A few random questions re: keel & stem construction (18th century)

[3DShipWright]

G'day Friends,

 

I have a couple questions regarding the joints of the keel and cutwater pieces. These pertain to my historically accurate build of the HMS Pandora, though for the most part these are very general questions:

 

1. Boxing of the Stem. I was led to believe that these pieces have this name because they actually clamp or 'box in' something - my question is what? Do they box in the back ends of the gripe, cutwater, stemson, gammoning piece, and gammoning knee? Or do they box in the front ends of the apron pieces? Or both?

 

2. Joint Between the Keel and Rising Wood. I know things become somewhat fuzzy when talking about the rising wood and various deadwood components atop the keel, so for simplicity's sake, I'm only asking about the wood inboard of the can't frames of the bow/stern; I'm talking about the rising wood that supports the perpendicular frames. It seems to me that the rising wood is a separate piece than the keel, but I don't know where that transition occurs - does the transition happen at the back rabbet line or at the inner (upper) rabbet line? I assume it's the latter but I would like to confirm.

 

3. Horseshoe and Dovetail Plates. How do the horseshoe and dovetail (a.k.a. fish) plates interact with the copper plating? Are these pieces later covered with copper link the rest of the ship that sits below the water line? If so, how is that done? Are the plates recessed into the pieces they hold together so they are essentially flush with the outer surface? Are they just very thin to begin with? Were they themselves made of copper on later vessels?

 

Thank You!

[Gregory]

You might look at Thukydides log for Perseus.   He is doing a lot of research regarding the stem.

 

(sorry I can’t post a link right now)

[druxey]

There are a number of good books on construction of this era that will explain all that you've asked about, and much more. Take a look at he SeaWatchBooks web site for a good selection.

[3DShipWright]

@Gregory and @druxey - Thank you both!

 

It was quite eye-opening to learn just how informal and variable stem construction was, especially compared with how precisely designed, documented and measured other components were. Scantling tables give us precise dimensions for gun ports, height above the decks, etc. One could write a novel on room and space calculations. But the stem pieces? 'Well, that depends largely on the shipyard and available timber.' Like, really???

 

Don't get me wrong, as a 3D artist, I enjoy modeling the parts where I have more creative leeway. I'm just surprised, is all.

 

Anyway, that's not to suggest I'm going to go completely off the cuff. What I think I'll do is to study up on multiple types of stem construction for similar ships of that period, that way I can ensure all the small joint details of my version of Pandora are historically plausible, if not historically accurate.

 

Thanks again,

-N.

 

[Thukydides]

On 11/20/2024 at 10:57 AM, 3DShipWright said:

Anyway, that's not to suggest I'm going to go completely off the cuff. What I think I'll do is to study up on multiple types of stem construction for similar ships of that period, that way I can ensure all the small joint details of my version of Pandora are historically plausible, if not historically accurate.

I am pretty sure I found all of the contemporary examples that have been published online or in print. That being said if you find any others please let me know as I would like to include them in my research.

 

One thing I will note with regard to the Pandora drawings in the McKay book. I have found no historical examples of the construction of the knee of the head that look like their depiction. I suspect what happened is they mistook the lines on the draught showing the location of the figure as marking off one of the joints.

 

A more historically consistent (I say consistent instead of accurate as there are so few examples and so we don't really know the breadth of methods used) would be to do something similar to what I propose for Perseus (either with or without the scarphs) or to use an arrangement similar to that used in the swan class books sold by seawatch (there are lots of builds of the ship on the site you can see the arrangement).

Edited November 23 by Thukydides

[3DShipWright]

On 11/23/2024 at 7:37 AM, Thukydides said:

One thing I will note with regard to the Pandora drawings in the McKay book. I have found no historical examples of the construction of the knee of the head that look like their depiction. I suspect what happened is they mistook the lines on the draught showing the location of the figure as marking off one of the joints.

 

Thanks Thukydides.

 

With regards to your comment above can you be more specific?  Are you talking about...

 

The overall profile of the cutwater? (See below) [Also note: model is a work in progress, Apron net yet complete]

 

OR

Are you talking about the arrangement of the pieces themselves? (see below)

 

I've seen plenty of examples where the general shape of the cutwater/knee of the head looks as depicted on Pandora (Swan and Porcupine class post ships almost all have the same profile) so I'm guessing you are talking about how the particular pieces are arranged, correct?

 

Assuming you are talking about the latter, where do you think the error lies? I'm of the general assumption that - where possible - fewer overall pieces are preferred from a stability standpoint - which is why the lacing/mainpiece is a single piece of wood, and also why the bobstay holes were cut there and not in a dedicated bobstay piece. Also, remember that these are small ships, and it is perfectly plausible to get each of the components above from the trunk of an oak tree.

 

Anyway, please elaborate on which line you believe was marked off incorrectly, and how you think that might affect the design. Happy to take any feedback under consideration. If it helps, my initial question was if there is any 'sandwiching' that occurs between the boxing of the stem and the gripe, lacing, chock, and gammoning piece?

 

Thanks again,

-N

[Thukydides]

3 hours ago, 3DShipWright said:

Anyway, please elaborate on which line you believe was marked off incorrectly, and how you think that might affect the design. Happy to take any feedback under consideration. If it helps, my initial question was if there is any 'sandwiching' that occurs between the boxing of the stem and the gripe, lacing, chock, and gammoning piece?

I will attempt to elaborate, but up front I should say that I think “incorrect” is a strong term. There are very few examples of how the knee of the head was constructed and lots of evidence that the shipwrights had broad latitude in the specific pieces that were used to construct them. This means that we can make our models consistent or not consistent with the examples that do exist, but there is no way to say definitively a particular arrangement is wrong. One could plausibly argue any given arrangement could plausibly have been used.

 

I should also clarify that yes I am referring to the pieces that make up the knee of the head. The overall shape of the knee of the head is laid out in the draught and it appears to match the one held at the NMM. One small note here, I think your stem should probably be a simple scarf (same joint as you have for connecting the gripe to the main piece). If you look closely at the original draught this appears to be what they did and this is the joint I have seen on every stem I have looked at from the period. (see the bottom picture ‘C’)

 

Also I just noticed that you have a scarf joint for the false keel. Again I am no expert, but I think that they were just diagonal connections as they were designed to come off easily if the ship ran aground.

 

The gripe as you have shown it looks fine and matches most historical examples I have seen. The part I am less sure about is the pieces above the gripe (broadly the main piece, lacing and chock). With regard to why I question the Pandora book arrangement it basically comes down to two factors:

1. The arrangement does not look like any of the historical examples I have found. If you have not already then please read through my two posts on the subject in my Perseus log. Every example I have found tends to use roughly parallel (or of a common curve) pieces which are more numerous than one might at first expect. It was much more economical to use more smaller pieces and there is lots of evidence to suggest that English shipwrights did this.
   • A lessor point with regard to this is the Pandora book example is missing a cutwater (a small thin piece that ran along the leading edge of the knee of the head where it hit the water).
2. There are also a number of practical issues / questions that I have regarding the arrangement that make me distrust the arrangement as described in the Pandora book:
   • The shape of part A looks suspiciously like the shape laid out in the draught for the same area. The problem with this is that area on the draught is not laying out the shape of a piece of the knee of the head, it is just marking out where the figurehead would go.
   • Part B is very thin at the top and is a very large complex shape. All examples I have seen for these pieces is they used simple shapes and I question if it makes structural sense to have such a thin piece at the front of it. It would make much more sense for the thin part of B to just be made part of A.
   • My understanding of the standard (part D) is that it ran all the way up to the back of the figure (see the examples of the Swan class or Winchelsea models. The cheeks start out against the knee of the head, but at the tope they but against the upper piece of the standard (I can’t remember the name of that piece).

This all being said it is your model and you are free to do what you want with it. As I said in the beginning this is not a question of right or wrong, rather consistent with historical examples or not. As I said previously, if you have any contemporary examples showing an arrangement similar to the Pandora books I would be happy to be proved wrong on this.

 

The model is looking very nice. Good luck with it.

 

[Pirate adam]

This conversation is interesting to me, as I am working on a POF model of another of the Porpoise class ships the HMS Crocodile 1781.  I am working from my interpretation of the admiralty draughts from the NMM. Working from the draughts is definitely something that “builds character” lol, as there is never ending learning to figure out how they guys did things back then.
 

One thing I would mention is I am deeply skeptical of the frame configuration in the Pandora book.  The authors don’t list a framing drawing in their references, and their drawings show a design that makes immense use of filling frames in a way that doesn’t seem practical.  I have the book, and it is a fantastic reference. That said I think the authors had to do a lot of guessing due to the drawings available. 

 

The National Maritime Museum has admiralty draughts of some of the ships in the class (see Hyena 1788) but they only show some of the frames. For my model I have recreated (ie, guessed) at the layout from the scantlings and what seems to make sense from the admiralty draughts. I ended up with something very similar the the HMS Sphinx 1775 framing patterns which they have available at the NMM.  You might check the Sphinx drawings as a reference, as it is a very similar ship. 
 

I just guessed at the structure of the head based on the designs in the Swan and Naiad books. You can see where I netted out in my Crocodile log. My conclusions were very similar to thukydides above. 
 

Adam 

[Pirate adam]

9 hours ago, Pirate adam said:

This conversation is interesting to me, as I am working on a POF model of another of the Porpoise class ships the HMS Crocodile 1781.  I am working from my interpretation of the admiralty draughts from the NMM. Working from the draughts is definitely something that “builds character” lol, as there is never ending learning to figure out how they guys did things back then.
 

One thing I would mention is I am deeply skeptical of the frame configuration in the Pandora book.  The authors don’t list a framing drawing in their references, and their drawings show a design that makes immense use of filling frames in a way that doesn’t seem practical.  I have the book, and it is a fantastic reference. That said I think the authors had to do a lot of guessing due to the drawings available. 

 

The National Maritime Museum has admiralty draughts of some of the ships in the class (see Hyena 1788) but they only show some of the frames. For my model I have recreated (ie, guessed) at the layout from the scantlings and what seems to make sense from the admiralty draughts. I ended up with something very similar the the HMS Sphinx 1775 framing patterns which they have available at the NMM.  You might check the Sphinx drawings as a reference, as it is a very similar ship. 
 

I just guessed at the structure of the head based on the designs in the Swan and Naiad books. You can see where I netted out in my Crocodile log. My conclusions were very similar to thukydides above. 
 

Adam 

I meant Porcupine, not Porpoise.  That's what I get for trying to type while eating a plate of nachos.

 

Adam