History of a 1960s Icebreaker & 1st British Waterways Inspection Boat, built by yarwood.

[agg221]

A little more information.

 

The 19th century horse-drawn ice boat appears to have been built to a largely similar design pretty much across the canal network. I can't comment on the large commercial waterways, but the narrow canals appear to have adopted a fairly standard design, around 30-40' long, round bottomed to enable the boat to rock, with a pointed bow, heavily reinforced with a D-profile, and a near-vertical stern post, the stern shape being similar to a conventional carrying boat (horse drawn). There appear to have been a few exceptions - the boats on the Leicester line were smaller but to the same general design and on broad beam canals such as the Grand Junction, larger boats were used, up to around 9' wide x 50' length but all to the same general design. The only substantial exception I am aware of is the Leeds & Liverpool where the boats had an almost triangular cross-section with a triangular transom at the stern.

 

Almost all boats were wooden with iron sheathing, which appears to have been for cost-saving reasons, but a handful of iron boats were built. Those I can recall are the six BCN boats (in age order from oldest to newest Laplander, Antarctic, Esquimaux, Baltic, Ross, Empress) and the two Leicester line boats but there were a few others, including one for the Coventry (ice boat No.1) and a few others, the original locations for which I am unaware of such as those currently named Erebus and Ice Dragon.

 

The earliest motor  tugs built with ice breaking in mind were Worcester, Birmingham and Sharpness, all built in iron and around 45' long. Although I have not seen any specific reference to ice breaking in the design specification, the bow shape is right and the DIWE records of the 1950s refer to their use for ice breaking.

 

There was then something of a gap in ice boat building, presumably due to WW1 and the subsequent financial issues. It seems to have been resumed in the mid-1930s with the building of a wooden horse-drawn ice boat Scott for the BCN. This was followed by Shackleton, which was converted to a motor ice boat shortly after completion (there are photographs of the trials in the CRT archive which don't appear to be complying with 4mph..! https://collections.canalrivertrust.org.uk/bw192.3.2.2.2.55). This appears to have been enough of a success that the final wooden ice boat Byrd was built shortly after, from memory in 1938 or 1939.

 

In the meantime, the Coventry converted their iron ice boat No.1 into a motorised ice boat/tug in the mid-1930s.

 

The main driver for conversion/building motorised ice boats and ice breaking tugs appears to have been the decreasing number of horses available, even on the BCN. The Grand Union as it was by then also appears to have converted Ice Boat no.95 and shortly after modified three (I think?) of its carrying fleet by shortening them and adding ice breaking rams to the bow. One of these was Sickle which Alan Fincher now owns and has already commented on. Another was Tycho which still retains its ice breaking ram - try googling to see how intimidating that would be heading towards you! These were originally so-called middle-Northwich boats which had more rounded chines, making them less stable and hence apparently less popular with the boatmen for carrying, but the ability to roll made them much more suited to ice breaking.

 

A couple of other privately owned tugs had been built in the 1930s with icebreaking bows, specifically Pacific and Bittell in 1934 by Yarwoods, fitted out by Harris of Netherton for Stewart & Lloyd. In 1940, Harris built Atlantic for Yates & Co as an ice breaking tug. There was then a War Department contract for a larger number of tugs, most originally named after WW2 aircraft. The exact number on the original contract and the number built are both unclear but a number of these survive, the best known of which is probably Caggy (originally Dakota), operated by Alan 'Caggy' Stevens of Oldbury for many years. Harris also built two other ice breaking tugs for the Oxford canal - Oxford No.1 and Oxford No.2, which have slightly different designs. These are both still extant.

 

Post-war there was a lot of movement, with nationalisation of the canal companies and the transfer of many privately owned fleets into national hands through closure. DIWE (later BWB) inherited an ongoing need for maintenance and for the first 15 years largely continued to keep canals operational for carrying, including breaking the ice. As the wooden boats reached end of life, other boats were required and a number of boats were modified/converted/commissioned including Nansen II in 1951, replacing the wooden Nansen, Tardebigge which was created by adding new ice breaking bows to the stern end of GUCCC Antlia (note, the stern and bows of Antlia have now been reunited and a new stern built for Tardebigge so it is now a completely separate boat). DIWE acquired Atlantic in 1953 and Pacific and Bittell in 1958. Sharpness and Worcester were also being used for ice breaking by this date.

 

As I mentioned previously, the latest date I have found any official record for the running of ice boats is 24th December 1962. This is within the Divisional Engineers' weekly reports. After this, the ice became too thick and breaking was abandoned, although unofficially ice boats were run in the Birmingham area in March 1963 when the canals started to thaw, to allow the frozen in boats to move. Many of the ice boats were then surplus and sold off gradually, many passing through the hands of Alan Picken of Stoke Prior who seems to have had great affection for them. The tugs were useful and so mostly retained for longer, Atlantic being sold to Alfred Matty in 1970 for example.

 

Almost all of the iron ice boats and icebreaking tugs still survive, with only a couple of exceptions having vanished. Very few of the wooden boats still exist - I know of seven or eight in total.

 

Hope that is of interest.

Alec

Edited September 6 by agg221

[Stroudwater1]

Very interesting Alec. 
Here is a recent image of Tardebigge at Bratch Staffs and Worcs canal society meet in 2022. 

 

Oxford number 1 at Braunsron historic rally 2024 

 

A number of tugs lining up ar Braunston 2024 ncluding Typhoon Oxford no 1 and Tardebigge 

Typhoon setting off 

 

Edited September 7 by Stroudwater1
Gap insertion and duplicate

[agg221]

20 minutes ago, Stroudwater1 said:

A number of tugs lining up ar Braunston 2024 ncluding Typhoon Oxford no 1 and Tardebigge 

 

 

Thanks for that - very useful illustrative photos. The boat next to Typhoon is Atlantic so both built by Harris of Netherton. You can see the similarity in the bows. Typhoon was one of the war department contract ice breaking tugs. These are surprisingly tender, ie you step on the front deck and the whole thing rocks, even more than Oates does.

 

Contrast the bow design of the outer three with Tug No.2 which is a cut down star class motor designed for carrying and you can immediately see what ice breaking bows look like.

 

Alec

[Rob-M]

Nansen II at the Roundhouse being used to tow Leo as part of the CRT Heritage Working Boats.

 

Nansen II was originally built with a wheelhouse but later converted to tiller steering.  I think I have a copy of a picture somewhere with the wheelhouse which I'll see if I can find.

[agg221]

These two are the Coventry ice boat No.1, one from the Blisworth tunnel 200th anniversary celebrations as 'Gilwern' and the other as the tug 'Coventry' from the Black Country Tug Gathering in 2024.

 

Alec

 

 

1 hour ago, Rob-M said:

Nansen II was originally built with a wheelhouse but later converted to tiller steering.  I think I have a copy of a picture somewhere with the wheelhouse which I'll see if I can find.

The drawing for Nansen II, with wheelhouse.

 

Alec

Edited September 7 by agg221

[Alan de Enfield]

 

 

Uncle Albert not only served on Submarines ...................

 

 

Buster Merryfield (aka Uncle Albert)

 

 

 

 

 

Edited September 7 by Alan de Enfield

[Stroudwater1]

21 minutes ago, Alan de Enfield said:

 

 

Makes for a lovely photo. Good to see someone skilled at the tiller TBF 👍 

 

I guess in part being tender helps to make rocking the boat easier ? 

[Francis Herne]

14 hours ago, Alan de Enfield said:

Uncle Albert not only served on Submarines ...................

That's Francis Stapleton, quite an authority on BCN tugs and dayboats.

 

While we're doing icebreaking boat photos, here are sisters Oates and Ross, Coventry and Tardebigge:

 

and Stewarts & Lloyds' Pacific:

Edited September 7 by Francis Herne

[alan_fincher]

Not sure what has been mentioned so far, either in terms of description or photo.

Here are a few images of ice  boats at work which are certainly post British Waterways, (i.e. post 1948),,,

TYCHO (which as has been pointed out still retains its ice ram to this day)....



The 1947 date in the captioning on this following one must be wrong.  It is clearly post Nationalisation, as TYCHO is painted in British Waterways colours.  One of the Oxford icebreakers is behind TYCHO.

 

 

Almost certainly SICKLE (my boat)  Sorry for poor state of image - I have extracted several promises of access to an original over the years, but have been let down every time.
The livery, (an interpretation of which is what we currently have, dates this picture to no earlier than 1959, I think,



Edited to add RENTON

RENTON was converted to an ice boat in the same time frame as SEXTANS, SICKLE, THEOPHILsS and TYCHO, but what was added as an ice blade was very much massive than that added to the 4 Middle Northwich boats.   It was still in place in the 1970s, and it is my understanding that when torched off it stayed on the boat as ballast.  I'm told it can still be found in the hold....

Edited September 8 by alan_fincher

[wanderinglotus]

Hi everyone, 

 

Thank you so much for all the knowledge shared on this thread- it's really appreciated! 

 

@agg221 @alan_fincher in particular- thanks for sharing such detailed interesting info, ill be compiling a list of boat names to look into & look out for from what you've written which is really helpful, so thank you lovely to see so many photos aswell- giving me lots of painting inspo

 

Don't suppose any of you may be able to advise on an issue with vigilante that's cropped up? (& Not sure whether id be better starting a new thread in the historic boat section?) 

 

I went to view vigilante again, got to see the historical stuff that comes with the boat, including plans, photos and lots of letters relating to the build when it was commissioned, so im satisfied that the history checks out. (The drawings look almost identical to the ones Alec shared) 

 

Additionally I saw a survey that the brokerage has had done, which was really detailed, everything that was more than just a recommendation to continue basic maintenance has been done & the hull measurements have a good amount of steel to work with, show very little corrosion over the 60 years. I was delighted! 

 

That was until, when in the boat again, I started digging a little more. Id been given permission to try & look under the floor boards to see the condition of the ballasts & beams. After alot of struggle, I found a few panels & unfortunately underneath found poured concrete, with a good few cm of water on the top & lots of underfloor wooden beams that were rotted. I could see what looked like some evidence of corrosion on the metal ballast beams, but it was kinda hard to tell as everything was covered in some kind of sticky black stuff (bitumen? or bilgeoil?). 

 

From what I understand, it was pretty standard at the time to build with poured concrete & it makes sense to me that u wouldn't want big heavy slabs rolling about in an icebreaker. but it also seems that how sound they are, depends on how they've been done & if they're compromised?

 

The broker reckons that a good enough amount could be negotiated off that if it was a case of having to strip all the wood in the flooring out, dry everything else, then sand down & re-bitumen & redo the flooring then I'd still want to buy, as honestly there's so many other features I love. But, if the hull is compromised- then i want to stay away! my question is- how can I know? 

 

Where there certain standards used at the time/by BW/Yarwood that i can trust to be sound? it would seem quite astonishing for so many old icebreakers to still be around, if they have all had to have the concrete removed! If that is the case tho- big props to everyone so dedicated to keeping them floating! 

 

I've seen some talk of it depending on how things are sealed at the side & whether there are any cracks. Problem is, i can't see the whole floor to examine that. They have said when I come back for a quote on the roof that I can try to pull more from the other side- but doubt I'll be able to see the entire thing. Is there any other way of telling? 

 

Would I have a challenge finding a surveyor who's knowledge enough in this to know whats sound & could asses it in the survey? I see internal corrosion as a very commonly listed limitation. Could the concrete have made the hull survey inaccurate? 

 

Any advice would be

really appreciated!

 

[alan_fincher]

It is highly unlikely that poured concrete would have ever been used as part of the original construction of a boat.

If this boat has poured concrete in its bottoms then I would say that invariably makes it at best a bodge, and quite possibly far far worse.

 

I would further stick my neck out and suggest that any of the truly reputable surveyors with expertise in historic boats is unlikely to be prepared to make any statement about the condition of the steel underneath the concrete.

This rings major alarm bells to me - I would be running away at this stage!

[wanderinglotus]

40 minutes ago, alan_fincher said:

It is highly unlikely that poured concrete would have ever been used as part of the original construction of a boat.

If this boat has poured concrete in its bottoms then I would say that invariably makes it at best a bodge, and quite possibly far far worse.

 

I would further stick my neck out and suggest that any of the truly reputable surveyors with expertise in historic boats is unlikely to be prepared to make any statement about the condition of the steel underneath the concrete.

This rings major alarm bells to me - I would be running away at this stage!

 

Thank u for ur response @alan_fincher  even if it's the answer i was fearing!

 

Genuinely curious, if they weren't using poured concrete how did they get around potential damage to the hull from slabs moving around when Icebreaking? 

 

Would be interested to hear from others with boats from this era, as I've had multiple historical boat enthusiasts (who arent affiliated with the broker) tell me it was standard? & Read about another BW inspection boat on here with poured concrete (which they believed it was built with) that was still fine. 

 

I'm not expecting them to comment on the corrosion inside the hull as I know that'd be impossible for them to tell- but is there a way they can tell if the concrete has been compromised? (especially if the broker did remove the floor to get a full look? as they do really seem to want to sort it properly) 

 

Don't know if it's worth mentioning that I couldn't get up enough of the floor to know whether it's been done as one large bit of concrete or in sections that can be lifted out? 

 

[Ogwr]

Does anyone have information as to where Vigilante was based whilst under BW ownership? Was ordered as a Ice Breaker come inspection vessel to get it past the bean counters? To my mind an inspection vessel would not have living accommodation aboard.. 

Edited September 9 by Ogwr

[wanderinglotus]

1 hour ago, Ogwr said:

Does anyone have information as to where Vigilante was based whilst under BW ownership? Was ordered as a Ice Breaker come inspection vessel to get it past the bean counters? To my mind an inspection vessel would not have living accommodation aboard.. 

 

If I remember correctly from the documents, it was stationed on the Leeds & Liverpool at some point during the 60s-80s when it was an inspection boat, but the letters seem to reference it being somewhere else previously. 

 

The letters confirm the living accommodation was added when it was converted to an inspection boat in 1962/3, before that it was just an icebreaker. 

[agg221]

4 hours ago, wanderinglotus said:

Hi everyone, 

 

Thank you so much for all the knowledge shared on this thread- it's really appreciated! 

 

@agg221 @alan_fincher in particular- thanks for sharing such detailed interesting info, ill be compiling a list of boat names to look into & look out for from what you've written which is really helpful, so thank you lovely to see so many photos aswell- giving me lots of painting inspo

 

Don't suppose any of you may be able to advise on an issue with vigilante that's cropped up? (& Not sure whether id be better starting a new thread in the historic boat section?) 

 

I went to view vigilante again, got to see the historical stuff that comes with the boat, including plans, photos and lots of letters relating to the build when it was commissioned, so im satisfied that the history checks out. (The drawings look almost identical to the ones Alec shared) 

 

Additionally I saw a survey that the brokerage has had done, which was really detailed, everything that was more than just a recommendation to continue basic maintenance has been done & the hull measurements have a good amount of steel to work with, show very little corrosion over the 60 years. I was delighted! 

 

That was until, when in the boat again, I started digging a little more. Id been given permission to try & look under the floor boards to see the condition of the ballasts & beams. After alot of struggle, I found a few panels & unfortunately underneath found poured concrete, with a good few cm of water on the top & lots of underfloor wooden beams that were rotted. I could see what looked like some evidence of corrosion on the metal ballast beams, but it was kinda hard to tell as everything was covered in some kind of sticky black stuff (bitumen? or bilgeoil?). 

 

From what I understand, it was pretty standard at the time to build with poured concrete & it makes sense to me that u wouldn't want big heavy slabs rolling about in an icebreaker. but it also seems that how sound they are, depends on how they've been done & if they're compromised?

 

The broker reckons that a good enough amount could be negotiated off that if it was a case of having to strip all the wood in the flooring out, dry everything else, then sand down & re-bitumen & redo the flooring then I'd still want to buy, as honestly there's so many other features I love. But, if the hull is compromised- then i want to stay away! my question is- how can I know? 

 

Where there certain standards used at the time/by BW/Yarwood that i can trust to be sound? it would seem quite astonishing for so many old icebreakers to still be around, if they have all had to have the concrete removed! If that is the case tho- big props to everyone so dedicated to keeping them floating! 

 

I've seen some talk of it depending on how things are sealed at the side & whether there are any cracks. Problem is, i can't see the whole floor to examine that. They have said when I come back for a quote on the roof that I can try to pull more from the other side- but doubt I'll be able to see the entire thing. Is there any other way of telling? 

 

Would I have a challenge finding a surveyor who's knowledge enough in this to know whats sound & could asses it in the survey? I see internal corrosion as a very commonly listed limitation. Could the concrete have made the hull survey inaccurate? 

 

Any advice would be

really appreciated!

 

I can offer some comment which may perhaps be more positive than Alan, although you will have to consider whether it is overly optimistic as it's your money rather than mine.

 

The presence of the concrete is not a good thing. However, the presence of water around the concrete is not a surprise, as the concrete makes it nearly impossible to remove the water. Either the concrete is well bonded to the hull (highly unlikely) in which case removing it would be a pain but the steel must necessarily be well protected by it, or the concrete has disbonded from the hull through a rust layer (highly probable) in which case you know it is relatively easy to remove. The concrete will have significantly reduced the access for oxygen to the baseplate so the rate of corrosion will have been reduced. Also, if it is disbonded, it means water can seep round the concrete so if the level is not increasing you probably don't have a hole.

 

The bitumen may well be a good thing, particularly if it is against the hull (between the hull and the concrete) as it can form a pretty effective barrier when thick, so could well mean you have very little internal corrosion at all. This has been found to be the case in some 1970s build leisure boats.

 

Hull thickness measurement is the critical question, and the method of measurement is fundamentally different depending on the material of construction. Early boats were built from wrought iron which gave way to mild steel from the 1870s, being considerably cheaper. However, old mild steel is very different from more modern mild steel due to better process control. This means it has far fewer inclusions in it. That matters here because of how you can measure the thickness.

 

When you have a homogenous material such as modern mild steel you can use ultrasonic measurement. This is based on 'pinging' a high frequency sound wave into the surface and detecting the reflected wave. If you know the rate of travel of the wave in the material then the time to return gives you the thickness. The reflection happens off the first interface, so you would expect that to be the back face of the steel. It does not give a false reading off rust or concrete, so you can measure the residual thickness of the steel, even with the concrete in place. If you have wrought iron or old mild steel then the inclusions within the structure cause the signal to bounce off them before reaching the back face so the reading is meaningless. For these materials, the only method is a tapping hammer, which cannot be used on a boat full of concrete as that will stop the hammer causing the metal to move properly.

 

You are looking at a relatively modern boat which will have been built out of relatively modern mild steel so ultrasonic inspection should work fine. That means a surveyor should be able to properly assess how thick the residual metal is without removing the concrete.

 

Given that you are clearly seriously interested in this boat, I would be inclined to book a proper survey and look to negotiate a price reduction to account for the amount of internal work needed to remove the floor and the concrete and replace the rotten wood.

 

If the survey did not show up any excessively thin regions I would go ahead. If there was some pitting to be dealt with I would regard that as normal, but if there was significant thinning I would have a serious conversation about the cost of a complete re-bottoming. In the end, it may still be worth their while to reduce the price to account for this as anyone seriously interested will pick it up. I would then talk to some relevant boatyards about timeframe and budgetary cost and go for a full replacement.

 

If the figures stack up, the bottom does not need replacement and the repair work is minor, I would then remove the floor and the concrete with the boat on land, as a priority and get any repair work done and the inside painted with epoxy before reinstating the floor. You would then have a very solid basis to fit the boat out as per your preferences.

 

Alec

Edited September 9 by agg221

[alan_fincher]

57 minutes ago, wanderinglotus said:

..................before that it was just an icebreaker. 

 

Hard to tell from the brokers images, but to me the bow doesn't look vaguely ice breaker like.

There doesn't seem to be much (if anything) to help break the ice.

I don't know what the credentials are of those who have advised you that some narrow boats came with poured ballast from new - I would love them to provide even a single example of where this might have been the case.

I'm confused that you talk about the concrete being compromised.  What you need to worry about is how compromised the steel is that it has been poured on top of.

[Stroudwater1]

I’m not sure any surveyor would be quite right to survey Vigilante. Are there any specific surveyors appropriate for Vigilante ? 
 

Re inspection launch on the Leeds and Liverpool I wondered whether this was one there as well? 
 

https://www.ebay.co.uk/itm/166959774221?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=O2P-icTrTIy&sssrc=4429486&ssuid=XllhT-BWQmi&var=&widget_ver=artemis&media=WHATS_APP

[agg221]

7 minutes ago, Stroudwater1 said:

I’m not sure any surveyor would be quite right to survey Vigilante. Are there any specific surveyors appropriate for Vigilante ? 

 

Assuming I am correct and ultrasonic inspection is suitable, it actually falls within the standard method for most hull surveyors with little to worry about from the perspective of method.

 

That said, if I was looking at it I think there are a couple of surveyors I would use for preference, mainly because their approach is to provide a work plan with guidance on timeframe required, rather than just a tick-box exercise on hull thickness for insurance reasons.

Alec

[alan_fincher]

2 hours ago, Stroudwater1 said:

Re inspection launch on the Leeds and Liverpool I wondered whether this was one there as well? 
 

https://www.ebay.co.uk/itm/166959774221?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=O2P-icTrTIy&sssrc=4429486&ssuid=XllhT-BWQmi&var=&widget_ver=artemis&media=WHATS_APP

 

No - that is very definitely a British Waterways conversion of a former working boat into a hire boat.

No suggestion there of any other purpose.

[Tonka]

https://www.facebook.com/share/r/eHK7KK7AXiYtJEKP/

 

Strangely enough there is a G & J Reeves built inspection launch with ice breakers bow being advertised on Facebook 

[zenataomm]

The purpose of an ice breaker was to, errr ... break ice.

To that end the design included bluff stem, thick plating and the ability to rock it from side to side, violently.

 

Is that obvious in this Yarwoods boat described as an inspection launch?

 

[Francis Herne]

The CRT archive appears to have the original drawings and correspondence.

They're generally very helpful and will scan/email copies on request.

 

Principal Engineer's correspondence and reports concerning the new inspection boat Vigilante, ship number 933

1960-1982

https://collections.canalrivertrust.org.uk/bw167.26.5.3.16.4

 

 Construction drawings for canal inspection vessel "Ship No 933 [Vigilante]"
12 October 1960-1 January 1961

https://collections.canalrivertrust.org.uk/bw177.5.5.19

 

"Proposed General Arrgt of Inspection Launch for use on narrow canals"

Plan, elevation and section with annotations. By R Taylor, WJ Yarwood & Sons Lts, The Dock Northwich.

12 October 1960

https://collections.canalrivertrust.org.uk/bw177.5.5.17

 

possibly relevant:

 "Inspection Launch for use on Narrow Canals General Arrangement"
Plan showing proposed layout. Stamped "British Transport Commission: British Waterways: South Western Division Gloucester"

1960

https://collections.canalrivertrust.org.uk/bw177.5.5.18

 

The titles, particularly on the 1960 documents, imply that Vigilante was designed from the outset as an inspection launch. Doesn't rule out her being designed to break ice as a secondary role but I'd be surprised. Of course you can break ice to a degree with any boat!

Edited September 10 by Francis Herne

[IanM]

18 hours ago, Stroudwater1 said:

I’m not sure any surveyor would be quite right to survey Vigilante. Are there any specific surveyors appropriate for Vigilante ? 
 

Re inspection launch on the Leeds and Liverpool I wondered whether this was one there as well? 
 

https://www.ebay.co.uk/itm/166959774221?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=O2P-icTrTIy&sssrc=4429486&ssuid=XllhT-BWQmi&var=&widget_ver=artemis&media=WHATS_APP

 

Water Willow was the stern of the Small Woolwich butty Indus.

 

 

[wanderinglotus]

21 hours ago, agg221 said:

I can offer some comment which may perhaps be more positive than Alan, although you will have to consider whether it is overly optimistic as it's your money rather than mine.

 

The presence of the concrete is not a good thing. However, the presence of water around the concrete is not a surprise, as the concrete makes it nearly impossible to remove the water. Either the concrete is well bonded to the hull (highly unlikely) in which case removing it would be a pain but the steel must necessarily be well protected by it, or the concrete has disbonded from the hull through a rust layer (highly probable) in which case you know it is relatively easy to remove. The concrete will have significantly reduced the access for oxygen to the baseplate so the rate of corrosion will have been reduced. Also, if it is disbonded, it means water can seep round the concrete so if the level is not increasing you probably don't have a hole.

 

The bitumen may well be a good thing, particularly if it is against the hull (between the hull and the concrete) as it can form a pretty effective barrier when thick, so could well mean you have very little internal corrosion at all. This has been found to be the case in some 1970s build leisure boats.

 

Hull thickness measurement is the critical question, and the method of measurement is fundamentally different depending on the material of construction. Early boats were built from wrought iron which gave way to mild steel from the 1870s, being considerably cheaper. However, old mild steel is very different from more modern mild steel due to better process control. This means it has far fewer inclusions in it. That matters here because of how you can measure the thickness.

 

When you have a homogenous material such as modern mild steel you can use ultrasonic measurement. This is based on 'pinging' a high frequency sound wave into the surface and detecting the reflected wave. If you know the rate of travel of the wave in the material then the time to return gives you the thickness. The reflection happens off the first interface, so you would expect that to be the back face of the steel. It does not give a false reading off rust or concrete, so you can measure the residual thickness of the steel, even with the concrete in place. If you have wrought iron or old mild steel then the inclusions within the structure cause the signal to bounce off them before reaching the back face so the reading is meaningless. For these materials, the only method is a tapping hammer, which cannot be used on a boat full of concrete as that will stop the hammer causing the metal to move properly.

 

You are looking at a relatively modern boat which will have been built out of relatively modern mild steel so ultrasonic inspection should work fine. That means a surveyor should be able to properly assess how thick the residual metal is without removing the concrete.

 

Given that you are clearly seriously interested in this boat, I would be inclined to book a proper survey and look to negotiate a price reduction to account for the amount of internal work needed to remove the floor and the concrete and replace the rotten wood.

 

If the survey did not show up any excessively thin regions I would go ahead. If there was some pitting to be dealt with I would regard that as normal, but if there was significant thinning I would have a serious conversation about the cost of a complete re-bottoming. In the end, it may still be worth their while to reduce the price to account for this as anyone seriously interested will pick it up. I would then talk to some relevant boatyards about timeframe and budgetary cost and go for a full replacement.

 

If the figures stack up, the bottom does not need replacement and the repair work is minor, I would then remove the floor and the concrete with the boat on land, as a priority and get any repair work done and the inside painted with epoxy before reinstating the floor. You would then have a very solid basis to fit the boat out as per your preferences.

 

Alec

 

Thank you so much for this really detailed & helpful response @agg221, it's very helpful to know what steps to take if I do go ahead. 

 

I really appreciate you not just telling me that the hull survey will be fine (as it was done with ultrasonic inspection) but fully explaining the why behind it! it's nice to know the actual science behind why they're still accurate readings

 

Am I right in thinking then that, no matter what, the concrete needs to be removed? even if I was to manage to get the floor up & it was still sealed at the sides, no cracks, with water only in that spot (it was by the bathroom so could be localized?). There's no chance of it being ok enough to be dried out & re-sealed in some way? 

 

In regards to going back to the broker to book a survey- would u recommend that I book it with the boat as it is & negotiate a big enough price reduction to account for the worst case scenario or could I ask for the floor to be removed before the survey & then base my price on what it finds?

 

If you would be happy to pass on the details of the surveyors you mentioned that give timescales as well as work to be done that would be super super helpful- as ideally i would like to get the boat up north to work on it properly & the winter stoppages are another concern! 

21 hours ago, alan_fincher said:

 

Hard to tell from the brokers images, but to me the bow doesn't look vaguely ice breaker like.

There doesn't seem to be much (if anything) to help break the ice.

I don't know what the credentials are of those who have advised you that some narrow boats came with poured ballast from new - I would love them to provide even a single example of where this might have been the case.

I'm confused that you talk about the concrete being compromised.  What you need to worry about is how compromised the steel is that it has been poured on top of.

 

The broker images do not do the boat justice at all to be honest. But, I believe the records@Francis Herne has helpfully shared are the ones that the broker has showed me, which refer to it having icebreaker qualities & it being built to a higher hull thickness. 

 

Both people were historic boat owners themselves, one of which has worked on many in their boatyard. If you search the forum here for posts on poured concrete ballasts, there are others with old inspection boats who still have a poured concrete ballast that's been fine with maintenance. 

 

I'm not worried about the steel being compromised, as the recent hull survey indicates a very small amount of corrosion over its 60 year life. So clearly, the concrete has protected it to some degree & the water is recent. What I'm worried about, is whether the concrete is now compromised & speeding up that rate of corrosion. 

Edited September 10 by wanderinglotus

[alan_fincher]

I think we will have to agree to differ.  I very much doubt there are large numbers of boats from the 1960s or earlier that have poured concrete added over their steel bottoms.  This is only something one tends to encounter as a bodged way of trying to fix a problem, namely a bottom that was already too thin, or, worse, already stating to hole through.

Put it another way - why otherwise would you lay concrete into the bottom of a narrow boat?  At best it is going to make future assessment of the condition of the hull harder, and indeed also make harder any remedial work needed.

I would be intrigued to know the names of the boats that you believe are known too have this feature.  Are you prepared to disclose which they are, please?