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Small tutorial: How to read a plan


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Since we have an incredible amount of plans in this subforum, but no tutorial on how to read them (at least I haven´t found one), I figured I have to make one myself. And it´s a nice starting point for my modelling tutorial :)
 
For this tutorial, I chose the plan of the Gefion, a danish 24-pounder frigate launched in 1843. Why choose a plan for a ship that´s out of the NA timeframe? Because it´s easy to read, contains a lot of information and I can explain a lot of things which woudn´t be possible with a contemporary british of french plan (some of the lines you won´t see on those, but on 'modern' reconstructions)
 
Let´s get started, here´s the original draught of the Gefion:
 
 
First, we´ll have a look at the dimensions given in the lower right corner and how they´re measured.
 


 
The information here seems to be pretty straightforward, length between perpendiculars ( p/p) 160', breadth moulded 41', depth in hold 21' 1', draught aft 18' 9'' draught amidships 18' 2'', draught forward 17' 7'' with a difference between the draught fore and aft of 1' 2''. The middle gunport is 6' 9'' above the waterline, the distance between the gunports is 7' 2''.

 

The rest are the results of the displacement calculations and not really important. What´s below the title is a bit more interesting as it tells us that the frigate should be armed with 28 long 24-pounders à 15 skp (~ 47,2 cwt with a length of 9' 6'') and 20 short-pattern 24-pounders à 8 1/2  skp (27,75 cwt). The total broadside weight - one side - is 576 danish pounds, converted to british pounds that´s 634,5.
 
 We have to keep in mind that the danish fod, as the french pied de roi, is a bit longer than the imperial feet, so if we want to compare these dimensions to a similiar british frigate like the Endymion or want to import and scale the plan in a modelling app, which probably only knows meter or feet, we have to convert them.
The conversion factor is ~ 1.0305 (1.06575 for the pied de roi, by the way), so the dimensions in imperial feet are:
 
length p/p                                      164' 10 1/2''

breadth                                          42' 3''

depth in hold                                 21' 9 3/4''

draught aft                                    19' 4''

draught foreward                          18' 1 1/2''

middle gunport above the WL       6' 11 1/3''

distance between gunports           7' 4 5/8'

 

Okay, let´s see how these dimensions are defined on the plan:

 

 

 

First, the perpendiculars on the outboard profile (green lines) .As the name implies, these are either perpendicular to the keel or the load waterline (WL, red line). On british plans, they´re always perpendicular to the keel. On most french ones, also perpendicular to the keel. Swedish and danish, it depends on the timeframe, but most probably perpendicular to the WL. But they´re always parallels to the station lines (the thin red lines with numbers and/or letters).

 

There were several ways to define the position of the perpendiculars, here it´s the intersection of the rabbet line (bright blue, shows where the inner edge of the planking is attached to the keel, stem and stern post) and the WL. I added the purple lines to show where the perps would have been on a british plan (at the stem and stern post, that´s the 'length of the gundeck'), these would give a length of 168' 7 1/3''.

 

 

Next stop, the breadth. Here we have the breadth moulded, that means the breadth inside of planking, as opposed to breadth extreme, i.e. outside of planking.

Here´s the body plan:

 

 

 

It shows the station lines (the thin red lines on the outboard profile, remember? ^^) and the breadth moulded is the distance between the two yellow lines along the red WL.

The station lines aren´t necessarily in the same positions as the actual frames, but they nethertheless define the shape of the hull.

 

What they don´t show, however, is what the hull looks like with planking. This a very important thing to know if you want to make a 3D ship model and sadly a beginner´s mistake that happens quite often.

 

If you don´t have a cross section that shows the thickness of the planking, you can measure the distance of the rabbet line (bright blue) to the keel, these are the two short orange lines, roughly 4''.

This gives you the thickness of the planking from the keel up to the wales. The wales are just 3 or 4 rows of thicker planks which run along the whole length of the ship; as a rule of thump, they have 1,33 times the thickness of the planking of the underwater hull.

 

 

 

The outboard profile shows the upper and lower edge of the wales (white line, 1. and 2.), the body plan only the upper edge (1.).

 

 

Depth in hold. The danes used the french method of measuring the depth in hold, so this is the distance (dark blue line) from the upper edge of the keel to the lower surface of the upper gun deck beams at the midship bent (where the breadth moulded is taken). The british would measure the distance from upper edge of the keel to the lower surface of the gun deck.

 

 

 

 

 

Draught fore and aft

 

Easy. This is the distance from the WL to the keel along the perpendiculars fore and aft.

 

 

Now let´s let get to the interesting bits:

 

 

 

Here you can see which lines correspond with each other on the profile, half-breadth and body plan.

Gefion´s tumblehome is pretty modest (2' 6''), especially compared to earlier ships like La Belle Poule and La Renommée. A large tumblehome can have positive effect on stabilty, but it also reduced the space available to operate the guns and may have made the ship a jerky roller.

 

X, X1 and X2, called buttock lines on modern plans, are lines to check the plan (and a 3D model) for errors. Here´s what these lines look like in 3D:

 

 

And in combination with the (unfinished) basic hull model:

 

 

The station lines and the buttock lines (red) should describe the same exact surface. The clipping effect is pretty nocticeable as both are low-res, but it´s a nice start.

 

 

The line called L'Estain (I only know the french term and you will find it only on french and danish plans) is especially interesting as it´s a simple diagonal on the half-breadth,

but quite a complex curve on the outboard profile.

It more or less defines the shape of the forward fashion piece, which can be seen here:

 

 

 

The line called 1 B on the original plan is the part of the wing transom where the planking ends.

 

So, now that we know  what line means what, it´s time to check the plan for inaccuracies and distortions. The first step is to measure the scale given on the top of the draught. There are four equal parts à 10 fod with 384 pixels per part. The largest horizontal dimension given is that of the length p/p, so we measure the distance between the perpendiculars along the WL.

 

That´s 6152 pixels, multiplied with the result of 10 fod/384 pixels gives us 160' 2''. Two inches off the mark, but very good for a plan that has been drawn 168 years ago.

The largest vertical dimension is the depth in hold. That´s 810 pixels, multiplied with the result of 10 fod/384 pixels gives us 21' 1 1/8'' instead of 21' 1''. 1/8 of an inch. Not bad, not bad :P

 

Another good check for distortions is to compare the distance between the yellow line and the middle of the body plan and the yellow line and the middle of the half breadth at the midship bend.

In this case, it´s 791 vs. 790 pixels, so pretty much perfect.

 

Pro tip: if you want to model a ship from the Architectura Navalis and use a plan from Chapman.net, this last check is absolutely necessary as those plans are heavily distorted along the x-axis.

 

Different types of measurements

Let´s have closer look at how perpendiculars can be defined (which in turn define the length of a ship).

Here´s the draught of a danish ship, dated 1807.

 

 

Perpendiculars

 

 

 

Danish shipwrights at the time dropped the perpendiculars (green lines) at the intersection of the LWL (load waterline, blue) and the rabbet line at the stem and stern post (without planking thickness).

This gives a length of 138' 6''. This method was also used by some shipwrights in France, by the way.

 

British shipwrights dropped the perpendiculars at the intersection of the lower surface of the gun deck and rabbet line at the stem and stern post (without planking thickness). Unfortunately, the gun deck isn´t shown on the plan, so I used the upper deck for the perpendiculars (yellow line).

This gives a length of the upper deck of 143'.

 

French shipwrights......well, they used a lot of different methods to define the perpendiculars :P One of the most common was the intersection of the outside of the stern post with the projection of the upper face of the wing transom aft and the outside of the stem fore (brown line). Another method was using the intersection of the LWL and the outside of stem and stern post (purple line).

This gives a length of 144' 3'' for the former and 141' 3'' for the latter.

 

Breadth

 

 

 

Danish and french shipwrights used outside of frame to outside of frame at the midship bent (red line), which is the same as the british breadth moulded, 36' 8'' in this case.

The british breadth extreme adds the thickness of the second strake above or below the wales to the breadth moulded. The thickness of this strake isn´t given on the plan, but in an additional document (5,5 ''). So breadth extreme would be 36' 8'' + 2* 5,5'' = 37' 7''.

 

Depth in hold

 

 

 

Danish and french shipwrights defined the depth in hold as the distance (black line) between the upper surface of the keel  - including rabbet line - and the lower surface of the deck beams of the closest armed deck (the upper deck, in this case). This ship has a depth in hold of 18' 2''.

British depth in hold was distance (green line) between the upper surface of the keel  - including rabbet line - and the lower surface of the deck beams of the closest continuous deck (the gun or lower deck in this case). Depth in hold measured this way is 12' 3''.

 

 

Easy, isn´t it? ;)

 

To complicate things a bit, let´s convert the danish fod used so far into french pied de roi and british feet and apply the corresponding measurement methods.

 

Danish

 

Length    138' 6''    Breadth 36' 8''  Depth in Hold 18' 2''

 

French

 

Length    139' 6''     Breadth 35' 4''   Depth in Hold 17' 7''

 

British

 

Length    147' 5''     Breadth extreme 38' 9''   Depth in Hold 12' 7,5''

 

 

 

 

Links:

 

http://www.marinewiki.org/index.php?title=Lines_plan

http://modelshipworldforum.com/resources/plans_and_research/InterpretingLineDrawings.pdf

Edited by Malachi
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This is AMAZING! I started building a 3d model for this game but got stuck and abandoned the whole project. You are an inspiration to start modeling a ship again. Thank you! :)

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You´re welcome :) Out of interest, where did you get stuck? Research, plan preparation, modelling itself etc. ?

 

By the way, I´m still searching for a suitable ship for the Blender tutorial, so if any of you has an interesting ship you want to see a hull model of, let me know.

Freia, L'Artémise or La Forte would be my choice for now.

The plan(s) should be available for free, though. 

 

 

 

 

 

Edit: Added two pics about the buttock lines and two links to the OP.

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You´re welcome :) Out of interest, where did you get stuck? Research, plan preparation, modelling itself etc. ?

 

By the way, I´m still searching for a suitable ship for the Blender tutorial, so if any of you has an interesting ship you want to see a hull model of, let me know.

Freia, L'Artémise or La Forte would be my choice for now.

The plan(s) should be available for free, though. 

 

 

 

 

 

Edit: Added two pics about the buttock lines and two links to the OP.

It started probably at the plan preparation and that caused problems while modeling. The part you call "L'Estain" caused a lot of problems in my head :). As you already said, this part looks very easy if you look at it form a certain angle, but it is actually a very complex shape. And as i am a perfectionist i want to have a clear picture of everything in my head. I hope this part is easier than it looked back then and maybe this tutorial will help me figure it out.

 

I prefer earlier ships because i really like those work of arts of the earlier times. I really like ships like Adolph Friedric(Swedish 24 gun Merchant), L'Ambitieux(French 80 gun). But i think, after looking at your selection, you are more drawn toward the later ships. Am i right?

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But i think, after looking at your selection, you are more drawn toward the later ships. Am i right?

 

That´s simply because the plans are better and contain a lot of information  :)

An earlier ship like the beautiful Hvide Orn of 1712 or the ships you mentioned would require a massive research job on my part before I can get started with the actual modelling.

 

 

It started probably at the plan preparation and that caused problems while modeling. The part you call "L'Estain" caused a lot of problems in my head

 

Hm, which ship was that? :)

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The "Frederika Louise Wilhelmina" a 36 gun frigate.

 

 

Ah, just had a look at the Frederika, I didn´t know that the dutch also used that line on their plans.

 

Anyway, this might have been a bit too tricky for someone new to historical ships as the plan is quite heavily distorted and there doesn´t seem to be an complete inboard profile.

 

Here´s the body plan:

 

 

By the way, l´estain shouldn´t be a part of the actual model, it´s just a very useful reference like the buttock lines :)

Edited by Malachi
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Ah, just had a look at the Frederika, I didn´t know that the dutch also used that line on their plans.

 

Anyway, this might have been a bit too tricky for someone new to historical ships as the plan is quite heavily distorted and there doesn´t seem to be an complete inboard profile.

 

Here´s the body plan:

attachicon.gifUnbenannt.jpg

 

By the way, l´estain shouldn´t be a part of the actual model, it´s just a very useful reference like the buttock lines :)

That should be the reason why i got stuck, i do remember some small trouble overall. What would you advice, try to restart building this ship or choose another one? And do you have some recommendations instead of the Frederika?

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Well, I might have a plan or two ;)

 

I´d definitely go for a small ship, in the 16 to 30 gun range, ideally with a nice contemporary model (or a well researched modern one) as a reference.

Do you prefer a certain nation? If it has to be dutch, the 24-gun frigate of 1760 or one the corvettes like the Lynx look quite nice.

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Well, I might have a plan or two ;)

 

I´d definitely go for a small ship, in the 16 to 30 gun range, ideally with a nice contemporary model (or a well researched modern one) as a reference.

Do you prefer a certain nation? If it has to be dutch, the 24-gun frigate of 1760 or one the corvettes like the Lynx look quite nice.

I am looking, at this moment, at different ship plans. It doesnt have to be dutch  ;). I like ships from the smaller(lesser presented) naval nations like Danish, Swedish or Dutch.

 

You make me curious, what are the plans you have in mind?

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You make me curious, what are the plans you have in mind?

 

 

The Langeland would be an ideal project, in my opinion. 18 guns, nice lines and a decent plan set. And she has a quite famous 'ancestry' as she is based on the british Royal Caroline.

I can send you the plans if you want, the preview pics are in my danish frigates thread :)

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The Langeland would be an ideal project, in my opinion. 18 guns, nice lines and a decent plan set. And she has a quite famous 'ancestry' as she is based on the british Royal Caroline.

I can send you the plans if you want, the preview pics are in my danish frigates thread :)

It is not really my kind of ship, but i think its a nice start. Can probably learn a lot from modeling this one. If you can send me the plans, that would be nice.

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If it´s not your kind of ship, then look for something else :) But I´ll send you the plans this evening.

Another good one would be the danish Triton or the 24-gun project by af Chapman.

 

The Triton would be a nice choice for the tutorial, now that I had a look at it again *thinkshard*

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If it´s not your kind of ship, then look for something else :) But I´ll send you the plans this evening.

Another good one would be the danish Triton or the 24-gun project by af Chapman.

 

The Triton would be a nice choice for the tutorial, now that I had a look at it again *thinkshard*

I agree, i should really model something i like. But for the sake of learning...

 

The Triton looks better, i like it more. What do you think of the Windhond? It's a 24 gun Dutch frigate. Is that a smart choice?  ;)

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  • 4 weeks later...

post-6853-0-99275000-1468469614_thumb.png What does the bottom half of this plan mean? I understand what the top curves mean but what about the bottom?

I'm thinking it's the curves of the ship when viewed from the side but I'm not sure. 

 

Also, do I need to use those curves when modeling, or can I just use the top?

Edited by Legioneod
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what you see shows the flow of the hull lines from fore to aft.

it indicates the width of the hull for the whole lenght.

 

The lower part should be according to the underwater parts whereas the upper parts show the lines above the watermark.

You can see that on the back end, where the sternpost ends the plan shows pretty square lines upwards.

 

For modeling.. I sometimes check them but generally speaking you better use the cross section view which show you the frame timbers.

Ion Aguirre uses a modeling technique which might be using these lines. But I only use them to check if the flow of the planking looks good.

 

Which concludes to: You have to make your own experiences :P

But you dont nessecary need these lines to model a ship.

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So they both show the curvature of the hull from a birds eye view?  The reason I asked was because I plan on using nurbs (I think thats what they're called) to model the ship and was wondering if I needed both. 

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