Past the point of no return....

[blackrose]

On 24/09/2018 at 01:30, Captain Pegg said:

 

And all the metallurgists I work with know that modern steel is a far superior product than anything produced 50 years ago. More importantly they also know why. I see the empirical evidence of that on a daily basis. Of course for the reasons stated above that has no bearing on corrosion of narrowboats.

 

JP

 

Interesting and completely contrary to the nonsense we constantly hear from boaters who actually know very little about the subject. Like some of their other erroneous mantras they just repeat what they hear. 

Edited September 30, 2018 by blackrose

[Athy]

On 27/09/2018 at 08:07, mrsmelly said:

Miss Max ? There's a blast from the past! Is she still aboard I wonder?

Has not visited the site since the end of 2016, so I think she's over the hills and far away.

[mark99]

I gotta do my handrails next year. How did you prep them etc?/what products.

 

PS you missed a bit.

[Captain Pegg]

4 hours ago, blackrose said:

 

No Liverpool Boat! My BT tunnel has never been blacked and the boat is now 14 years old. The tunnel was fine the last time I looked at it. Still with the coating of primer. Why would it need blacking any more than the baseplate?

 

I've been hearing this sort of nonsense ever since I bought my boat. Some people told me the steel was so brittle I wouldn't be able to drill it, others said it would be need overplating soon. All utter claptrap.

 

It's funny how some people can predict the future. Perhaps we should give Collingwood a fair chance and actually see what they're like after 10 years before condemning them? 

A bow thruster tube is presumably made of thinner steel than the baseplate and may also be subject to the effects of cavitation which will repeatedly destroy the stable layer of rust and present unstable parent metal to continue an ongoing cycle of corrosion. It may also simply be a trap for dirt.

 

The obvious conclusion from my assertion that environment is the principal cause of corrosion is that you should protect steel from its environment by painting it. It's a better bet than hoping your environment is friendly.

 

The only logical reason I can see that a baseplate is thicker than the side plates on a conventional new build narrowboat is the expectation that it won't be painted.

 

JP

[Athy]

1 minute ago, Captain Pegg said:

 

 

The only logical reason I can see that a baseplate is thicker than the side plates on a conventional new build narrowboat is the expectation that it won't be painted.

 

JP

Doesn't it aid stability, having the heaviest part at the bottom?

[Chewbacka]

4 minutes ago, Captain Pegg said:

...............The only logical reason I can see that a baseplate is thicker than the side plates on a conventional new build narrowboat is the expectation that it won't be painted.

 

JP

And being thicker it is heavier so less ballast and therefore less underfloor ballast space is required giving more internal headroom.

[Captain Pegg]

15 minutes ago, Athy said:

Doesn't it aid stability, having the heaviest part at the bottom?

The ballast fulfils that function and I suspect has a lot more to do with trim than it does stability given that stability is largely inherent in the design of a narrowboat. Using steel as ballast is an expensive way of doing things. I don't think it's the reason for a thicker baseplate.

 

JP

[Captain Pegg]

38 minutes ago, Chewbacka said:

And being thicker it is heavier so less ballast and therefore less underfloor ballast space is required giving more internal headroom.

But that weight doesn't have to be on the bottom of the boat. That same principal could apply to any part of the boat. If it was about weight then the most cost effective solution would be to build a hull of a predetermined weight using the same thickness of steel throughout.

 

If there is an argument for a thicker baseplate on structural grounds it is probably so that the transverse stiffeners can be shallower and hence headroom can be increased. However the same could be achieved by having more stiffeners with the same baseplate thickness. 

 

Personally I am sceptical that these things are ever calculated in a scientific way for narrowboats. They are built rather than engineered.

 

JP

Edited September 30, 2018 by Captain Pegg

[Stilllearning]

5 minutes ago, Captain Pegg said:

But that weight doesn't have to be on the bottom of the boat. That same principal could apply to any part of the boat. If it was about weight then the most cost effective solution would be to build a hull of a predetermined weight using the same thickness of steel throughout.

 

If there is an argument for a thicker baseplate on structural grounds it is probably so that the transverse stiffeners can be shallower and hence headroom can be increased. However the same could be achieved by having more stiffeners with the same baseplate thickness. 

 

Personally I am sceptical that these things are ever calculated in a scientific way for narrowboats. The are built rather than engineered.

 

JP

My untrained feeling is that having, for example, 10mm steel all round would tend to make the boat less stable than having a 10/6/4 construction. Cost of a thick base plate may be highish, but ballast tends to not be free either. And headroom really does matter.

[matty40s]

5 hours ago, blackrose said:

 

Interesting and completely contrary to the nonsense we constantly hear from boaters who actually know very little about the subject. Like some of their other erroneous mantras they just repeat what they hear. 

I don't repeat what I hear, I see what I see being launched. Your boat has Primer in its tube, no C boat is finished to this standard im that area in the 3/4 years I have been watching them arrive off a lorry.

You tell me that the raw welding slag in this tube is going to help it's longevity.

[mrsmelly]

13 minutes ago, Stilllearning said:

My untrained feeling is that having, for example, 10mm steel all round would tend to make the boat less stable than having a 10/6/4 construction. Cost of a thick base plate may be highish, but ballast tends to not be free either. And headroom really does matter.

My previous narrowboat had 15 mil bottom. The extra weight meant we had no ballast just some engineering bricks for trim and the floor was low enabling a slightly lower roof line than most of my previous boats. I doubt the boat was going to last longer than others as my old 1981 colecraft is still going strong with little repairs to the hull and its a 6 mil bottom and sides.

[Captain Pegg]

My initial thoughts on the 10mm baseplate were that I believe that it is a requirement for a new build to have such whereas the side plates can be 6mm. That's the bit which seemed illogical other than it being a safety requirement around corrosion protection.

 

In reality steel narrowboats have always had thicker base plates than side plates as the earlier ones were typically 1/4" baseplate and 3/16" side plates which is 6.4mm and 4.8mm respectively. Whether this is a carryover from carrying boats I don't now as there would be some logic in having a thicker baseplate in a working boat albeit overall weight was probably at a premium.

 

I am not convinced that headroom would have been a major factor in early steel boats but ease of construction may explain why a thicker baseplate is used if the hull needs to be of a certain weight. The baseplate is one or more large plates welded together that sit on the floor and the boat is built on top of it. It has very little in the way of fabrication requirements in itself. The sides consist of numerous plates which at fore and aft are considerably bent, shaped and welded. Much easier to do that with a thinner plate.

 

The difference in stability of a hull of 10mm base and 6mm sides versus say 8mm for both I doubt is even close to critical for a narrowboat. There must be a reason why no one builds the latter and I suspect it's the above.

 

The point about ballast that gets missed is that the floor sits on the top of the knees (for want of a better word) which are part of the structure of the boat and aren't just there just to provide an air gap between the baseplate and the floor for the ballast to sit in. A thicker baseplate could only ever be economical if it allows the knees to be formed of a smaller section, say 50mm deep channel instead of 76mm, or less of them to be provided. There is naturally space for ballast whether it's filled or not.

 

JP

Edited September 30, 2018 by Captain Pegg

[matty40s]

Phew, out at last, went for a celebration cruise. That was a long 9 days, but well worth it.

[Athy]

Unfortunately, on my computer at least, your video clip will not play anything: I get just a black screen with, in its centre, a grey circle.

[cuthound]

Very disappointed in you Matty, cruising with fenders down ☹

[matty40s]

4 hours ago, cuthound said:

Very disappointed in you Matty, cruising with fenders down ☹

Short cruise, no locks,  and I knew when I got back I would have to squeeze between the bank and a slab sided hysterical butty so though I would keep my paint on a bit longer with them down. I guess the video is working then?

[cuthound]

1 minute ago, matty40s said:

Short cruise, no locks,  and I knew when I got back I would have to squeeze between the bank and a slab sided hysterical butty so though I would keep my paint on a bit longer with them down. I guess the video is working then?

 

Excuses excuses bah ?

 

Yes the video works, well at least for me. Old Friends is looking in fine fettle. Not that she looked scruffy before the repaint.

[Richard T]

2 hours ago, matty40s said:

Short cruise, no locks,  and I knew when I got back I would have to squeeze between the bank and a slab sided hysterical butty so though I would keep my paint on a bit longer with them down. I guess the video is working then?

No video on my computer. The paint job looks very good. It will need keeping clean and scratch free.