How Many Ways Can A Boat Sink?

[davidc]

Is it possible that when the water level in the canal dropped only the middle of the python rested on the uneven canal bed, therefore bending python at its stern just enough to open the micro fissure letting in water, the same way that at speed through the water might bend the hull to open said fissure.

 

Farfetched it possible would this product help

 

http://www.sprayon.com/products/welding_defect_detector_penetrant

[ditchcrawler]

When you say she sunk but the water was not over the gunwales, was she on the bottom or still just floating. I would have thought that if the canal was deep enough for her to sink as far as the gunwalls it would be to deep for her to first ground and then sink, the level would have to fall well over a foot for that.

[cheshire~rose]

I was a tad reluctant to post any further on this thread because I was aware that I as at risk of alienating some of the very experts I was hoping to help us out but as there are a number of potentially valuable posts been added I feel it only fair to respond to those people who have taken their time to try and help.

 

I have tried to read as much of this as possible, but I always struggle to get a good idea in situations where it is virtually all textual description, and there are very few pictures.

 

If knowledgeable people on the ground have failed to identify what caused it, when they can peer at every bit of the boat, I think it is quite hard to add a lot here except pure speculation.

 

I would be interested in seeing as many pictures as can be provided, particularly of everything pertaining to weed-hatch, that lid in the rear deck, and associated drains and pumps.

 

An assumption has been made, (indeed perhaps it is definitely known!), that a weed-hatch was put there by BW when they "cut" the boat. Now, I'm no expert, but have never until now heard of BW putting a weed-hatch into any former working boat that they shortened and converted for maintenance use. Are we sure that is its origins, because it is outside of my (albeit limited!), knowledge of such things.

 

Thank you for your input Alan

I have learned only today that the weedhatch was an addition to the boat after The Trust took delivery of it. I don't think any of the photo's I have are in any way useful in assisting with visualisation. I never thought to take detailed photo's of that sort of thing! I will see if any of the crew who might be visiting her in the short term are not too much of a techophobe to get some pics and email me with them

 

I'm also interested in this bulkhead forward of the engine. Are you definitely saying that all the water that made it into the engine space was contained in the rear part by that bulkhead ? Something doesn't quite add up to me, if it is really true that the boat was then found with the gunwales not far from under water, as it would seem to imply to me that the back end had sunk by virtually the complete depth of the counter. I don't know how far forward that bulkhead is, (how far is it ?), but I'm surprised that if you had the complete buoyancy of the entire boat forward of the bulkhead, with no water making it in it any of that space, that the boat was actually capable of sinking as far as you describe.

 

I'm also surprised if the back-end was that far down that the engine was not sufficiently engulfed that trying to restart it would not have been sensible. Did all places water could have entered the engine manage to remain above the flood water, or did they just wing it, hoping it would not make things worse ?

 

What volume of water is it estimated was in there, and subsequently bailed out, please ?

 

We cannot be 100% certain that all the water was contained behind that bulkhead as when people found the boat the front hold was already filling up fast (the obvious visual point of entry for water into the hold was the skin fitting where the previously removed bilge pump had been.) As the water was baled out of that compartment and the level dropped the water was pouring out around the closed doors of both the day cabin and the heads but until the water level was brought well down in the hold no one even attempted to open those doors.

In the engine room the level of water was described as being 3/4 of the way up the batteries. The batteries are standing on the ledge at the side of the engine room which is the same level as the uxter plate. They are on the starboard side and it was that side the boat had listed to. I have no idea how I could even start to estimate how much water was in there and as there were no photo's taken of her when she was on the bottom I do not know the angle of the list either. The bulkhead position is approximately where the reflection of that post draws a line down the cabin side on this photo:

Certainly inside the day cabin there is just a small shelf between that side hatch and the bulkhead, if anything I would draw the line a little closer to the side hatch.

With regard to the engine - the water was over the exhaust outlet. I will quote from the blog entry of the crew that were on board at the time:

"We opened the compression levers on the engine and fitted the hand crank and turned the engine over a few times. It all seemed OK with water only making it's way into the exhaust and possibly the air cooling ducts.

So we tried cranking with the starter motor and then we tried starting. I'm not sure if I can describe the noises but after a few turns the engine fired and out came white smoke. Robin said "Does that mean we've elected a Pope?" By the time he had said that, the engine was running normally and has done since."

I think we were extremely fortunate the water did not come higher! The crew have said they were pumping/bailing out for 3 hours before they felt the level of water inside the boat was low enough to try moving her. There was still a lot of water inside and the pumps were reducing that all the time but they needed to try and get moving as they had CRT booked to facilitate getting her through Stret Lock the next day. Stret is too narrow to get her through without raising the pound and it has to be booked some time in advance. It was now more important than ever we tried to get her back to her home mooring and as she had been stuck behind the stoppage on The Erewash and missed a tide on The Trent it seemed like the crew were destined to miss the appointment for the lock.

Finally, I appreciate the last thing people think of doing in a situation like this is to photograph the carnage, but if that had been done, it would probably have aided our understanding.

No sadly not!

I wish they had, it would have helped everyone to understand how she looked when they found her. As the water level was coming close to the gunwhales at the time and still coming in I think with hindsight I am glad they did not waste any time taking photo's prior to starting the recovery operation though

[AMModels]

Is it possible that when the water level in the canal dropped only the middle of the python rested on the uneven canal bed, therefore bending python at its stern just enough to open the micro fissure letting in water, the same way that at speed through the water might bend the hull to open said fissure.

 

Farfetched it possible would this product help

 

http://www.sprayon.com/products/welding_defect_detector_penetrant

 

doesnt even have to have opened a seam/fissure it could have been a leaky pipe when the boat dropped on the shelf, have seen it happen.

[cheshire~rose]

That is not so bad an idea. They originally tried this when the boat was out for blacking, but I don't think there was enough water in the hull to rise water pressure enough to reveal a leak. I also think running the motor when out of water might have revealed a loose plate or rivet etc as the vibration plus water pressure might have enabled water to seep out. I would have liked the hull to have been x-rayed when out as well. (Very costly for a charity I know). I've read C Roses blog as well, and I think they tried all the obvious things so its a real quandary. From the blog, , and it is an assumption, I dont think there is much in the way of skin fittings, been aircooled, and very basic plumbing.

 

When she was out of the water and dried out and they were still unsure of where water might have got in I conveyed twice to the crew that were on site that I thought it would be a good idea to get a few buckets full of water (or a hose pipe) into that bilge, stand everyone clear of the prop and run her in gear to try and recreate the conditions that had been causing water to come in. Due to there being a number of different people at the boat yard over a number of different days I do not actually have any idea if this was ever done or not.

You suggest the plumbing is basic? - I wonder what gave you that idea

 

For anyone who is interested the blog written by the crew who were with her when she sunk it is available here:

Wyvern to Home

 

Someone's going to have to kip in the engine'ole for a few nights and days with an auto switched bilge pump attached to an audible alarm. If they're lucky they might catch the Faeries at it.

 

She's an ex-Josher, but I presume she's all steel nowadays?

 

She has an iron hull

[Derek R.]

She has an iron hull

 

Changed from original then, as she is stated in the HNBC sheets as Coppered Steel composite (wooden bottoms). It's irrelevant to the topic, but did Waterways remove and replace the wooden bottom with steel?

Edited October 2, 2012 by Derek R.

[cheshire~rose]

Have you got any deck access hatches?

 

Only reason I ask is because in the early days with my 1st boat, she filled up here engine room to halfway up the block due to heavy rain & blocked drainage holes for the weed hatch access cover on the stern counter. Thank goodness for the steel bulkhead that contained the water in the engine room only! My ignorance at the time could have cost me dearly, a lucky escape.

 

 

The deck hatch has a gutter around the underside. This gutter had two drains put in at the low front corners while at the boatyard a week before. I have no reason to believe that these would be blocked.

 

Is it possible that when the water level in the canal dropped only the middle of the python rested on the uneven canal bed, therefore bending python at its stern just enough to open the micro fissure letting in water, the same way that at speed through the water might bend the hull to open said fissure.

 

Farfetched it possible would this product help

 

http://www.sprayon.com/products/welding_defect_detector_penetrant

 

I am liking your idea a lot! It may be far fetched but let's face it, as there is nothing staring us in the face we have to look at all possibilites

 

Yes, my website designers and I are having creative discussions

 

Richard

 

How do I sink thee? Let me count the ways.

I sink thee to the depth and breadth and height

my arm can reach, when feeling out of sight

for the ends of Bearings and ideal Grease.

...

 

Richard

 

Richard, you need to join the Snakey Fan Club - I am unsure if anyone has ever written poetry for Python before. I am sure she will be touched!

 

When you say she sunk but the water was not over the gunwales, was she on the bottom or still just floating. I would have thought that if the canal was deep enough for her to sink as far as the gunwalls it would be to deep for her to first ground and then sink, the level would have to fall well over a foot for that.

 

The water was close to the gunwhales on the starboard side only as that is the way she listed. She was sitting on the bottom and it was the contour of the canal bed that caused the list

 

Changed from original then, as she is stated in the HNBC sheets as Coppered Steel composite (wooden bottoms). It's irrelevant to the topic, but did Waterways remove and replace the wooden bottom with steel?

 

Thank you Derek. I clearly have a great deal to learn about this boat yet! I was told she was iron! In asnwer to your question she is now an all metal hull

[Derek R.]

The history of smelting is long and full of almost mystical techniques. Had my Grandfather lived long he may have been able to have taught me more as he was a Blacksmith, but our lives did not overlap, so my learning has been more recent but nonetheless still ongoing. Some might say there is little difference between iron and steel, but not in earshot of a foundry-man!

 

With regard to the leak/non-leak, it does sound like something is opening under certain circumstances. Unusual, but not impossible.

[Laurence Hogg]

Changed from original then, as she is stated in the HNBC sheets as Coppered Steel composite (wooden bottoms). It's irrelevant to the topic, but did Waterways remove and replace the wooden bottom with steel?

FMC Dock records record the hull as coppered steel.

[alan_fincher]

I think it would be well worth trying to get photos of the weed-hatch that has been added to the boat, particularly now you confirm it was acquired from Waterways without it, and is a subsequent change. Was it done by someone reliable ?

 

Pictures of it with the lid off, of the seals, and with something like a ruler in the picture to give an idea of how high it sits above the waterline might give some clues, (or rule it out ?).

 

Obviously without being able to crawl over the boat I'm guessing, (I'd probably still be guessing if I could!), but it is the one large hole that the boat clearly potentially is known to have in it, if for any reason it is not properly sealed

 

For something like a stern gland to let in enough water to achieve a sinking overnight seems highly improbable to me - as do loose weeping rivets. You are talking shed-loads of water, and I'd be amazed if someone didn't see it pi$$ing through a stern gland, for example, when you had the initial issues.

 

If the boat is metal bottomed, I'm guessing it is a latish change in welded steel, because as has been said, it must once have been wooden. I can't see that is likely to leak in a variable way - it either has holes in it, or it doesn't. I'm not knowledgeable enough about sides still in the original riveted coppered steel, but whereas I might accept that a wrought iron plate can crack, does that really happen to steel, I'm not sure, and certainly not convinced.

 

Even if it is thought to be in good order, the weed-hatch is my best possible bet. But then I have seen several steel boats sunk due to weed hatch, and very few for any other reason, so perhaps that is clouding my judgement!

Edited October 2, 2012 by alan_fincher

[cheshire~rose]

I think it would be well worth trying to get photos of the weed-hatch that has been added to the boat, particularly now you confirm it was acquired from Waterways without it, and is a subsequent change. Was it done by someone reliable ?

 

Pictures of it with the lid off, of the seals, and with something like a ruler in the picture to give an idea of how high it sits above the waterline might give some clues, (or rule it out ?).

 

I agree, it would be good to get some decent photo's of the layout at the back. I am going to see if someone who is going there can get some for me. With regard to it being fitted by someone reliable? As I don't know who did it I really can't comment but if I were to guess I might conclude that it were done at the same place that advised the rudder were too large! - Need I say more?

 

I have one photo which I took while crew were dealing with a prop foul which is far from ideal but it will hint at the layout:

 

 

You will see how far below the deck hatch the weed hatch is. You will also see a length of hose running from one of the drains in the front corner of the deck hatch.

I don't know if you can glean any other info from that photo but it is all I have at present.

[bizzard]

I agree, it would be good to get some decent photo's of the layout at the back. I am going to see if someone who is going there can get some for me. With regard to it being fitted by someone reliable? As I don't know who did it I really can't comment but if I were to guess I might conclude that it were done at the same place that advised the rudder were too large! - Need I say more?

 

I have one photo which I took while crew were dealing with a prop foul which is far from ideal but it will hint at the layout:

 

 

You will see how far below the deck hatch the weed hatch is. You will also see a length of hose running from one of the drains in the front corner of the deck hatch.

I don't know if you can glean any other info from that photo but it is all I have at present.

That weed hatch lid i'd say is rather large not to have any cross bracing welded on top to keep it flat, and if the seal is old and thin and not thickish and pliable i'd say would leak, underway at least. I'd try screwing it down as normal and try a knife blade all round between lid and box flange to see if the blade passes through. I wouldn't be surprised if it does.

[cheshire~rose]

That weed hatch lid i'd say is rather large not to have any cross bracing welded on top to keep it flat, and if the seal is old and thin and not thickish and pliable i'd say would leak, underway at least. I'd try screwing it down as normal and try a knife blade all round between lid and box flange to see if the blade passes through. I wouldn't be surprised if it does.

 

Thanks for that Bizzard

Whilst I take on board your comments that some strengthening may be adviseable but by cross bracing I am unsure what you might mean.

The bar you can see lying on the deck is the bracing bar that tightens the hatch down and runs across the centre of the hatch

 

I would just repaet that the weed hatch was checked several times when the initial water ingress was causing problems. On each occasion there was no evidence of any dampness around the lid or the seal or any breaks in the seal. As the water ingress problem while under way appears to have been fixed and what we are now looking to find a possible cause for is a problem of the boat sinking while static I do not feel it is likely to be due to a failure of the seal on the weedhatch.

Edited October 3, 2012 by cheshire~rose

[BargeeSpud]

The deck hatch has a gutter around the underside. This gutter had two drains put in at the low front corners while at the boatyard a week before. I have no reason to believe that these would be blocked.

 

I presume that these channels drain straight down directly into the canal. I'd still check that they still drain as, unlikely I know having only been fitted the week before, they could still be blocked by a spider's web or something. My drainage channels looked clean, but a combination of dirt & spider's web had built up, it wasn't obvious when lifting the access hatch & having a quick look. My drainage channels ran horizontally under the stern counter & it was under here where the blockage occured. A good long bottle brush helps me to keep my current channnels clear.

Edited October 3, 2012 by Spuds

[cheshire~rose]

I presume that these channels drain straight down directly into the canal. I'd still check that they still drain as, unlikely I know, they could still be blocked by a spider's web or something. My drainage channels looked clean too, but dirt had built up & wasn't obvious when lifting the access hatch & having a quick look. My drainage channels ran horizontally under the stern counter & it was under here where the blockage occured. A good long bottle brush helps me to keep my current channnels clear.

 

Thanks Spuds

 

They drain through into the weed hatch and if you look at the photo you will see they are drained through clear hose and so it is far more likely to see if a blockage occurs and I feel that they had become blocked in only a week then it would be rather unusual

[bizzard]

Thanks for that Bizzard

Whilst I take on board your comments that some strengthening may be adviseable but by cross bracing I am unsure what you might mean.

The bar you can see lying on the deck is the bracing bar that tightens the hatch down and runs across the centre of the hatch

 

I would just repaet that the weed hatch was checked several times when the initial water ingress was causing problems. On each occasion there was no evidence of any dampness around the lid or the seal or any breaks in the seal. As the water ingress problem while under way appears to have been fixed and what we are now looking to find a possible cause for is a problem of the boat sinking while static I do not feel it is likely to be due to a failure of the seal on the weedhatch.

Nothing to do with the removable clamp. That large lid i doubt is perfectly flat and possibly slightly warped although it looks quite thick. Angle iron welded cross wise on top of it to all four corners crossing in the middle where the clamp screw socket is to keep it rigid and flat, and after welding these on check for flatness on the bottom side of the lid with a steel ruler edge. Or at least i'd renew the seal with thicker softer material to allow for any warpage of the lid.

[alan_fincher]

You will see how far below the deck hatch the weed hatch is. You will also see a length of hose running from one of the drains in the front corner of the deck hatch.

I don't know if you can glean any other info from that photo but it is all I have at present.

 

Well it gives an idea, but, as you suggest, there's a lot you can't tell from it.

 

It does look like there is a reasonable margin between the normal water line, and the top of the lip around the weed-hatch, but I'd certainly like to know the distances involved.

 

Hard to tell how big it is, but clearly bigger than most leisure boats having broadly similar arrangements. So, depending on how thick the steel is, as Bizz suggests potentially more likely to flex and distort as the securing bar is clamped down on it. It also looks like the securing bar hooks around the lip on the side of the weedhatch, rather than what I would say is the more usual method of passing around or under welded supports not actially forming part of the seal. What you have is trying to pull the lip on two small lengths the edges of the weedhatch up, whilst trying to push the middle of the plate down, hoping it all remains flat, and doesn't bow, or distort. It would be useful to know how thick the plate is, and see pictures of the ends and middle of the securing bar whilst in place......

 

But, all that said, the potential problem areas look high enough above water that, whilst I think it could easily leak underway, I can't immediately see how it can if the boat is static, and not already low in the water. Problem is I can't see what else may be doing it. Unless the stern gear is totally shot, I can't see it is that, (I think the crew would actually hear it, if it were leaking that fast!), and if she has welded bottoms, I can't see how they will be watertight one minutes, but leaking badly the next.

 

Brings us back to cracked plates, I suppose, but does that happen to coppeed steel - I don't know!

[BargeeSpud]

Thanks Spuds

 

They drain through into the weed hatch and if you look at the photo you will see they are drained through clear hose and so it is far more likely to see if a blockage occurs and I feel that they had become blocked in only a week then it would be rather unusual

Ah, you were quick off the mark. I was editing my response at the time to say that.

 

That's a great idea to have clear hoses. As you say, a blockage would be obvious.

[cheshire~rose]

Well I have to say I am extremely impressed by the way this forum manages to communicate to through the ether!

This morning I posted that I was going to see if any of the crew could get some photo's of the weedhatch for me and had every intention of sending an email out to ask if anyone was going over there today but never got around to it. I also mentioned on Facebook that I had woken up early today and could not sleep because I was yet again mulling over in my head potential theories of what might have happened.

Before lunchtime two crew members had been in touch to tell me Snakey has not sunk, she is floating away happily with a bilge as dry as bone and one of them has even been and taken the photo's for me - What a great team they are!

 

Alan Fincher - Eddie sent these especially for you - I hope they help ;

 

 

The weed hatch as viewed through the hatch in the counter

 

 

A view of the canal through the weedhatch (it looks very yellow!)

 

 

This one shows the front edge of the weedhatch looking into the engine room of Python. You can see 3 drains. the two outer ones are the drains from the counter hatch and the centre one is for the engine bay bilge pump.

 

It has been confirmed to me today that the weedhatch was fitted by the same people who decided to hack half the rudder off I will say no more about that except that we have taken on board the comments about getting some strengthening on that top plate and I know Eddie will have had a good look at the seal etc today. We have a crew meeting next week so a lot of maintenance issues will be discussed then.

 

It was also confirmed to me today that when Python was surveyed the hull was described as being iron and that is why she does not need any annodes fitted. The discussion continued with two of us, neither of which know much about it tried to work out the differences between iron, steel, copper composite etc to the point where we realised it was the blind leading the blind and all either of us could go on what what we had been told which may or may not be correct but we are always willing to listen to people who may know a lot more than us

[alan_fincher]

Well that helps.

 

It is certainly hard to see how that could be a problem when not underway.

 

However a couple of observations......

 

If the hatch is meant to be correctly located and screwed down in the "through the hatch" (first) picture, then it looks like either the cover plate does not fully cover the "lip" on the tunnel, or (maybe ?) that it does but some of the seal is sticking out. Probably no issue, but looks a bit odd.

 

I'm not a fan of the "bilge pump into the weed-hatch idea. At the very least, unless the pump is fully protected against water being able to flow back through it, you are placing a point that water could enter the boat far lower than it need be, (albeit well above canal level, if the boat is not moving). But when the prop is working hard, who knows what is going on down there - I would have thought water getting pushed back through the pump is not at all impossible.

 

Mind you, most of my concerns are about if the boat is under power - not the situation it was in when it sank - so I'm aware I'm probably not helping on the main topic of conversation - well other than to try and rule some things out of the equation.

 

 

I can't imagine why a survey would say all the boat is iron. Even if the information about it being built in coppered steel is wrong, (which sounds unlikely), surely any replacement of wooden bottoms by metal must be in steel. People just don't use wrought iron for narrow boat modifications any more, do they ?

[Keeping Up]

Certainly I would be very wary of the bilge-pump arrangement unless there was a non-return valve fitted. Most bilge pumps will happily allow water to flow backwards through them when they are not running.

 

As has been pointed out, that would only be a problem EITHER if the boat was underway OR if the level of the stern was low enough to put the end of the pipe underwater. However one thing you could guarantee is that if the stern did sink to the level of the bilge pipe, without a non-return valve the boat would sink - whereas the usual weedhatch arrangement is sealed against being completely underwater. Is it possible when the water level of the canal dropped overnight, the front end hung up so that the back end dropped too far?

[cheshire~rose]

The non return valve question was one that was communicated to the team who are doing the upgrade and maintenance jobs on her. I did not get an answer to my question first time around and so I have just asked it again and they are going to check the pumps have them and if not they will be fitted as a matter of course. If the bilge pump did not flow into the weed hatch then it would need a skin fitting to empy out of and so while I take on board the fact that the prop will be splashing water about in there the baffle should stop all but some splashes from going up into the hatch. Any skin fittings can, given the wrong conditions, be just as prone to taking on water so the NRV is the way forward.

 

I have also found out something else which contradicts my original understanding of things and actually places the whole sinking into a new light. It appears the engine bulkead is not sealed right to the bottom of the boat and the bilge runs under the day cabin (and probably the heads too) The day cabin has a steel door with a step that is a couple of inches high, the sort of thing you will often come across on "functional" boats, The bilge area under this floor is not accessible to bail out and was full of water (there are some holes in the boards) The crew pushed something through the holes to try and leasure the depth of water in that area and it was goin down all the time as the engine bilge was continuing to pump out. This means that as the engine room filled with water so would the bilge under the cabin until it came to the height of the step then it could simply flow under the door and fill the hold area. Once it has started filling it would have caused the list allowing water to come in through the open skin fitting in the side.

[Tam & Di]

 

 

A view of the canal through the weedhatch (it looks very yellow!)

 

 

What is the yellow thing at the top left that looks a bit like hose? Is that something that could allow water to syphon back into the boat under certain circumstances?

 

On intermittant leaks while under way, was the weed hatch lifted at any point? It has no bracing, as people have said, and it is therefore possible that one person tightened/overtightened it so it was warped at one point but then making a seal the next time it was refitted? Or perhaps the lid had something jammed under it after one inspection of the blades.

 

The real difficulty we keep coming back to is that it would take an enormous amount of water to sink a boat, so it is not something that is just weeping, plus the lid of the weedhatch is well above water level when stationary.

 

Edit, as your post came through while I was typing.

 

That seems to alter things. What you refer to as the "day cabin" is presumably the extension forward of the engine room? It still needs a hell of a lot of water to get to that point.

Edited October 3, 2012 by Tam & Di

[alan_fincher]

What is the yellow thing at the top left that looks a bit like hose? Is that something that could allow water to syphon back into the boat under certain circumstances?

It is a pull out tape measure, presumably intended to show the depth ?

 

Unfortunately it is out of focus, so I can still only guess the depth!

 

(Actually it looks maybe 30cms / 1 foot, so that plate, and even the rather dubious connector for the bilge pump are well above uxter plate level, I would say)

[ditchcrawler]

Thanks for that Bizzard

Whilst I take on board your comments that some strengthening may be adviseable but by cross bracing I am unsure what you might mean.

The bar you can see lying on the deck is the bracing bar that tightens the hatch down and runs across the centre of the hatch

 

That is basically the same design as mine. I use to seal it with the strip material sold by most chandlers but it always leaked, even dovetailing the corner joints. A couple of yeas ago a friend advised using a sheet of closed cell foam with just a hole cut in the centre for the "anti cavitation" plate to go through. I did this and now have a bone dry bilge. However I think the leak rate would have taken many months to have sunk the boat and it would need to be below the water level to start with.