HMS Bellona 1760 by SJSoane - Scale 1:64 - English 74-gun - as designed

[druxey]

I use a very well sharpened 4H lead in a mechanical pencil. Thanks for your kind compliment.

 

As for "Do I paint? Don't I paint?", I have one suggested solution. Build two models!

 

The stern looks like it's shaping up well, Mark. I like your micro-adjustable support. 

[Wintergreen]

I use a very well sharpened 4H lead in a mechanical pencil. Thanks for your kind compliment.

 

As for "Do I paint? Don't I paint?", I have one suggested solution. Build two models!

 

The stern looks like it's shaping up well, Mark. I like your micro-adjustable support. 

And add another 20 years worth of building?

 

Regarding your build Mark, I can't find the words to comment. It is too darn stunning. 

[SJSoane]

 

Hi everyone,

 

So here is a perplexing issue, that shows I don't really understand these ships yet. 

 

I was setting up a sanding template for the quarterdeck beams, in anticipation of making the transom at the stern. I measured from my Admiralty drawings in the sheer plan that the deck rounds up 8 ½" at midship, which is 40'-8" wide. At the stern transom it measures a 5" round up, over a width of 21'-5". This clearly is not the same radius at midship and at the stern. The ship is roughly twice as wide at the center as at the stern, but the roundups do not double.

 

So, are the radii of the beams different along the length of the deck? This was less noticeable on the gun deck, with a smaller roundup.

 

Best wishes,

 

Mark

[EdT]

Mark, the round up of the beams is a constant radius over he length of the deck. That is why the deck lines at the center and those at the side converge going forward and aft of midship coming together at the bow and almost together at the tern..

 

Ed

[dvm27]

Perplexing, is it not Mark? I would certainly trust Ed's research but I I have read this is precisely the case. As I recall, each beam progressing aft has a slightly smaller round up as they approach the transom. I don't recall if this is the case in the fore section. I'm sure others can provide a more definitive answer with source references. I suppose one could place 5" round up beams aft then fay the others to a batten connected to the 8 1/2" beam fore. But I suspect you'll develop a table of offsets and do this more scientifically.  Gary...Druxey...?

Edited January 5, 2014 by dvm27

[druxey]

The fallacy in your argument, Mark, is assuming that the round up is directly proportional to the with of the beam. A moment's thought will tell you this is not so. As the beam narrows, the 'fall off' of the round up is quite small. The wider the chord of the circle (i.e the width of the beam), the more rapid the increase in round up.

 

In the upper half of the illustration, twice the beam width is not twice the round up! The corollary of this idea is shown in the lower half. Hopefully this clears up your dilemma.

[SJSoane]

 

Hi everyone,

 

First of all, thanks druxey for helping me past my misunderstanding about geometry. On further investigation the problem still continues, though.

 

I discovered a mistake in measuring width (I was measuring to the inside of the frames), but now corrected to outside the frames I still come up with different radii at midships and at the stern transom. I forgot to mention that I got into this because I was using some large radius template for drafting the beam roundup, and I discovered I needed a different radius for the two locations.

 

So then I looked up some arc calculators online, and calculated the radius at midships as 60" at midships (42'-6" wide, 8 ½" rise converted to 1:64 scale); the radius calculated at the stern (25'-5" wide, 5" rise converted to 1:64 scale), calls for a 36" radius. These correspond to the templates I needed when I physically constructed them.

 

Whichever way I look at it, the radius of the beam roundup at the stern appears to be smaller (giving a higher rise at a given width), than at midships. And I have measured these heights on the sheer drawing showing the top of beam lines at the side and at the center, so I am not getting confused by a transom that is a different radius from the deck beams.

 

I am pretty sure at this point that the radii change, but in this case, they are getting smaller further aft, creating a higher rise. Greg, do you recall where you read about changing radii? I am suddenly very interested, and also soberly thinking about how efficiently I am going to construct beams with unique radii aft of midships....

 

It would be tempted to fudge this, except that an accurate radius at the stern is essential to the overall effect of the roundups of the windows, counter knuckles, etc. And the stern radius would make the deck at midships look quite rounded.

 

There is always a new problem to solve!

 

Best wishes,

 

Mark

[garyshipwright]

Hi Mark.  Confusing isn't it. To make this simple for my self, when I made the template for the mid ship beam, all of my beams were cut to the same length as the mid ship beam in length, and all beams were given this round up using a template of the mid ship beam. This way, as the beams were fitted going aft or fwd the round up didn't change but length did bringing the round up under control. I know that when I got to my last beam, being short in length, when I looked at it doesn't seem that there is a lot of round up, but it was right.  Mark you may of already thought about this but the sheer of the deck also comes in to play with the round up of the beams  as they go forward or aft. Hopefully this makes sense. 

 

Gary

Edited January 6, 2014 by garyshipwright

[druxey]

OK, Mark: assuming that the midships round up is correct at 8½" as measured on the draught, what is the round up at the stern if you use the same radius? Is it much different from the 5" that you've measured?

Edited January 6, 2014 by druxey

[Gaetan Bordeleau]

I asked myself the same question and I also thought that the radius was different. When I was looking beams from the end on the plan, they had different length. Later I understood that a taller length implies a taller height.

 

All the beams I did  have the same radius on the french ship.

 

May be this drawing can help.

[EdT]

OK, this topic keeps coming up.  The answer lies in Steel - and it is consistent to my earlier response and the comments of druxey and Gaetan.  I quote from the instructions on preparing the Sheer draft.:

 

“All the decks having been drawn in, representing their heights at the middle, we must now proceed to draw their heights at the side.  To do which correctly, take the round up of the beam of its respective deck from the table of dimensions, and set it up in the middle of a line drawn at pleasure: then on each side of the middle of this line, set off the half breadth at deadflat, or the broadest place, taken at the height of the deck.  Then raise an arc, that shall intersect the round up set off at the middle, with the spots at the breadth, and the round up of the deck will be described at any part of its breadth (my underline).  Thus, take the half breadth at the height the deck at any timber, in the body plan, and set it off equally from the middle of the round up till it intersects the curve; whence draw a line parallel to that first drawn, and the distance from the line last drawn to the round up curve in the middle, is what the beam rounds at that place.  Thus may the round up be taken at as many timbers as may be found necessary, and set below the underside of the deck at its respective timber in the sheer plan;  then a curve passing through those spots will represent the deck at the side:  but observe, that the decks are to have a sufficient round abaft, to correspond to the round up of the stern above the lights.”

 

Simple language: 1) construct an arc above a horizontal line that is the width of the deck at deadflat with a height at the center equal to the round up of the beam at midship.  2) At any timber along the deck take the half breadth and set it out from the center of the arc drawn, and drop a line to the arc on each side.  3) draw a line parallel to the first horizontal line through these interseection points on the arc. 4) the height from this line to the center of the arc is the height below the deck centerline at that timber.

 

Note that there is only one arc for each deck - common to all the beams.  And for this reason, in the sheer plan, the lines representing the center of the deck and the lines for the sides converge - completely at the bow and partially at the stern.

 

Ed  

[EdT]

Let me just toss in a couple more thoughts. Having a constant radius of curvature for all the beams of one deck would be a major facilitator in the shipyard - one template for each deck for all its beams. In addition, this would assure that the tops of the beams would be in a fair line for planking. Consider he complexity of a different arc radius for every beam, requiring unique templates for each beam as breadth of the deck narrowed the ends.

 

These considerations will also apply to the model work.

 

In addition, as the ends of the ship are approached a constant arc radius assures the the slant of the deck will be relatively constant. Consider how drastically the slant of the deck and its height at the center would increase as the deck narrowed - especially at the bow.

 

Ed

Edited January 6, 2014 by EdT

[michael mott]

Mark Just catching up, first your line up of the deck beams and carlings is most impressive that shows the level of skill and attention that you are using to build this fine model. looking at your work makes me feel a bit like a wood butcher.

 

I am not familiar with the Preac elevating screw, and when I saw it my immediate reaction was what a great looking adjustable screw jack. I have made a few out of short lengths of rigid PVC with 1/4 x 20 bolts in the past. they are very useful on the mill. when working on one end of long pieces.

 

Interesting discussion on the curvature of the deck beams, I had always considered that the curve was a constant, at least in my naive knowledge of ship and boat design, it has been how I have approached the issue so far anyway.

 

That is a great looking model Druxey

 

happy new year Sirs.

 

 

Michael

[EdT]

Sorry, just one more thought: Drawing the deck line at the sides as Steel describes is extremely inportant because in the tables of deimensions the heigth of the ports is given as a fixed height above that line - the deck line at the side - not the center. The line of the port sills (and for that matter all the inboard clamps, spirketing,waterways and planking ) is parallel to that line at each deck. This assures that gun barrels will be at the same correct height at every port - hence the attention Steel gives to this.

 

Enough from me. Cheers,

 

Ed

[michael mott]

Ed your thoughts are exactly how I cut the deck beams for my Maria boat, I used the first beam as a template for the rest regarding the top curve.

 

Michael

[EdT]

I don't know why, Mark, but I read your note on the beam rounding again. I missed the bit about the deck round up ratio at the stern first time through. See the last sentence in the Steel paragraph. I can only assume that there were rules for the stern windows round up or that the round up of that structure was done on the drafts before and independently of the round-up of the deck beams - so they could be slightly different. Hence Steel's note.

 

In any event it looks like you are only differing by about .5" - (21.42/40.67)x 8.5 = 4.5" vs. 5" At your scale the difference is only 0.008". Thats only a few sandpaper swipes.

 

Ed

[SJSoane]

 

Thanks, everyone, this is perplexing. I completely understand why the shipyard--and the model shipbuilder--would want constant radii on beams. I did the calculation druxey suggested, and if I kept the radius constant based on the 8 ½" at midships, then the roundup at the stern transom would be a shade over 3"; or 2" short of what I measure in the admiralty sheer plan as the difference between the beam heights at the side and at the center. I was intrigued by Ed's quote from Steel, which says the decks are to have sufficient round abaft, to correspond to the roundup of the stern above the lights; but I could only read this as the curve in plan, not cross section. 

 

I think I am reconciled to the possibility that there is a mistake in the Admiralty drawing, or there is something else going on that I cannot resolve. I think that the roundup at the stern is more important to maintain, so the lines of the heads and sills of the stern lights are agreeable with each other. So I think I will split the difference, and use a constant roundup based on 4" at the stern transom which would equate to 9 ½" at midships. That makes a sanding difference, as Ed wisely advises, split between midships and at the stern.

 

Thanks, everyone, onwards and upwards (until someone finds and obscure quote somewhere that would explain this).

 

Best wishes,

 

Mark

[druxey]

Sometimes headroom in the great cabin was improved by progressively raising the deck clamp aft, relative to the deck below. I suppose it might be possible that deck beams were of decreasing radius to achieve a similar result. However, that would be far more complex and time consuming. It seems unlikely, but one never knows….

[dvm27]

I can't remember what I had for breakfast but I do remember obscure references for some reason, Mark. Unfortunately, a search of the usual sources failed to turn up the reference to back up my statement. It might have been in one of the hundreds of journals in my basement. Or, the author could have been mistaken. It'll turn up, no doubt, five minutes after you've completed the beams.

[EdT]

Mark, I do not believe that Steel is referring to the rounding of the deck at the stern in plan. If that were the case I believe he would use the term round aft. Abaft means closer to he stern or toward he stern. I believe he is referring to the round up of beams toward the stern. The round aft would be set by the shape of the deck transom - see below.

 

I believe druxey is quite correct that the height between decks at the stern was usually increased to provide additional headroom for the big shots. I also agree with druxey that cutting beams of varying radius along the deck would be unlikely. My opinion, for what its worth, is that Steel's final comment was directed more at the drafting community than at the shipwrights. I would - and did - ignore it.

 

If you are looking for some further obscure notes, I would refer you to the paragraphs in Steel relating to the laying off of the transons - I have been assuming that the problem you are facing is the round up of the upper deck deck transom. Correct? Once that member is set, the deck clamps can be brought to it and with a consistent beam round up all will be well - the deck planks will lie fair and the captain's table will not wobble.

 

I have read these sections several times over the past few years and they certainly qualify as obscure - and very technical with regard to method. I would not venture a definitive conclusion from them. However, while the round up of the deck beams is used in the described lofting process, there is no mention whatever of adjusting the transom to suit the stern lights, ie the round up of the upper counter.

 

So, good luck with this - and happy reading if you so choose.

 

Ed

[Sailor1234567890]

Ed,

"Abaft" is actually nautical speak for "behind" more so than "closer to the stern". As in, the mizzen mast is abaft the mainmast.  Be default this will put the mizzen closer to the stern but I don't think that is the intent of the word. Petty nuances I know. A ship is not abaft another ship however, it is (as we all know) astern of her. The admiralty and indeed any sailor of the day (today as well) would refer to this roundup as "Camber". I have not read Steel however it sounds like he is using incorrect terminology and his incorrect terminology is throwing everyone off. Unless I am missunderstanding the use of the term "round up". Round up would mean to anyone in Nelson's navy or today's sailors to come up into the wind. A vessel will round up into the wind before dropping her anchor.  I'm a bit of a stickler for terminology as it's so important to us at sea to use the correct terminology for everything. It avoids mistakes and ensures we're all refering to the same thing. Makes things challenging when "floors" are not something you walk on and "ladders" look like staircases. I have seen this a few times and hope this clears things up a bit for many. Love your build as well as this one. Truly you are both masters of your craft,

Cheers,

Daniel

Edited January 7, 2014 by Sailor1234567890

[druxey]

Daniel: back in Steel's day what you now refer to as 'camber' was called round up. Camber (back then) was used to describe a deck that curved downward longitudinally. Confusing, eh?

 

'To round up' is a verb, 'round up' is a descriptive noun.

Edited January 7, 2014 by druxey

[SJSoane]

Hi everyone,

 

Thank you for your thoughtful contributions to this interesting question of the beam roundup. I am reconciled to averaging the roundup between midships and at the transom. But just for the record, I have attached an annotated drawing of the situation. The deck would droop if the radius for the beams is held constant.

 

I have also attached my photo of the 1760 Bellona model, showing that the quarterdeck decking clearly sits on top of the transom above the lights, and so the transom does not have a different roundup from the deck.

 

It may be druxey, Greg and Ed have the right idea; the roundup must have increased over the gunroom in the final set of beams in the quarterdeck. But more subtle than I think I want to address in my model....

 

Best wishes,

 

Mark

 

 

 

 

 

[druxey]

From your drawing I would hesitantly say that round-up did increase in this specific case. Lucky you, Mark! If you don't increase it, the 'spring' of the stern gallery will not look right. You are correct to be concerned about this detail.

[SJSoane]

 

Thanks, druxey, I began to think I was going mad. Tomorrow I'll have to look at how many beams in the stern will have to be adjusted from the standard radius for this to work. It may only be a few, since I assume the deck would want to be at the standard roundup at least past the sternmost gunport. I will keep in mind Ed's good thought that the captain's table will want a smoothly faired deck to sit on so it doesn't rock. I would certainly be annoyed if I were the captain, and there was an abrupt lump in my deck...

 

Best wishes,

 

Mark

[EdT]

Daniel,

 

Differences in meaning over the centuries can be very confusing, to be sure. Let me add to druxey's comments with some information on the word "abaft". It occurs frequently in the technical literature of the day. I will quote from the Universal Dictionary of the Marine, William Falconer 1732- 1769:

 

"ABAFT, the hinder part of the ship, or all those parts within and without, which lie towards the stern, in opposition to afore; which see.

 

Abaft is also used as a preposition, and signifies further aft, or nearer the stern; as, the barricade stands abaft of he main-mast, i.e. behind it or nearer the stern."

 

As is frequently the case meanings have perhaps evolved.

 

Perhaps. Webster's current definition: "to the rear of; secif. toward he stern."

 

One learns to look these up.

 

Ed

[Gaetan Bordeleau]

Mark, you cannot take a decision only from drawing one, you need the drawing from behind with the same provenance as your drawing.

Also, I am asking myself this question, are these 2 beams witness of the beam curvature of the decks?

[Sailor1234567890]

Seems time bends meanings and changes definitions. Another complexity to it is that often times a word had a certain meaning somwhere and a different meaning in another geographic area. Not only that but a certain part or action may have a certain name in one place but be called something completely different in another place. Rigs and their differences are an area that this comes up in very often. (Brigantine vs. Hermaphrodite brig comes to mind). The etymology of it all is still interesting to learn about.

[EdT]

Mark,  you are probably getting a lot more help(?)  than you expected on this, but I am going to reluctantly add some more.  Further to Gaetan's point looking at the stern view, I looked at Plate I in Steel that shows a lines draft for his 80-gun example ship.  It includes the stern view that I attached below as a pdf.  It can be seen in this view that the curvature of the upper deck transom is less pronounced, and not parallel to the round up of the lower counter.  Nor is it parallel to the upper counter rail – the rail below the lights.  Although dificult to measure, this deck round up appears close to the midship round up specified based on the deck width ratio.  The line of the quarterdeck is, however, parallel to the line of the pedestal rail – the line above the lights and therefore matches the tops of the lights.  The deck round up at this point also appears to be greater than the specified round up at midship.

 

So, it would appear that the qdeck round up was set to match the stern lights, while the upper deck round up was not.  The quarter deck transom would apper to form the top of the lights.

 

I realize that this does not solve the mystery of the sheer plan side deck line height on your draft, but it may be helpful.

 

Steel 80-gun stern.pdf

 

Ed

Edited January 8, 2014 by EdT

[michael mott]

 

I realize that this does not solve the mystery of the sheer plan side deck line height on your draft, but it may be helpful.

I realize this might be a silly question or statement, but could the drawing that mark posted have an error in it, it would not be the first time that a model proved an error in a drawing or plan.

 

I once saved Skidmore Owens and Merrill a Major problem by finding that they had made an error in their plans for a large center in downtown Denver.

 

Michael