Hull material question

[Yoda]

I love the sound of fibreglass crunching in the morning

[dove]

Hello again Andrew

Not too knowledgeable about copper pipes but I would not expect cracking from the amount of cold work, involved in canal boat making, in the type of alloys involved.

I have never noticed either of my boats flexing in locks, although the sides vibrate in and out a bit in sympathy with the engine. Hopefully aluminium would be thicker and vibrate less, although I do not imagine the stresses involved would be very high anyway.

Arthur

 

Arthur,

hello again too, you will find that the early Sea Otters were of a 6, 6, 4, build. However I did make the ballast tank with a "v" bottom for strength. This was to make them as light as possible but strong enough for trailing.

I had quite an rate of failure when folding the side sheets for the gunwales and roof, so there is quite bit stress built in.

I don't know what the longer ones are made off, I'm not involed now.

Andrew

[dove]

Offtopic but I'm pleased Dove has her real name back and that dodgy steel Britannia top has gone. Nice boat, with a nice thick STEEL bottom. Doesn't stainless steel suffer from weld corrosion and aluminium is advertised as 'free from rust'. I had an ally windlass out of the cut and it was wickedly pitted, not 'rust/iron oxide' but corrosion nonetheless.

 

Sorry I missed this "off topic" I don't know what the bottom is made of, could be a bit Red Diamond Caggy had laid about, but it's been welded with Stainlees rods ??? dam good job though.

 

Andrew

[Glenn]

Surely a fiberglass covered wooden structure is a good material for the outside of a hull?

[carlt]

Surely a fiberglass covered wooden structure is a good material for the outside of a hull?

Very, but not, perhaps, for the rough and tumble of the canals. I have to (grudgingly) agree that steel is the best material for canal boats but fibreglass is better on rivers and wood is by far the best in the salty stuff.

[Teadaemon]

Getting back to the original question, although stainless steel is expensive, it does have a pedigree as a material for building hulls from, having been used in a number of yachts designed for offshore racing (where price is less important than winning).

[Grasshopper]

As the owner of an early 26 ft Sea Otter, I would just like to say that she hasn't fallen apart in a lock yet.........

 

And I've hit plenty of things without getting any dents yet.

 

You might be interested in the 28th Sept entry on the following link when one of the first 23 ft Sea Otters - High Jump - is hit by a fully laden french commercial barge. She survived with very minor damage & the owners still cruise the french waterways.

 

http://www.nbhighjump.com/Autumn2004.html

 

I don't think that Sea Otters are as delicate as people seem to think..........

[dove]

Getting back to the original question, although stainless steel is expensive, it does have a pedigree as a material for building hulls from, having been used in a number of yachts designed for offshore racing (where price is less important than winning).

 

By using Stainless you can reduce the thickness to reduce cost and still maintain strength. However you would have to make few design changes to the standard narrow boat, due to the shrinkage and distortion created when welded.

 

There is another material, Yarwoods called it "Coppered Iron" now known as "Core 10" I used this on 20' x 10' supply boat. the plate was 3mm thick but very strong due to the shape.

 

Andrew

[Ottocat]

Thanks chaps this thread is really interesting

[Chris Pink]

There is another material, Yarwoods called it "Coppered Iron" now known as "Core 10"

Andrew

 

What did Yarwoods use it on?

[Speedwell]

Cor-ten - theres a blast from the past. I vaguely remember, from college days, that small additions of copper to mild steel greatly alters its "rusting" characteristics. Here is a link to Wikipedia

http://en.wikipedia.org/wiki/Weathering_steel

Arthur

[dove]

What did Yarwoods use it on?

 

FMC boats - Panther, Python, Acacia Apple and Bream

 

Andrew

[Malarky]

Surely a fiberglass covered wooden structure is a good material for the outside of a hull?

 

Not so, wood expands and contracts at a substantialy diffrent rate to fibreglass, and wood needs to breathe, fibreglass will cause the wood to immediately start to rot if used in such a way. In traditional fibreglass boats the wood is completely sealed to prevent any water contamination.

 

Ferrocement, but needs new improved design methods.

[Speedwell]

As the owner of an early 26 ft Sea Otter, I would just like to say that she hasn't fallen apart in a lock yet.........

And I've hit plenty of things without getting any dents yet.

You might be interested in the 28th Sept entry on the following link when one of the first 23 ft Sea Otters - High Jump - is hit by a fully laden french commercial barge. She survived with very minor damage & the owners still cruise the french waterways.

I don't think that Sea Otters are as delicate as people seem to think..........

I hope nobody has taken any of my posts as decrying Sea Otters or any other particular type of boat. The comments were based purely on the properties of metals. This is only one factor in designing a boat that is "fit for purpose".

Arthur

[Speedwell]

Arthur,

hello again too, you will find that the early Sea Otters were of a 6, 6, 4, build. However I did make the ballast tank with a "v" bottom for strength. This was to make them as light as possible but strong enough for trailing.

I had quite an rate of failure when folding the side sheets for the gunwales and roof, so there is quite bit stress built in.

I don't know what the longer ones are made off, I'm not involed now.

Andrew

Andrew

At 6, 6, 4, an aluminium boat would be more flexible than a steel one of the same shape but this is not intended to imply that there is a problem with Sea Otters.

I'm a bit surprised that there were problems with the forming but I think discussing that would be even if anybody were interested.

Arthur

Edited February 7, 2008 by Speedwell

[dove]

Andrew

At 6, 6, 4, an aluminium boat would be more flexible than a steel one of the same shape but this is not intended to imply that there is a problem with Sea Otters.

I'm a bit surprised that there were problems with the forming but I think discussing that would be even if anybody were interested.

Arthur

 

Arthur,

 

before this goes any further I will correct myself, looking back in my notes the 6,6,4 buid was the prototype, production models went 10,6,4 but lead to other probems.

 

If wish to take this to another topic please do and I'll catch up later

 

Andrew

[Timleech]

Coppered steel, coppered iron

 

(Chris Pink @ Feb 7 2008, 10:44 AM) *

What did Yarwoods use it on?

 

 

 

FMC boats - Panther, Python, Acacia Apple and Bream

 

Andrew

 

I wonder whether any definitive information has survived from Yarwoods about the hull materials used, and their sources of iron?

 

The 'usual suspects' refer to those boats as having been built from Coppered Steel.

I was told by Peter Froud, the then owner of the Hawk aka Jupiter, that she was built (in 1927 iirc) of Coppered Iron. The iron was certainly different from that on most other iron boats that I've worked on, it was harder and tougher, and my impression/recollection from 20 to 30 years ago is that lamination was less obvious. Welding it gave the impression of a higher carbon content than mild steel, whereas bog standard Wrought Iron has a low carbon content and should weld easily (apart from lamination). I've come across the welding issue on at least one other iron boat, and on the knees but not the plating of others.

 

Anyone out there who knows??

 

Going back to Stainless, it is a very unforgiving material to work with, when compared with mild steel. Also it does suffer corrosion. The original name was 'Stain Less', which has rather different implications from 'Stainless'.

 

Tim

[Big Steve]

I seem to remember some round the world sailing yachts were made of cupro nickel because it doesn't corrode and has a natural anti fouling property. probably cost a fortune though.

[carlt]

I seem to remember some round the world sailing yachts were made of cupro nickel because it doesn't corrode and has a natural anti fouling property. probably cost a fortune though.

Bigger boats have had their hulls clad with cupro nickel but actual Cu-Ni hulls tend to be restricted to smaller boats.

 

Aside from the corrosion resistance, there is no need for cathodes and the biofouling resistance is remarkable.

[Barno Kaison-Flower]

Copper has some interesting properties such as auto unfouling the hull. In humans it can replace iron in the blood to carry hemaglobin and you get green blood.

[Big Steve]

here's a fascinating read on cupro nickel boats, http://www.copper.org/applications/cuni/tx..._boat_hull.html, apparently they cost 12% more than steel, but need almost no maintenance. there is also a boat called the Pretty Penny which was based on the Swale which was CuNi, is she still there?

 

Just found out Cu Ni plate is about £4 per kilo, so how much is in a narrowboat, bearing in mind you won't need more than 6/4/4 construction?

Edited February 9, 2008 by Big Steve