Good morning to all modelers.

Before including in the list of the first message, the data from the models of Ronald, Scratchbuilder and others (who kindly gave me permission to do so) I would like to analyze the first results.

Anyone who has done statistics (at least one exam) knows very well that these data are too few for a serious scientific analysis, but we do it for pleasure.

It is useless to repeat what I have already written.
Actually no, maybe it's not useless but I don't want to rewrite the same things with the risk of boring people and making this message too heavy.
Therefore anyone who wants can read message no. 11 of this topic.


Furthermore:
Italcantieri engineers certainly won't come to visit us to get information on how to build the propellers and how to size them.
But a beginner (who doesn't have a kit or a reference model) who doesn't know which propeller to put in and who is making a model the same or similar to yours, could have good information.
This is the meaning and possible practical usefulness of the document.

Oh by the way! Because of this research, I'm looking at RC scale model kits, I was surprised, the costs are really high.

The problem for the modeller, without a kit and without a reference project, who wants to build a model from scratch or restore one without a propeller or make RC a static model, is that the information on the propellers is a bit scattered.
Now this information is found in three different topics ("Proportions between ship size and propeller diameter " - "manufacturers and sellers of nautical propellers for rc model building " and - "Do we want to talk about propellers?") but I hope the search with the word PROPELLER produces its results.


But now we come to the data collected so far.

So far, the section with the most data is the one relating to tugboats and work boats.
It's normal for this to be the case, in fact I've noticed that among RC modelers it's the most popular category (I really like it too).
I didn't think the range was so limited (shots not scattered, excellent), yet even in this section there are many variables and at least two subsections should be created between the tugs:the port ones (stockier) and the oceanic ones (slender).
We are between 1:16.5 and 1:22.
From the port to the ocean.
The modeler who wants to delve deeper, after reading this ratio, can have a general idea, but then can go and see ColinH's, or Wolle's, etc. model in detail. etc., and discover more details (by analyzing those variables in concrete terms).

Even including fishing, rescue, fire, police and pleasure vessels the range is still very narrow with more central data. 1:19 to 1:26.
From 1:16.5 to 1:26.

By reading the information carefully, anyone with a little attention already understands that even in the modeling field, a tug or a fishing boat has a relatively low ratio.
The tugboat with a nice diameter available, short wheelbase is like a car that climbs uphill. Capable of notable efforts (as ColinH testified with his amazing anecdote) but incapable of useless high speeds.


Modern warships are different.
The ratio rises and reaches (for now) a range between 1:30 and 1:34, but I am convinced that it could rise much further. We'll see with the next data.
I remember that there could be a lot of difference between real ships and models in this length/propeller ratio and this will be interesting to verify.

I'm very curious about battleships from the Second World War; I would be very curious to compare the data of the real ones collected so far with scale models.
However, it is very difficult to find RC sailing scale battleships.
Yet I remember seeing them in this forum too.

Some fields are still empty or too sparse.

I have to agree with Doug. There are to many variable in comparing the ship size to a propeller diameter. Not even close.

Lew
Florida, USA

Yet, something interesting is emerging.

https://www.building-model-boats.com/model-boat-motor.html

Truth be told, I started to get a bit freaked out by the numbers too! 😂

Jumpugly - I wasn't reading it properly! For some reason I was thinking of the length in millimetres. What makes it particularly bad is that I was a designer in the building industry for over 40 years and worked in metric for many of them! Mainly millimetres and metres though and rarely use centimetres for anything. In my defence I posted after travelling and blame it on brain fog!

Chris

Keeps the synapses zinging Jump😁

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I did not! Which just goes to show that you learn something new every day!
😊

Hi,
"played around with the scale calculator".
Did the same with Titanic's props Jump.
7.2m comes out at 0.19459m or 19.46cm (7.66") as you predicted.👍
BTW; did you know that her centre prop was smaller? 5.2m.

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That's the main thing Jump👍
No confusion, not on my part anyway🤕 (Doh, my bwain hurts😂😉)

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