked at a lock filling?

[Machpoint005]

Air under the base plate? Ever looked at a lock filling?

Not for long enough for tinworm to get a start, Dave.

 

Polish the bottom as you go along, that's my view FWIW.

[mayalld]

Not for long enough for tinworm to get a start, Dave.

 

Never been through a lock flight?

 

The point being that aerated water in contact with the BP is NOT rare.

 

Blacking the BP may be overkill, but it sure as hell can't do any damage.

 

Belt and braces

[Tim Lewis]

My understanding is that the bottom doesn't get blacked typically because:

1) Rust only forms where there is air and water together in contact with the metal (if you've got air under the base plate then that would be interesting!)

2) It would get rubbed off very quickly as you brush the silt on the bottom of the cut.

 

I'm sure others will be able to give a more informed reason, but that is my understanding...

HTH

Alan

 

Scuse the ignorance but this is correct how do baseplates get thin/pitted.

 

We used to paint the baseplate on Fulbourne and when we came to re-paint there was a surprisingly amount of paint still left on the bottom, bitumen is harder to knock of on a soft canal bed than you may imagine.

 

As others have said finding a place where you can get access to the bottom is the main problem. We used the dry dock at Uxbridge a couple of times but the gap is not fantastic. Using a boatyard that cranes boats onto high trestles is prob the best option. One of the best/easiest I know is the gantry crane at Debdale marina near Foxton.

 

Tim

Edited September 16, 2008 by Tim Lewis

[FORTUNATA]

The boat I'm about to buy is in dry dock and I also noticed the bottom wasn't blacked. In fact, the bottom is covered in pebbles and shells that collectively pong. The surveyor told me not to worry about blacking it, as have the boatyard staff. I have to decide. First, the hull will be given a survey and then I'll have to think it over.

Personally, I tend to be swayed by the argument a hull should be totaly blacked and fitted with anodes as a code of practice. I'd be quite willing to crawl under it and do it myself but scraping all those shells wouldn't be my idea of fun.

 

Hi all...

When a boat is dry docked or craned out to be blacked, do they do the underneath bit too? I've seen a few photos of boats being blacked and they're placed on metal girders that look really low to the ground - too low to crawl under to paint underneath? Doesn't the bottom bit get protected by anything? If not, why not? I'm just interested to know why its left to rust when it seems to me to be a really important part of the hull that should be protected with even more coats of blacking than the sides? Can anyone tell me why this is the case?

Thank you!

Kay

x

[saltysplash]

If its of any interest to any one, Ive always antifouled the underside of any keel ive owned.

 

Keeping that length of wood in mint condition was very important to me considering that every frame and plank on the boat eneded up relying on that base.

 

When i eventually get LE out of the water either dry dock or hard standing I will be treating the base plate even if it means lying on my back with an extended paint roller

[Machpoint005]

1. Never been through a lock flight?

 

2. Belt and braces

 

1. Still not long enough in contact (O-level chemistry)

 

2. Waste of money

[Proper Job]

......bitumen is harder to knock of on a soft canal bed than you may imagine.

 

Tim

It's not the soft canal bed that is usually the problem. Its the hard rocks and metallic object that 'gouge' there way along the bottom listing the boat over at an alarming angle. Some of the disused lift bridges along the Southern Oxford have more masonry in the bridge hole than around the top of it !

 

I'm sure there must be very little, if any, left on the bottom of Ocelot. The original 15mm base plate is quite reassuring though

[mayalld]

1. Still not long enough in contact (O-level chemistry)

 

2. Waste of money

 

If you go through a lock flight, you could be spending 3 hours with aerated water being actively introduced under the baseplate. Anywhere around locks, the water is pretty aerated. All in all, plenty of oxygen to cause oxidation of the BP

 

As to a waste of money, bitumen is cheap.

[richardf]

I was told by the surveyor, Jim MacDonald, that you should black the bottom and on his ex working boat, he always made a note of where the paint had been missed and made sure that when it was done the next time, the boat rested on it's supports at different positions.

He told me that the supports are known as 'Bostocks' - which evolved from 'Boat Stocks' - could have been bo**ocks though!!!

[Gary Peacock]

The biggest problem is finding someone to go under the boat to do it.

 

If you do it officially or the HSE show an interest it becomes nigh on impossible, we had to prove the trestles we used to do narrowboats with were up to it the HSE required proof that the design capability was sufficient and that they were tested and certified yearly.

 

Without you have your own indemnity insurance and even then it can be complex, for a marina or yard owners to allow a member of staff or public to go under a boat that is in effect propped up in the air would be risky because of the potential legal action they might face in the event of an accident.

[carlt]

I've always known them as "stocks". I've never heard them called "Bostocks" before but there are regional variations for just about every term.

 

The biggest problem is finding someone to go under the boat to do it.

 

If you do it officially or the HSE show an interest it becomes nigh on impossible, we had to prove the trestles we used to do narrowboats with were up to it the HSE required proof that the design capability was sufficient and that they were tested and certified yearly.

 

Without you have your own indemnity insurance and even then it can be complex, for a marina or yard owners to allow a member of staff or public to go under a boat that is in effect propped up in the air would be risky because of the potential legal action they might face in the event of an accident.

Come off it Gary! You know it's perfectly safe if done properly:

[kayDee]

Oh no! What HAVE I started here!?!? Hehe! ;-)

 

So, when it first gets docked, I need to jet wash all the old blacking off right? Does it come off that easily then?

I've heard a lot of talk of angle grinders when blacking is mentioned - is this just to rough up the surface for the new stuff going on?

If there are any rusty spots, do you have to fill them in like you do with car bodywork? Sorry, just trying to find out all I can as next blacking is going to be DIY! Eeeek! ;-)

I really wish there was a way of protecting underneath the boat just to be sure - its got me all worried! :-(

Is there anywhere in the Lancashire area that has a dry dock for such use?

Kay

x

[Machpoint005]

If you go through a lock flight, you could be spending 3 hours with aerated water being actively introduced under the baseplate. Anywhere around locks, the water is pretty aerated. All in all, plenty of oxygen to cause oxidation of the BP

 

As to a waste of money, bitumen is cheap.

 

3 hours - still not long enough

 

Bitumen may be cheap but labour isn't (whether you pay money for it or not).

[denboy]

Oh no! What HAVE I started here!?!? Hehe! ;-)

 

So, when it first gets docked, I need to jet wash all the old blacking off right? Does it come off that easily then?

I've heard a lot of talk of angle grinders when blacking is mentioned - is this just to rough up the surface for the new stuff going on?

If there are any rusty spots, do you have to fill them in like you do with car bodywork? Sorry, just trying to find out all I can as next blacking is going to be DIY! Eeeek! ;-)

I really wish there was a way of protecting underneath the boat just to be sure - its got me all worried! :-(

Is there anywhere in the Lancashire area that has a dry dock for such use?

Kay

x

99% of flat bottomed boats are not blacked, power washing if you have a powerful one will take some of the blacking off mainly the loose stuff no you dont fill the pits(unless you spot weld them) the only real reason to try and get all the blacking off is if you want too put a 2 pack epoxy on the boat

[kayDee]

Thanks for that denboy, so its just to get the yuck off the hull really before more coats are added to it. That's okay, I can cope with that.

It should be a fun job to do! I'm going to get soaked and full of back yuck so I don't think it will be a skirt and heels kind of job! Eeeek!

Kay

x

[FORTUNATA]

My hull survey is tomorrow so I'll ask the surveyor about blacking the bottom. It's out of the water but they only blacked the sides. The bottom is covered in stone-like things. If they can blast all that junk off, I don't mind going underneath and doing the blacking myself. But the boatyard people say nobody blacks the bottom. So, how come so many boaters wind up with replating after a decade or so? I'm confused.

John C Payne who wrote my marine electrical guide, recommends for sea boats full painting of the hull and anodes correctly bonded and fitted. He recommends testing for eloctrolytic and galvanic causes of hull corrosion. Of course, in sea water this is more of an issue.

 

Thanks for that denboy, so its just to get the yuck off the hull really before more coats are added to it. That's okay, I can cope with that.

It should be a fun job to do! I'm going to get soaked and full of back yuck so I don't think it will be a skirt and heels kind of job! Eeeek!

Kay

x

[denboy]

My hull survey is tomorrow so I'll ask the surveyor about blacking the bottom. It's out of the water but they only blacked the sides. The bottom is covered in stone-like things. If they can blast all that junk off, I don't mind going underneath and doing the blacking myself. But the boatyard people say nobody blacks the bottom. So, how come so many boaters wind up with replating after a decade or so? I'm confused.

John C Payne who wrote my marine electrical guide, recommends for sea boats full painting of the hull and anodes correctly bonded and fitted. He recommends testing for eloctrolytic and galvanic causes of hull corrosion. Of course, in sea water this is more of an issue.

salt water is a whole different ballgame if a boat needs replating after 10 years it was probably a crap build to begin with and bad electrics and poor maint any combination of the three main cause of electrolysis is bad 240 volt connections especialy in a marina when your moored 2 foot away from the boat next to you which may have poor electrics on it this will probably set the galvanic isolator debate off again

[Guest]

Oh no! What HAVE I started here!?!? Hehe! ;-)

 

So, when it first gets docked, I need to jet wash all the old blacking off right? Does it come off that easily then?

I've heard a lot of talk of angle grinders when blacking is mentioned - is this just to rough up the surface for the new stuff going on?

If there are any rusty spots, do you have to fill them in like you do with car bodywork? Sorry, just trying to find out all I can as next blacking is going to be DIY! Eeeek! ;-)

I really wish there was a way of protecting underneath the boat just to be sure - its got me all worried! :-(

Is there anywhere in the Lancashire area that has a dry dock for such use?

Kay

x

Wigan, bottom of Wigan flight. Ring BW for appointment. I helped to black a boat called Tyto earlier this year at Wigan.