Replating

[moggyjo]

In what way? Was the overplating eaten away from the inside out?

There's at least three other causes of pitting too.

 

cheers,

Pete.

What are they?

[blackrose]

The chemical process that causes steel boats to rust is not unique to the marine industry. It affects steel fabrications in agricultural, industrial and automotive situations in just the same manner.

 

I don't dispute that overplating is a standard teqhnique for maintaining steel hulls and is carried out by boatyards worldwide. What I am saying is it doesn't make the hull as good as new again as it does nothing for the structural integrity of the boat, merely keeps the water out.

 

I'll happily settle for agreeing with Tim Leech's opinion on it, and he should know. He says overplating is ......"done to tired old hulls to give them a stay of execution".

 

Yes, I'm happy with Tim's opinion too but I never said overplating made hulls as good as new - I don't think anyone said that.

 

However if the structural integrity of the a thinning hull is sound (and as long as no internal corrosion to knees, stringers, etc, then has occured I don't see why it shouldn't be), then overplating only really needs to keep the water out.

Edited December 7, 2007 by blackrose

[Timleech]

No. Virtually the whole boat was overplated from the top strake down whether it needed it or not. The original hull plating, still visible in the open hold, is like a net curtain. The boat is probably in the worst condition of any of the ex Grand Union steel motor boats.

 

But.......

It's been that way for many years, it's kept going (and incidentally done some serious work, I remember watching it breaking 4 - 5" of ice 20-odd years ago) when without that overplating it would have been dead long ago, I doubt that anyone would have contemplated proper replating at the time that work was done.

Probably not entirely fair to say that she was destroyed by the overplating, but it's certainly true that once you go down that road it's very difficult to turn back, the longer term options become very limited.

Just to add to the fun, she has more recently had overplating done internally, between the knees, probably more cosmetic/safety than structural.

 

Tim

[Gnome K Gnome]

Just to add to the fun, she has more recently had overplating done internally, between the knees, probably more cosmetic/safety than structural.

 

Tim

 

I guess this is the equivalent of what is known in the motor trade as an MOT carpet. Basically the carpet is firmly glued down to prevent the tester seeing the poor standard of the repair work hidden underneath.....

 

It will be a brave (and expensive) effort when she is eventually restored.

 

but it's certainly true that once you go down that road it's very difficult to turn back, the longer term options become very limited.

 

Like I said, a bodge.

[smileypete]

There's at least three other causes of pitting too.

What are they?

 

For new boats with millscale covered steel, temporary pitting can occur where the millscale gets chipped off initially.

 

For boats built with very poor steel, impurities can cause pitting.

 

Algae can also cause pitting though oxygen depletion.

 

Best not to worry too much about it though and just enjoy your boat

 

cheers,

Pete.

[wrigglefingers]

Okay, a bit confused - what's a kelson? I think I know what knees are - but does anybody have any pictures? Thanks guys.

[bottle]

Hi Wriggle

 

Kelson, american for keelson.

 

Wikipedia.

A timber or girder fastened above and parallel to the keel of a ship or boat for additional strength.

[wrigglefingers]

Hi Wriggle

 

Kelson, american for keelson.

 

Wikipedia.

 

Hello Bot (or should that be Bott?) or perhaps I'll stick to Keith. Apologies, I think I've asked the question about keelson before. I should have realised the terms were interchangeable. Lost as to why a narrowboat needs one though. Is it a good idea? I didn't see one on Surprise when I had the floor up last year.

[Timleech]

Hello Bot (or should that be Bott?) or perhaps I'll stick to Keith. Apologies, I think I've asked the question about keelson before. I should have realised the terms were interchangeable. Lost as to why a narrowboat needs one though. Is it a good idea? I didn't see one on Surprise when I had the floor up last year.

 

Wooden bottomed Narrow Boats boats had them, partly as a means of tying the (transverse) bottom boards together. The general framing style of wooden and composite boats tended to be carried over to all steel working boats, so they also usually had/have a keelson.

Modern NBs are framed in a different way, and don't need one.

 

Tim

[wrigglefingers]

Wooden bottomed Narrow Boats boats had them, partly as a means of tying the (transverse) bottom boards together. The general framing style of wooden and composite boats tended to be carried over to all steel working boats, so they also usually had/have a keelson.

Modern NBs are framed in a different way, and don't need one.

 

Tim

 

Thanks Tim,

 

I asked the question because my new boat will have one according to the builder and I can't work out why. I think I'm going to have to confess to even more ignorance than usual and ask him. It must be due to the method of construction he uses - I've left that part to him on the basis that he knows what he's doing and I don't, but I would like to know how it works as this must be different from normal. I suspect I've made an assumption that isn't correct about the shell fabrication. Still, I'm viewing this process as a slooow learning experience ....

 

Jill

[Timleech]

Thanks Tim,

 

I asked the question because my new boat will have one according to the builder and I can't work out why. I think I'm going to have to confess to even more ignorance than usual and ask him. It must be due to the method of construction he uses - I've left that part to him on the basis that he knows what he's doing and I don't, but I would like to know how it works as this must be different from normal. I suspect I've made an assumption that isn't correct about the shell fabrication. Still, I'm viewing this process as a slooow learning experience ....

 

Jill

 

I hadn't realised there were still nb builders using them - it is narrow is it? - though some builders did favour them (Allen bros?)

 

Tim

[Hairy-Neil]

Modern NBs are framed in a different way, and don't need one.

 

Tim

 

And often use a base plate double the thickness of the early steel bottom working boats, so stronger, plus mostly have a steel superstructure adding even more bracing to the structure.

[wrigglefingers]

I hadn't realised there were still nb builders using them - it is narrow is it? - though some builders did favour them (Allen bros?)

 

Tim

 

Yep, 62' narrowbeam.

 

Currently agonising over the baseplate. The builder recommended 10mm as he couldn't see any benefit from using 12mm and would, in view of rising costs, increase the steel costs considerably. Moreover, I'm planning to put on an AGA or Rayburn in addition to the usual complement of batteries and engine so I'm quite anxious about ballasting the boat, as much deeper than 2' 3'' may cause me a few problems in summer getting out of the marina.

 

Jill

Edited December 16, 2007 by wrigglefingers

[magnetman]

I think there's someone at Streethay who still builds nbs with a channel kelson. I've had two boats with this feature, Allens of Oldbury and Tony Gregory but they don't often use them now.