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What was she doing?.....and why?


Wanderer Vagabond
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Having just read the letters section of December's Tillergraph, there was a letter included that left me somewhat puzzled. The lady concerned was writing in complaint about speeding narrowboats (a fairly common topicrolleyes.gif ) but what she complained about left me a bit puzzled, perhaps others could suggest what the manoeuvre she was doing was,and why.

To quote from the letter, she said,

 

"......Not long ago I moored on a tidal section of the Thames where twice a day the water goes out completely and the boat sits on the river floor. There's always a slightly nervous period when you worry that your boat will settle on something that could damage the hull, so imagine my horror when, with less than two foot of rapidly vanishing water left, a narrowboat came by at full tilt, behaving with the blithe ignorance you'd associate with weekend speedboat idiots. The wash was so great that my boat struck the riverbed several times before things eventually calmed down. Mercifully I suffered nothing worse than a few smashed crocks, and I don't suppose the narrowboat owner ever knew the near disaster they had caused......."

 

Now my first question was why she wanted to moor on the tidal section of the Thames in the first place, but then each to their own. She highlights the risk by the concern she shows that the boat may settle onto something that could damage the boat, so she is already accepting that it is a risky maneouvre. The bit I can't get my head around though is her criticism of some narrowboater who she claims 'came by at full tilt'. Well unless he can get his narrowboat up onto planing mode I'm not entirely sure how he is going to exceed the 8 knot limit above Wandsworth Bridge or 12 knot limit below it (she doesn't identify where she was letting her boat sit on the bottom).

 

I was going to write a query to Tillergraph questioning what exactly the lady concerned was doing but thought I'd post here first to see if I'm missing something. Are there some splendid moorings that I've missed on the tidal Thames? Do people regularly and intentionally put their boats onto the mud banks? Have I missed something?

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I was going to write a query to Tillergraph questioning what exactly the lady concerned was doing but thought I'd post here first to see if I'm missing something. Are there some splendid moorings that I've missed on the tidal Thames? Do people regularly and intentionally put their boats onto the mud banks? Have I missed something?

Yes there are and yes they do.

 

 

post-261-0-99279000-1480183494_thumb.jpg

Edited by ditchcrawler
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Surely Full Tilt means the maximum speed of the boat (or thereabouts) rather than the speed limit of the river?.

The Thames is a big river so I would not normally expect boats to slow down nearly as much as they would on a canal.

Settling on the mud can be a tricky operation but it is very rare so can't really expect the "typical" narrowboat owner to understand this?.

 

I assume this was somewhere between Brentford and Richmond.

 

Another factor is that as the tide was well on its way out maybe the narrowboat had left things very late and was rushing to avoid getting grounded?

 

.............Dave

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Lovely,

No mooring fees (probably)

No BSS

No licence

Magic....

 

Any vessel moving down the inside of Chiswick Ait on a falling tide is going to make a fair bit of wash - especially against a sloping bank. Just like being beside the seaside - no boat necessary...

 

As on the canal system or anywhere on the water - you have to be careful where you moor as there may be some hazard or other.

I suspect that nobody / few folks would normally navigate that section approaching low water.

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Attitude of the PoLA on wash from boats is very clear - these are MCA category C waters with a normal maximum wave height of 1.2 metres. Unless the wash of a passing vessel exceeds 1.2 metres then what is the problem?

 

Some of the passenger boats around Tower Bridge might make a wash that big, but not much else will...

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Surely Full Tilt means the maximum speed of the boat (or thereabouts) rather than the speed limit of the river?.

The Thames is a big river so I would not normally expect boats to slow down nearly as much as they would on a canal.

Settling on the mud can be a tricky operation but it is very rare so can't really expect the "typical" narrowboat owner to understand this?.

 

I assume this was somewhere between Brentford and Richmond.

 

Another factor is that as the tide was well on its way out maybe the narrowboat had left things very late and was rushing to avoid getting grounded?

 

.............Dave

 

Boats do bottom out below Brentford, this photo taken at Hammersmith:

 

007%20River%20Thames%20Hammersmith%2014t

 

Tim

  • Greenie 1
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Surely Full Tilt means the maximum speed of the boat (or thereabouts) rather than the speed limit of the river?.

The Thames is a big river so I would not normally expect boats to slow down nearly as much as they would on a canal.

Settling on the mud can be a tricky operation but it is very rare so can't really expect the "typical" narrowboat owner to understand this?.

 

I assume this was somewhere between Brentford and Richmond.

 

Another factor is that as the tide was well on its way out maybe the narrowboat had left things very late and was rushing to avoid getting grounded?

 

.............Dave

Yes, I'd also thought of that, if she says that it was the last bit of tide before she bottomed out then it would suggest that the passing narrowboat had left things a bit late. To be honest however, in his position, I would probably have been doing the same. On a tidal river such as the Thames I expect boats to be passing at their normal cruising speed and I'd do much the same, slowing down for moored boats (or in this case mooring boats) would not be a big consideration unlike on the canals.

 

Attitude of the PoLA on wash from boats is very clear - these are MCA category C waters with a normal maximum wave height of 1.2 metres. Unless the wash of a passing vessel exceeds 1.2 metres then what is the problem?

 

Some of the passenger boats around Tower Bridge might make a wash that big, but not much else will...

That sounds pretty reasonable and with a narrowboat you'd be unlikely to get a wash of that size unless you have got a lot of horsepower and can get it up on the planesad.png .

 

Thanks for the replies, I'd never have thought of mooring on the tidal Thames precisely for the reason that the lady in the letter mentions, you cannot be sure what you are settling on until it's too late to do anything about it. I enjoy the tidal Thames but for me, stopping on it is something only to be done in an emergency and preferably in deep water on an anchor. I'd be too wary of the bow settling on an obstruction as the tide goes out leaving the stern down with the risk of the boat flooding as the tide returns, natural pessimist meunsure.png

Edited by Wanderer Vagabond
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No A trio at least.

 

Thought springers had funny bottoms, if they sit on the bottom like this then why do you pay extra in the drydock????

 

..............Dave

 

The only Springer that has a true V shaped hull is/was the Waterbug, and that actually has a central flat section about a foot wide. The rest have flat bottoms but with a sort of double chine so the bottom is not the full width of the boat but is basically flat.

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There will always be a period between first touching and fully sitting on the bottom where any movement in the water will cause the boat to bounce on the bottom, if that same movement in the water will cause the boat to move (heave up & down etc) when fully afloat.

At first this can be disconcerting until you get used to it, the main concern is when drying out on an unknown bottom. If the boater had already been there for a couple of tides (original report is a bit vague), I don't see how the boat would settle down on something that could damage the hull - that would have happened when first drying out.

Having spend several years operating landing craft (regular drying out was part of the job) I would never intentionally dry out at a mooring or landing without having surveyed (visual check previous low tide) the area first to ensure there were no unexpected surprises once we had dried out.☺

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Seems a bit odd to single out probably the slowest vessel ever likely to pass her, so I find it hard to believe it's a Narrowboat issue. Perhaps there's something more to the story?

 

My thoughts too, but she does sound new to the life - I've not heard the term "river floor" before. Here are snippets from the latest user group meeting with the PLA - no mention of narrowboats causing wash, but the recommendations for mooring lines are "interesting".

 

".. wash incidents are an increasing issue for them as the fast ferries, trip-boats, tourist Ribs, lifeboats, fire-boats and other recreational craft, even travelling at the designated speed limit, can and do make excessive wash – especially at low water. The situation is so grave that the PLA have set up separate forums to discuss the issue and impact of wash on houseboats. The PLA are now issuing secret guidance to houseboat owners about securing your mooring. There will be a public consultation on the guidance later this year. The guidance is poorly thought out – at one point they recommend six lines of 40mm diameter rope (regardless of houseboat size) and at the same time say that the mooring ropes should be the weakest link in the mooring arrangements. The PLA do not seem keen to tackle the root cause – excessive wash created by inappropriate speed".

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There will always be a period between first touching and fully sitting on the bottom where any movement in the water will cause the boat to bounce on the bottom, if that same movement in the water will cause the boat to move (heave up & down etc) when fully afloat.

At first this can be disconcerting until you get used to it, the main concern is when drying out on an unknown bottom. If the boater had already been there for a couple of tides (original report is a bit vague), I don't see how the boat would settle down on something that could damage the hull - that would have happened when first drying out.

Having spend several years operating landing craft (regular drying out was part of the job) I would never intentionally dry out at a mooring or landing without having surveyed (visual check previous low tide) the area first to ensure there were no unexpected surprises once we had dried out.☺

it is extremely discourteous to cause enough wash or waves to make a springer bounce on her bottom. mad.gif

 

bearing in mind the river bed slopes, this effect may be felt by different boats over a period of several hours on each tide, so they will all lose valuable sleep. rolleyes.gif

 

the responsible authority should put up a barrage to stop wind-generated waves from worrying the little darlings. unsure.png

  • Greenie 1
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