The Ship Model Forum

That still leaves lpp as the scale factor. If you want to know if a waterline model scales accurately, get the profile plan of said ship, scale it to the scale you want using the lpp in the drawing and measure the loa and and lwl in the same scaled profile drawing. If Aoshima can do it you can do it -:)

Yes: as Pieter and Maurice have said, the length between perpendiculars (LPP) is valid in determining the scale length of a model though the latter has indicated that there are problems, apart from the matter that the parameters for the LPP have changed over time. In a nut shell this is that one needs to known where the fore and aft perpendiculars on a given model are. That will be difficult for a waterline hull where it is likely to be impossible to establish the position of rudder post aft and where the scale waterline is on the model for the forward perpendicular. A model-builder is unlikely to want to get so involved with the problem.

Maurice that is interesting information, thanks

As Pieter noted, the primary shipbuilders' figure is the length between perpendiculars. The real problem is that almost all published data, both from official sources and others, rarely includes that figure.

The second problem is that the length between perpendiculars is not always a fixed number. As an example, there are two different lengths for the carrier Victorious, one as built and the other as reconstructed. The latter is greater because Victorious had a deeper draught after reconstruction. Since the bow was not vertical but raking, the length between perpendiculars increased, but the ship's hull itself was not changed. An additional element is that, because the stern also raked, the new design waterline length also increased but again without any structural changes to the hull.

A third problem with figures, even official numbers, is determining what the numbers published actually signify. One example is the large light cruiser (converted into an aircraft carrier) Furious. All published data correctly indicates that Furious had a greater beam than its semi-sisters Glorious and Courageous. What is not apparent from this fact is that the greater beam was solely a result of deeper bulges below the water on Furious and the three ships were dimensionally identical above the waterline. Thus, the dimensions of a waterline model of Furious as built would be the same as those for the other two ships.

Maurice

Thanks everyone, this is good feedback on this topic.

Look for official plans cover sheets that list the various dimensions. I prefer basing scale off of "length between perpendiculars". Both inboard and outboard profiles will show the perpendiculars in question.

Unless you are building something pre-1860 the main measure used by 1: 1 ship builders is length between perpendiculars (lpp). This is length between the design waterline entry point at the bow and the point where the rudder vertical crosses the waterline the the stern. The latter point is also the " zero" point for lines and frame plans. The difference between overall length, waterline length and length between perpendiculars can be confusing for kit manufacturers.

Seaforce,

For what this is worth, I offer my two-penny-worth to the advice you have received to date.

That given in FFG-7's post of 10 March is the one I would follow if the scales of LoA and beam differ. Concerning the matter of the best Reference to seek the measurements in, I would consult the official sources where possible or failing that the most authorative book available commercially: that depends on whose navy one favours when making one's models.

Beware of taking your measurements directly off copies of the official drawings. The medium on which the original was drawn on may have suffered distortion over its life-time and the scale measurements may differ from the official dimensions. Whoever supplies the drawings to you should make this clear when you purchase them: certainly the National Maritime Museum does.

Alright, I know that you are making a model of a specific ship. This is therefore a word on warning to anyone sufficiently interested in reading this diatribe. First: thanks! Secondly, treat what you see on the purchased copies of drawings with circumspection. In drawing plans for a "scratch" model of a well-known German battle-cruiser, I have found one "frame interval" left out on the original of a deck plan and the measurement across a deck from the middle (centre) line to the outer edge differing on the port and starboard sides. Given the German reputation for reputation and engineering excellence, I was amazed. However, a now deceased retired naval architect friend of mine was not. Mistakes are made, even in the best drawing offices and one has to make the best of it down the line.

Your original question was a good one. Few people would have thought to bring it up. Thanks.

had already linked him with BOGPs for the Forrest Sherman & Charles Adams classes which has dimensions on the plans.

What ModelFunShipyard said about consulting official plans (NOT online -pedia sites) is the primary and best way to determine the correct dimensions. Using a quality set of rulers is the second best way to determine measurements. I've never had a problem using my wooden K & E scales, both in metric and ft/inch. Currently, I have 4 "go to" stainless steel rules (6", 12", 18", 24") which don't lie. They are two sided - inches on one side, metric on the other. I wouldn't leave home without them

Hope this helps!

patrick camilleri You right about drawings/plans, I seen a few drawing that are off in size/scale, brought a new ruler 18" went and remeasured a few ships models and ship drawings, the drawing off the same way models are beam too wide LWL too short leaves LOA as the primary measurement that matches the scale.

I find that plans don't always match up. You get two sets of plans and invariably they show slightly different hull lengths. It's always a problem to reduce / enlarge plans to 1:600. When working out the scale of a model, I don't just rely on the length, I give a lot of importance to the breadth of the hull. It is not so easy to go wrong there.

I have seen 2 tape measures go out of whack to each other. had to use a 3rd 1 to see which 1 matched.

Figured out the issue of 4mm, was using two clear rulers taped together, one of the rulers is off about 1mm every inch, so when I would measure first 12 inches would be correct, then next 12 inches would be off, in the case of F.Sherman hull 15.75 inches or 40cm/400 mm
first 12 inches/ 305 mm is correct the next 3.75 inches is short by 4 mm, as shown in the photo, just brought the ruler last weekend F**king defective ruler shown in the photo, only checked this out after going into tool box using a tape measure. the tape measure and the two rulers not matching up.

I just grab the 1 that was closes to me then set the jaws of the micrometer to both ends of the model & it read 40cm, not plus or minus just 40. what are you using to measure with?

FFG-7 did you measure all seven, (I am joking), I just measured my 4th one I get 396 mm hull stern to bow, the beam I get 46 mm same as your 4.6 cm. The hull Loa difference of 4mm ???

the actual hull length scale is what I posted as I measured 1 of mine as I have about 7 of them.

Thank everyone for the replies, and thoughtful input, I used 1/318.55 scale when did the F.Sherman conversion into DDG-32, mostly based on the mk42 gun turret from front to back, (I get the turret at around 1/318.95 /used 318.55) the width is too wide, did not measure any thing else at the time, as to FFG-7 ideal 1/318.897 rounds out to 1/319, I can live with that, was thinking of using 1/319.5 as the hull length is about 1/321.

go with 1/318.897 scale as the model measures 40cm long & a beam of 4.6(I have a 24" micrometer which comes in handy for measuring less then 24" long models). the model is 3mm to wide or 1.5mm per side so walkway on either side of 01 deck will be just a bit wider then it should be.

The longest reference measure you have data for is the best, as this reduces the error, when measuring on a given model. However, some of the measuring points may not be accessible, e.g. the points where LoW is measured, or a measure given inside plating/planking, etc.

LoA usually is not a good reference, unless you have an exact data and photograph to confirm the hull shape, because sometimes hull shapes are changed during reconstruction etc.

Another option is compare standardised items, such as door heights, but as these are short lengths the measurement error on the model would be larger.

It seems also that kit manufacturers have to make allowances for other constraints, such as fixed box sizes. Designing a kit involves certainly a number of optimisations also with respect to economics of production vs. price that the market takes.