Pit Holes

[Pot Noodle Adventurer]

Hi all

 

Other than a spot weld what remedies have you tried?

 

I have heard car body filler, liquid metal and plumbers epoxy resin mentioned but I am a little sceptical!

 

Any thoughts and experiences welcomed.

 

Thanks

[Paul C]

What do you mean by spot weld, because I don't think you've used the term properly - a spot weld requires access to both sides of the panel, for example. I am guessing you mean a weld where you touch the gun/electrode on the pit and press the trigger or contact momentarily, creating a "spot" of weld metal?

 

Personally I'd use MIG and get the wire right into the pitting, then blip the trigger.

[bizzard]

You can get Mig shrouds with a bridge piece on them that fits the gun nozzle. You hold this shroud hard up against and centred over the spot to be welded and give it a buzz with the trigger.

[bizzard]

You can get Mig shrouds with a bridge piece on them that fits the gun nozzle. You hold this shroud hard up against and centred over the spot to be welded and give it a buzz with the trigger.

The trouble is by using any type of goo fillers in the pits is the mess of all the tiny grains of it which you have to sweep up when the rest of the steel hull has rusted away and disappeared completely.

[blackrose]

The only type of filler that would work for underwater applications would be a two part epoxy marine filler. Don't use car body filler.

 

http://www.boatpaint.co.uk/acatalog/International_Fillers.html

 

However the best solution is to get the pits filled with weld.

[magnetman]

The trouble is by using any type of goo fillers in the pits is the mess of all the tiny grains of it which you have to sweep up when the rest of the steel hull has rusted away and disappeared completely.

Hi all

 

Other than a spot weld what remedies have you tried?

 

I have heard car body filler, liquid metal and plumbers epoxy resin mentioned but I am a little sceptical!

 

Any thoughts and experiences welcomed.

 

Thanks

Do the pits actually go right through the steel?

 

I ask this as the title is Pit Holes.

 

Edit to correct annoying phone autocorrect

Edited September 13, 2015 by magnetman

[Boat&Bikes]

I have used metal putty for various fixes involving machine and pump castings. I have wondered how it would perform. Agree that welding is the obvious solution.

 

Ian.

[Bloomsberry]

With pitting being caused by conductivity of metals and the epoxy filler being non conductive then wouldn't the expoxy filler cure the pitting too ?

 

I realise pitting will probably begin in another area of the hull but at least the weakest spot is protected ?

[blackrose]

With pitting being caused by conductivity of metals and the epoxy filler being non conductive then wouldn't the expoxy filler cure the pitting too ?

 

I realise pitting will probably begin in another area of the hull but at least the weakest spot is protected ?

Yes if the pits are properly cleaned out and the rust removed then a good filler and painting should stop the corrosion. However, I have no knowledge about how well the filler will adhere to the inside of the pits but I would imagine bouncing off lock walls etc might knock it out.

Edited September 13, 2015 by blackrose

[The Bagdad Boatman (waits)]

lead solder would do but you cannot weld across the repair as it creates a weak joint. .

[Bloomsberry]

Yes if the pits are properly cleaned out and the rust removed then a good filler and painting should stop the corrosion. However, I have no knowledge about how well the filler will adhere to the inside of the pits but I would imagine bouncing off lock walls etc might knock it out.

 

The widest part of a narrowboat is above the waterline so any contact with the lock wall would be here ?

 

There is also the sacrificial edge of the base plate that offers protection so contact with the side of the hull below the waterline would be quite rare anyway ?

[David Schweizer]

 

The widest part of a narrowboat is above the waterline so any contact with the lock wall would be here ?

 

There is also the sacrificial edge of the base plate that offers protection so contact with the side of the hull below the waterline would be quite rare anyway ?

 

But you are overlooking the presence of the ubiquitous projections from lock walls and gates, which can catch the hull sides between guard irons, and often do.

[Neil2]

I think Belzona would work very well on a grit blasted hull and could be done without resort to specialist help ie welders.

[Sea Dog]

It always seemed to me that, when someone posted questions such as this on this forum, knowledgeable folks with experience in the subject would be along pretty soon to achieve a reasonable collection of sound advice. Lately we seem to have a preponderance of wild-ass guesses, interspersed by the odd sage comment. I can't help the OP on this subject as it's quite specialist, but I would be interested to read constructive comment that helps him to solve his problem. We have some really helpful folk here with an amazing range of knowledge and experience - perhaps we could make a little space for them?

[Traveller]

+1

 

But perhaps they are all off cruising in this wonderful weather!

Edited September 14, 2015 by Traveller

[Paul C]

It always seemed to me that, when someone posted questions such as this on this forum, knowledgeable folks with experience in the subject would be along pretty soon to achieve a reasonable collection of sound advice. Lately we seem to have a preponderance of wild-ass guesses, interspersed by the odd sage comment. I can't help the OP on this subject as it's quite specialist, but I would be interested to read constructive comment that helps him to solve his problem. We have some really helpful folk here with an amazing range of knowledge and experience - perhaps we could make a little space for them?

 

I re-read the thread and didn't see what you described - which post numbers do you mean?

[Traveller]

Paul, don't want to take sides here as there enough in fighting on this forum at times. But I read Sea Dogs post to mean that there was no comment from anyone who had first hand experience of using filler on pits. That is quite probably because nobody has tried it.

[Sea Dog]

I'm not intending to point fingers Paul, in this thread or any others. It's just an observation that has crept up on me over the last little while, hence why I said "lately".

 

Edited to add that the post above has interpreted me correctly as far as this thread is concerned.

Edited September 14, 2015 by Sea Dog

[Paul C]

But recommending welding the holes isn't a "wild ass guess" due to inexperience over fillers.

[David Schweizer]

It always seemed to me that, when someone posted questions such as this on this forum, knowledgeable folks with experience in the subject would be along pretty soon to achieve a reasonable collection of sound advice. Lately we seem to have a preponderance of wild-ass guesses, interspersed by the odd sage comment. I can't help the OP on this subject as it's quite specialist, but I would be interested to read constructive comment that helps him to solve his problem. We have some really helpful folk here with an amazing range of knowledge and experience - perhaps we could make a little space for them?

 

I am not sure which catagory my observations come into, but I will try and relay some "sound advice" i received when a few pits were identified in the hull sides of our boat a few years ago. I was advised by various peiople who earn tyhweir libvingh working on boats that the only long term solution was welding, either by overplating, cutting and filling, or by weld filling the pits. As the pits were quite small the third alternative was chosen. I was also advised that any type of chemical filler would eventuually fail and that any future hull survey would nor find chemical filling acceptable in an underwater location.

 

The weld filling was inspected during a recent hull survey, and was deemed to be satisfactory, with no degrading at all.

[Sea Dog]

David, perhaps I didn't pick the best post on which to make a general observation but, as I wasn't aiming to have a dig, this quite mild one seemed a reasonably non-contentious choice at the time. No one here is particular example of a wild-ass guess, but it's probably fair to say that your input above is an example of the knowledge or experience I was referring to.

[Murflynn]

as with any welding, preparation of the area to be welded is important.

you would need to grind out the pit until you get a clean depression and then build up weld metal proud of the original surface.

then grind back to a smooth surface.

Yes if the pits are properly cleaned out and the rust removed then a good filler and painting should stop the corrosion.

in fact if you build a hull from epoxy in the first place, possibly reinforced with some strands of glass, there will be nothing to corrode.

[Midnight]

as with any welding, preparation of the area to be welded is important.

you would need to grind out the pit until you get a clean depression and then build up weld metal proud of the original surface.

then grind back to a smooth surface.

in fact if you build a hull from epoxy in the first place, possibly reinforced with some strands of glass, there will be nothing to corrode.

 

 

I bought a job lot of those round grinding balls you get 3 holes per ball before they wear out. You get a nice concave pit ideal for mig welding. I found the white ones best and the local hardware shop had lots of them at a good price

 

[blackrose]

 

The widest part of a narrowboat is above the waterline so any contact with the lock wall would be here ?

 

There is also the sacrificial edge of the base plate that offers protection so contact with the side of the hull below the waterline would be quite rare anyway ?

Not necessarily, haven't you ever seen protrusions from lock walls? If contact from locks, moorings, etc, with the side of the hull is so rare I wonder why one sees so much scraped blacking on narrowboats?

 

Anyway, it may not necessarily need a "direct hit" to knock filler out.

[gazza]

as with any welding, preparation of the area to be welded is important.

you would need to grind out the pit until you get a clean depression and then build up weld metal proud of the original surface.

then grind back to a smooth surface.

 

in fact if you build a hull from epoxy in the first place, possibly reinforced with some strands of glass, there will be nothing to corrode.

Correct on both counts

 

If you have a boat slow turning back to Fe2O3 then put the fillers away - its not the correct solution - especially given how rough handled many boats are....

 

Welding is the only correct repair as David has already pointed out.

 

Small pits can be ground back and welded up with no problem whatsoever.

 

Large pits may need overplating, neater solution is to cut out and insert fresh steel but this is often too time consuming and expensive for the average teabag boat owner - especially if the teabag concerned has no historic value.

 

Beware the boat bodger brandishing a tin of snot to make good hull corrosion

Edited September 14, 2015 by gazza