pros and cons of digital switching vs traditional fuse/breaker panels?

[steve yates]

I had never heard of this till a marine electrician mentioned it as an option when I rewire the longbow.
Can anyone with any experience comment on the good points and bad points in comparison to a traditional fused switch panel?
In real life, I reckon ais is probably the most advanced instrument I would have installed, my initial reaction is that fuses are simple, if they blow you just replace them. I dont want to introduce more complexity and greater risks of things going wrong, but I also dont want to be hidebound and ignore modern technology to my detriment where it does a better job of tradional means.

 

[PaulRainbow]

For your boat, stick with traditional equipment.

Digital switching is basically canbus. You have something akin to a control box, where all of the equipment is connected to, this box connects to a digital switch module by a single cable. You can have multiple switch modules. You program the system to tell it which switch performs which function, etc, this requires the knowledge and software/hardware to be able to do it.

If you wanted to add something, someone would need to come and do it for you and program the new equipment switches.

There are a certain amount of backups/failsafes, depending on whos system you use.

If you had, say, a big gin palace, where you might want to switch the cabin lights etc on from different places, it's great. On a Longbow, whoever suggested it is on another planet.

As an example, a 12 channel load module with a backup fuse module from Maretron would set you back circa £700, £300 for the gateway to configure it, plus switches, cabling etc. and you still need all of the wiring from the load module to the equipment.

 

[steve yates]

Kinda what my gut reaction was, thanks paul.

 

[Wing Mark]

See Wandsworth's thread about the horrors of old boat wiring. If only that was all replaced with 3 wires: power, GND and data....

Maybe not!

 

[Stemar]

See Wandsworth's thread about the horrors of old boat wiring. If only that was all replaced with 3 wires: power, GND and data....

Maybe not!

Then you get a bit of corrosion on a data cable connection. Of course, that would never happen on a boat...

ISTR an article in a PBO when canbus was fairly new. Someone (Nigel Calder?) specified it for his new boat, but soon chucked it out. Spaghetti wiring may be frustration, but given a modicum of maintenance, it's more reliable because a little bit of resistance at a connection won't affect a couple of amps, but milliamps will struggle.

Were I to specify a new boat (won't ever happen, but...) I'd want a diesel engine with a minimum of electronics, and old fashioned wiring, though with modern waterproof connectors.

Signed,

Steveosaurus ?

 

[jwfrary]

Large boats yes sure. small sub 50 ft boats I cant see the point. Theres not enough of a weight saving to be had.

 

[Buck Turgidson]

Agree with all the above.
It's great for distribution over a large area so on a large yacht or in my work life medium size aircraft it's ideal but on a small yacht where weight savings isn't an issue you don't need a distributed power network so no need for the extra complication.

In my industry the nodes have typically 20 cards with 4 to 16 electronic switches on each card. Current aircraft has 5 nodes known as Control and Distribution Centres. So for this application it makes a lot of sense to take a couple of large feeder cables to the extremities of the fuselage and do local distribution from there.

For a 40ft yacht, not so much.

 

[PaulRainbow]

See Wandsworth's thread about the horrors of old boat wiring. If only that was all replaced with 3 wires: power, GND and data....

Maybe not!

That's not how digital switching works. The clue is in the title, it's digital switching.

Consider a large flybridge motor cruiser. It will typically have a central power distribution centre, usually situated in the main saloon, in a cupboard, behind a panel, behind the helm etc. The helm station will be populated with switches to operate most of the onboard equipment, wiring will go from those switches to the various equipment. Some equipment, particularly lights and some electronics might need to be two way switched, nav lights could be two way switched at the upper and lower helms, cabin lights could be two way switched from either end of the saloon or a cabin. There needs to be wiring to and from all of those switches and the equipment they switch and a big fat loom up to the flybridge.

With digital switching you can fit the load module/s in the most convenient place/s with little regard for the switching cables. The load modules can simply be though of as relay packs (although they are more than that). We can then fit digital switches wherever they need to be. The load modules and switches are all networked, this is where the wiring saving and additional versatility comes in. The flybridge is a great example, we can fit one or more digital switching sets on the flybridge and bring a single N2K cable down into the boat and connect it to the network. We don't need to fit analogue instrument clusters up there either, we can fit digital displays for the engine instruments and the engine stop, start, heat, warning lamps and alarms etc can all be digital. We can even just fit a digital touch screen that displays all of the engine data and has virtual switches. Network the lot at the helm and still only a single N2K cable coming down from the flybridge. Most current MFDs can display engine data and have virtual switches and warning "lamps". so one doesn't even need a dedicated digital interface.

You can obviously port that arrangement to other areas of a large boat. A single cable from the galley to the distribution centre, for example, or any of the cabins. Any switch, in any location, can be made to operate any equipment on the network. Switches and load circuits are configurable too, so you could have (for example) a piece of equipment that has its load module configured as latching (most would be anyway) and the switch as momentary (again, most would be anyway) and you could control that equipment from any location on the boat and as many different locations as you wanted to.

How about a 30ft/40ft sailboat ? The distribution centre is typically around the chart table, which makes sense. The switches are typically there too. Digital switching would allow us to move the distribution centre (load modules) or the digital switching panels. But, where would we move them to, that would be any benefit ? Don't forget, all of the wiring to the equipment, in both of the above examples, still has to go from the equipment to the load modules.

There is a good case for having "satellite" busbars and fuse/switch panels. It's a worthwhile saving to run a single, thick, negative to areas of the boat that need multiple negative connections, connect to a busbar and distribute locally. It's also sensible to do the same for the positives, in many cases, by running a thicker cable to "satellite" fuse and/or switch panels.

 

[Wing Mark]

That's not how digital switching works. The clue is in the title, it's digital switching.
...

Digital switching can be done in many ways, there are a lot more options than what you may have seen in gin palaces.

I'm not saying it's what we should want in a yacht, but there are possibilities.
It's not just about the weight or the cost of the wire.
It can also be about the effort needed to install more wire.
Consider maybe if you wanted to control a dozen lights and there were only a few existing wires. You could provide each with power and data, then tell each whether it's supposed to be on or off.
There are many ways of doing this, dozens of data/bus standards.
It can be done very cheaply using for example PIC and Arduino

The load modules of which you speak can be built into the loads.

In some ways, boats and cars seem to be a long way behind other fields of electronics.

 

[PaulRainbow]

Digital switching can be done in many ways, there are a lot more options than what you may have seen in gin palaces.

There are virtually infinite options, i cited two possible examples to highlight situations where digital switching offers a good solution and one where it's totally not suited.

I'm not saying it's what we should want in a yacht, but there are possibilities.
It's not just about the weight or the cost of the wire.
It can also be about the effort needed to install more wire.
Consider maybe if you wanted to control a dozen lights and there were only a few existing wires. You could provide each with power and data, then tell each whether it's supposed to be on or off.

If i wante3d to control a dozen lights i'd need to supply each light with power, if i wanted to globally switch them i would wire them in parallel and connect them to a switch/switches. Digital switching doesn't change that, it's not what digital switch is, as i told you before.

There are many ways of doing this, dozens of data/bus standards.
It can be done very cheaply using for example PIC and Arduino

No, there are not dozens of standards for marine digital switching, there are two current mainstream systems, both based on canbus. It's possible to DIY some fairly basic stuff with Arduino or Pi, but nothing remotely as sophisticated or robust as the like of Maretron and other commercial systems. I doubt any professional installer will want to be involved in half arsed Arduino or Pi based systems for customers boats.

The load modules of which you speak can be built into the loads.

I'm sure they could be, but they aren't.

In some ways, boats and cars seem to be a long way behind other fields of electronics.

With most small to medium sized leisure boats there just isn't any point in installing complex electronic systems. They offer little to no additional functionality over traditional wiring and switches. Where advantages are to be had, systems exist.

I wouldn't say cars are a long way behind. My car has a 9 speed electronically controlled transmission, traction control, ABS, ESP etc. The wipers are automatic. The headlamps are automatic LED, they dip themselves, they leave an unilluminated area ahead if i'm following another car. It parks itself. It tells me of speed and safety signs. It has sat nav. It monitors the tyre pressures. It adjust my seatbelt tension when i put it on. It connects to my phone, to wifi, to the internet. I can control many functions by voice. It tells me if i'm too close to another car, breaking if i ignore the warnings.

It does a ton of other stuff i can't even remember. If it does any more, i'll be able to sit in the back and have a snooze while it reads my mind and takes me to where i was thinking of.

 

[starfire]

There are virtually infinite options, i cited two possible examples to highlight situations where digital switching offers a good solution and one where it's totally not suited.



If i wante3d to control a dozen lights i'd need to supply each light with power, if i wanted to globally switch them i would wire them in parallel and connect them to a switch/switches. Digital switching doesn't change that, it's not what digital switch is, as i told you before.



No, there are not dozens of standards for marine digital switching, there are two current mainstream systems, both based on canbus. It's possible to DIY some fairly basic stuff with Arduino or Pi, but nothing remotely as sophisticated or robust as the like of Maretron and other commercial systems. I doubt any professional installer will want to be involved in half arsed Arduino or Pi based systems for customers boats.



I'm sure they could be, but they aren't.



With most small to medium sized leisure boats there just isn't any point in installing complex electronic systems. They offer little to no additional functionality over traditional wiring and switches. Where advantages are to be had, systems exist.

I wouldn't say cars are a long way behind. My car has a 9 speed electronically controlled transmission, traction control, ABS, ESP etc. The wipers are automatic. The headlamps are automatic LED, they dip themselves, they leave an unilluminated area ahead if i'm following another car. It parks itself. It tells me of speed and safety signs. It has sat nav. It monitors the tyre pressures. It adjust my seatbelt tension when i put it on. It connects to my phone, to wifi, to the internet. I can control many functions by voice. It tells me if i'm too close to another car, breaking if i ignore the warnings.

It does a ton of other stuff i can't even remember. If it does any more, i'll be able to sit in the back and have a snooze while it reads my mind and takes me to where i was thinking of.

Does it make tea & do the ironing ?

 

[AngusMcDoon]

Consider maybe if you wanted to control a dozen lights and there were only a few existing wires. You could provide each with power and data, then tell each whether it's supposed to be on or off.
There are many ways of doing this, dozens of data/bus standards.
It can be done very cheaply using for example PIC and Arduino

The load modules of which you speak can be built into the loads.

In some ways, boats and cars seem to be a long way behind other fields of electronics.

I've often thought about developing a YAPP to do this. You don't need to have a data line. You can superimpose the data onto the power line. Just a single 2 core power cable running around the boat to each device that needs powering connected to a tiny circuit board at each device that needs to be powered - probably PIC based as they cost buttons and have very low power consumption in standby (microamps). A per-device fuse could be on these boards to prevent failure of the power line fuse taking down everything. A central board at the switch panel would also need a processor with some not very onerous electronics or code. The address of each device board could be programmed with a couple of these to negate the need for an expensive configuration system...

https://uk.farnell.com/multicomp-pro/rbh2-10rbvb/rotary-switch-10-pos-24vdc-thd/dp/2671726

Two of those would allow 100 addresses. Multiple devices could have the same address so switch on or off together. I wouldn't expect a professional installer to be interested in a half arsed PIC based system like this, but it would be a fun open source project. The only tricksome bits would be the electronics for superimposition of the data on the power lines, and getting the standby consumption of the remote modules down to the microamp range.

As a cheeky afterthought, I could 'invent' a new Seatalk 1 message code, and hang it all on a Seatalk 1 network to power low consumption devices. The existing instruments would ignore the messages as unknowns. Got all the circuit design and software to do that already. Could have it up and running by teatime, just need to butcher this project...

Return of the YAPP | YBW Forum

 

[steve yates]

Now I am totally lost. I'll be sticking to red n black wires with ring terminals and fused switchboards.

 

[Wing Mark]

I've often thought about developing a YAPP to do this. You don't need to have a data line. You can superimpose the data onto the power line. Just a single 2 core power cable running around the boat to each device that needs powering connected to a tiny circuit board at each device that needs to be powered - probably PIC based as they cost buttons and have very low power consumption in standby (microamps). A per-device fuse could be on these boards to prevent failure of the power line fuse taking down everything. A central board at the switch panel would also need a processor with some not very onerous electronics or code. The address of each device board could be programmed with a couple of these to negate the need for an expensive configuration system...

https://uk.farnell.com/multicomp-pro/rbh2-10rbvb/rotary-switch-10-pos-24vdc-thd/dp/2671726

Two of those would allow 100 addresses. Multiple devices could have the same address so switch on or off together. I wouldn't expect a professional installer to be interested in a half arsed PIC based system like this, but it would be a fun open source project. The only tricksome bits would be the electronics for superimposition of the data on the power lines, and getting the standby consumption of the remote modules down to the microamp range.

As a cheeky afterthought, I could 'invent' a new Seatalk 1 message code, and hang it all on a Seatalk 1 network to power low consumption devices. The existing instruments would ignore the messages as unknowns. Got all the circuit design and software to do that already. Could have it up and running by teatime, just need to butcher this project...

Return of the YAPP | YBW Forum

I did briefly work on a low voltage DC, two wires, power and data system.
It's not terribly hard to do, provided you don't want to connect any random devices to the power, they may 'short out' the data energy. So you need filters at each node to sort data from power, or some such.
It's much easier to do with a 3rd wire for data, and getting to be silly cheap to just send the data over the airwaves.
Getting the standby consumption down is a fun part of such a project, some people are using bespoke protocols where low power units only wake up to receive some fraction of the time.
Looking at what people do with devices run from a little lithium coin cell or a couple of AAs, you could do a lot before the consumption became noticeable in the shadow of lead-acid self discharge.

I can't immediately see much use on the boat, especially as a retrofit..
Maybe make the front hatch close itself when windspeed and STW exceed certain values? What as they say, could possibly go wrong?

The YAPP stuff looks fun!

 

[KompetentKrew]

The address of each device board could be programmed with a couple of these to negate the need for an expensive configuration system...

https://uk.farnell.com/multicomp-pro/rbh2-10rbvb/rotary-switch-10-pos-24vdc-thd/dp/2671726

Aren't DIP switches usually used, an 8-way one allowing 64 binary addresses?

 

[AngusMcDoon]

Aren't DIP switches usually used, an 8-way one allowing 64 binary addresses?

DIP switches could be used, but need an understanding of binary to enter a numerical address. Setting a 2 digit address on 2 rotary switches is much more intuitive.