The Ship Model Forum

What is determining factor of model ship scale, when Loa, Lwl, Beam do not match in scale, I am assuming Loa ?

It depends. Usually discrepancies can be accounted for by cross referencing sources, for example Wikipedia is usually not a good reference source for that. It often lists incomplete info or outright incorrect. Navypedia is usually a good one to quickly check if information about dimensions is correct.
Even better would be to check on an official source like a book, either paper or pdf, by an established author (Norman Friedman is the go to for the USN, D. K. Brown for the Royal Navy, etc.), or another authoritative source like Conway's All the World's Fighting Ships. Jane's not always good or correct.

But even then, supposing the dimensions listed are not a match, you can go one of two ways: either trust your source on those dimensions, or check official plans and drawings for that ship or class if you have access to them. The second option is fairly obvious, but sometimes difficult to do outside of USN, Royal Navy or Kriegsmarine vessels because they are not easy to access. They usually have dimensions listed on them so you can see by yourself what is correct and what not.
The first option I recommend when you have nothing else to rely on, and would still involve having if not official drawings, at least some second hand blueprints you can counter check these things on. The process is as follows: take full size one dimension (say loa), convert it to match the length of the ship on your plans, then do the same with beam (it is generally easier to compare and contrast length and beam than draught, because draught changes based on load, so it is not a constant). If they match, loa is the correct one. If they don't, check with lwl. If they match, this one is correct. If they don't again, then either the plans aren't good enough, or the source you pulled it from is not accurate enough.
There is also a third possibility: not all plans show the entire ship in profile and plan view in full, so dimensions stated may be correct, but may also be hard to check due to items that are not shown that protrude outside the hull but count towards the total beam of the vessel. An easy example is the rebuilt USS Pennsylvania BB-45 that had walkways added to the sides of the hull after the 5''/38 mounts were added on the weather deck, to allow passage fore and aft. The deck is technically X ft wide, but actual width of that same deck is X+6-7 ft more due to the width of the walkways.

Hopefully I have explained it in not too convoluted a way, but in short it's not always easy to counter check these things. Your best bet is cross referencing different sources to start with.

Cheers

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We can have all of the resources in the world and still get it wrong. Not out of any incompetence, it's just because of how difficult it is sometimes to implement a physical feature without having seen it with your own two eyes. - the Chieftain

cannot add those walkways on the Pennsylvania as she has had them since her late 1920s rebuild. all they did was made them longer then what they were originally.

seaforce, go with overall length, does it concern a certain Arizona model?

Thanks ModelFunShipyard for the reply, as to FFG-7 Arizona kit is not reason for the ?, Do not have the Arizona kit, I was looking at measurements for the Forrest Sherman Revell Atlantis kits and others so I can get the measurements for scratch build superstructure, layout, notice that Loa, Lwl, Beam are off to ,do not match up in scale, example: F.Sherman kit model listed as 1/319 Revell or 1/320 Atlantis, I get Loa and Lwl 1/321 scale and beam at 1/297 scale, mk42 5" /54 turret 1/318 scale. Needed a number to work from to continue the build was thinking to by Loa then everything be base on 1/321 for this build , before I used the Mk42 turret measurement it was the only thing I had measured at that time assume rest of the kit would be the same.

so the beam is 3.446mm wider at 1/297 scale. what I do in situations like that is use 1 scale for length & 2nd scale for width or sometimes use the beam scale as the main scale which could result a slightly longer or shorter model. you have to remember most model companies do not use actual naval plans so mistakes are made in these models. examples of those mistakes is the exposed keel on your model & the concave stern on the Arizona model which was not actually there.

As FFG-7 already explained, given it's Revell it's most likely they made a mistake when making the kit. They are definitely not noted for their accuracy in the ship modelling world (at least as far as I'm aware, except perhaps their U-Boots) so you're better off doing as he suggested.

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We can have all of the resources in the world and still get it wrong. Not out of any incompetence, it's just because of how difficult it is sometimes to implement a physical feature without having seen it with your own two eyes. - the Chieftain

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.

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Eberhard

Former chairman Arbeitskreis historischer Schiffbau e.V. (German Association for Shipbuilding History)

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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.

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.

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

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 ???

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?

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

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.

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.

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!

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HMS III
Mocksville, NC
BB62 vet 68-69

Builder's yard:
USS STODDARD (DD-566) 66-68 1:144, Various Lg Scale FC Directors
Finished:
USS NEW JERSEY (BB-62) 67-69 1:200
USN Sloop/Ship PEACOCK (1813) 1:48
ROYAL CAROLINE (1748) 1:47
AVS (1768) 1:48

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

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.

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.