Yes, Ross is right, we invaded your topic a bit, sorry Ron.
But by doing so your magnificent work will get more visibility.
My intention was only to reassure Jumpugly. His model will have no problems because, as already said, it has space to spare and does not have sails.
The sails are the big problem because they raise the center of gravity and (especially when the wind is abeam) tilt the ship to one side.
However, in this regard I want to clarify something that many people are confused about. Let's say they don't have clear ideas.
In scale naval models we can more or less easily obtain a "weight stability" (in Italian manuals this term is used when the center of gravity is below the center of the hull).
In reality (with a few exceptions) almost all ships and boats (passenger ships, ferries, motorboats, oil tankers, ocean liners, cruisers, aircraft carriers, destroyers, frigates, corvettes, auxiliary ships, icebreakers, container ships, but also ancient galleons and vessels, as well as naos, caravels, carracks, triremes, liburmes, etc. etc.) only had "stability of form" (in Italian manuals this term is used when the center of gravity is above the center of the hull).
It follows that the righting thrust exists when the metacentric height is positive. In other words, the ship is able to right itself only within a certain angle of heel, not beyond.
Ships with "stability of form" beyond a certain angle will no longer be able to right themselves and will capsize.
Most ships, even in adverse weather conditions, do not suffer dangerous inclinations (except for a few cases in where tragedies occur).
Ross, regarding your fin, I am not able to establish how long it should be, calculations should be made with all the data available (almost impossible to find). It is much easier to do empirical tests.
As you know, the longer the fin is under the keel, the less weight you need to put at the end of it.
If you want less draft you need to increase the weight at the end of the fin or the thick fin (in case the weight is distributed and does not have the final bulb), so as to be able to shorten it.
Logically the weight can be increased within certain limits. Until reaching the waterline.
I completely agree with luckyduck: it is important to already place the necessary weights (not considered ballast) as low as possible (at least under the waterline).
Since I made the project from scratch I was able to make the choices I wanted and I managed to position the relevant weights as low as possible. I am referring to the two batteries, the motor and the propeller shaft, the large electrical cables, etc. etc.
In this way I managed to obtain a good righting thrust (I cannot say without calculations whether I obtained a "stability of form" or a "stability of weight") even without ballast.
When I then added the 400 gram ballast (in place of the keel) I obtained a truly satisfactory righting thrust.
All empirically.
Doing as luckyduck says is better. Create a stable ship already without ballast (if that is possible).
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