Rusty Bottom

[Moley]

I will update my build log in due course, but NB Talpidae is now stripped back to a bare shell. She was bought without a survey (as I couldn't get one done for about 6 weeks) on the basis that the hull has been well maintained and regularly blacked. That might apply to the outside, but the inside's a different matter!

 

Years of condensation and leaking plumbing and windows have allowed some water ingress, and much flooring was rotten in the galley / toilet / shower areas. On removing side panels and insulation I found the main offender!

(The electrics hanging loose was my doing, they have now been removed).

 

 

There has previously been a pump-out toilet, long since replaced by a Thetford. I assume the pipe pictured was a breather. However, it has been cut off, has since cracked at gunwhale level, and wasn't sealed effectively anyway, so it would appear that rainwater has been trickling in for some time. I then lifted the flooring and ballast to discover sheets of rust in the (dry?) bilge and rising up the walls. I've read the thread about the nature of corrosion, how it forms in layers and looks worse than it is but, removing sheets of rust with a wallpaper scraper, chisel and shovel, it looked bad enough to me!

 

 

Having scraped and brushed down to base metal then tapping gently, hitting a bit harder and finally walking on the base plates it still feels solid enough to me (quite enough metal left), but should I be worried, is there any way of testing thickness from the inside, and what does overplating cost?

 

I am now proposing treating with Vactan, (stopping the leaks of course), painting with bitumen, laying roofing felt while the bitumen's still wet and then re-laying ballast - would this be acceptable?

 

Thanks, Ade.

[ChrisPy]

hmmm......

 

.. interesting, ref. the thread related to the surveyor who didn't or couldn't lift any floor panels to examine the bottom from the inside.

 

I think your remediation proposal is sound. Just make sure you get all the loose stuff out of those awkward corners with a stiff hand brush and give it a good vacuum before the vactan. avoid the temptation to get back to shiny metal, it is counter-productive.

 

it sounds as if your boat is afloat, otherwise sounding it out everywhere will give you an idea of the comparative thicknesses of remaining steel plate.

[khaffra]

you need an ultrasonic thickness tester to check the plate thickness this will work from the inside or outside, don't know if you can hire one but they are expensive to buy, maybe have a word with a surveyor to come and check the thickness if you are worried about it, shouldnt cost much if they are already in the area.

[John Orentas]

That kind of rusting always looks bad but a few minutes with a grinder and you will realise it is very superficial. It is a good idea not to do anything that is cannot be removed or inspected, laying roofing felt on wet bitumen sounds like a good idea but things would be very messy if you had a need to get in there again and it could be a moisture trap.

 

Better to simply paint the base with bitumen or Waxoyl, sit the concrete flagstones on old rubber cable or something like that so that things can drain and dry out.

[stuart]

Bitumen is cheap and works well - Waxoyl from experience is very waxy and can be hard to do in cold weather. Can also be difficult to see where you have done.

 

I think I would use the Vactan stuff and perhaps Bitumen over the top of it?

 

I'd also get someone to weld a plate over the old pump-out hole so once and for all its sealed and wont cause you trouble in the future.

 

Perhaps you could "borrow" the ultrasound machine from a hospital!?!

 

While you've got the floor up, remember to layout the ballast for your new room layout/positioning. You wont need much ballast under stoves/tanks/showers etc.

Edited October 17, 2005 by stuart

[nigel carton]

http://www.inlec.com/view_product.php?product=102

 

try the above

[Moley]

Thanks folks,

 

Do bitumen or waxoyl stink - if so, for how long?

 

To Stuart - thanks for the suggestion re. ultrasound machine, but doubt if the wife could sneak one out of work un-noticed as they tend to be none too portable! Nice idea though.

And re. ballast, I understand your boat lists a little, should I line the walls and then fit floor so it was possible to re-arrange ballast later?

 

Cheers,

Ade.

[DaveR]

I was once told that 10mm of rust comes from 1mm of steel a 10 : 1 expansion factor - is that right?

[Carrie]

Thanks folks,

 

Do bitumen or waxoyl stink - if so, for how long?

 

To Stuart - thanks for the suggestion re. ultrasound machine, but doubt if the wife could sneak one out of work un-noticed as they tend to be none too portable! Nice idea though.

And re. ballast, I understand your boat lists a little, should I line the walls and then fit floor so it was possible to re-arrange ballast later?

 

Cheers,

Ade.

 

 

Bitumen doesn't stink. However it does cling to your hair forever. (yes, I know you're not supposed to be painting your hair with it - it just happens!)

[nigel carton]

Bitumens great for the boot of your car to, specially when you go around a round about and the full 5 litres empties all over your floor! DOH sorry

[anthony]

chris polley i hear you matey.

 

IM not to consearned as the previous owner stripped the boat and put all new floorin in and fixtures and fitings.

The boat is bone dry.

We have had 2 surveys have a warranty and insurance.

So if it sinks f it.

[anthony]

chris polley i hear you matey.

 

IM not to consearned as the previous owner stripped the boat and put all new floorin in and fixtures and fitings.

The boat is bone dry.

We have had 2 surveys have a warranty and insurance.

So if it sinks f it.

 

 

He he, talk about eat my words.

 

It was bone dry.

 

Hows the job going?

 

Did you scrap it when it was sitting in the water?

[Moley]

Yes Anthony,

 

I was a bit concerned about how hard I could chisel and scrape, but she's been in the water all along and I've not gone through yet. The only minor weep I found was in the bulkhead between the cabin and the engin'ole, but that was only 2 or 3mm to start with. Shouldn't be a problem now I've dried out engine bilge, assuming I keep it that way.

 

Mole.

[John Orentas]

Life will seem a lot better when you have scraped off the rust and cleaned things up a bit. You will realise just how little metal you have lost.

[anthony]

Can it not just be left to dry out then left?

[Moley]

No, it needs to be removed, and it's easiest to do that while it's still wet or damp.

 

When it dries out the flakes hold tighter and then you have to get the end of a chisel under the layers.

 

Then rustproof with Vactan (got this tip from Chris Polley, and the stuff really is the dog's danglies) or Kurust, followed by bitumen.

[Yamanx]

From the outside in I have managed to put the scraper right through in two places. Unfortunately it leaked all the oil, diesel and water mixture from the engine area all over the boatyards nice clean concrete

 

Emptied out the muck though!

 

Overplating this weekend

[Moley]

...managed to put the scraper right through ....... leaked all the oil, diesel and water mixture from the engine area all over the boatyards nice clean concrete

 

Emptied out the muck though!

 

Well done Yammy, saved a few quid on cat litter and JCB hire too

[Supermalc]

Bitumens great for the boot of your car to, specially when you go around a round about and the full 5 litres empties all over your floor! DOH sorry

 

This happened on my boat last year. Had just pulled her out and straightened the original prop shaft. I saw some friend at Bardney moorings so stopped to see them. While demonstrating the new winch I had fitted (yet to use it btw) I moved the new gallon can of bitumin, which was on the floor in the front V. I had only used a brushfull, and didn't realize the lid was loose fitting.

 

It fell off, with the WHOLE TIN emptying

 

Luckily it missed most of my stuff, only ruining 1 of the cushions (gifted or out of a skip) and blacking my porapower box that I had on the boat, as I had used it for the work earlier.

 

We cleaned up most from the top planks, and there is a partition under the floor in the middle of the boat, which stopped it going under the engine.

 

However the next day, most of it had not dried. I spent the morning collecting it, and returning it to the tin with a paint brush. Honestly, this is the first time I have been 'un-painting'. I collected about 3 litres, the rest I managed to paint around the inside of the hull, where it was dry.

 

ALWAYS, ALWAYS make sure your paint tin lids etc. are a tight fit.

[Guest]

From the outside in I have managed to put the scraper right through in two places. Unfortunately it leaked all the oil, diesel and water mixture from the engine area all over the boatyards nice clean concrete

 

Emptied out the muck though!

 

Overplating this weekend

Out of interest, have you decided how to overcome baseplate welding problem?

[Yamanx]

Quote:

 

Out of interest, have you decided how to overcome baseplate welding problem?

 

Well I havent come up with a definative plan yet. I've enlisted some expert welders from work and between us we will come up with a plan of action on Saturday.

 

I've seen another boat recently having a new bottom and the method didnt involve any welding to the boat bottom. What they did was make a shoe, the same shape as the boat and about 500mm up the sides. Lifted the boat in and welded just around the top. We not going to do this, but it illistrates that we may not need to worry about attaching the steel in the centre.

[Guest]

Quote:

 

Out of interest, have you decided how to overcome baseplate welding problem?

 

Well I havent come up with a definative plan yet. I've enlisted some expert welders from work and between us we will come up with a plan of action on Saturday.

 

I've seen another boat recently having a new bottom and the method didnt involve any welding to the boat bottom. What they did was make a shoe, the same shape as the boat and about 500mm up the sides. Lifted the boat in and welded just around the top. We not going to do this, but it illistrates that we may not need to worry about attaching the steel in the centre.

That is interesting-I think that is how a Springer I once saw must heve been done. It looked very tidy.

[anthony]

That is interesting-I think that is how a Springer I once saw must heve been done. It looked very tidy.

 

Interesting, ive seen boats that have been overplated and i think they look a mess so it would be good to see an example of this.