Iron plating on Erebus and Terror

[Shickluna searcher]

I am building the OcCre Terror.   Soon I will be adding the iron plates that protected the bow from heavy ice.  The kit includes since pieces for this.  Reference books and the kit say the plates were riveted on.  How is this possible?  To rivet you have to be able to access both sides, with the rivet being passed through red hot from the inside in this case.  And a bolster has to be held at rhe preformed end while the cylindrical end is flattened.  Does anyone have any insight on this?  

[wefalck]

A rivet does not necessarily need to be red-hot, but indeed, it needs to be accessible from both side. The planks of clinker-built hulls are rivetted together, but there the rivets are made from copper. During the Viking-age, I think also iron rivets were used, but they tend to rot the wood or corrode due to tannins in the wood.

 

If the iron used for the rivets was sufficiently malleable, one could form the the heads on the outside using cold hammering.

 

Another possibility is, that the bolts were not actually rivetted, i.e. a head was formed, but clenched, i.e. the points were turned over and driven back into the wood. This, howver, requires space inside the hull to work in. Given the realtively blunt bows of the time and that it would be at waterline level, this should have been possible.

 

I gather, the term 'rivetted' refers to the fact that the plates were not just nailed on, as copper sheathing would be, but fastened with through-bolts/rivets.

 

Today, one probably would use coach-bolts for such a task, but at that time threads and nuts were made still individually to match, no norms and only rudimentary thread-cutting technology. The thread-cutting lathe hadn't been invented by Maudslay until somewhat later in the 1840s.

Edited December 31, 2023 by wefalck

[druxey]

I believe that Maudsley had such lathes earlier; around 1800. The principle was earlier still: Leonardo da Vinci sketched such devices.

[wefalck]

Yep, you were right Maudslay constructed his first lathe around the turn of that century - I was quoting from memory and that sometimes fails. Still at that time bolts were expensive and the first standardised thread by Joseph Whitworth had only just been proposed (1841).

[catopower]

I've noticed that some manufacturers of models kits of wooden ships, and some modelers, tend to throw around the term "riveted", when in fact they're referring to things that were nailed or bolted. If it's any help, Matthew Betts in his book on HMS Terror, describes the iron plates as being "bolted" to the bow. 

 

 

Edited January 2 by catopower

[Shickluna searcher]

I saw that reference in Betts's book to "bolted" plates.  He also talks of simulating "rivets" on the model hull plating. But he also modeled the plates as overlapping however in his drawing on pg 141 he shows them butted together.  I am going to conclude that that they were lag bolted to the hull, with washers. That technology existed then.  Wood screw threads do not require the precision machine screw threads or threads to be used on matching bolts and nuts and don't require hull penetrations by the hundreds.  I will butt them together,  not overlap them.  These plates ran from just below deck level to the keel and from the stem to back to the point where the bow curve in the hull sides begins.  So it is an extensive area.  Again, the hull thickness and bracing on these ships were at least double thickness in that area.  Thanks for the discussion all.  By the way, on the actual Terror wreck,  the iron bow plates appear to still be in position.  So, whatever they used, it lasted.

[Shickluna searcher]

On 12/31/2023 at 6:32 AM, wefalck said:

A rivet does not necessarily need to be red-hot, but indeed, it needs to be accessible from both side. The planks of clinker-built hulls are rivetted together, but there the rivets are made from copper. During the Viking-age, I think also iron rivets were used, but they tend to rot the wood or corrode due to tannins in the wood.

 

If the iron used for the rivets was sufficiently malleable, one could form the the heads on the outside using cold hammering.

 

Another possibility is, that the bolts were not actually rivetted, i.e. a head was formed, but clenched, i.e. the points were turned over and driven back into the wood. This, howver, requires space inside the hull to work in. Given the realtively blunt bows of the time and that it would be at waterline level, this should have been possible.

 

I gather, the term 'rivetted' refers to the fact that the plates were not just nailed on, as copper sheathing would be, but fastened with through-bolts/rivets.

 

Today, one probably would use coach-bolts for such a task, but at that time threads and nuts were made still individually to match, no norms and only rudimentary thread-cutting technology. The thread-cutting lathe hadn't been invented by Maudslay until somewhat later in the 1840s.

Interestingly,  I was watching an old "Time Team" rerun recently.   They were excavating a suspected Norse ship burial site.  The way in which they determined a ship had been there was by carefully recording the exact location of the many rivets they found and it outlined the shape of a ship.   I can't recall for sure the material used in the rivets. 

[wefalck]

Copper was quite expensive in the old North, but they had plenty of bog iron inter alia. To my knowledge these ships were always iron-fast.

 

In fact, for some of the famous boat finds, the nail pattern is the only thing that was found, the wood has long be decomposed.

[Shickluna searcher]

15 hours ago, Shickluna searcher said:

I saw that reference in Betts's book to "bolted" plates.  He also talks of simulating "rivets" on the model hull plating. But he also modeled the plates as overlapping however in his drawing on pg 141 he shows them butted together.  I am going to conclude that that they were lag bolted to the hull, with washers. That technology existed then.  Wood screw threads do not require the precision machine screw threads or threads to be used on matching bolts and nuts and don't require hull penetrations by the hundreds.  I will butt them together,  not overlap them.  These plates ran from just below deck level to the keel and from the stem to back to the point where the bow curve in the hull sides begins.  So it is an extensive area.  Again, the hull thickness and bracing on these ships were at least double thickness in that area.  Thanks for the discussion all.  By the way, on the actual Terror wreck,  the iron bow plates appear to still be in position.  So, whatever they used, it lasted.

Another interesting point is that acc to Betts, from sources he detail in his book, the iron plates are believed to have been "galvanised", but that nonetheless they rusted quickly.