How Many Ways Can A Boat Sink?

[alan_fincher]

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.

This makes far more sense now!

 

I really couldn't see how you could achieve enough water in just the engine part of the boat to sink it down to "nearly over the gunwales". Python is a big enough boat that I would expect that a sealed space forward of the engine room would have kept it well above sinking point, even if there had been free access of water into the back. Yes, with a big Lister and a load of water at the back, it might have gone down a long way...... but enough to sink it ???.......

 

However......

 

What you have said now puts a whole new complexion on it, because of water can flow forwards from engine room to rest of boat, then (naturally) it can go the other way as well - water that got in at the front will end up draining back towards the engine room as the rear end is lower.

 

This means that it could be just as likely that your point where the water is getting in is forward of the engine room, rather than somewhere in it. We seem to have up until now concentrated on a leak near the back. So what is the situation with skin fittings, and bilge pumps, and any other apertures cut in the forward part of the boat, then ?

[ditchcrawler]

Having now seen your weed hatch photo I would like to suggest that when giving it some welly your weedhatch chamber is full of water, this in turn will find its way trough the bilge pump and if the pump is not constantly connected to the supply will fill your bilge with water. Probably the cause of you taking on water while travelling.

 

I take there is no seal on the lower plate of the weedhatch lid.

 

However when you stop the weedhatch "should" drain down again because you have two pipes connected that allows the air in. On my boat with no pipes if I try to remove the weedhatch lid as soon as I stop it is under vacuum and the water level in it is therefore higher than the canal level. So it should stop the syphoning into the bilge. I take there is no seal on the lower plate of the weedhatch lid.

 

That could be the answer to one of your problems

[Matthew Dowson]

I heard of a boat who's water tank leaked and filled the bilge, drained to stern and pushed the engine vents under, whole hull bar a few inches went under (refilled the now emp[ty tank). They refloated it and the same thing happened again. Where's your water tank?

Edited October 3, 2012 by Matthew Dowson

[David Mack]

 

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.

 

 

If Python is covered by the Non-Private Boats BSS, then the weed hatch should be watertight up to 150mm above water level under normal load (i.e. with crew standing on the counter etc). Is the bilge pump connection that high above water level?

 

Since the hose heads directly down from the skin fitting to the pump, then as others have said, once the boat is underway you may well have water going the wrong way down that hose and into the bilge. And after you have shipped some water into the stern, that hose connection might be at water level, at which point the water will continue to flow in....

 

I think this is a more likely scenario than some sort of self-sealing sprung hull plate.

 

I wouldn't want to rely on a non-return valve to stop my boat from sinking. I really think you should change all those hose connections to drain out through skin fittings in the side of the hull. The BSS specifies that they should be at least 250mm above water level, but more would do no harm.

[smileypete]

I wouldn't want to rely on a non-return valve to stop my boat from sinking. I really think you should change all those hose connections to drain out through skin fittings in the side of the hull. The BSS specifies that they should be at least 250mm above water level, but more would do no harm.

+1

 

I'd certainly move the bilge pump connection to a skin fitting, with non crush hose.

 

Sounds like there's 2 different causes for taking on water when underway, and taking on water when moored up.

 

cheers, Pete.

~smpt~

[cheshire~rose]

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?

 

The yellow thing is a tape measure that has been placed into the photo to try and give some idea of perspective. Sadly it has blurred so it does not help a great deal but it is not usually there and so would not be a cause of any possible leaks

[cheshire~rose]

I have read the various replies and would like to thank everyone for their continued interest and input into this query.

 

I realise there are a number of questions that need me to type an answer to them but I am sorry I have what I believe to be the start of a migraine this evening and I am struggling to get my head around what has been asked let alone try and formulate replies that make sense so I will leave it now and see if I can respond tomorrow.

 

I will just note that there seems to be a number of people suggesting that the current set up with drains running into the weed hatch will cause Python to take on water when under way. I would like to just repeat that since the visit to the boat yard Python HAS NOT taken on water while under way. The set up of drains you have seen photo's of was done while at the boatyard and so it was impossible that was the cause of the earlier, now cured ingress of water we were experiencing before she came out of the water and while I can understand how people suggest it may cause water to fill the bilge while under way so far this has not happened. The only problem we have had since this set up has been installed was one (admittedly fairly major) overnight ingress of water while stationary

 

I will get back to people on the other issues when my head function has recovered a little

 

Thanks everyone

[Ray T]

I

 

 

Completely , sorry about this but I cannot resist: Is this a precedent for working boats having the mooring rope on the tiller?

Edited October 4, 2012 by Ray T

[Keeping Up]

I have read the various replies and would like to thank everyone for their continued interest and input into this query.

 

I realise there are a number of questions that need me to type an answer to them but I am sorry I have what I believe to be the start of a migraine this evening and I am struggling to get my head around what has been asked let alone try and formulate replies that make sense so I will leave it now and see if I can respond tomorrow.

 

I will just note that there seems to be a number of people suggesting that the current set up with drains running into the weed hatch will cause Python to take on water when under way. I would like to just repeat that since the visit to the boat yard Python HAS NOT taken on water while under way. The set up of drains you have seen photo's of was done while at the boatyard and so it was impossible that was the cause of the earlier, now cured ingress of water we were experiencing before she came out of the water and while I can understand how people suggest it may cause water to fill the bilge while under way so far this has not happened. The only problem we have had since this set up has been installed was one (admittedly fairly major) overnight ingress of water while stationary

 

I will get back to people on the other issues when my head function has recovered a little

 

Thanks everyone

 

Just staying for a moment longer on the subject of water ingress while underway, the relative positions of the weedhatch and the propeller can complicate matters. For example on our boat the propeller is a short way behind the weedhatch; as a consequence, when travelling forwards in forward gear it is actually possible to remove the weedhatch and to travel at any speed without any ingress of water. However, water splashes up as soon as reverse gear is engaged, and revving the engine in reverse causes a fountain.

 

However, I realise that this does nothing to solve the mystery of the overnight sinking.

[Laurence Hogg]

Who was the surveyor who couldnt recognise a coppered steel FMC boat and concluded it was iron? Certainly sounds like someone to keep away from old historic craft.

I have a copy of the actual dock record from FMC which states C/S in the boats entry it is one of the coppered steel batch.

 

The incorrect type of hoze fitted to the bilge pump also says a lot about who fitted that, when underway and under good power there would be in my opinion a good chance of leakage occuring through the pump.

Edited October 3, 2012 by Laurence Hogg

[David Mack]

When you put the weedhatch lid back on there will be an airspace below. But on some boats, once under way this air is sucked out into the prop, and thw whole weedhatch trunk fills with water. I know this because next time you open it up, as you loosen the lid and crack the seal you hear the air rushing in.

 

On Python, if you got the trunk half full of water you might just set up a syphon with the bilge pump hose.

 

Its quite hard to see how this could start - perhaps lots of reverse gear just before stopping? But if it did the boat would quietly fill up with water after you had left.

 

And moving that bilge pump outlet would certainly prevent it!

[alan_fincher]

I will just note that there seems to be a number of people suggesting that the current set up with drains running into the weed hatch will cause Python to take on water when under way. I would like to just repeat that since the visit to the boat yard Python HAS NOT taken on water while under way. The set up of drains you have seen photo's of was done while at the boatyard and so it was impossible that was the cause of the earlier, now cured ingress of water we were experiencing before she came out of the water and while I can understand how people suggest it may cause water to fill the bilge while under way so far this has not happened. The only problem we have had since this set up has been installed was one (admittedly fairly major) overnight ingress of water while stationary

To be absolutely clear, hen you talk about "the drains", does that include the bilge pump, please ?

 

That is, was the bilge pump not being directed into the weed-hatch until the docking ?

 

If it wasn't, why was it decided to do that, please ? How did the bilge pump use to discharge ?

[cheshire~rose]

That is, was the bilge pump not being directed into the weed-hatch until the docking ?

 

Because the only engine bay bilge pump that was available prior to the episode experienced on the last few weeks of Pythons tour this year was a manually operated hand pump

 

Just a reminder of why I started this thread:

 

 

The reason for this thread is three fold:

 

1, If I air on here what happened along with the facts it means that the next time I meet you out and about on the system or at a banter or talk to you on the phone I will not have to relay all the details to you one by one. This will allow you to come up with your own theory as to why it happened. You can if you wish share your theory with me when I see you but please bear in mind that no matter how good you think your personal theory is I may already have heard that one several times before

 

2, The forum is full of real experts and armchair experts who love to argue discuss stuff and as this subject is such a potentially rich vein of poential subject matter for discussion I thought it only fair I shared it with you all

 

3, It is maybe just possible that someone might come up with a theory we have not already heard which might help us to find the cause.

 

1, Well everyone knows as many facts as we know now

2, Everyone has had the opportunity of a good discussion

3, No one has actually come up with any theory we had not already thought of ourselves.

 

There have been a lot of people who have made valuable suggestions and a number of these are in the process of being implemented and to those people we are all very thankful.

 

I would like to remind people that although I have been the only member of Python's crew who has been posting on this thread there are a lot of them who are reading it.

 

Python may be owned by The Chesterfield Canal Trust but like all historic narrow boat owners they are simply custodians of a small piece of history, We as a crew see it as our responsibility to do whatever we can within our power and budget to preserve Python so she can continue to be a source of pleasure for future generations.

 

None of the crew profess to be experts in the field of historic boats. They are an enthusiastic and passionate bunch which a wonderful range of skills and talents and each of them voluntarily applies their skill and talent to ensuring Python gets to as many festivals as possible looking reasonably well presented and most importantly is preserved from deteriating

 

In my view this thread appears to have run it's course. As people have, just as we did, run around the full range of possible theory's as to what happened and decided upon their own personal theory but with the knowledge that none of us is ever likely to be certain of exactly went wrong that night many have now turned to trying to find fault.

 

Some of the fault finding, we as a crew, are able to brush off as work has been carried out in the past by people we are unlikely to choose to carry out work on her again and decisions have been made which, with hindsight, may not have been the best decisions. We were aware of that before this thread even started and it is nothing new to us.

 

If there is any boat owner out there that truly cannot say that given their time over again, and with the benefit of hindsight, they might have done things a little differently? Indeed there are a lot of ways that things can be done on boats and often there is not only one correct way but a number and which method an idividual thinks is best is a matter of opinion.

 

When fault finding on this thread is not only irrelevant to the question that was originally asked, but is also picking fault with things that well meaning individuals are doing out of the goodness of their heart, then it becomes hurtful.

 

An interogation about who did what, said what or made a certain decision in the past is not going to stop her sinking and so I will not get drawn into further conversation along those lines.

 

I would once again like to thank everyone who has has taken their time to offer constructive advise on this thread.

There has been a lot of benefit from it but I now feel it has been done to death and so it is time to draw a line.

 

Thank you to everyone who has given contructive input into this thread

[RLWP]

<snip>

 

Thank you to everyone who has given contructive input into this thread

 

And artistic input! Don't forget the Peotry

 

Richard

[cheshire~rose]

And artistic input! Don't forget the Peotry

 

Richard

 

Richard - among the crew I have become known as the person who kept fundraising while the boat was sinking so just like the band kept playing while Titanic sunk so perhaps you can be known as the poet that kept rhyming while........

 

No - she is NOT sinking!

[alan_fincher]

Because the only engine bay bilge pump that was available prior to the episode experienced on the last few weeks of Pythons tour this year was a manually operated hand pump

Fair enough, but if you explained where that original hand pump actually connected to, I must have missed it.

 

I was trying to clarify whether the existing pump, (which I realised was a hand one) was already using that connection to the weed-hatch.

 

I now understand that is new, as at the docking.

 

It may not appear to be letting in water, but there are enough people who think it unwise, I think it would be sensible to get it changed.

 

3, No one has actually come up with any theory we had not already thought of ourselves.

May be not, but it is not until yesterday evening, and post 97, that you have added the following, which may be very pertinent.....

 

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.

I think from the original information most of us were not unreasonably assuming that any ingress of water had to be taking place rearward of a sealed bulk-head, because that is how I thought it was being described. The big change to that information provided only yesterday now seems to open up the possibility it could have been in any part of the hull.

 

I haven't looked through again to see if there were references to open skin fittings previously, but if there were, I can't remember it being picked up on.

 

My strong feeling is you can not now rule out any part, when previously it sounded like you needed to concentrate on just the back end.

 

Good luck with it, anyway........

[matty40s]

Richard - among the crew I have become known as the person who kept fundraising while the boat was sinking so just like the band kept playing while Titanic sunk so perhaps you can be known as the poet that kept rhyming while........

 

No - she is NOT sinking!

 

Cheshire Rose

 

[bluegreencanal]

Is it possible that the pipe which drains the flow of water from the counter during heavy rain is blocked so that the channel itself overflowed and emptied into the stern locker?

[Derek R.]

Is it possible that the pipe which drains the flow of water from the counter during heavy rain is blocked so that the channel itself overflowed and emptied into the stern locker?

 

Been there - done that. In fact - been everywhere. Haven't visited Mystic Meg though.

 

It's a long winded thread, but originated through genuine concern - as have all the replies (well, most) and with a genuine interest in discovering the cause of sinking. However, after much scratching of heads, that will only be done by those with hands on experience, and 'being there' over an extended period of time will be the only way to reveal the cause.

 

Good luck.

[bizzard]

I still wouldn't discount foul play here. ''Someone with a length of hose pipe'' when the boat was moored and unattended.

Over the last few years i've raised two boats which were almost certainly sunk by that method, one was also set on fire, both owners it turned out had enemies.

Easy to do, just start the syphon by sucking the hose then pop it into the boat and walk away and leave it to sink. The only thing is they usually leave the hose in situ and don't return to the scene.

Edited October 4, 2012 by bizzard

[David Mack]

I would once again like to thank everyone who has has taken their time to offer constructive advise on this thread.

There has been a lot of benefit from it but I now feel it has been done to death and so it is time to draw a line.

 

Oh you can't just end a thread like that you know!

 

Seriously, although we haven't determined with certainty what the cause of the problem is, there is one point you should nevertheless take forward. And that is to remove the bilge pump connection from the weedhatch and seal the connection. I would suggest you instead run the hose to a skin fitting higher up on the hull side, but equally you could just have a length of hose you stick out through a dooor or a vent opening when pumping the bilge. The cost will be minimal and it takes away an area of risk which several of us here are a bit concerned about.

 

Personally, I don't like the hoses draining down from the deck lid to the weed hatch either, but as long as the hoses are undamaged and the connections at each end are tight they aren't going to sink the boat.

[mykaskin]

So, what do we know... first of all, is this a reasonably accurate (if rather poor) diagram of the boat?

 

 

Red circles are the more obvious possible ingress points.

 

Second, from the log:

 

Boat was listing after being left over night, automatic bilge pump running, and water was pouring into the hold through the pump outlet hole, and then running to the back of the boat through the bilge?

 

Water had previously been entering while under way, but source not found. No water was previously entering static before the blacking.

 

After the blacking, no water was found to be entering either under way or static, or after this near sinking event.

 

I think we can discount rain water, as even if particularly heavy rain was experienced over night I don't believe that enough could have entered to cause other inlets to go under.

 

Hold outlet pipe I assume is on the lower side of the boat as it listed pushing it under water?

 

When pumped out the boat was freely floating and not hard aground?

 

Any more known facts?

 

We'll get to the bottom of this somehow! :-)

 

Mike

 

ps. Not sure what went wrong with the prop!!

Edited October 4, 2012 by mykaskin

[David Mack]

ps. Not sure what went wrong with the prop!!

 

You had this problem (from another Python):

 

[bluegreencanal]

Been there - done that. In fact - been everywhere. Haven't visited Mystic Meg though.

 

It's a long winded thread, but originated through genuine concern - as have all the replies (well, most) and with a genuine interest in discovering the cause of sinking. However, after much scratching of heads, that will only be done by those with hands on experience, and 'being there' over an extended period of time will be the only way to reveal the cause.

 

Good luck.

 

It was kindly meant.

[Derek R.]

Kindly meant - and please don't get me wrong. As it is a long thread and with many replies in a short space of time, it's easy to miss something that has been asked before, though doubtless the OP is aware of this and appreciative still. I do not know Cheshire Rose personally so am jumping the gun a bit there.