Surveyor reccomendations - Drilling to measure baseplate

[Jennarasion]

Hi everyone, 

Recently I bought a narrowboat, but didn't have a survey beforehand (i know). The boat is currently on the hard, and I've had a surveyor come round. Pretty much everything was okay, including the baseplate thickness. Issue is, during the auditory tests, he could hear a lot of scale as well, meaning the measurements could be off. He has said to complete his inspections the measurements must be taken from the inside.

The thought of removing the tiles, floorboards, ballast, and everything else (and then having to put it all back again) fills my heart with woe.

I was explaining this to one of my neighbours, and they reccomend drilling into the boat to take the measurements, and then having a welder plug up the holes afterwards. I've never heard of this before, and after searching the forums I've found that it's what used to be done, before the technological advances. 

Does anyone know of a surveyor who would still do measurements this way, preferably in the london/surrey area? What are your thoughts of doing things this way? Obviously putting any holes in a boat is generally not a good idea, but removing everything seems like a fate that i want to avoid. I'd rather have a surveyor do it for insurance purposes. 

[alan_fincher]

My first reaction is that if you want to drill through the base-plate at various positions then the boat will need to be raised from the ground by more than the length of a suitable drill armed with a suitable drill bit.

 

Many narrow boat docking arrangements would not raise the boat up sufficiently.

 

Once you have the holes how would you propose to measure how much solid steel you have before it changes to scale or rust?

 

You have really got to trust whoever is welding up those holes, and hope they don't get t sightly wrong at any point!

[Tracy D'arth]

If the floor and ballast is still in place, how does the surveyor know that it is scale that is rattling on the base plate and not pieces of ballast?

 

If you want to inspect the top of the base plate I would drill 19mm holes in the floor sheets in out of the way areas and use a cheap borescope camera on a laptop.  There should be a floor trap at the back up against the rear bulkhead to check for water under the floor anyway.

[MtB]

21 minutes ago, Jennarasion said:

Issue is, during the auditory tests, he could hear a lot of scale as well,

 

Eh?

 

The ultrasound thickness testers are silent to the human ear, I'd have thought. Never used one though. 

 

[BoatinglifeupNorth]

Ask your neighbour is he had this done when he bought the boat/had a survey.

 I imagine the answer will be “No”.  I’ve never heard of this being done by a surveyor, or any surveyor recommending it or would accept responsibility in recommending it should the boat sink afterwards.
 A lot of neighbours have good ideas for their neighbours boats that they don’t do to theirs😂  

[Captain Pegg]

What does “auditory testing” actually mean?

 

It could surely only come up with measurements if it were ultrasound. That shouldn’t be corrupted by scale and only the test device can ‘hear’ the sound.

 

@MtB beat me to it but this statement made very little sense to me.

[BEngo]

It was once not uncommon for a boiler inspector to request a hole be drilled in order to confirm metal thickness, (afterwards tapped and a bolt fitted and peened in).  That has long gone and ulrasonics are the tool now.

 

If your surveyors meter cannot distinguish between metal and scale it is not fit for purpose.  Possibly it is an model, which did need clean metal or if may be just a cheapy.

N

[Crewcut]

I'm reminded of this...

 

Seriously though, was the surveyor using a hammer to test the hull in addition to using a meter?

Edited February 24 by Crewcut

[MtB]

23 minutes ago, BoatinglifeupNorth said:

Ask your neighbour is he had this done when he bought the boat/had a survey.

 I imagine the answer will be “No”.  I’ve never heard of this being done by a surveyor, or any surveyor recommending it or would accept responsibility in recommending it should the boat sink afterwards.
 A lot of neighbours have good ideas for their neighbours boats that they don’t do to theirs😂  

 

I've long noticed this effect too.

 

Towpath experts pontificating may well be experts, but they are just as likely to be clueless, just like on here. 

[Jennarasion]

43 minutes ago, alan_fincher said:

My first reaction is that if you want to drill through the base-plate at various positions then the boat will need to be raised from the ground by more than the length of a suitable drill armed with a suitable drill bit.

 

Many narrow boat docking arrangements would not raise the boat up sufficiently.

 

Once you have the holes how would you propose to measure how much solid steel you have before it changes to scale or rust?

 

You have really got to trust whoever is welding up those holes, and hope they don't get t sightly wrong at any point!

The hight of the raise is a good point - mine is rather low up so could be difficult 🤔

39 minutes ago, Tracy D'arth said:

If the floor and ballast is still in place, how does the surveyor know that it is scale that is rattling on the base plate and not pieces of ballast?

 

If you want to inspect the top of the base plate I would drill 19mm holes in the floor sheets in out of the way areas and use a cheap borescope camera on a laptop.  There should be a floor trap at the back up against the rear bulkhead to check for water under the floor anyway.

 

Youre asking the wrong person 😂 there was tons of scale on the baseplate in general that I had to clean, so possibly because of that? Or maybe he's just guessing. 

 

 

- I havent seen any floortraps, but I'll have a look

42 minutes ago, BoatinglifeupNorth said:

Ask your neighbour is he had this done when he bought the boat/had a survey.

 I imagine the answer will be “No”.  I’ve never heard of this being done by a surveyor, or any surveyor recommending it or would accept responsibility in recommending it should the boat sink afterwards.
 A lot of neighbours have good ideas for their neighbours boats that they don’t do to theirs😂  

He did actually! The same surveyor told him that he needed overplating. He instead drilled the holes and found he was fine. This neighbour isnt the most reliable person though, so all insight is considered 😂

41 minutes ago, Captain Pegg said:

What does “auditory testing” actually mean?

 

It could surely only come up with measurements if it were ultrasound. That shouldn’t be corrupted by scale and only the test device can ‘hear’ the sound.

 

@MtB beat me to it but this statement made very little sense to me.

Sorry, I used the wrong word. During the percussive testing he heard scale. He did use ultrasound, but because of the scale doesn't trust the results

37 minutes ago, BEngo said:

It was once not uncommon for a boiler inspector to request a hole be drilled in order to confirm metal thickness, (afterwards tapped and a bolt fitted and peened in).  That has long gone and ulrasonics are the tool now.

 

If your surveyors meter cannot distinguish between metal and scale it is not fit for purpose.  Possibly it is an model, which did need clean metal or if may be just a cheapy.

N

I know the model he used, is there anything in particular thats a red/green flag?

31 minutes ago, Crewcut said:

I'm reminded of this...

 

Seriously though, was the surveyor using a hammer to test the hull in addition to using a meter?

I was working at the time so wasn't outside, but the was a hammer-like sound 😂

[David Mack]

58 minutes ago, MtB said:

 

Eh?

 

The ultrasound thickness testers are silent to the human ear, I'd have thought. Never used one though. 

 

The traditional technique is to hit it with a hammer. If you get a clean ringing sound then you have hit solid steel, if you get a dull thud that is indicative of significant softer material. On an old boat that could either be surface rusting/scale or slag inclusions within the plate thickness. On a leisure narrowboat built within the last 50 years you shouldn't find any inclusions (because steel production techniques have improved since the 1930s) but there may well be surface corrosion. But a decent quality ultrasound meter will determine the plate thickness from the test surface to the first slag/scale boundary, so should highlight either problem anyway.

Edited February 24 by David Mack

[MtB]

1 minute ago, David Mack said:

The traditional technique is to hit it with a hammer. If you get a clean ringing sound then you have hid solid steel, if you get a dull thud that is indicative of significant softer material. On an old boat that could either be surface rusting/scale or slag inclusions within the plate thickness. On a leisure narrowboat built within the last 50 years you shouldn't find any inclusions (because steel production techniques have improved since the 1930s) but there may well be surface corrosion. But a decent quality ultrasound meter will determine the plate thickness from the test surface to the first slag/scale boundary, so should highlight either problem anyway.

 

 

Yes I was beginning to conclude the OP's term "auditory tests" was just a euphemism for the crude method of just whacking it with a hammer and listening, rather than using an ultrasound thickness tester. 

 

 

[PeterScott]

2 hours ago, Jennarasion said:

...surveyor come round. Pretty much everything was okay, including the baseplate thickness. Issue is, during the auditory tests, he could hear a lot of scale as well, meaning the measurements could be off. He has said to complete his inspections the measurements must be taken from the inside.... neighbours, and they recommend drilling into the boat to take the measurements, and then having a welder plug up the holes afterwards....Obviously putting any holes in a boat is generally not a good idea...

Is this cure worse than the disease ??

[Mike Adams]

1mm of metal loss produces about 10mm of scale so you don't need much rust to produce some scale. The first survey I had on the tidal Thames in the 1980's was done with a man with a big hammer - no ultrasonics. You could tell the thickness of the plates by the sound. If they are thin and scaly you get a dead sort of note and very thin you make a dent or a hole otherwise a sharp  note if they are OK. Not very scientific but seemed to be the standard method at that time. In my experience you don't tend to get so much pitting inside than out but If I had the boat I would want to know what is going on in the bilges so would make so access points to ensure there is not any water in there anyway. You don't say how old the boat is but you shouldn't allow rain water from the bow or stern to get  into the cabin area.

[Captain Pegg]

2 hours ago, Jennarasion said:

Sorry, I used the wrong word. During the percussive testing he heard scale. He did use ultrasound, but because of the scale doesn't trust the results

That suggests the surveyor doesn’t really understand how the device they are using works.

Ultrasound works by pulsing sound waves into the test piece and measuring the time it takes for them to return having reflected off any boundary that it encounters, be that the opposite edge of the piece concerned or a crack within its volume. The wave will not significantly penetrate beyond any change in the basic material density and therefore will not pick up any form of different material beyond the test piece.

 

The ultrasound wave will predominantly reflect off the boundary between sound steel and the ‘scale’ beyond it. A small amount will be lost and some may even return to the test device as a shadow having bounced off a further interface.

 

If the measured thickness gives a sensible outcome that is not too far removed from the nominal plate thickness I’d be very inclined to believe it.

 

Note also that original quoted plate thickness (if you know it) is a nominal value. The actual manufactured thickness of steel plates can vary significantly from that nominal thickness.

 

And only worry about whole numbers of millimetres. Quoting thicknesses to the nearest tenth of a millimetre is kidding yourself.

Edited February 24 by Captain Pegg

[blackrose]

Drilling holes in the baseplate sounds like a stupid idea to me. The whole rationale behind ultrasonic testing is that it's a non-invasive/non- destructive test. If conducted properly by someone competent with decent equipment it should differentiate been good steel and scale. I suggest you ditch whoever has been advising you and find someone who knows what they're doing.

[BoatinglifeupNorth]

1 hour ago, blackrose said:

Drilling holes in the baseplate sounds like a stupid idea to me. The whole rationale behind ultrasonic testing is that it's a non-invasive/non- destructive test. If conducted properly by someone competent with decent equipment it should differentiate been good steel and scale. I suggest you ditch whoever has been advising you and find someone who knows what they're doing.

Hopefully her neighbour isn’t this guy😂

 

[Rickent]

3 hours ago, BoatinglifeupNorth said:

Hopefully her neighbour isn’t this guy😂

 

Jesus christ.  That's grim.

[ditchcrawler]

11 minutes ago, Rickent said:

Jesus christ.  That's grim.

 

4 hours ago, BoatinglifeupNorth said:

Hopefully her neighbour isn’t this guy😂

 

Did you find the video for the following week. When I moored at Napton one of our moorers use to do that and go round the water line, it was better nick than that.

[blackrose]

What a pair of clowns. I heard of doing that 25 years ago but only for touching up blacking around the waterline. If the boat hasn't been out the water for 20 years and is in a bad state as he says, then what he's doing is a waste of time.

[MrsM]

10 hours ago, Rickent said:

 

 

14 hours ago, BoatinglifeupNorth said:

Hopefully her neighbour isn’t this guy😂

 

I can only see that potentially damaging the mooring ring and hand rail as well as polluting the canal with grindings and filler, blacking etc. Get it docked and do it properly.

[David Mack]

13 minutes ago, MrsM said:

as polluting the canal with grindings and filler, blacking etc.

Where do you think the grinding, filler and blacking end up if you do the job in the average dry dock?

[Jennarasion]

17 hours ago, Mike Adams said:

1mm of metal loss produces about 10mm of scale so you don't need much rust to produce some scale. The first survey I had on the tidal Thames in the 1980's was done with a man with a big hammer - no ultrasonics. You could tell the thickness of the plates by the sound. If they are thin and scaly you get a dead sort of note and very thin you make a dent or a hole otherwise a sharp  note if they are OK. Not very scientific but seemed to be the standard method at that time. In my experience you don't tend to get so much pitting inside than out but If I had the boat I would want to know what is going on in the bilges so would make so access points to ensure there is not any water in there anyway. You don't say how old the boat is but you shouldn't allow rain water from the bow or stern to get  into the cabin area.

A few of my windows leak, so possibly some water in the cabin under the floor, however since I've been here the amount isnt extraordinary. He mentioned using rust inhibitor as well, so probably something down there, but he indicated that it was pretty much the entire baseplate that needs checking, so also could very well be pieces of ballast as suggested above. I agree that i should get a few traps, but i would rather install these in a few discreet places down the road rather than from scratch. Boat is a 1980s (i think), springer.

16 hours ago, blackrose said:

Drilling holes in the baseplate sounds like a stupid idea to me. The whole rationale behind ultrasonic testing is that it's a non-invasive/non- destructive test. If conducted properly by someone competent with decent equipment it should differentiate been good steel and scale. I suggest you ditch whoever has been advising you and find someone who knows what they're doing.

 

17 hours ago, Captain Pegg said:

That suggests the surveyor doesn’t really understand how the device they are using works.

Ultrasound works by pulsing sound waves into the test piece and measuring the time it takes for them to return having reflected off any boundary that it encounters, be that the opposite edge of the piece concerned or a crack within its volume. The wave will not significantly penetrate beyond any change in the basic material density and therefore will not pick up any form of different material beyond the test piece.

 

The ultrasound wave will predominantly reflect off the boundary between sound steel and the ‘scale’ beyond it. A small amount will be lost and some may even return to the test device as a shadow having bounced off a further interface.

 

If the measured thickness gives a sensible outcome that is not too far removed from the nominal plate thickness I’d be very inclined to believe it.

 

Note also that original quoted plate thickness (if you know it) is a nominal value. The actual manufactured thickness of steel plates can vary significantly from that nominal thickness.

 

And only worry about whole numbers of millimetres. Quoting thicknesses to the nearest tenth of a millimetre is kidding yourself.

So maybe I should just look into another surveyor for the baseplate in general 🤔 what you guys are saying makes sense to me. The original surveyor has put that an inspection is needed from the inside on the report though, so hopefully won't be an issue for insurance purposes? 

14 hours ago, BoatinglifeupNorth said:

Hopefully her neighbour isn’t this guy😂

 

This guy seems more of a reliable source than my neighbour 😂 you can see why i needed to fact check 😂

[Alan de Enfield]

12 minutes ago, Jennarasion said:

Boat is a 1980s (i think), springer.

 

What size (length) is the boat ?

 

Springer were (lets be kind) an 'economy' builder and their smaller boats were built with a 3.75mm thick base plate. With anything less than (or even approaching) 4mm todays insurers will not cover you fully comprehensively.

 

What thickness did the survey indicate (accepting that it may be wrong) ?

 

It is worth further investigation as it could be the difference between being able to insure the boat, or not. 

I'd suggest spending as little as possible on the boat until you can ascetain if it is insurable**.

 

** You could insure in 3rd party only which is sufficient to get a licence, but obviously if anything happens to the boat (damage, sinking etc) you will have no cover for the value of the boat.

 

If you are planning to live on the boat and have all your worldly possessions with you it is something you need to carefully consider.

[Captain Pegg]

21 minutes ago, Jennarasion said:

A few of my windows leak, so possibly some water in the cabin under the floor, however since I've been here the amount isnt extraordinary. He mentioned using rust inhibitor as well, so probably something down there, but he indicated that it was pretty much the entire baseplate that needs checking, so also could very well be pieces of ballast as suggested above. I agree that i should get a few traps, but i would rather install these in a few discreet places down the road rather than from scratch. Boat is a 1980s (i think), springer.

 

So maybe I should just look into another surveyor for the baseplate in general 🤔 what you guys are saying makes sense to me. The original surveyor has put that an inspection is needed from the inside on the report though, so hopefully won't be an issue for insurance purposes? 

You have to bear in mind that you’re asking the surveyor to make an inspection of your boat which results in them carrying a professional liability in relation to what they report.

 

It’s your responsibility to make your boat available for a suitable and sufficient inspection and if the top of the baseplate can’t be inspected then you haven’t done that. The natural response of the surveyor then is to caveat their findings. Any surveyor would likely do that. It’s sensible, suggesting drilling a hole instead is lunacy.

 

What is incorrect is to suggest that the presence of scale (rust?) would corrupt a properly conducted ultrasound scan.

 

Do you know the recorded thicknesses and the nominal plate depths of the baseplate?

Edited February 25 by Captain Pegg