Thames Safety Notice-Narrowboat Sinking

[PaddingtonBear]

Why not mock continuous moorers?

[John Williamson 1955]

From my armchair, I struggle with the basic causation mentioned. An additional displacement, even allowing for some see-sawing, of 115mm (at the vent) arising from three persons persons standing on the stern deck seems very high. Is anyone willing to have a crack at an estimate of the probable weight required - of does anyone have a reasonably similar boat that reacts similarly? I did once witness a boat sink at Llangollen due to it being overloaded whilst moored - the water came over the transom but it was a small cruiser and there were a good few aboard. Interestingly, no mention is made in the Bulletin of listing even though those in the cabin could also contribute to this effect.

Reading the MAIB report, the distance from the static waterline to the top of the plate that had been installed covering part of the vent with the boat empty was only 65mm. The waterline with three people standing on the back deck was above the top of this plate. Both as shown in the pictures.

[LoneWolf]

From my armchair, I struggle with the basic causation mentioned. An additional displacement, even allowing for some see-sawing, of 115mm (at the vent) arising from three persons persons standing on the stern deck seems very high. Is anyone willing to have a crack at an estimate of the probable weight required - of does anyone have a reasonably similar boat that reacts similarly? I did once witness a boat sink at Llangollen due to it being overloaded whilst moored - the water came over the transom but it was a small cruiser and there were a good few aboard. Interestingly, no mention is made in the Bulletin of listing even though those in the cabin could also contribute to this effect.

 

Assuming each person made a pro-rata contribution, arithmetic would suggest just two would have been enough to put the vent below the water line - maybe even one if the stern digs-in under way. Was it the case that (since overplating) there had never been more than one or two persons on the stern deck? It is possible, I suppose.

 

The "new" factors as stated appear to be (possibly) choppy waters and the previous days launching. Maybe water was taken on due to the boat being lifted aft-down?

 

The safety lessons makes sense.

 

I know the people who used to own this boat.

 

They sold it while it was still out of the water for overplating. The new owners took it by road to london & it seems like they put it in the water and then locked out fairly soon after that.

So it was the first time ANYONE had been on it since the overplating

and the water tank was probably empty as well

Why not mock continuous moorers?

 

why not mock grumpy gits who only ever post negative things?

 

.... because you're not worrfffff it

[Tacet]

Yup the link works fine for me.

 

I don't get what you are trying to say, care to elaborate?

 

Well, the article is found on the MAIB website, but attributed to the Risk Management Director for Thomas Miller P&I Ltd - there is nothing to say that it incorporates the findings of the MAIB and certainly some of the other case studies are unlikely to have been. It seems more probable that it is a rehash of the PLA report. This does not mean that it is necessarily wrong, of course, but the MAIB are the specialists.

 

Another poster has kindly advised that the boat had only been afloat for a day or so since replating, which may well account or substantially contribute to the sinking; I have no difficulty with marginal freeboard being the main issue.

 

But a boat of this length and style that settles in the water by more than 1.5 inches per person, at the stern is far from usual. An attempt measure the additional depth caused by me standing on the stern deck of Tacet was maybe 1/4". At the rate suggested by the PLA half a dozen persons would use up the (former) recommendation of 10 inches before any opening above water level and should you risk a stag weekend made up of rugby players, you would need a rota for fore and aft movements as without this, the stern deck would be awash, with or without any hull piercings.

 

If three persons on the back deck caused this boat to sit 115mm deeper, Something Else is going on - maybe free water effect?

[howardang]

 

Well, the article is found on the MAIB website, but attributed to the Risk Management Director for Thomas Miller P&I Ltd - there is nothing to say that it incorporates the findings of the MAIB and certainly some of the other case studies are unlikely to have been. It seems more probable that it is a rehash of the PLA report. This does not mean that it is necessarily wrong, of course, but the MAIB are the specialists.

 

Another poster has kindly advised that the boat had only been afloat for a day or so since replating, which may well account or substantially contribute to the sinking; I have no difficulty with marginal freeboard being the main issue.

 

But a boat of this length and style that settles in the water by more than 1.5 inches per person, at the stern is far from usual. An attempt measure the additional depth caused by me standing on the stern deck of Tacet was maybe 1/4". At the rate suggested by the PLA half a dozen persons would use up the (former) recommendation of 10 inches before any opening above water level and should you risk a stag weekend made up of rugby players, you would need a rota for fore and aft movements as without this, the stern deck would be awash, with or without any hull piercings.

 

If three persons on the back deck caused this boat to sit 115mm deeper, Something Else is going on - maybe free water effect?

Do you mean free surface effect? Wasn't there a comment somewhere that tanks were empty? (apart from fuel of course)

 

 

Howard

[Tacet]

Do you mean free surface effect? Wasn't there a comment somewhere that tanks were empty? (apart from fuel of course)

 

 

Howard

 

Yes, that's right - but could there have been water sloshing about under the floor? Difficult to know, after the event.

[Dharl]

And of course with a couple of larger than average waves, which happens often in the Limehouse and Wapping reaches especially if a fast cat, trip boat or RIB goes past, and the water will go higher than 115 mm and slop into the engine compartment. Doesn't take much water for a "free surface effect" to take place also this added water would alter the GZ curve of the vessel and affect the stability in paricular both the aft trim and the " Loll" ( NOT Laugh Out Loud). As soon as water started to enter the engine room there could only be one result.