Replacement of Engine Compartment

[Ian Thomas]

Hello everyone, I am new here and have been trying to buy a boat for about 10 months. Found a 60 foot semi trad and had an out of water survey completed by a highly recommended surveyor. His hull thickness readings highlighted a problem at the stern, starting as he reached the engine compartment. Readings dropped from 9. something to 5 something. He accessed the engine compartment and found extensive corrosion to the plate on the bulkhead and the sides. The boat is 25 years old and the rest of the steel is excellent. The perceived knowledge at the boatyard was that she was a good boat and worth rescuing. The best course of action agreed on was to remove the engine, cut off the rear section, thereby removing the offending damage and then weld in a complete new stern from good 10 mm plate. The whole hull needs a good coat of sealing anyway it would then appear to be a total solution.

My question to your learned brains is twofold: 1, Does this seem like a correct course of action or just a false path that should be avoided. And 2. Will this potentially negatively affect the value of the boat in the future as she will always appear to any surveyor as a 'cut and shut'. 

Many thanks

[Tony Brooks]

1. It sounds one course of action, amongst others. Possibly better that over-plating, it is really just re-plating.

2. Why would it be any different to any other re-plate?

 

3. I am suspicious of this post. Why would anyone remake the swim and hull sides in 10mm plate when they were probably only 6mm from new, or is it just the baseplate that needs renewing. I think Uxter plates are often thinner than baseplates, so it may have started life as 6mm and just need a good derust and paint if this is what the surveyor measured. A complete new stern seems a very odd recommendation to me because much of it above the waterline is likely to be serviceable.

[Ian Thomas]

Hi Tony, thank you for replying and my newness to this world might have confused. You are right, it is the engine bay below the baseplate that needs replacement. I have added a picture in the hope it helps. 

[Tony Brooks]

Then I don't see any more of a problem that for any other re-plate. In general, re-plating is considered a better option than over-plating, and it should not need any ballast removed. This is as long as the weld at the join is carries out to the full depth of the plate. It will be no different to any other weld joining the baseplate lengths. It all depends upon competent welders. If properly welded and ground flush, I am not sure how a future surveyor would know some new plate work had been welded in.

 

From the photo - comparing the depth of the lip on the base late and the uxter plate (the upper of the two horizontal plates, it looks to me as if the baseplate in that area may have been thinner than 10mm from new - hence the thinness starting at the rear bulkhead. I don't think the baseplate lip in that area would be subject to much thinning.

 

Interested to hear others opinions.

Edited October 13 by Tony Brooks

[agg221]

I'm with Tony on this.

 

So that everyone is on the same page, I have marked up your drawing with what I would call each of the areas - other names get used in different boatyards or parts of the country.

 

 

With reference to the named parts, is it just the base plate which is being considered for replacement? If so, that is relatively minor. Re-plating is directly equivalent to the original build if done properly, so there is no loss of value.

 

The standard construction of canal boats for a long time was 10/6/4 (base, sides cabin, thickness in mm). Earlier it had been 6/6/4, well actually 1/4" probably. If you replace the base plate in 10mm plate rather than overplating it will be completely back to as built.

 

Whilst you are at it, if corrosion is pretty much internal, I would expect it to have gone a bit up the side plates too, so the bottom of the lower side plates need considering.

 

The swim plate normally corrodes from the outside and it is usually possible to see what's going on with the inside. The other parts which often get neglected for painting and general maintenance are the weed hatch access and the rudder tube. These want careful inspection as if they corrode through the boat sinks. If your surveyor has done a good job they will have been inspected, but they are areas I would specifically ask about.

 

I have marked an area with a red oval because I don't like the look of it. It could be purely superficial in which case no issues but it's somewhere I would be paying close attention to. I would also be having a good check to see that the guard irons are fully welded top and bottom because if you are beginning to see a bit of corrosion in the side plate at that region, it will be much worse behind the guard irons unless they are sealed.

 

Hope this helps. I do not claim to be an expert and others are likely to be able to chip in with a lot more knowledge than me. It is certainly not designed to put you off a boat that you like - doing a bit of welding becomes something on an inevitability as boats age, particularly if they are used as the baseplate can wear as much as it corrodes.

 

If this is a boat you are going to keep, I would be inclined to have the whole thing blasted off, any deep pitting filled by welding and then paint with epoxy, including the baseplate. It will stop the outside from getting materially worse through corrosion and give a good long interval between painting.

 

If you do decide that you want to do more than just the repairs identified by the surveyor (e.g. blast cleaning, remedial welding if any is needed, epoxy etc) then it will be more cost-effective to do it all at once. On that basis, I would get a quote for the repair work identified by the surveyor, get the price reduced by that much and then add in the rest on top (get the quote at the same time but it isn't really part of the purchase price to have that work done).

 

Alec

[Ian Thomas]

Thank you Tony and Alec,

It is a slightly confusing world, the narrowboat. I am glad I asked the questions on the forum and am grateful for your replies. I need to proceed with great caution in terms of a potential purchase and will post the outcome when all is decided.

Many thanks 

[blackrose]

1 hour ago, Ian Thomas said:

1, Does this seem like a correct course of action or just a false path that should be avoided. 

 

1. Yes it's the correct course of action and yes it may be false path that should be avoided. The two are not mutually exclusive. 

 

If the reduction in the price of the boat roughly reflects the cost of repairs including docking, and this is a project you really want to undertake then by all means get a quote for the work and go ahead. However most sensible potential buyers would walk away at this point. Why get involved and take on somebody else's problem?

Edited October 13 by blackrose

[Alan de Enfield]

Comments have been made about 'overplating' or 'replating'.

 

Replating is basically what your suveyor suggested - cut away the bad metal and replace with new. This will give you a 'new bottom' and will improve the value of the boat, not reduce the value. 

 

Overplating is a 'cheap and cheerful' way of covering the problem with another skin of metal welded over the top of the corroding / corroded existing metal.

This is not an ideal way of proceeding as it will add weight to the boat and will require ballast to be removed. The welding needs to be done 'well' and not just the edges of the sheet of metal, it also needs welding across the width / length of the sheet to stop sagging.

Overplating will generally reduce the value of the boat as the buyer (or their surveyor) has no idea how bad the original corrosion was, is water still sealed in there corroding the bottom, or, how well the overplating was attached.

 

I would never buy an overplated boat.

 

Does you budget only allow you to buy a project boat, or, will it buy a boat you can use ?

Do you want the hassle of having a boat 'rebuilt' or do you want a 'jump on and go' boat ?

Edited October 13 by Alan de Enfield

[Gybe Ho]

1 hour ago, Ian Thomas said:

 it is the engine bay below the baseplate that needs replacement.

 

 

Do you mean the bad rust is confined to the triangular bit of the hull that the propellor comes out of?

 

Is the proposal to chop off the triangular section from the pointy bit where the propellor is and right back to where the triangle stops? That would be 7ft or 8ft long?

 

On a second and more psychological matter I am going to give some general boat buying advice because I suspect you have fallen into a common boat buying trap that happens like this:

1. You search for ages to find a boat then finally find one that suits.
2. On a second visit you look around in more detail and before an offer is accepted you mentally move aboard.
3. With the offer now accepted the boat seems virtually yours bar some admin stuff.
4. While waiting for the survey, you plan improvements, your cruising itinerary and the mid summer towpath BBQs with friends.
5. Next a shock is revealed in the survey and at this point the costly psychological trap springs on the boat buyer.
6. Because you have already taken ownership in your mind, you now feel the serious problem is your responsibility to fix.

Walk away, an engine out and partial hull rebuild is a £13k problem. That problem is the current owner's problem, not yours.

 

Tell them you are pulling out because a £15k problem has been found.

 

If the boat is still languishing on the market in early January, the owners will take your current offer minus £10k.

 

 

[Ian Thomas]

Thank you, 

I completely understand the psychological trap of buying houses and now a boat. You were entirely right in your assessment except for the last step. As with previous house buys I always feel its the sellers duty to bring the item to the marketplace in the best condition and fully documented. I will need to see where my sellers are in relation to the survey findings.

You were correct on the removal of the 8 foot 'pointy' bit from the stern.

Thanks for your time and thoughts

[Tony Brooks]

23 minutes ago, Ian Thomas said:

Thank you, 

I completely understand the psychological trap of buying houses and now a boat. You were entirely right in your assessment except for the last step. As with previous house buys I always feel its the sellers duty to bring the item to the marketplace in the best condition and fully documented. I will need to see where my sellers are in relation to the survey findings.

You were correct on the removal of the 8 foot 'pointy' bit from the stern.

Thanks for your time and thoughts

 

It is far from clear what both of you are talking about. I would suggest that the "pointy bit at the stern" is the sides of the swim and that is not the area where the thin plate was found. The original question did say "found extensive corrosion to the plate on the bulkhead and the sides"  but then went on to talk about rebuilding it in 10mm steel. It would be a very unusual boat to have 10mm sides and bulkheads, so exactly what are the areas that need attention. 10mm suggest baseplate and possibly uxter plate, but that photo suggests something may be very odd with the original baseplate in that area, thickness wise and if the impression the photo gives is correct then why did the surveyor not see what agg221 and I see. If it is the side plate (as per agg221's labels) then a reading of 5mm is not unreasonable on an older boat made with 6 mm steel.

 

I agree that the rust above the rubbing band needs investigating, but why did the survey not mention this, I wonder.

 

I don't think that you can receive PMs yet, so I have to make any comments here. Please look back at @Gybe Ho's various posts and then look at those from Alec and myself so you can decide where the greater expertise of steel canal boats lay.  If you can, please can you be clearer about exactly what work and what steel thickness has been suggested for the remedial work. Photos or diagrams may help.

 

I would urge any other experienced members to come in and give their opinions.

 

In the end this comes down to the buying price and the cost of rectification. Rebuilding with adequtely dimesioned new steel by a competent welder would not, in my view, affect any future resale price.

 

 

Edited October 13 by Tony Brooks

[Gybe Ho]

35 minutes ago, Ian Thomas said:

Thank you, 

I completely understand the psychological trap of buying houses and now a boat. You were entirely right in your assessment except for the last step. As with previous house buys I always feel its the sellers duty to bring the item to the marketplace in the best condition and fully documented. I will need to see where my sellers are in relation to the survey findings.

You were correct on the removal of the 8 foot 'pointy' bit from the stern.

Thanks for your time and thoughts

 

Pleased to read this.

 

If you do proceed ensure that the boatyard braces the remaining stern hull counter because with such a large piece of hull removed the remainder will be a bit wobbly. You don't want a strong but slightly twisted boat that snags on tight lock walls. With the engine removed and fuel drained the stern will be lighter though the weight of lead acid batteries on the raised engine compartment side floor would concern me.

 

Forget over-plating, it is the equivalent of a surgeon sewing skin together over an active gangrene flesh infection.

23 minutes ago, Tony Brooks said:

 

I agree that the rust above the rubbing band needs investigating, but why did the survey not mention this, I wonder.

 

 

Let me guess... the surveyor spent +2 hours crawling around this boat inside and out with a scrapper, high powered torch and plate thickness gadget. Having surveyed 500 narrow boats in the past decade, he used his vast cumulative professional wisdom and offered his best assessment on a vessel with serious corrosion.

 

I also suspect this surveyor would not challenge the findings of another surveyor from only a single photo on the internet and a problem description offered by someone new to boating.

Edited October 13 by Gybe Ho

[Tam & Di]

Having been involved with narrowboats since the late 50s and having had a canal boatyard 1970-1995 I'm sorry, but I have no idea what you are talking about. I assumed that "removal of the 8' pointy bit" actually means renewal of the rear section of the hull sides and bottom plate below the level of the uxter plate, but I don't quite see where the 'wobble' comes into it. Obviously the work requires bracing adequately to avoid distortion as the renewal is done, but I can't understand how the stern becomes lighter.

 

It does help to use standard terminology for the sections of boat and the work required - agg221's post is a good start.

[blackrose]

2 hours ago, Gybe Ho said:

 

1. You search for ages to find a boat then finally find one that suits.
2. On a second visit you look around in more detail and before an offer is accepted you mentally move aboard.
3. With the offer now accepted the boat seems virtually yours bar some admin stuff.
4. While waiting for the survey, you plan improvements, your cruising itinerary and the mid summer towpath BBQs with friends.
5. Next a shock is revealed in the survey and at this point the costly psychological trap springs on the boat buyer.
6. Because you have already taken ownership in your mind, you now feel the serious problem is your responsibility to fix.

 

7. Because a prospective buyer has already paid quite a lot of money for the survey + crane or docking they already feel financially and psychologically involved and some have difficulty backing out.

[Graham Davis]

5 hours ago, Gybe Ho said:

 

Do you mean the bad rust is confined to the triangular bit of the hull that the propellor comes out of?

 

Is the proposal to chop off the triangular section from the pointy bit where the propellor is and right back to where the triangle stops? That would be 7ft or 8ft long?

 

On a second and more psychological matter I am going to give some general boat buying advice because I suspect you have fallen into a common boat buying trap that happens like this:

1. You search for ages to find a boat then finally find one that suits.
2. On a second visit you look around in more detail and before an offer is accepted you mentally move aboard.
3. With the offer now accepted the boat seems virtually yours bar some admin stuff.
4. While waiting for the survey, you plan improvements, your cruising itinerary and the mid summer towpath BBQs with friends.
5. Next a shock is revealed in the survey and at this point the costly psychological trap springs on the boat buyer.
6. Because you have already taken ownership in your mind, you now feel the serious problem is your responsibility to fix.

Walk away, an engine out and partial hull rebuild is a £13k problem. That problem is the current owner's problem, not yours.

 

Tell them you are pulling out because a £15k problem has been found.

 

If the boat is still languishing on the market in early January, the owners will take your current offer minus £10k.

And where did you pull that little gem from?
I can see nowhere in this thread that a sum has been mentioned, other than your furtile imagination.

[Alan de Enfield]

41 minutes ago, Graham Davis said:

And where did you pull that little gem from?

 

U-Tube !

[Bee]

My thoughts are that the whole hull should be given a thorough wash with a proper high pressure machine, - this is normal when any boat comes out and is an opportunity to give the hull a coat or two of paint. It is really not possible to see the pitting and corrosion present without getting most of the weed and gunk off. Readings of 5mm or so are not too bad unless there is deep pitting. That swim plate looks to be a hefty bit of plate but its all about the pits. Same with the whole underneath, if that is jet washed it might look worrying - then again it might not- you cannot tell. The surveyor has seen bad corrosion presumably  on the inner bulkhead / bottom / sides and probably along the welded joins and I would really like to see if this is on the other side of the bulkhead under the cabin floor, if the bilge is wet or very damp that could be serious. I think the surveyor has pointed out clues that need further investigation so you should tread carefully.

[Gybe Ho]

8 hours ago, Tam & Di said:

Having been involved with narrowboats since the late 50s and having had a canal boatyard 1970-1995 I'm sorry, but I have no idea what you are talking about.

 

 

This thread drifted off course for a couple of hours because the underlying problem raised buy the OP was not clarified or comprehended by the resident veteran forum experts until I spoke to the OP in plain language. I was using non standard boating language because I am offering advice to the OP, he comprehended my post and his response provided clarity to the forum. I call that a commendable result for the plain English campaign. If a narrowboater with your vast experience cannot map simple boating language onto official expert terminology, that is your failing.

 

8 hours ago, Tam & Di said:

but I don't quite see where the 'wobble' comes into it.

 

 

Yes you do. You just agreed with me that such a substantial structural hull repair will require "bracing". Why is this? Because the stern counter overhang  might distort once large sections of hull have been removed and that distortion might then become locked into the hull shape following the rewelding. What causes distortion other than bending and wobbling, a heaving bloke walking on the unsupported stern mid-job would induce wobble. If the main base plate is partially detached from the transverse bulkhead that divides engine compartment from the cabin then the weight of the ballast creates a risk of distortion there.

 

8 hours ago, Tam & Di said:

but I can't understand how the stern becomes lighter.

 

 

The OP mentions at the start of this thread that the engine will be removed. Given the scope of this job I assume consideration will be given to draining the fuel tank. I suggested that lead acid batteries should also be removed because they are a substantial asymmetric weight in the stern and the plate they are mounted on will lack support from below. Hence the remaining stern counter becomes lighter.

 

8 hours ago, Tam & Di said:

It does help to use standard terminology for the sections of boat and the work required - agg221's post is a good start.

 

 

I agree providing the OP benefits from the discussion and trade terminology does not prevent the OP communicating with the forum.

 

 

5 hours ago, Graham Davis said:

And where did you pull that little gem from?
I can see nowhere in this thread that a sum has been mentioned, other than your furtile imagination.

 

And what is you estimate for a job of this scale?

[Graham Davis]

9 minutes ago, Gybe Ho said:

And what is you estimate for a job of this scale?

I don't have one, and am not willing to guestimate, but looking at the price of steel at the moment probably less than half of your figure.
So now tells us how you came about the figure of £13k?

[Gybe Ho]

1 hour ago, Graham Davis said:

I don't have one, and am not willing to guestimate, but looking at the price of steel at the moment probably less than half of your figure.
So now tells us how you came about the figure of £13k?

 

Here is my estimate, I was only a penny out on this morning 90 second hunch estimate.

 

Haul out and relaunch	400
Engine removal	700
Other engine bay services removal.	500
Decommission of engine bay electrics	200
Removal of insulation and other combustibles in cabin near welding site.	300
Removal of fuel	100
Removal any any electrical equipment in cabin adjacent to welding	300
Bracing of stern counter and base plate	100
Degrease of engine bay due to fire risk	100
Grind out other minor engine bay corrosion	200
Removal of cabin floor back 1 ft from aft bulkhead	300
Removal of swim to 6” beyond aft bulkhead	800
Interim survey to confirm scope of corrosion	200
Cut out corroded sections of aft bulkhead	300
Rebuild whole swim	4500
Rebuild aft bulkhead and weld to new swim	700
Repaint engine bay	200
Re install engine and realign prop shaft	1200
Re install other engine bay services such as central heating	600
Reinstate all engine bay & internal electricals	400
Rebuild removed cabin floor	250
Final survey	200.01
Epoxy paint swim externally.	350
Post launch test drive	100
	13000.01
Inc VAT	15600.012

[Paul C]

7 hours ago, Gybe Ho said:

 

Here is my estimate, I was only a penny out on this morning 90 second hunch estimate.

 

Haul out and relaunch	400
Engine removal	700
Other engine bay services removal.	500
Decommission of engine bay electrics	200
Removal of insulation and other combustibles in cabin near welding site.	300
Removal of fuel	100
Removal any any electrical equipment in cabin adjacent to welding	300
Bracing of stern counter and base plate	100
Degrease of engine bay due to fire risk	100
Grind out other minor engine bay corrosion	200
Removal of cabin floor back 1 ft from aft bulkhead	300
Removal of swim to 6” beyond aft bulkhead	800
Interim survey to confirm scope of corrosion	200
Cut out corroded sections of aft bulkhead	300
Rebuild whole swim	4500
Rebuild aft bulkhead and weld to new swim	700
Repaint engine bay	200
Re install engine and realign prop shaft	1200
Re install other engine bay services such as central heating	600
Reinstate all engine bay & internal electricals	400
Rebuild removed cabin floor	250
Final survey	200.01
Epoxy paint swim externally.	350
Post launch test drive	100
	13000.01
Inc VAT	15600.012

Is this AI-generated?

[MtB]

On 13/10/2024 at 08:08, Ian Thomas said:

Readings dropped from 9. something to 5 something

 

Something looks wrong here. Either the surveyor is a total numpty or there has been a fundamental failure of communication. 

 

Point is, steel starting off 9mm thick doesn't corrode uniformly down to 5mm. It corrodes horribly randomly and I'd expect the thickness results to be all over the place. Far more likely as others have said, these 5mm bits actually started life as 6mm not 9mm, and half of the missing 1mm is a combination of measuring instrument error and (the surprisingly large) original steel plate manufacturing tolerances. 

 

Secondly, please take the stuff posted by Gyb Ho with a pinch of salt. He is a fairly new poster here and told the forum recently he has never even been on a narrowboat. Draw your own conclusions about where he is getting all this incredibly detailed stuff from that he posts. 

 

Thirdly, my gut feeling is there is little wrong with this boat from the photos and you are falling victim to the tendency of professional advisors to catastrophise when they have no skin in the game. I'm sure you encounter this in houses too given your experience you mention in this field too!

 

 

 

Edited October 14 by MtB
spelling

[Tony Brooks]

9 hours ago, Gybe Ho said:

This thread drifted off course for a couple of hours because the underlying problem raised buy the OP was not clarified or comprehended by the resident veteran forum experts until I spoke to the OP in plain language. I was using non standard boating language because I am offering advice to the OP, he comprehended my post and his response provided clarity to the forum. I call that a commendable result for the plain English campaign. If a narrowboater with your vast experience cannot map simple boating language onto official expert terminology, that is your failing.

 

That is just you thinking that the OP confirmed he understood. All I can see he confirmed is that he understood the psychology of boat buying. I can see nothing in the whole topic to indicate that he understands exactly what has to be done, and so far has not clarified that, so I have no idea where you get the idea that he does. That is unless "I spoke to the OP in plain language" means you had a private conversation by PM (difficult when he has such a low post count, spoke to him face to face, or both of you are actually the same person. In any case, your terminology "the pointy bit" applies to the plates either side of the swim, the baseplate, or both. I think that, unlike you who has gone off into detail costings and  methods, the rest of us are still trying to get the OP to clarify what needs doing and exactly what the surveyor wrote before we can give much considered advice.

 

The OP has not really confirmed he has grasped the importance of the rust on the hull sides above the rubbing band, he has not clarified the visual oddities about the thickness of the uxter plate and baseplate, and has not clarified why he seems to have been told that the whole back of the boat has to be rebuilt in 10 mm steel, rather than the usual 10mm baseplate and 6mm vertical bits. The talk of 10mm suggests to me that it is just the baseplate that needs replacing, but no one can know because the OP hasn't done his best to clarify any of it.

 

If the whole back end is rebuilt in 10mm steel, then that will make the back of the boat very much heavier than it is now, especially if that baseplate really is as thin as it looks.

 

If the baseplate is as thin as it looks then, as has been said, maybe that 5mm thickness that worried the surveyor is a true reading with just 1mm of wear, rather than the 5mm of wear as implied.

 

The thread did not drift off-topic, but it did move from trying to get more information and giving such advice as possible to warning the OP to be very wary about your posting because it showed a number of deficiencies. The OP has as much information as he can be given at present to decide who to take notice of.

 

Until the OP can clarify exactly what has been proposed, together with the baseplate and uxter plate APPARENT differences in thickness, then any advice, let alone detail costings and discussion of methods is pointless.

 

I would suggest that your habit of pronouncing on a whole range of topics, sometimes without adequate information, is a very bad failing of your own.

[MtB]

6 minutes ago, Tony Brooks said:

If the whole back end is rebuilt in 10mm steel, then that will make the back of the boat very much heavier than it is now, especially if that baseplate really is as thin as it looks.

 

And considerations of overkill aside, the sheer cost of constructing a whole new stern from scratch would surely make the project unviable!

 

Most of the work in building a shell lays in forming up of the bow and the stern. The straight bit in the middle is the quick and easy bit. 

[Tony Brooks]

Just now, MtB said:

 

And considerations of overkill aside, the sheer cost of constructing a whole new stern from scratch would surely make the project unviable!

 

Most of the work in building a shell lays in forming up of the bow and the stern. The straight bit in the middle is the quick and easy bit. 

 

Absolutely, until clarified, I simply can not believe the proposal is to fit a whole new back end. Then there is the question about how a boatyard will form the swim and probably the stern in 10mm steel. The original post made very little practical sense. Until I get more info I believe the OP was told that a new baseplate and possible a bit of the swim side needs renewing, but has not understood what that actually means, so put it into his own words.