How Many Ways Can A Boat Sink?

[bizzard]

Dave 69700 mentioned ''rudder tube''. If the rudder stock tube ''does not'' pass through an integral fuel tank then as Dave says it could be ''rusted perforated just above the water line and letting in water as the stern tucks down when under power, as could a weed box problem. If of course the rudder tube pass through an integral fuel tank it would contaminate the fuel and would soon have stopped the engine.

[cheshire~rose]

Dave 69700 mentioned ''rudder tube''. If the rudder stock tube ''does not'' pass through an integral fuel tank then as Dave says it could be ''rusted perforated just above the water line and letting in water as the stern tucks down when under power, as could a weed box problem. If of course the rudder tube pass through an integral fuel tank it would contaminate the fuel and would soon have stopped the engine.

 

It does not pass through a fuel tank.

 

If it were a problem it would, I feel have either been found and fixed when in the boatyard or would still be causing a problem post boatyard.

 

It is unlikely to have caused it to sink when the boat was static.

 

Come on Bizzard - we need a wheez to ensure she does not sink again - surely we can rely on you for that?

[bizzard]

It does not pass through a fuel tank.

 

If it were a problem it would, I feel have either been found and fixed when in the boatyard or would still be causing a problem post boatyard.

 

It is unlikely to have caused it to sink when the boat was static.

 

Come on Bizzard - we need a wheez to ensure she does not sink again - surely we can rely on you for that?

Wrap the boat completely in a Butyle rubber nappy.

 

You have an enemy who comes along when the boat is stationary and unattended and syphons water from the canal into the boat with a length of hose pipe.

Edited September 30, 2012 by bizzard

[haggis]

To attempt a look at the logic of the situation, it has firstly to be a hole/split of some size for the boat to sink quickly. The hole could just above ordinary waterline so it is under water when you apply power on deeper water, but you would expect to be able to see signs of it. It could be behind a guard, which might make it less easy to see. It could also have gone below water level when the pound was lowered by 4" which could set Python on the bottom and induce a list. It could be a split which opens up with the vibration when the engine is working hard, or it could be one which is semi-sealed by weed on the exterior which moves/clears occasionally. However if the hull has just been blacked that would seem to cancel that possibility. I can't really see a reason for a stern gland to leak so badly as to sink the boat at one point but then stop completely of its own accord.

 

Hamsterfan's suggestion of water coming initially via the air vent seems a good possibiity. I mostly subscribe to the syphonnage back through the bilge pump.

 

Some possibilities there, but no great assistance I guess.

 

That's a possibility as she didn't leak on her way from the Erewash (where she was blacked) to the Chesterfield. The blacking would seal the possibly hairline crack but it repopned again.

 

haggis

Edited September 30, 2012 by haggis

[cheshire~rose]

That's a possibility as she didn't elak on her way from the Erewash (where she was blacked) to the Chesterfied. The blacking would seal the possibly hairline crack but it repopned again.

 

haggis

 

This is true but if the hairline crack had been letting in water prior to blacking then why did it open up again to leak only when the boat was stationary and then seal itself again when the boat started moving?

 

I would like to thank everyone who has posted so far for all their suggestions. I hope you all realise I am not just being obtuse when I offer a suggestion as to why their theory might not be the answer. We really have all been round and round with the theories in our heads to the point it is making us dizzy. I truly suspect we may never actually get to the root of the issue. There are a number of the crew pointing the finger of blame at a widdling stern gland but it was greased before they left the boat, it had been repacked by a reliable engineer only a week before (with the correct size packing) and would a dribble (that had not happened during the last few days of travelling) really sink a boat overnight?

 

Keep the theories coming, I live in hope that someone out there thinks of something that is so blinking obvious we have not thought of it. Failing that to see people who I can often rely on to have a perfectly good answer to many a boating problem bit by bit give up on this one does make us all feel a little better about answering those who ask what caused it with "We don't know" a lot better!

[bizzard]

I'm not certain on that boat but if the stern-tube assembly screws into the stern-post collar as is normal this can leak water in quite fast ''wire in'' around the threads if loose, stationary and when under power. Ive had to sort out a couple of boats with this trouble recently, They thought it was the packing gland leaking badly and it wasn't.

 

ps Worth checking for tightness with Stilsons.

Edited September 30, 2012 by bizzard

[haggis]

Is there any chance of getting a pressure washer to hose down the inside of the hull in the engine area? It might just dislodge some crud which is capable of moving and sometimes sealing over a weak bit in the hull? I don't know, some flakey rust or similar. For this to be any use as a method of finding the leak all of the inside of the hull in that area would need to be hosed. Not an easy job, I imagine, but it could be done in small bits with the mess cleared up between times and movable things, like batteries removed.

Good luck with finding the answer.

 

haggis

[NB Esk]

For clarity (apologies if I missed it) could you say how the hatch on the rear deck, drains?

I know it's been stated that the water is canal & not rain, but I don't know how this can be for certain, given it's been sloshing around in a sunken boat. Also, I understand you think the boat went down stern first, if she did go heavy to stern, would the hatch drain still continue to work? If your area was anything like mine, there was a huge amount of rainwater overnight.

 

Slightly tongue in cheek, a video camera wired thro' a tilt switch should find it Seriously tho', it's a mystery, hope you sort it...

[luctor et emergo]

Technically speaking, there is only one way a boat can sink..

[cheshire~rose]

For clarity (apologies if I missed it) could you say how the hatch on the rear deck, drains?

I know it's been stated that the water is canal & not rain, but I don't know how this can be for certain, given it's been sloshing around in a sunken boat. Also, I understand you think the boat went down stern first, if she did go heavy to stern, would the hatch drain still continue to work? If your area was anything like mine, there was a huge amount of rainwater overnight.

 

Slightly tongue in cheek, a video camera wired thro' a tilt switch should find it Seriously tho', it's a mystery, hope you sort it...

 

One of the things that Paul Barber put right for us while Python was at his place was to sort out the incorrect drains on that rear hatch. It had been somewhat odd before because there was a single drain at the rear of the gutter which was the highest point!!!

We suspect that way back in the 80's when BW converted her someone welded in the weedhatch back to fromt. Paul has now added two drains to the front corners of the gutter where it is at it's lowest point. The rear drain is still in place and so in fact regardless of the kilter of the boat it is pretty much certain to drain.

 

Technically speaking, there is only one way a boat can sink..

Yes you are of course correct and this was hinted at by Richards post (post~2) I feel

[twbm]

In line with Haggis's's' suggestion, might you pressure wash the outside of the boat whilst watching for water ingress? A possibly over-elaborate aid would be to feed the pressure washer from a tank filled with clean water and fluorescein dye, so even if you miss the ingress the result will show up in the bilge.

[Tam & Di]

There were various other people who know their stuff who cast an eye over her while out of the water too. While we are all human and it is very easy for these old cast iron hulls to keep secrets in even the most vigourous inspection but realistically would something that was ONLY letting water in when on the move be missed by so many people when out of the water then behave itself perfectly for the next 5 days and fail again overnight while standing?

 

It leads me to think that the original leak has indeed been cured as there is no evidence of it whatsoever but then suddenly and without warning she goes down overnight. Where, if at all, is the link between the two? If there is no link between the two then how can a boat sink overnight then apparently be fine again once bailed out?

 

Exactly. But as I noted, a small weep would not cause Python to sink overnight - it had to be a pretty big leak, or if not a leak as such, some other way for so much water to be on the wrong side of the hull. Vandalism does not seem plausible, as the earlier ingress of water would be too much of a coincidence, and you don't regard the possibility of rain as likely. Occasional faults are always much more difficut to trace.

 

Is there any way of fitting some sort of bilge alarm - a bilge pump with a float switch and with the hose poked out of the engineroom so it can be seen if the pump starts to operate? At least that way someone can look for it when water is actually coming in.

[David Mack]

There are a number of the crew pointing the finger of blame at a widdling stern gland but it was greased before they left the boat, it had been repacked by a reliable engineer only a week before (with the correct size packing) and would a dribble (that had not happened during the last few days of travelling) really sink a boat overnight?

 

If the stern gland is a possible candidate for the leak I would suggest you get in the habit of, after you have moored up at the end of a trip, lifting the floor and checking that there is no water dripping from the stern gland. On Fulbourne our gland sometimes continues to leak even after pumpting some grease in. Half a turn of the stern shaft is usually enough to stop it - presumably this distributes the new pumped in grease around the circumference of the shaft.

 

David

[ditchcrawler]

Sorry if this is stupid but, The new bilge pump emptied through a drain on the weed hatch how does that work, is it possible water could siphon back through the pump?

I do know of one old boat that sank at least twice due to the end of the discharge pipe from the bilge pump dipping into the water, when the pump ran and stopped it set up a syphon which won the day after the battery was flat.

[RLWP]

Technically speaking, there is only one way a boat can sink..

 

I think I covered that comprehensively in post #2

 

Richard

[the grinch]

It has never yet been experienced - whist admitted that rain could potentially creep into a vent or something in exceptional weather like we had that night - enough to sink a boat?

 

certainly enough if combined with a list already caused by a low pound. might be worth getting some water containers or anything very heavy and making her list badly to one side to check the hull isn't leaking above the normal water line

[cheshire~rose]

In line with Haggis's's' suggestion, might you pressure wash the outside of the boat whilst watching for water ingress? A possibly over-elaborate aid would be to feed the pressure washer from a tank filled with clean water and fluorescein dye, so even if you miss the ingress the result will show up in the bilge.

 

As she is freshly blacked and back in the water there is now that much of the bottom we could get to with a pressure washer (and as she is on her home mooring where there is no power or water and cannot wind without booking passage through a lock which is a snug fit for her with CRT anything to do with a power washer is something we would be able to do easily.

I do tend to think that if a bit of crud or rust has loosened enough to allow enough water in to sink her overnight then that same piece of crud/rust would likely to have been swept away in the rush of water coming in and leave a visible scar/ weep/ rust spot.

[luctor et emergo]

I think I covered that comprehensively in post #2

 

Richard

 

Technically, according to the post numbering, your post is no.3

 

That besides, is one realy supposed to read every post, when tempted to leave a witty reposte?

I could be here all day....

[cheshire~rose]

I'm not certain on that boat but if the stern-tube assembly screws into the stern-post collar as is normal this can leak water in quite fast ''wire in'' around the threads if loose, stationary and when under power. Ive had to sort out a couple of boats with this trouble recently, They thought it was the packing gland leaking badly and it wasn't.

 

ps Worth checking for tightness with Stilsons.

 

I have not forgotten your theory - I am not sure enough about what you describe to know if it applies or not so I need another crew member to check this for me

 

 

Is there any way of fitting some sort of bilge alarm - a bilge pump with a float switch and with the hose poked out of the engineroom so it can be seen if the pump starts to operate? At least that way someone can look for it when water is actually coming in.

 

I am liking this suggestion. Although the neighbour has contact numbers for various crew it might be an idea if at least the outlet pipe was visible so if it was pumping it could be seen. Even if it was only a temporary measure while she over winters and until we all feel a little more relaxed. I will mention it to the team

 

If the stern gland is a possible candidate for the leak I would suggest you get in the habit of, after you have moored up at the end of a trip, lifting the floor and checking that there is no water dripping from the stern gland. On Fulbourne our gland sometimes continues to leak even after pumpting some grease in. Half a turn of the stern shaft is usually enough to stop it - presumably this distributes the new pumped in grease around the circumference of the shaft.

 

David

 

It is standard (and expected) practice for all crew to twist the stern gland greaser at the end of any journey. The usual rule is to twist the greaser until any water dripping stops. The fact that prior to stopping there was little or no evidence of any major drips from the stern tube (and the fact that it had so recently been repacked with using the correct size packing) makes me wonder how it could be possible for so much water to enter the boat this was overnight.

 

One of the crew suggested "When the stern greaser was filled, air bubbles were left in it, so at some stage, instead of grease going to stern gland, only air went in. If this happened Wed night, it would explain why it leaked badly" Indeed this has happened to us on our own boat before now but although there was far more water in the bilge that we were comfortable with, after 5 days the boat had not sunk!

 

I do know of one old boat that sank at least twice due to the end of the discharge pipe from the bilge pump dipping into the water, when the pump ran and stopped it set up a syphon which won the day after the battery was flat.

 

As the end of the discharge pipe is only just below the rear counter the stern would need to be fairly well submerged before this could happen

 

certainly enough if combined with a list already caused by a low pound. might be worth getting some water containers or anything very heavy and making her list badly to one side to check the hull isn't leaking above the normal water line

 

This may be something worth trying to do. In practice we could not get water containers of any size into the engine room but perhaps we could just get plenty of people to stand on the gunwhales at the same time. one side then the other with someone inside looking for leaks. She rolls around well enough when going over debris in the bottom of shallow canals anyway and I suspect there are numerous occasions when areas that are not usually below the water line end up that way. I suspect for the short time this occurs it is unlikely we would notice a potential problem though

 

Technically, according to the post numbering, your post is no.3

 

That besides, is one realy supposed to read every post, when tempted to leave a witty reposte?

I could be here all day....

 

Clearly you did not need to read every post because Richard solved the problem within minutes of my opening post.

 

Another feather in the cap for Primrose Engineering

[Chalky]

Is there anything else in the engine room that contains water and could have leaked? (having succeeded in flooding mine after the PRV didn't seal on the calorifier and the pump emptied the water tank into the bilge!)

 

One difference between moving and stationary will be the heat and vibration caused by the engine. Could this have opened up a weep in seam/weld/rivet which has now been filled with silt/rust and effectively sealed until it lets go again?

[smileypete]

Mayeb worth having a small bilge pump and Rule 'wedge' float switch to deal with everyday bilge grot, then a bit higher up a bigger pump and float switch as back up for if/when the smaller one fails or gets blocked.

 

cheers, Pete.

~smpt~

[cheshire~rose]

Is there anything else in the engine room that contains water and could have leaked? (having succeeded in flooding mine after the PRV didn't seal on the calorifier and the pump emptied the water tank into the bilge!)

 

One difference between moving and stationary will be the heat and vibration caused by the engine. Could this have opened up a weep in seam/weld/rivet which has now been filled with silt/rust and effectively sealed until it lets go again?

 

Python does not have a calorifier fitted. There is just the engine and the fuel tank in the engine hole.

 

If it sunk due to a weep on a seam/weld/rivet then it happened without any vibration or heat as it was static at the time. If there as a weep before it went to the boat yard (when your suggestion was much more of a possibility) then no one could find it and the symptoms did not recurr after it left the boatyard

[Tuscan]

My stern gland bolts used to work lose with vibration when under way with reasonable revs leading to water ingress which would often stop when the revs dropped. But if you are greasing and checking every day this can't be it. Worth standing a few heavies on he counter to replicate being under way and see if any water comes in. A real mystery.

[cheshire~rose]

Mayeb worth having a small bilge pump and Rule 'wedge' float switch to deal with everyday bilge grot, then a bit higher up a bigger pump and float switch as back up for if/when the smaller one fails or gets blocked.

 

cheers, Pete.

~smpt~

 

Yes I agree it could be worth it, it could also be worth renting a covered dry dock to store her over winter just in case ... I am sorry my remark is somewhat flippant.

 

We are costing up making the hold bilge pump into an auto one at the moment. We will do whatever the team consider good value for money things to ensure we are not faced with the same scenario again. We could go on and on but a line has to be drawn and there will always be different people who have different ideas about how necessary a piece of equipment is on a boat (for example when we got involved earlier this year we could not comprehend there being NO electric bilge pump at all on an old boat. She had been run that way for 2 years though.

We prefer not to spend any money that is unnecessary as by spending it on Python we are nt spending money on restoring a canal. It is a fine line to tread to safeguard, maintain and protect Python as a piece of our boating heritage without it costing more than can be justified when her role within The Chesterfield Canal Trust is as a publicity vehicle for their cause. All of the crew love the old lass to bits but she is much more than just a boys toy and she has to earn (or we have to fundraise) every penny that is spent on her.

[Smelly]

I've seen a badly fitted stern gland present the symptoms you describe when underway Jan. Was the crud blocking the bilge pump grease?