"Dave Arquati" wrote

[snip]

Can you get from Heathrow to Canary Wharf by boat?

Well, it would be a bit slow, but actually you can, although not by a
scheduled service. The nearest point of the Grand Union Canal is
close enough that you could probably hitch a lift in one of
Heathrow's off-site parking shuttle vans

Or from most parts of
West London, Paddington, the West End etc?

Well, Paddington has the Paddington Basin. The canal is generally a
bit outside the route of the Circle Line.

It's not really relevant to
compare boat subsidies to the cost of Crossrail - or even the
Thames
Gateway Bridge for that matter (where did you get the £40m figure
from?). Boats won't take you from Thamesmead to Romford, or Abbey
Wood
to Barking.

There is the Ford Works ferry from Thamesmead, unless it has closed
down along with the Ford factory. Barking is on the water - it had a
huge fishing fleet at one time. the Beam River, which heads up to
Romford is, I grant you, about as unnavigable as it can get.

To arrive at Heathrow, and be met by your own canal barge, seems like
a neat service to offer frazzled foreign tourists.

Jeremy Parker

Aidan Stanger wrote:
Dave Arquati wrote:

Aidan Stanger wrote:

Yet they're eager to spend far more on infrastructure projects like the
£40m bus lane on the Thames Gateway Bridge, and the Canary Wharf branch
of Crossrail, which would cost far more than subsidies for boats ever
would. The cost of running boats is on the high side, but so are the
benefits: they can quickly provide plenty of capacity, link communities
N and S of the river, and serve remote parts of London which do not have
bus services (parts of Thamesmead are more than 500m from buses, and
some riverside industrial estates are much further).

Can you get from Heathrow to Canary Wharf by boat? Or from most parts of
West London, Paddington, the West End etc? It's not really relevant to
compare boat subsidies to the cost of Crossrail

It is really relevant to compare them to the cost of THE CANARY WHARF
BRANCH OF Crossrail, as its function would be very similar: providing
capacity to Canary Wharf, and linking communities across the river.

The Canary Wharf branch of Crossrail would only save about ten minutes on
the journey from Heathrow, or W.London, Paddington etc. to Canary Wharf,
compared with Crossrail to Stratford and then a short DLR journey.

DLR doesn't have the capacity to deal with large numbers of passengers
transferring off Crossrail at Stratford and heading for Canary Wharf.
The Jubilee line might, but it's a still a very poor second best to a
Crossrail branch.

The Crossrail branch will also provide a new route into central London
from the North Kent line, which should aid capacity into London Bridge etc.

I'm not saying such a branch should never be built, but it should be a
lower priority than Crossrail Line 2. Meanwhile, boats can provide the
connectivity at a sensible cost.

What connectivity can the boats provide? They already provide
connectivity from southern part of the City, but the service is
expensive to provide and only accessible for destinations close to the
river.

- or even the Thames Gateway Bridge for that matter (where did you get the
£40m figure from?).

TfL expect the entire project to cost £400m, and the bus lanes were
expected to come to 10% of the cost. Actually they did say "up to 10%" to
it could be less, though somehow I doubt it. Anyway, it would be an
appalling waste of money, as tolls would ensure that traffic on the
bridge would be free flowing anyway.

I think the Dartford Crossing provides a lesson here. Unless toll
collection is electronic, the buses will need to bypass queues for
payment. A lack of public transport lanes will also endanger the
acceptability of the whole project - those lanes are meant to be
convertible to tram or DLR later on should they be needed.

Boats won't take you from Thamesmead to Romford, or Abbey Wood
to Barking.

Buses would do that without bus lanes.

No use if they get stuck in the toll queues, or in queues at the bridge
exits.

Boats can be useful but the river serves a limited catchment area;
interchange is also difficult between river and other modes except at a
few choice locations (although I accept that that can be remedied).

Many locations upstream of Greenwich, and a few town centers downstream!

Downstream means a lengthy passage around the peninsula and through the
Thames Barrier, just to reach Woolwich, which will be getting a decent
link via the DLR to Canary Wharf anyway. Upstream, I don't see how more
value can be extracted out of river services than the current commercial
ventures without a massive subsidy. Beyond Westminster, the riverside
area isn't particularly teeming with demand, as demonstrated by the
current limited commercial services to Chelsea Harbour and not really
beyond.

The problem with the river is that any pier will by its nature only have
half the catchment area of an inland rail/Tube station.

But development density is high enough for that not to be a problem.

There must be a problem somewhere or TfL wouldn't have dismissed the
idea of subsidised river services.

--
Dave Arquati
Imperial College, SW7
www.alwaystouchout.com - Transport projects in London

"Dave Arquati" wrote in message
...

snip

DLR doesn't have the capacity to deal with large numbers of
passengers transferring off Crossrail at Stratford and heading for
Canary Wharf. The Jubilee line might, but it's a still a very poor
second best to a Crossrail branch.

The Crossrail branch will also provide a new route into central
London from the North Kent line, which should aid capacity into
London Bridge etc.


Last I heard, the Crossrail branch for the North Kent line was going
to terminate at Abbey Wood, and not run on to Ebbsfleet for CTRL
station, or link into the North Kent line itself.
With this in mind, I can't see the branch doing a great deal to
relieve capacity into London Bridge, as the crossrail branch will only
really benefit passengers who want Docklands, all others will prefer
to stay on the train they're on to get into London and get the tube
from there.

In message , Dave Arquati
writes

Upstream, I don't see how more value can be extracted out of river
services than the current commercial ventures without a massive
subsidy. Beyond Westminster, the riverside area isn't particularly
teeming with demand, as demonstrated by the current limited commercial
services to Chelsea Harbour and not really beyond.

One big disincentive is the speed limit of 8 knots above Wandsworth
Bridge. I suspect there could be some demand from Putney/Hammersmith/
Barnes/Mortlake/Kew if high-speed river services were possible - but
raising the speed limit would need a vast amount of work on riverbanks
and I don't see that happening. Also, most of these places already have
good public transport into central London, so even a high speed river
service might well not prove competitive.

--
Paul Terry

Mike Bristow wrote:
Aidan Stanger wrote:
TfL expect the entire project to cost £400m, and the bus lanes were
expected to come to 10% of the cost. Actually they did say "up to 10%" to
it could be less, though somehow I doubt it. Anyway, it would be an
appalling waste of money, as tolls would ensure that traffic on the
bridge would be free flowing anyway.

What would make those tolls any better than the tolls on the M25 crossing
(which doesn't keep the bridge free flowing)?

They'd be higher.

Dave Arquati wrote:

Aidan Stanger wrote:
Dave Arquati wrote:

Aidan Stanger wrote:

Yet they're eager to spend far more on infrastructure projects like the
£40m bus lane on the Thames Gateway Bridge, and the Canary Wharf branch
of Crossrail, which would cost far more than subsidies for boats ever
would. The cost of running boats is on the high side, but so are the
benefits: they can quickly provide plenty of capacity, link communities
N and S of the river, and serve remote parts of London which do not have
bus services (parts of Thamesmead are more than 500m from buses, and
some riverside industrial estates are much further).

Can you get from Heathrow to Canary Wharf by boat? Or from most parts of
West London, Paddington, the West End etc? It's not really relevant to
compare boat subsidies to the cost of Crossrail

It is really relevant to compare them to the cost of THE CANARY WHARF
BRANCH OF Crossrail, as its function would be very similar: providing
capacity to Canary Wharf, and linking communities across the river.

The Canary Wharf branch of Crossrail would only save about ten minutes on
the journey from Heathrow, or W.London, Paddington etc. to Canary Wharf,
compared with Crossrail to Stratford and then a short DLR journey.

DLR doesn't have the capacity to deal with large numbers of passengers
transferring off Crossrail at Stratford and heading for Canary Wharf.

It would if Bow to Stratford were double tracked and platforms were
lengthened.

The Jubilee line might, but it's a still a very poor second best to a
Crossrail branch.

Maybe, but Canary Wharf's just got the Jubilee Line, while much of
Central London still hasn't got the railways it needs to solve the
overcrowding problems. Which do you think should take priority?

The Crossrail branch will also provide a new route into central London
from the North Kent line, which should aid capacity into London Bridge etc.

It won't do much in the way of tph capacity, as the Greenwich Line will
still have to be served. As for passenger capacity, if they were serious
about that then they'd finish the work needed to introduce 12 car
trains.

I'm not saying such a branch should never be built, but it should be a
lower priority than Crossrail Line 2. Meanwhile, boats can provide the
connectivity at a sensible cost.

What connectivity can the boats provide? They already provide
connectivity from southern part of the City, but the service is
expensive to provide and only accessible for destinations close to the
river.

I think I meant to type "capacity" there - providing capacity would be
far cheaper (per passenger) to provide if there were more passengers.
As for Connectivity, there is more potential downstream of Canary Wharf,
but the Wapping and Rotherhithe areas could also benefit.

- or even the Thames Gateway Bridge for that matter (where did you get the
£40m figure from?).

TfL expect the entire project to cost £400m, and the bus lanes were
expected to come to 10% of the cost. Actually they did say "up to 10%" to
it could be less, though somehow I doubt it. Anyway, it would be an
appalling waste of money, as tolls would ensure that traffic on the
bridge would be free flowing anyway.

I think the Dartford Crossing provides a lesson here. Unless toll
collection is electronic, the buses will need to bypass queues for
payment.

Tolling is planned to be electronic (probably similar to the Congestion
Charge).

A lack of public transport lanes will also endanger the
acceptability of the whole project - those lanes are meant to be
convertible to tram or DLR later on should they be needed.

That's rather a poor location for a tram to cross the river, and the
plans for the DLR to use it are dead and buried.

Boats won't take you from Thamesmead to Romford, or Abbey Wood
to Barking.

Buses would do that without bus lanes.

No use if they get stuck in the toll queues, or in queues at the bridge
exits.

Considering the roads they flow out onto, that's unlikely.

Boats can be useful but the river serves a limited catchment area;
interchange is also difficult between river and other modes except at a
few choice locations (although I accept that that can be remedied).

Many locations upstream of Greenwich, and a few town centers downstream!

Downstream means a lengthy passage around the peninsula and through the
Thames Barrier,

Assuming they're going to Central London. However, if you assume they're
going to the E side of the Isle Of Dogs, it would be quite a direct
route.

just to reach Woolwich, which will be getting a decent
link via the DLR to Canary Wharf anyway.

Another TfL project that's a wast of money. They should've concentrated
on the NLL/Crossrail tunnel instead.

Upstream, I don't see how more value can be extracted out of river
services than the current commercial ventures without a massive subsidy.
Beyond Westminster, the riverside area isn't particularly teeming with
demand, as demonstrated by the current limited commercial services to
Chelsea Harbour and not really beyond.

Yes, potential is greater in E London, at least initially.

The problem with the river is that any pier will by its nature only have
half the catchment area of an inland rail/Tube station.

But development density is high enough for that not to be a problem.

There must be a problem somewhere or TfL wouldn't have dismissed the
idea of subsidised river services.

That assumes that TfL are

Matt Wheeler wrote:
"Dave Arquati" wrote in message
...

snip

DLR doesn't have the capacity to deal with large numbers of
passengers transferring off Crossrail at Stratford and heading for
Canary Wharf. The Jubilee line might, but it's a still a very poor
second best to a Crossrail branch.

The Crossrail branch will also provide a new route into central
London from the North Kent line, which should aid capacity into
London Bridge etc.

Last I heard, the Crossrail branch for the North Kent line was going
to terminate at Abbey Wood, and not run on to Ebbsfleet for CTRL
station, or link into the North Kent line itself.
With this in mind, I can't see the branch doing a great deal to
relieve capacity into London Bridge, as the crossrail branch will only
really benefit passengers who want Docklands, all others will prefer
to stay on the train they're on to get into London and get the tube
from there.

If Crossrail goes near your desired destination, then it will be
preferable to change from the North Kent Line at Abbey Wood rather than
at any London terminus to the Tube, as you will get a seat on Crossrail
right into the centre; if you cram onto the Tube with everyone else at
London Bridge etc. then it will be much more uncomfortable.

--
Dave Arquati
Imperial College, SW7
www.alwaystouchout.com - Transport projects in London

Aidan Stanger wrote:
Dave Arquati wrote:

Aidan Stanger wrote:

Dave Arquati wrote:

Aidan Stanger wrote:

Yet they're eager to spend far more on infrastructure projects like the
£40m bus lane on the Thames Gateway Bridge, and the Canary Wharf branch
of Crossrail, which would cost far more than subsidies for boats ever
would. The cost of running boats is on the high side, but so are the
benefits: they can quickly provide plenty of capacity, link communities
N and S of the river, and serve remote parts of London which do not have
bus services (parts of Thamesmead are more than 500m from buses, and
some riverside industrial estates are much further).

Can you get from Heathrow to Canary Wharf by boat? Or from most parts of
West London, Paddington, the West End etc? It's not really relevant to
compare boat subsidies to the cost of Crossrail

It is really relevant to compare them to the cost of THE CANARY WHARF
BRANCH OF Crossrail, as its function would be very similar: providing
capacity to Canary Wharf, and linking communities across the river.

The Canary Wharf branch of Crossrail would only save about ten minutes on
the journey from Heathrow, or W.London, Paddington etc. to Canary Wharf,
compared with Crossrail to Stratford and then a short DLR journey.

DLR doesn't have the capacity to deal with large numbers of passengers
transferring off Crossrail at Stratford and heading for Canary Wharf.

It would if Bow to Stratford were double tracked and platforms were
lengthened.

DLR capacity is constrained by the layout of the North Quay junctions.
I'm not sure whether the junctions or indeed Canary Wharf station could
handle a very high combined frequency of trains from Bank and Stratford.

The Jubilee line might, but it's a still a very poor second best to a
Crossrail branch.

Maybe, but Canary Wharf's just got the Jubilee Line, while much of
Central London still hasn't got the railways it needs to solve the
overcrowding problems. Which do you think should take priority?

CWG said they will contribute towards the cost of Crossrail. AIUI the
scale of future developments at Canary Wharf will also mean Jubilee line
capacity will become a problem. Waiting until after CR2 to build the
Crossrail branch might be too long.

If we assume the CW branch will be needed sooner or later, and we assume
the real cost of the CW branch will remain the same (which may not be
true), then whether it's built now or later is the issue; building it
later means going through the whole consultation and hybrid bill process
again later, wasting money. In the meantime, the money not spent on the
CW branch would only cover a small portion the cost of Crossrail 2,
which I believe is costed as even more expensive that Crossrail 1.

The Crossrail branch will also provide a new route into central London
from the North Kent line, which should aid capacity into London Bridge etc.

It won't do much in the way of tph capacity, as the Greenwich Line will
still have to be served. As for passenger capacity, if they were serious
about that then they'd finish the work needed to introduce 12 car
trains.

I did mean passenger capacity (for stations from Plumstead onwards into
London Bridge). You have a point about the 12-car project - but I didn't
mean that the CW branch is exclusively for freeing up passenger capacity
on the Greenwich line; it provides other benefits too, and the whole
package is attractive.

I'm not saying such a branch should never be built, but it should be a
lower priority than Crossrail Line 2. Meanwhile, boats can provide the
connectivity at a sensible cost.

What connectivity can the boats provide? They already provide
connectivity from southern part of the City, but the service is
expensive to provide and only accessible for destinations close to the
river.

I think I meant to type "capacity" there - providing capacity would be
far cheaper (per passenger) to provide if there were more passengers.
As for Connectivity, there is more potential downstream of Canary Wharf,
but the Wapping and Rotherhithe areas could also benefit.

Boats still can't reasonably provide a capacity of around 30,000
passengers per hour per direction. Providing capacity is cheaper per
passenger if there are more passengers, yes... until you have too many
passengers and have to provide more boats.

I still think that the subsidy per passenger would be higher than any
other public mode, even if every boat were full. I looked up what's been
said in the London Assembly about the affordability of river services;
the answers I found are at the bottom. They're quite extensive.

- or even the Thames Gateway Bridge for that matter (where did you get the
£40m figure from?).

TfL expect the entire project to cost £400m, and the bus lanes were
expected to come to 10% of the cost. Actually they did say "up to 10%" to
it could be less, though somehow I doubt it. Anyway, it would be an
appalling waste of money, as tolls would ensure that traffic on the
bridge would be free flowing anyway.

I think the Dartford Crossing provides a lesson here. Unless toll
collection is electronic, the buses will need to bypass queues for
payment.

Tolling is planned to be electronic (probably similar to the Congestion
Charge).

In which case I accept that toll queues will not be a problem.

A lack of public transport lanes will also endanger the
acceptability of the whole project - those lanes are meant to be
convertible to tram or DLR later on should they be needed.

That's rather a poor location for a tram to cross the river, and the
plans for the DLR to use it are dead and buried.

Where else would a tram cross the river other than at the bridge? The
idea of the bus lanes is to link Greenwich Waterfront Transit and East
London Transit, which should have built up a good passenger base by the
time the bridge opens.

The Mayor keeps mentioning the possibility of the DLR using it; I heard
him say so a couple of weeks ago. Of course, he might be wrong, but he
does seem to have it in his head.

Boats won't take you from Thamesmead to Romford, or Abbey Wood
to Barking.

Buses would do that without bus lanes.

No use if they get stuck in the toll queues, or in queues at the bridge
exits.

Considering the roads they flow out onto, that's unlikely.

TfL's own report on the bridge showed that during the peaks, demand
would exceed capacity, even at the desired tolling levels. That implies
slow-moving traffic which would hamper non-segregated bus services. The
bridge traffic will also be flowing out onto roundabouts I believe;
these are either be the standard kind or signalled (I'm not familiar
with the Thamesmead one, but I know the Barking one is signalled).
Signals definitely mean traffic will build up to some extent, and
standard roundabouts definitely seem to cause queues under busy traffic
conditions (the Headington roundabout in Oxford comes immediately to
mind; I rarely drive in London but I'm sure there are examples around here).

Boats can be useful but the river serves a limited catchment area;
interchange is also difficult between river and other modes except at a
few choice locations (although I accept that that can be remedied).

Many locations upstream of Greenwich, and a few town centers downstream!

Downstream means a lengthy passage around the peninsula and through the
Thames Barrier,

Assuming they're going to Central London. However, if you assume they're
going to the E side of the Isle Of Dogs, it would be quite a direct
route.

That's true. However, Crossrail will be faster from further afield (e.g.
Erith changing at Abbey Wood), and there will be DLR or Tube links
nearer (Woolwich, Silvertown, North Greenwich). I don't see where the
demand would come from for those services.

just to reach Woolwich, which will be getting a decent
link via the DLR to Canary Wharf anyway.

Another TfL project that's a wast of money. They should've concentrated
on the NLL/Crossrail tunnel instead.

They obviously see a good cost-benefit ratio for the DLR to Woolwich, so
it's probably not a waste of money. The money is coming from the
Treasury, and we know how stingy they can be!

The DLR will provide a better service over the Stratford-Woolwich
corridor than the NLL ever could, given capacity constraints west of
Stratford and the operating costs of heavy rail.

(snip)

The problem with the river is that any pier will by its nature only have
half the catchment area of an inland rail/Tube station.

But development density is high enough for that not to be a problem.

There must be a problem somewhere or TfL wouldn't have dismissed the
idea of subsidised river services.

That assumes that TfL are

Sorry, I didn't get the rest of that sentence...

--
From Mayor's Question Time answers at www.london.gov.uk:

http://mqt.london.gov.uk//public/question.do?id=8289
Dee Doocey: "[...] Why can't travelcard holders use the Riverboat
service for free and what consideration has been given to at least
increasing the discount travelcard holder receive?"
Mayor: "[...] Extending the discount for Travelcards on River services
is unlikely in the foreseeable future. Given the difference between
revenues per passenger mile that would be received via the Travelcard
scheme and the cost of boat operation, substantial subsidy would be
required to make good the shortfall, which would be unlikely to be good
value for money."

http://mqt.london.gov.uk//public/question.do?id=3963
Bob Neill: "What consideration has been given by the Mayor and
Transport for London to run a boat service connecting Erith, Woolwich,
Canary Wharf and Central London?"
Mayor: "Prior to inviting tenders for a mulit-stop riverboat service
between Chelsea Harbour and the Isle of Dogs and Rotherhithe, London
River Services (LRS) commissioned consultants KPMG to assist in
determining the likely costs and revenues of the scheme. Although LRS
have not specifically looked at providing the service you have
suggested, KPMG were asked to assess the implications of an extension of
the proposed service to Thamesmead. The conclusion was that, even
without taking the costs of new pier provision into account, the
additional costs of the extension would be substantial and the level of
financial assistance required would be likely to increase relatively
heavily.In the light of these findings and bearing in mind pressure on
existing resources, LRS officers decided there was no justification in
further considering extending the scheme to Thamesmead. It is unlikely,
given these findings, that a service between Erith and Central London
could be justified."

http://mqt.london.gov.uk//public/question.do?id=3288
Mayor: "There have been many attempts to use the Thames for
transporting commuters which have failed financially. Neither of the
current commuter services generate any profits for their operators. LRS
recently sought bids for the operation of commuter services on the
Thames. Following negotiations with one of the bidders, LRS has
submitted a business case for funding to support that bidder's proposal.
An earlier bid for funding to support commuter services from April 2002
was cut from the final TfL budget during discussions with Assembly
Members.There are a number of demand studies underway that will be used
to inform our future strategy in terms of river services. TfL will keep
the Assembly informed of developments. It must be remembered that it is
more expensive to provide riverboat services than it is to provide land
based services. The main reason being the high capital cost of vessels
and higher staffing levels. It is unlikely that a major expansion of
riverboat services could be justified as representing 'value for money',
and nearly every journey can be made faster and more cheaply by other
public transport modes. Nevertheless, as I stated previously, LRS will
consider proposals put to them."

http://mqt.london.gov.uk//public/question.do?id=2707
Mayor: "LRS is currently considering a proposal from three riverboat
operators who have joined forces to offer a London River Card which
would enable passengers to purchase zonal tickets allowing unlimited
travel for a day.Further integration between riverboat fares and
Travelcard is unlikely in the foreseeable future. Given the difference
between revenues per passenger mile that would be received via the
Travelcard scheme and the cost of boat operation, substantial subsidy
would be required to make good the shortfall. Free travel at the margin
for Travelcard holders on the river would be likely to generate demand
vastly exceeding existing capacity creating a need for further subsidy
for additional vessels. Neither scenario would prove to be value for money."

http://mqt.london.gov.uk//public/question.do?id=2883
Mayor: "There have been many attempts to use the Thames for transporting
commuters; all of them have failed financially. Neither of the current
commuter services generate profits for their operators. In fact, it's
been widely reported that Thames Trippers are seeking sponsorship from
businesses at Canary Wharf in order to support the continued operation
of their services. Currently, Travelcard holders are offered discounts
on fares as an incentive.

London River Services has now received bids in response to the recent
invitation to tender for the operation of commuter services on the
Thames. The results of the tender evaluation will be known around the
end of this month. It is unlikely that this process will result in any
great expansion of river services for commuters.

The financial facts are that it is more expensive to provide riverboat
services than it is to provide land-based alternatives and they are also
often slower. It is unlikely that a major expansion of riverboat
services could be justified as representing value for money and there is
currently no provision for revenue subsidy for a multi-stop service in
the TfL budget and business plan."

--
Dave Arquati
Imperial College, SW7
www.alwaystouchout.com - Transport projects in London

Jeremy Parker wrote:
"Dave Arquati" wrote

[snip]


Can you get from Heathrow to Canary Wharf by boat?


Well, it would be a bit slow, but actually you can, although not by a
scheduled service. The nearest point of the Grand Union Canal is
close enough that you could probably hitch a lift in one of
Heathrow's off-site parking shuttle vans

Or from most parts of

West London, Paddington, the West End etc?


Well, Paddington has the Paddington Basin. The canal is generally a
bit outside the route of the Circle Line.

It's not really relevant to

compare boat subsidies to the cost of Crossrail - or even the

Thames

Gateway Bridge for that matter (where did you get the £40m figure
from?). Boats won't take you from Thamesmead to Romford, or Abbey

Wood

to Barking.


There is the Ford Works ferry from Thamesmead, unless it has closed
down along with the Ford factory. Barking is on the water - it had a
huge fishing fleet at one time. the Beam River, which heads up to
Romford is, I grant you, about as unnavigable as it can get.

To arrive at Heathrow, and be met by your own canal barge, seems like
a neat service to offer frazzled foreign tourists.

LOL! I've driven a narrowboat before on the Grand Union (not in London),
and it's a very relaxing experience, but at a maximum speed of 4 knots,
it would take an awfully long time to reach Canary Wharf from
Heathrow... :-)

--
Dave Arquati
Imperial College, SW7
www.alwaystouchout.com - Transport projects in London

"Dave Arquati" wrote in message
...

LOL! I've driven a narrowboat before on the Grand Union (not in London),
and it's a very relaxing experience, but at a maximum speed of 4 knots,

4 (statute) miles an hour. Inland waterways don't use knots. Well now they
don't use MPH either thanks to the EU and the government forgetting to get
exemption for waterways from metric measurements.

it would take an awfully long time to reach Canary Wharf from Heathrow...
:-)

Dave