Cracks in cabin sides

[dizzypanic]

Hi,

 

Im looking for a first boat and have found one which fits the bill. However, I have noticed that the cabin walls have crached in a couple of places. The boat is from 1977 and the superstructure is 4mm steel. The crack appears to propagate from the corner of one of the windows (De Havilland Comet anyone!!!) and is approx 8-10 inches in length. There is a similar crack at the opposite corner of the window. What I want to know is if this is acceptable for a boat of this age, and whether it can simply be welded shut. I have noticed similar fatigue cracks on other, similar boats in brokerages, so this isn't an isolated phenomenon.

 

Any response will be much appreceiated,

 

Regards,

Dizzy.

Edited May 17, 2010 by dizzypanic

[Guest]

Hi,

 

Im looking for a first boat and have found one which fits the bill. However, I have noticed that the cabin walls have crached in a couple of places. The boat is from 1977 and the superstructure is 4mm steel. The crack appears to propagate from the corner of one of the windows (De Havilland Comet anyone!!!) and is approx 8-10 inches in length. There is a similar crack at the opposite corner of the window. What I want to know is if this is acceptable for a boat of this age, and whether it can simply be welded shut. I have noticed similar fatigue cracks on other, similar boats in brokerages, so this isn't an isolated phenomenon.

 

Any response will be much appreceiated,

 

Regards,

Dizzy.

 

I'm certainly no expert at all - but perhaps an adverse result of a poorly managed 'crane out' at some point.....

 

I don't think I would be happy unless a surveyor could look at the damage and advise. You might want to try to get some pics up on here and you might get more feedback.

 

Cheers,

Edited May 17, 2010 by MJG

[Tim Doran]

I agree that a crack could have been caused by some stress along the hull. Definatly get a survey for all the other reasons as well.

 

Tim

[Naughty Cal]

If a surveyor looks at it and suggests it is little more than superficial stress cracking you could use it to your advantage as a bargaining tool.

[alan_fincher]

Hi,

 

Im looking for a first boat and have found one which fits the bill. However, I have noticed that the cabin walls have crached in a couple of places. The boat is from 1977 and the superstructure is 4mm steel. The crack appears to propagate from the corner of one of the windows (De Havilland Comet anyone!!!) and is approx 8-10 inches in length. There is a similar crack at the opposite corner of the window. What I want to know is if this is acceptable for a boat of this age, and whether it can simply be welded shut. I have noticed similar fatigue cracks on other, similar boats in brokerages, so this isn't an isolated phenomenon.

 

Any response will be much appreceiated,

 

Regards,

Dizzy.

I've never heard of anything remotely like this in a steel narrowboat cabin.

 

If it's really 4mm steel, I'd expect bending or buckling before cracking, even if the boat has been abused.

 

I can't imagine how you would crack 4mm steel, and certainly not over a 10" length.

 

Personally I'd go nowhere near it.

[paulcatchpole]

I've never heard of anything remotely like this in a steel narrowboat cabin.

 

If it's really 4mm steel, I'd expect bending or buckling before cracking, even if the boat has been abused.

 

I can't imagine how you would crack 4mm steel, and certainly not over a 10" length.

 

Personally I'd go nowhere near it.

 

I'm with Alan, seems a bit unlikely on mild steel... It'd have to harden up quite a bit before you'd crack it... That much flexing, to work-harden? Surely not...

 

Not actually plastic is it?

 

PC

[alan_fincher]

Any chance of pictures of the boat, and (particularly), the "cracks" ?

[nb Innisfree]

If the window holes were cut without a corner radius then I would think it is possible, corners cut to a point will be stressed at that point with any metal, basic engineering fact really.

[ChrisPy]

If the window holes were cut without a corner radius then I would think it is possible, corners cut to a point will be stressed at that point with any metal, basic engineering fact really.

we're not talking about the window openings of a DH Comet here, just a narrowboat.

There should be no 'cracks' (whatever they are). 4mm mild steel does not normally crack.

Soemthing wrong somewhere.

[casper ghost]

These cracks, they aren't just where the cabin steel sheets join are they, maybe not fully welded from the outside and the paint has cracked with a slight movement?

My 1970 boat had a cabin top that was not made from normal mild steel, it was difficult to weld, almost iron, I wonder if this is something similar and it's delaminating or just cracked..

[magnetman]

Hi,

 

Im looking for a first boat and have found one which fits the bill. However, I have noticed that the cabin walls have crached in a couple of places. The boat is from 1977 and the superstructure is 4mm steel. The crack appears to propagate from the corner of one of the windows (De Havilland Comet anyone!!!) and is approx 8-10 inches in length. There is a similar crack at the opposite corner of the window. What I want to know is if this is acceptable for a boat of this age, and whether it can simply be welded shut. I have noticed similar fatigue cracks on other, similar boats in brokerages, so this isn't an isolated phenomenon.

 

Any response will be much appreceiated,

 

Regards,

Dizzy.

 

I've never seen this although I have seen cracked welds here and there specially when ground down too much. the cabin side plates could well be joined at the edge of a window for ease of build - are the cracks vertical?

[nb Innisfree]

we're not talking about the window openings of a DH Comet here, just a narrowboat.

There should be no 'cracks' (whatever they are). 4mm mild steel does not normally crack.

Soemthing wrong somewhere.

 

True it's not a Comet, but if there was distortion from regular expansion and contraction in the sun it might be possible? any thickness can crack if stressed.

Edited May 17, 2010 by nb Innisfree

[OldGoldy]

I've never seen this although I have seen cracked welds here and there specially when ground down too much. the cabin side plates could well be joined at the edge of a window for ease of build - are the cracks vertical?

We have a boat on our moorings where the window apertures were made by 'piecing' the steel, rather than cutting the windows from a 'solid' sheet. These have some cracks, as magnetman says, where the welds weren't deep enough and have been ground down too much. The final effect is one of a capital H over some of the windows.

 

If the cracks are NOT vertical, well, I'd be inclined to keep clear, but then you're going to have a survey aren't you? See what the man say!!

[Guest]

we're not talking about the window openings of a DH Comet here, just a narrowboat.

There should be no 'cracks' (whatever they are). 4mm mild steel does not normally crack.

Soemthing wrong somewhere.

Agreed. I know the old adage about square holes in sheets, but something is wrong if steel of this thickness is cracking. Are you sure it is not the paintwork that is cracking.

[Martin Kedian]

Agreed. I know the old adage about square holes in sheets, but something is wrong if steel of this thickness is cracking. Are you sure it is not the paintwork that is cracking.

 

 

Hi The sheet joins in most cabins are placed in this area to avoid having full joins from top to bottom of the cabin thus the joins are less visable through the paint it would be reasonable to assume that this is the case the weld should have been done on both the outside and then backed up on the inside the cleaning off of the weld on the outside would have reduced its strength and that is probably the reason that it has failed there is ne reason why a repair could not be made in this case The only isue would be that the external paint would be dammaged localy in the rewelding process if done correctly there should be no further problems It would not seriously undermine the soundness of the boat and it is a good point to haggle on for a reduction If you want to speak furter please feel free to ring me on 01604 511512 or PM me Hope this helps If you get four boaters together you will get at least seven opinions this is mine based on 37 years as a steel fabricator and boat builder Martin

[alan_fincher]

If you get four boaters together you will get at least seven opinions this is mine based on 37 years as a steel fabricator and boat builder Martin

If the assumption that this is actually the failure of welds, rather than cracking of steel plate, as originally implied, proves to be correct, I think you might get rather less conflicting opinions.

 

The OP does not mention whether these are "cracks" running truly vertically up the cabin sides. That's why I think prompts to the OP to give more information, (and preferably some pictures) are worthwhile.

 

Until we know where the "cracks" actually are, I think we might all be guessing a bit ?

[blackrose]

Sounds like subsidence to me...

[dizzypanic]

Hi guys,

 

thank for all the responses! Unfortunately I didn't take pictures, although I may go and see the boat again at the weekend and in that case will do so. To try to answer some of the questions;

 

1. A survey would certainly be arranged if I do decide to go for this boat.

 

2. Its definitely steel, and steel definitely does fatigue.

 

3.They are cracks, a penknife blade fits through to a depth of approx. 8mm (before the blade gets too thick).

 

4. Sorry for the MS paint, but this shows the location of the cracks in relation to the window. It is on the right hand side (from the steerers POV) and is on the foremost window.

pic

 

Regards,

Dizzy

[DHutch]

My only thought is that window in question lies between two section of the cabin sides and that these 'cracks' are along the joins in the sheet.

 

These joins may have only been welded from the inside, possibility only with only a small number of short tacks, or prehaps ive no welding at all between the roof/gunnel and the window apatute, before being made good with filler and painted. If you can stick a blade into them for 8mm unless there very thick sides i would suggest that goes right through!!

 

Might not be a huge issue, and could either be welded with a series of small runs, or just filled and painted. Assuming as said, there no sighs of bending, buckling or other broken welds.

 

 

 

Daniel

[RLWP]

I agree with Daniel, except the cracks must go right through. There's no way the top is made out of plate 8mm thick. They look like the joins in the siode sheets to me.

 

Richard

[Guest]

Mmm lot's of speculation and still no pictures as per post #2

[RLWP]

Mmm lot's of speculation and still no pictures as per post #2

 

That's almost true. There is a sketch now:

 

 

Richard

 

For me, on a welded steel boat, those cracks are a reason to walk away. They shouldn't happen, you have to take the window out to weld them up, and then the cabin sides need a repaint. More to the point, if a simple, unstressed cabin side weld has cracked, what's the rest of the workmanship like?

[OldGoldy]

That's almost true. There is a sketch now:

 

 

Richard

 

For me, on a welded steel boat, those cracks are a reason to walk away. They shouldn't happen, you have to take the window out to weld them up, and then the cabin sides need a repaint. More to the point, if a simple, unstressed cabin side weld has cracked, what's the rest of the workmanship like?

Could this boat have been stretched?

 

I have seen two or three lengthened boats and they all have had staggered joins at the windows. Look for signs of work on the hull below the lower (RH) 'crack' and look about, oh, 8ft away fore or aft and see if there is any evidence of any more welding/grinding work. Check for work across the roof over the LH crack. Check for colour differences of the panelling inside.

[Guest]

When we are talking about cracks where a pen knife can be pushed through, I am beginning to get nervous. I would be wanting a significant reduction in price, plus a very thorough survey of the rest of the shell. You have to ask yourself as to why the owner is unloading this boat.

[nb Innisfree]

If it was a stress crack from too sharp an angle it would have gone at 45ish degrees, so a joint crack.