Brief post on scan placement. I find the easiest approach is as follows. Firstly ensure that the existing 'trace' is at 1:1 scale. The easiest way to do this is to use one of the provided 'figures' on the plans - lower deck length of breadth. This is easily seen on the plans as both Aft and Fore perpendiculars (vertical dotted lines) start from either end of this line. Work out the current distance between the two lines then divide one (I can never remember which) by the required figure (in my case 144ft so 1728 inches) to get the scale factor. This is then applied to one of the ratios in turbo cad (note whether you have keep aspect ratio on or off - if off then be aware that you are only adjusting one axis and will need to repeat for the vertical).
Length of breadth once correctly sized to 1:1
Once the trace is sized correctly we can attempt to match the next scan to the existing image. Firstly I would recommend cropping the image and possibly saving with a lower quality ratio. Most scanners contain far too much info and using the image 'as is' can contain extra junk that will slow your pc down. In my case I have turbo cad 20 64 bit so I have plenty of memory to play with. if you have less or an old pc then things will slow down if you do not do this first.
Anyway insert the image. Once done our first job is to straighten it. I find it easiest trusting the keel or rabbet lines. I straighten by starting a line at a point on the keel near the stern and ensuring this line is horizontal (press shift) plus dragging it past the end of the image at the bow side. Next starting from the same point (press v) I draw a different coloured line which follows the middle of the line I am using. Usually i start the line and just scroll to a point near the bow and place the line there then lengthen it past the image with the first.
Now we can drop a horizontal constructor and measure the angle (dont do the distance)
this then can be applied to the rotate to straighten the plan.
Note if your keel line is not straight then you may need a different line.
Once this is done validate the plan 'stability' by putting a line or a vertical constructor over the two perpendiculars. This will give you a good impression of whether the plan is square of warps slightly at either end
This plan is good at the bow and slightly off at the stern
Our next job is to place the image over the trace. Ensure the trace perpendiculars exist well beyond the trace and you can use one of those to get the image 'close'
Once placed re-place a new horizontal constructor on the image keel line and then measure the distance between this and the actual perpendicular
This can then be added/subtracted from the relevant axis (if using the keel it is the y if adjusting horizontally then you would be hitting the x) In any adjustment case look at the image when the adjustment occurs as it is easy to adjust the opposite way - this is usually blindingly obvious.
Once done on both axis I tend to validate the results by placing a horizontal line against an object which is clear on both plans and making sure when the image is made invisible that the line covers the same part on the trace.
You can also measure certain heights on plan and compare them to the actual plans to ensure you have no problems with any size adjustments.
Finally you can start tracing the new image. One thing to remember is that the plan is unlikely to match exactly and you have to make decisions as to which plan is the master. For example I am treating my sheer plan as my primary plan but for the gunports the frame plan should take precedence as the gunports would be placed according to the edges of the frames so as long as the framing plan gunports are similarly placed to the sheer plan then there would be little difficulty. The other thing I do is to use the force vertical (shift again) and right angle tool to draw most of the frame lines. Most of the time these match quite well (for the square frames only!) and it allows me to validate both the framing plan and sheer plan at the same time.
For example here is a shot of the rough trace of the framing plan over two central gunports
If I strip the image and include the sheer gunports you can see that though they are not exact they are very close. Also that the frames end points hits the dotted line of the sheer plan which is as expected as the barrier (probably not the correct term) moves up to that point and thus you would expect the frames to as well.
That'll do for now and I will go back to spending a week or so tracing over my next plan.