@DJW
Hi DJW, this is a very interesting topic.
A while back, I was thinking about designing a ship model specifically for these specific needs.
Since the specifications and tasks I'd outlined are very long, I'll put them at the end of this post so only those interested will read them.
In reality, the tasks were much more extensive.
However, the project is behind many others, and for now I've used and am using alternative systems.
Since the lakes where I take my models are very large, I can't rely on leeway.
In a small pond designed for modelers, sooner or later (if there's a bit of wind) the model will end up on a bank. It doesn't matter which bank; you can easily reach it on foot and it will always be in sight if the pond is very small.
For large bodies of water, however, the problem is that the wind could blow it offshore or to an unreachable bank.
For this reason, I use another model ship, which will push the other if it becomes immobile.
Without a docking and undocking system, this isn't very easy, especially if there's a lot of wind.
For this reason, I have a rowboat ready for recovery (as shown in the photo). If it's not winter, a recovery by swimming is possible.
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These were the characteristics of the
N.A.M. (MODEL AUXILIARY SHIP):
General information
The project concerns a scale ship model, specifically conceived and designed to provide assistance to other sailing models; aids ranging from simple close-up shooting to recovery in the event of failure.
The project will have initial specifications, which can be changed if it is realized that they are difficult to implement as they were initially thought of.
SPECIFICATIONS
Ship type and scale
The model, without particular requirements of reproductive fidelity and attention to detail, will be a merchant ship (preferably not modern container ships) with a central or rear island. The famous "sea carts" are also good.
The scale will be adapted in relation to the length of the model which will be between 80 and 100 cm.
The model will have to fit (even diagonally) into the rear trunks of most sedan cars, without necessarily having to fold down the seats.
Proportions
The width of the model, measured on the maximum beam, must not exceed a quarter of the overall length.
If it is necessary to increase, during the design phase, the immersed volume, in order to compensate for the total weight which, with the various additions (tending to satisfy all the specifications) could increase, the height of the topsides and the width of the vessel will be adjusted, given that its length is limited.
For the limit of the height of the immersed part, freedom is left to the good aesthetic taste of the designer, while for the width it is believed that it should certainly not exceed the proportion of a quarter. However, for aesthetic reasons it is advisable to remain below 1/5.
Therefore, if the ship was 90 cm long overall, its width would be a maximum of 23 cm.
Type of propulsion, power and steering of the ship.
Central thruster consisting of a short-pitch, large-diameter propeller (three- or four-bladed), preferably made of metal, capable of strong thrust rather than speed, driven by an electric brush motor (12 to 24 volts). The drive axis must be parallel to the keel (not inclined).
One or two compensated rudders controlled by a servomechanism, with a large excursion angle (in any case greater than 150 degrees).
Two lateral thrusters made up of propellers (two-bladed or three-bladed) possibly made of metal, capable of developing a lot of speed, driven by independent brush (or brushless) electric motors.
The motors can all be operated in forward and reverse gear. Maneuvers can be carried out either with the rudder or with the side engines or with both.
The power supplies and radio controls are totally separate and independent.
The minimum autonomy of each propulsion system must be at least one hour in continuous navigation.
Rechargeable batteries of any type can be used (except lithium)
Possibility to change configurations and electronic connections easily.
At least one of the two propulsion and maneuvering systems (for example single engine/rudder) must have a low battery warning circuit (visual and, possibly, also acoustic) and automatic insertion of a reserve battery. The reserve battery must guarantee at least half an hour of continuous navigation.
It must have a righting thrust on the roll axis of up to no less than 40°. Minimum requirement, even better if it can straighten itself even at greater angles.
The model must have a navigation camera with live broadcast.
It must be unsinkable already with the volumes internal to the design shape, even without removable external additions.
This requirement can be waived, in the design phase, only if to achieve it other more important ones must be given up.
It must have a buoyancy reserve (amount in cubic decimeters to be established) to support by itself (without external additions) a ship, displacing half of the N.A.M., which is sinking and which has been firmly attached to the N.A.M. This requirement can be waived, in the design phase, only if to achieve it other more important ones must be given up.
Provision of hooks for additional floating cylindrical bodies on both sides.
The model must be able to return to a pre-established point following the GPS in case of lack of radio control signal. The latter is priority.
Specification achievable using ready-made equipment for drones, only possible and not mandatory given the high costs.
Evaluate anti-collision sensors to change the route automatically in the event of obstacles, when re-entry with GPS is active due to loss of radio signal.
Optional.
Displacement
From a maximum of 12 kg at full load, with intermediate configurations, up to a minimum of 5 kg.
Arrangement of the weights of the fixed equipment on board.
They must be placed in the first and last quarters of the vessel, imagining you see ...it lengthwise and divide it into four equal sections. The second and third quarters of the vessel—the central sections—will be left clear for any additional payloads.
This is to facilitate the model's longitudinal stability; indeed, any weight added in the central area will have far less impact on the overall trim.
Naturally, there must be perfect weight balance from a lateral perspective.
FIXED EQUIPMENT
Position lights: colored LEDs.
Red on the left side (visible only from the front, rear, and left side)
Green on the right side (visible only from the front, rear, and right side)
The sides that are not visible are because they are covered by the topside control island.
In low light or complete darkness, you can determine whether the model is sailing toward you (you will see the green light on the left and the red light on the right), whether it is sailing out to sea (you will see the green light on the right and the red light on the left), whether it is sailing to the left (you will see only the red light), or whether it is sailing to the right (you will see only the green light).
Lights for night or twilight navigation:
Medium and low-power LED floodlights to illuminate the ship (remotely activated)
Directional and powerful LED front headlights.
Directional and powerful LED rear headlights.
Directional and powerful LED left side headlights.
Directional and powerful LED right side headlights.
(All can be activated remotely separately).
Telemetry for battery voltage data, power consumption, and temperature if necessary.
Extendable lateral arms, two on each side, with interchangeable ends, magnets, electromagnets (remotely controlled), hooks (slide and spring for non-return attachment).
Video recording equipment for navigation (front, side, and rear shots) with video transmission, with power separate from propulsion and maneuvering.
Provision and platform with mounting points for additional payload:
One or more recording cameras with or without ginbal.
Multifunctional mechanical arm, remotely controlled.
Provision with mounting points for underwater filming.
Additional, removable, inverted C-shaped foam bow.
TASKS
Recovery of stationary damaged models.
Recovery of moving damaged models.
Extinguishing an active fire on a stationary model.
Extinguishing an active fire on a moving model.
Video recording (with stationary NAM, with moving NAM, stabilized and unstabilized)
Underwater video recording.
GPS tracking.
Placement of marker buoys and/or wind vanes and recovery.
Wind vanes.
Lighting.
Recovery of a damaged model still afloat but starting to sink.
Below is a detailed description of the tasks with possible example scenarios.
... the possible operational scenarios follow in the next message...