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[rayna]

  Hi Folks I have almost completed my build of an RNLI lifeboat station and launch ramp and am considering some additional options to make things more interesting for the spectators. Rather than just hand operate a launch release lever I think it would be much better to be able to start the sequence then stand back and let it all happen.
I am unsure how practical any of it is but will ask the questions anyway.
I am thinking that totally unconnected the the lifeboat itself I might have a circuit or whatever that does the following actions

• A switch that starts the sequence that
• Turns on flashing LEDs
• opens slipway doors (servo or small motor and worm drive, whatever)
• starts an audio clip
• releases the lifeboat and maybe resets.

All ideas people greatly appreciated.Rayna

[kinmel]

I never got round to building a boathouse.
I forgot to drop the masts during the recovery    ,  everything is all managed on one  transmitter.....    https://www.youtube.com/watch?v=dAx9-lbyFvc

[malcolmfrary]

Old way, a motor driving a multi worm drive to get the long timing required.  Output drives a shaft carrying a series of cams to operate switches controlling the effects in sequence.  Like a washing machine from a few years ago with a mechanical timer.
Modern way, an Arduino or similar doing the same job.  Requires a trip up the learning curve of coding.  Some hints and tips elsewhere on this site.
Middle way, use logic chips to make timers that trigger outputs to start the functions.  Requires a journey along the learning curve of logic chips.  A bit of reading matter here - https://archive.org/details/PracticalElectronicsHandbook  Chapters 4 and 5 cover the chips involved and take away a lot of the "magic and mystery".


Given that these methods just provide a set of timed outputs to start the functions, actually providing the individual functions is possibly another subject.

[RST]

Another variant on a timer apart from off the shelf ones is a big disc as a cam on a servo operating microswitches.  Can use a servo slow if speed can't be adjusted on the tx. Guess it depends what parts you have in spares box.

[nemesis]

|I remember Ted Potter doing this sort of thing at regattas many years ago. The launching was good, the retrieval of the Lifeboat was even better. nemesis

[dpbarry]

Well Kinmel

Two of our guys have done that on the real thing. Ouch!!

One as it was being rehoused and one when it was being shunted out onto the Apron. 

I never got round to building a boathouse.
I forgot to drop the masts during the recovery    ,  everything is all managed on one  transmitter.....    https://www.youtube.com/watch?v=dAx9-lbyFvc

[rayna]

  Many thanks for all the supplied wisdom. I was thinking the worm drive and cam/s option myself as I have gathered together all sorts if ridiculously cheap worms wheesl and small geared motors etc from the china www.and for audio a mobile bluetooth with some recorded stuff.NOT sure about the methods for automatic recovery back up the ramp . Maybe that's the next challenge.thanksallRayna

[tigertiger]

Thinking about a less traditional approach, a lot of modelers, including on here, are using microprocessors to do this kind of thing. There are lots of cheap programable microprocessors now, that are smaller than a credit card. The two most popular seem to be Arduino and Raspberry Pi. There is a bit of a learning curve, but nothing massive.
There is so much being done with the robots hobbies, with a wide range of micro-servos, stepper motors, multiple switching, and other tools that you could build a very elaborate sequenced display, and extend the number of tricks over time.
There is a separate board on Mayhem, just for microprocessor control. Maybe someone who has posted on there can help you with either basic knowledge and ideas, or even do some programming for you. https://www.modelboatmayhem.co.uk/forum/index.php/board,181.0.html

[malcolmfrary]

Launching is one thing - everything starts where it is expected to be. 
Recovering is a whole different story.  Spacex and NASA will likely call you if you get a working recovery system.  I once spent a n enjoyable half hour watching a small fishing boat being recovered to a trailer in Paphos harbour.  Could have been a Greek Cypriot edition of Last of the Summer Wine.   Recovery entails a lot of  manual hands-on in the real world, conditions tend to change unexpectedly.

[tigertiger]

I have seen harbors that are part of model railway exhibitions, where boats are moved by magnets moving on a track under the water. I think without direct contact between the magnet and the boat. Obviously this is on a very small scale.
I am not sure if this idea is scalable, or feasible, and if so how powerful an electric magnet would need to be to capture the model lifeboat and direct it to the ramp.

[kinmel]

You can get some extremely powerful Neodymium magnets, my 17Kg Tamar was captured in the water and winched up the slipway with a 15Kg magnet ( that is a 15Kg vertical lift )

You can purchase up to 120Kg magnets, but those are are too powerful.
Speak to an expert... https://www.first4magnets.com/neodymium-t137

[Colin Bishop]

And don't have a pacemaker fitted! Some of those magnets are so powerful you have to be very careful with them.

Colin

[rayna]

  Even more useful information there thanks all. Not sure I am up to Ardino and Rasberry Pi but will take a look anyway. Magnets I have some coming but only small ones will see as may be some use also.Now with respect to TX-RX optionsI believe that if I had a traditional crystal 4 channel set with an RX on the boat for channels 1 and 2, I could have a matching one in the launch building and use channels 3 and 4 there for ecovery etc operations ---correct?I don't believe I can do that with any 2.4Hz set. I would need two TX,s I think.Rayna

[kinmel]

If you are going to control the sequences manually using radio control then it all becomes much simpler.

You can have one Tx controlling both an 8channel Rx in the boat and a second 8channel Rx in the boathouse and those channels are programmable.  Read up about OpenTx.

The hardest part is latching the boat onto the winch cable at the bottom of the slipway.  Fit a radio controlled floating arm on each side of the slipway at water level with the arms normally at right angles to the slipway.  When the boat returns, move both arms 60^o to form an open funnel and as the boat reverses into it towards the slipway, you narrow the funnel and the boat will align with the bottom of the slipway ready for the cable to latch onto the stern.   
 

[DJW]

The OpenTX programming options would give you immense flexibility for this task. It's a learning curve though. I have a FrSky system, and as has been mentioned, you can bind more than one Rx. I use OpenTX companion too this is windows software that allows programming to be done, tested then uploaded to the Tx.


My approach to the docking latch for recovery would be to close a microswitch when boat is in correct position, then get a servo to close a latch on the recovering, that could be programmed off the microswitch. OpenTx has the notion of timers too, so say a second after latch is closed the recovery winch could be powered up.


Lots of flexibility but lots of reading up too.


Best of luck
David.