Carver Owners Forum

I have a 1992 Carver CPMY 430 that has a hydraulic dinghy lift. Very unique to the vessel as I have never seen anything like it.
Very nice when it works but I think its original to the vessel and in those days used relay switches for the operating the hydraulic unit and it has a remote control wireless. The relay system is old and I want to modernize it perhaps to a PLC unit. If anyone has knowledge on this type of stuff I'd like to pick your brain on some ideas.
Below is the video I posted on Youtube so you can see the function.
It rests the dinghy on a V cradle which tucks into the swim platform for cruising.
Once you at the destination you can move the cradle out about 3 feet and then drop the cradle into the water which lowers it by 3 feet. The remote control allows you to do this and then just drive off with the dinghy.
All the relays do is activate a sensor when your fully extended out with the lift that then will only allow the down position once it reaches the sensor. Sensors are proximity probes. The problem I have is that the sensors / bracket / adjustments are very finicky and not reliable so too often I end up towing the dinghy. I want to change it over and modernize it to something more reliable.
Any suggestions????

What an idea! well, I think many have had the idea and then discarded it as it would take a lot of work on the stern. Not DIY work I mean, meaning: expensive.

But you have al that already and it actually works so you've got a great starting point.

My thoughts (based on the video, I probably missed some characteristics or features))
1 - you have two directions: out/in ward and up/down.
2 - electric motors start turning until some part touches a switch, flipping it makes a relay switch and the movement in the last direction is made impossible, only the other way remains possible.
3 - something smart to not have the unit move inward while cradle is down, or down when not outward.
4 - something that does not allow the unit to move outward (or at all) when the boat is moving

Curious how the relays and switches are put together in the current situation?

Choices:
simply replace worn relays and switches. The solution was simple and worked, keep it simple.

but that's boring.

So new solutions:
A) analogue: re-do the current system with better materials. If there are recurring problems that can be eliminated by tweaking the design, using better materials or just newer (not worn) than were available then.

clever, the wise thing to do. but....

let's go over the top:

B) Let's go really smart: use a PIC (arduino, raspberry, IC) with a bit of software that you make with the help of some friends, hardware you have (perhaps replaced when worn) plus some sensors and leds.

The in/out motors and the up/down motor(s?) are needed in any case (unless you want to go hydrolic or pneumatic, talk about over the top ) and you'll need some way to know when the endpoints are reached. Such as a moving or non-moving switch (a switch that clicks (and wears out or may get in trouble when wet often, or a magnetic sensor that can be covered in waterproofing stuff, it just needs to get close)).

First use is simple: you hit a button, carrier starts procedure: move out, move down. stop. Or: move up, move in, stop.

When you get that done it becomes interesting. Especially when you don't have issues like anchor chains stuck, engine problems, electrical problems, not enough time and such.. automation will take all of your time and imagination to realise and then it does work in another way.

The remote control is one. Why does it have that? To stay in your dinghy untill it is up and inboard? Or to avoid having buttons in a dashboard that is in the wrong place and gets wet?

Two options: your phone and 1 button.
Your phone: If you use bluetooth to connect to your car and leave it on when on the boat you can readout the battery state (through some chinese cheap thingy) but you could also connect to the controls of this unit. However, we've all experienced connecting to a device and all the trouble with that.

1 button: as the IC takes over the control, you only need 1 button: push to unroll the procedure untill the boat is out. Or unroll the procedure to take the boat in. Press in the meantime and something went wrong (forgot to put the boat in the right place) and return to previous location. You could even hide that button function: touch two metal parts of the railing at the stern and the unit magically moves....

Now while there is a little computer there anyway, lets add some smartness:
- no operation when GPS reports a moving position.
- when the boat moves, set an alarm: you forgot your dinghy
- if it's getting dark: switch the underwater lights on
- smart light in the dashboard: green when stationary (dinghy could be lowered), red when stationary and unit is down (dinghy is not home) nothing when moving (dark dashboard or only after 15 minutes: you're not going back for it now anyway )
- add a weight sensor: unit is up but no dingy. add a little LCD in the dashboard: 'no dinghy present' warning
- connect through mobile data, use gps positions: dinghy coming home, lower unit.
- add a dinghy location unit: whatever is in the unit, it's not the same dinghy that left...
- connect said PIC to the rest of the boat and go all out with things like 'dinghy not present, fridge not cold so start fridge because beer is on the way...


Just kidding, I'm in a waiting line and had some time to fantasize. Sorry for the long read.


back to your situation: the A above is quite relevant: why not simply renovate the existing hardware? If I were to design it from scratch, I'd probably also use some relays, motors and switches to analoguelly and mechanically solve it in a way that I can understand, follow and fix when on a trip. Perhaps some added direct control buttons just in case and end-switch drowned but otherwise: keep it simple and tidy.

Bottom line may also be that the original solution was too complicated in the first place as it wanted to solve the end points as well. So how about simplifying it and using your own presence to control it all: loose the sensors that inhibit movement while they should allow it. Have two 2-way buttons to control the whole thing. You as the controller are quite capable of judging if the unit should go out/in or up/down. You might want to look at motors with some over-current stop (like windows in your car). And you can mechanically make it impossible for it to go down while not out (simply block it; motors will stop as overcurrent is sensed) and not in when not up. Less points of failure; more control to you.




Cheers and have a nice holiday period.

Like the sense of humor- I was following intently until you got to lights etc. The beer part got my attention again.
Anyways the drive unit is all hydraulic on huge cylinders. The slide are constructed out of solid S.S not tube.
Your description on the prox probes is correct only movement is out / in - up/down prox probes are a safety feature so one cannot circumvent the sequence.
There is a small panel that houses the relay switches. The remote is strictly convenience.
I'm thinking of just changing the relays to a PLC and simple ladder logic program. Your right keep it simple.
The only other issue would then be the remote, not sure how to rig that up yet. Maybe a pendant hardwired to the PLC.

Hydraulic, so evrything is wired directly from that panel to the unit?

Can you narrow the problems to that panel/box or are there troubles due to the mechanical parts?

The remote is a wired button holder? As in not a wireless hand held thing like used for bow props or anchor.

And another rotten question; why not just replace the relays for new ones, would that solve problems?