Why Aren't Narrowboats Built With ...

[system 4-50]

10mm sides from the baseplate to say 6" above the water line?   This is where most of the attrition is done, so wouldn't it be beneficial in the long run?

[mrsmelly]

8 minutes ago, system 4-50 said:

10mm sides from the baseplate to say 6" above the water line?   This is where most of the attrition is done, so wouldn't it be beneficial in the long run?

My widebeam had 8 mil sides and a 12 mil bottom. Unlike most so called widebeams that skim across the water, it was so heavily built it had a 3 foot draught. No problem on the decent sized waterways that it was built for and used on. I wouldnt have liked it on a narrow shallow ditch such as the K and A or GU though.

[Mad Harold]

10mm sides would make them more durable no doubt,as there would be more metal for the rust to go at.

I suppose on a new build the buyer could specify the thickness of metal to be used,but on used boats you would no doubt have a survey to determine metal thickness.

There is a bit of mystery (to me at least) as to why some boats rust quicker than others,even younger 10,6,4mm ones I have heard have been overplated.

I know from various posts here that several factors are at work; lack of hull blacking,electrical corrosion, microbiological corrosion,and corrosive chemicals in the canal.

I  had a 1978 built narrowboat 6,5,3mm original metal thickness and no overplating which passed it's survey for comprehensive insurance.

After I sold it,it changed owners twice,and it has now had an overplate on the baseplate and sides to the waterline.

That's forty three years on the original build,so hence my saying I find it a bit of a mystery why some boats rust quicker than others.

 

 

 

[Captain Pegg]

Did any naval architect ever say "Hey, I've got a great idea, let's build it in thicker steel"?

 

There is no need for thicker side plates since the sides are easily painted and I believe common wisdom is that the trend for 10mm baseplates stems from the practice of not painting baseplates. They certainly never used to be 10mm thick and side plates weren't even always 6mm thick.

 

It would likely be more cost effective to revert the baseplate to 6mm and apply a modern paint system.

Edited December 31, 2021 by Captain Pegg

[David Mack]

1 hour ago, system 4-50 said:

10mm sides from the baseplate to say 6" above the water line?   This is where most of the attrition is done, so wouldn't it be beneficial in the long run?

That would involve an extra welded seam along the length of both sides, the cost of which needs to be factored in.

It would also involve bending 10mm plate in the bow and stern areas, which may be beyond the capability of the average boatbuilder.

[magnetman]

Yes, a bit awkward to get the curves right. 

 

The only narrow boat I know that was built to this specification (10mm sides) is Comet which belongs to Roger, @J R ALSOP 

 

It does look a bit different to the more normal 6mm plated craft. 

Edited December 31, 2021 by magnetman

[BEngo]

I asked Phil Trotter about building Jarrah with 8mm sides, way back when, but he said that his supplier could not bend the side shape or roll the counter plates in that thickness so they would have to be fabricated and the bow would also  have to be 6 mm anyway, so he could pull the plates to shape.

 

Something like a double curved planked and welded washer josher bow would be a nightmare in 10mm. 

 

N

[Bee]

Bending 10mm plate is the sort of work great big shipyards with great big machines do.There is plenty of bits of design that could be built into narrowboats that could improve longevity, A slightly V bottom would help to avoid corrosion along the bottom / sides joint and the bilge could drain along the centre, in fact a bit of a chine would be even better. Builders could offer shotblasted steel with proper paint and boat fitters could make floors possible to get up and not just permanently nail plywood onto bearers then build everything onto a sealed for life void. And all that would cost money so many narrow and wide boats will continue to be built as cheaply as possible and develop wxpensive problems sooner rather than later.

[blackrose]

2 hours ago, system 4-50 said:

10mm sides from the baseplate to say 6" above the water line?   This is where most of the attrition is done, so wouldn't it be beneficial in the long run?

 

You may as well ask why aren't they made from stainless steel. In the end it all comes down to production cost.

[waterworks]

Stop making the Fuel tanks part of the stern, fit an insulated separate stainless tank with a v bottom and proper drain cock. This will stop rusting, codensation and will be easy to flush out the sediment on a regular basis.

[Mad Harold]

4 hours ago, Captain Pegg said:

Did any naval architect ever say "Hey, I've got a great idea, let's build it in thicker steel"?

 

There is no need for thicker side plates since the sides are easily painted and I believe common wisdom is that the trend for 10mm baseplates stems from the practice of not painting baseplates. They certainly never used to be 10mm thick and side plates weren't even always 6mm thick.

 

It would likely be more cost effective to revert the baseplate to 6mm and apply a modern paint system.

That sounds sensible,but for durability   the hull and baseplate would need to be properly coated from build,and re- done every couple of years or perhaps longer if coated with epoxy two pack.

How many owners do that?

From what I have seen,not many.

[Athy]

Referring back to the topic title: fuel and water gauges?

[Alan de Enfield]

9 minutes ago, Athy said:

Referring back to the topic title: fuel and water gauges?

 

Both are readily available so it surely just depends on what the original owner specified.

Retro-fit is also an option.

[Feeby100]

1 hour ago, Mad Harold said:

That sounds sensible,but for durability   the hull and baseplate would need to be properly coated from build,and re- done every couple of years or perhaps longer if coated with epoxy two pack.

How many owners do that?

From what I have seen,not many.

We all do don’t we ?

Edited December 31, 2021 by Feeby100

[ditchcrawler]

2 hours ago, Athy said:

Referring back to the topic title: fuel and water gauges?

Where does it say that?

[Bacchus]

25 minutes ago, ditchcrawler said:

Where does it say that?

 

thread title -- "why aren't narrowboats built with...?"

 

I guess, judging by the need for dredging -- "why aren't narrowboats built with...?" - "wheels"

 

 

[Captain Pegg]

3 hours ago, Mad Harold said:

That sounds sensible,but for durability   the hull and baseplate would need to be properly coated from build,and re- done every couple of years or perhaps longer if coated with epoxy two pack.

How many owners do that?

From what I have seen,not many.

 

I was thinking of something a little longer lasting.

[Mad Harold]

6 minutes ago, Captain Pegg said:

 

I was thinking of something a little longer lasting.

Me too.

Had two fibreglass boats and one steel narrowboat, and although a steel narrowboat again would be nice,I am leaning more towards fibreglass.

[MtB]

Just now, Mad Harold said:

Me too.

Had two fibreglass boats and one steel narrowboat, and although a steel narrowboat again would be nice,I am leaning more towards fibreglass.

 

You need to redistribute your ballast then...

 

 

 

[blackrose]

17 hours ago, waterworks said:

Stop making the Fuel tanks part of the stern, fit an insulated separate stainless tank with a v bottom and proper drain cock. This will stop rusting, codensation and will be easy to flush out the sediment on a regular basis.

 

I'm not sure a separate tank would prevent condensation? It's more to do with temperature differential between fuel and air inside the tank and I'm not sure that condensation is any worse in an integral tank? Anyway, I'm happy with integral fuel and water tanks. No worry about fixings giving way when the boat encounters waves on tidal rivers. Imagine a separate fuel tank coming loose and smashing about inside an engine space! 

 

Doesn't your tank have a proper drain cock?

[Alan de Enfield]

6 minutes ago, blackrose said:

No worry about fixings giving way when the boat encounters waves on tidal rivers. Imagine a separate fuel tank coming loose and smashing about inside an engine space! 

 

 

 

 

Having been on some very rough seas with 10-15 feet high waves in both outboard powered boats (where the fuel tank is held down onto 'loops' with a couple of elastic bungees), and inboard engines with a 1000 litre polythene tank with flanges screwed down to wooden beams and, never having had a tank break loose I very much doubt that a tank breaking loose on even the roughest tidal river is very likely

[Captain Pegg]

13 hours ago, Mad Harold said:

Me too.

Had two fibreglass boats and one steel narrowboat, and although a steel narrowboat again would be nice,I am leaning more towards fibreglass.

 

I meant a paint system that lasted a lot longer than 2 years should be applied at build.

 

Out of interest how long do you think a steel narrowboat will last?

[system 4-50]

Does anybody know what sizes the raw steel sheets that boat builders get in are?

[Captain Pegg]

I have the steelwork schedule for my boat and it is clear that the largest sizes possible were ordered. However my boat is small enough that the largest piece (32' x 7' for the baseplate) could be transported on a standard flat bed trailer. I suspect for a 70' boat two plates would be joined for the baseplate. The sides are made from 24' x 3' sheet.

[Alan de Enfield]

29 minutes ago, Captain Pegg said:

I have the steelwork schedule for my boat and it is clear that the largest sizes possible were ordered. However my boat is small enough that the largest piece (32' x 7' for the baseplate) could be transported on a standard flat bed trailer. I suspect for a 70' boat two plates would be joined for the baseplate. The sides are made from 24' x 3' sheet.

 

I think that the 'modern' availability of steel plate is just 2 metres (6'6") which is why NB's are now manufactured to 6'10" max beam (at the gunwale)