FRAME LOFTING DIAGRAM - DRAWING FRAME TRACINGS


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RESEARCH

RESEARCH CONT.

DRAWING A FRAMING DIAGRAM

DRAWING FRAME TRACINGS

USING YOUR DRAWINGS

 

The first thing that you will have to do when coming up with frame tracings if you havn't already through your research, is to establish the thickness of your frames, from the inside of the hull to the outside. Many times your plan will give you at least a hint of frame thickness.  Otherwise you may just have to look at general practice. In the case of the Wasa plans that are available right now, you are given several cross sections that denote thickness.

 

 Image Courtesy of Statens Maritima Museer and drawn by Eva Marie Stolt.

If you examine the frame drawings above, they show the frames as being the same thickness at the same relative elevational point. I used the deck levels for this determination since the frames seemed to stay the same thickness at each deck line even though the decks slope up towards the stern and up less obviously towards the bow. You will need to study your plans and figure out these relationships before you start drawing. At the least you will need to figure out a few reference lines as to where you are going to make thickness measurements and determinations. Notice how I drew in red lines to denote where I took common frame width measurements from. All of this will fit in to our discussion in a minute.

For the purposes of this practicum, I am going to show you how to draw a frame at the bow of the ship where there is a lot of bevel because of the hull shape changing rapidly. These are the tougher kinds of frames to draw since, at the middle portion of the ship, the bevels almost dissapear and the frames are square.

Image Courtesy of Statens Maritima Museer and drawn by Eva Marie Stolt.

In the above picture I have drawn the red lines along my deck reference points just to show you how one part of the plan corresponds to another. And to show you as well where, on the hull line diagram, that we are going to be drawing our frame. Notice it is in between hull section #38 and #40. (you may have to click on it to get a larger version)  

Notice in the below framing diagram that we came up with in the last section based on our knoweledge of shipbuilding practices of the time, that between section #38 and section #40, there are four frames. They are numbered 86 through 89. You can click on this picture in order to get a larger, more detailed view.  

So, between hull sections #38 and #40 on the hull shape diagram we need to put four frames. This is achieved in two steps. First, since most plans have their hull shape lines on the outside of the planking, we need to subtract the width of the outside planking and add a line on the inside of section lines #38 and #40 that denote the outside surface of the frames. The thickness of the outside planking at the scale that I am working at, and hence the amount of space that I had to move the line towards the inside of the ship happened to be about 3/32". 

The second step is actually taking the distance between the two new lines that you drew on your plan and dividing it up equally through measurement so that there are four lines that will denote the outside edge of each of the frames between the two hull section lines. Notice in the below diagram, since I started from the midship section and worked forward, the aft line that subtracts the planking thickness will not be an outside edge of a frame in this series.  it was the forward, outside edge in the last series of frames between hull sections #34 and #38. Notice in the below picture how almost every section is divided up in this way since this picture was taken after all of the frame tracings were drawn.

Image Courtesy of Statens Maritima Museer and drawn by Eva Marie Stolt.

I devided the distance between hull lines up in many different places using a ruler, made tick marks on the division lines, and then connected them by hand.

The next step involves taking our plan with the divided up sections and placeing it on the light table. I like to tape the edges down so it doesnt go anywhere. Next, take a piece of blank computer paper and lay it over the hull line drawing. Get this piece of paper where you want it and tape it down as well. Then turn on your light table and draw in horizontal reference lines as you see them through the paper. These are denoted as "VL" lines on the plan.

Remember that I went over how I was going to use the level of the deck in order to reference my frame thickness? The levels of these decks are the next thing that need to be drawn.

I apologize in advance for the chunky/uneven nature of these drawings. I did the drawing in paint so that I could give you a clear digital image and present the main concepts. The frame tracing at the end of this section is much better and will be most like what your end results will be. 

Now, for the next step, we need to remember what frame we are on. There were four frames in between hull sections #38 and #40. These frames are numbered 86 to 89. For this practicum we are going to draw frame #88. This means that we have to look at the third line in our sequence that divide the space evenly between these hull sections. This is because frame #88 is the third frame in this sequence. In order to start actually drawing the frame, we start by tracing this third line from the beginning of the sequence as is shown below.  Notice also, the centerline of the frame is drawn on the diagram at the center of the keel.

Next, we need to remember our frame thicknesses at the reference lines that we designated for them. Measure along each reference line to the thickness of the frame, remember that in this case they were the levels of the decks, and make a tick mark on the inside edge of the frame. Do this along each of your references. Now you will have the inside edge of the frame once you connect your tick marks. Additional tick marks can be made between the references by going back and measuring your cross section references. This will give you more to guide your hand as you connect your tick marks.

Now, it is time to draw in a bevel. Remember that we are at the bow of the ship and on the port side. Along the floors, the hull is coming up and along the sides of the ship the hull is turning in. We show this by placing a dotted line to represent our bevel at the location of what will be the very aft outside edge of the next frame. Or in other words, it will be at the next line that devides the space between hull sections #38 and #40. 

Next we want to add the inside bevel. To represent this, we draw a dotted line along what will be the inside aft edge of the next frame.

It is important to realize that for the other side of the ship, the bevels for the counterpart frame will be to the same degree but will be decreasing/increasing on the opposite side.

The below picture shows the locations of the ends of the framing members drawin in red. In order to get these we look at our framing diagram and note that the top of the second futtock ends right below VL 10, the bottom of the top timber ends slightly above VL 8, the top of the first futtock and the bottom of the second futtock is right around VL 5, and the wronghead or end of the floor timber is around VL 4.

Now, we can turn our light table off and our frame tracing is complete.

The above picture shows the frame still on the light table and the below picture shows it as a scanned image. Click on either to get a bigger, more detailed view.

 

Now, repeat this process with all of your frames and you will have a full set of frame drawings for your model!

It should be mentioned here that if your model is unlike the Wasa in that it has cant frames, you will not be able to draw them using the method outlined thus far. You may have to use traditional frame lofting methods or simply use the Charles Davis method that is outlined in the next section and shape your cant frames to the moulds.

There is a good thread on more traditional frame lofting methods on the Model Ship World site.