Integrated Electronics and All Your Eggs in One Basket

[goboatingnow]

Originally Posted by Paul L

So how accurately do you think you could create a compass correction table based on eyeballing the sunrise?

that's actually one of the tasks in the RYA Ocean yachtmaster practical !! done properly corrections of under 1 degree are possible

[skipperpete]

Originally Posted by Paul L

So how accurately do you think you could create a compass correction table based on eyeballing the sunrise?

Very easily, that’s what the shadow pin is for in the centre of the compass. Just do a slow 360°and record the deviations in the log.... ok , there will be some areas of shade but you can check them when the sun is in a different position. Easy on a sestrel moore.

[Paul L]

Originally Posted by goboatingnow

that's actually one of the tasks in the RYA Ocean yachtmaster practical !! done properly corrections of under 1 degree are possible

Come show me you getting my compass deviation under 1 degree after a lightning strike offshore in typical tradewind sea conditions.

[goboatingnow]

Originally Posted by Paul L

Come show me you getting my compass deviation under 1 degree after a lightning strike offshore in typical tradewind sea conditions.

are you aware of the techniques of celestial navigation , including compass correction by using the amplitude of the sun ??

[mvweebles]

Without context threads like these are meaningless. Day sailing? Coastal cruising? Long distance sailing?

In the end, you will resort to dead reckoning. Whether by sight (day sailing) or by calculation (distance) or somewhere in between, you need to be prepared to make decisions based on that. Some destinations may not be safe without full electronics. So move on to the next one.

Peter

[s57ra]

Very good question.
My experience confirms your thoughts. I had a failed network issue on the passage from NZ to Fiji. In the mid night squall, electric discharge caused all the instruments connected to the N2K network to go down. No wind, no chartploter and worst, no autopilot.
Luckily we had compass, so one person kept steering the boat and i did a research. After some trials i decided to shut down and restart all the electronics and luckily the autopilot worked again in compass mode and most of the instruments too, however there was no communication between them.
After arrival i fixed myself the electronics, the canbus drivers were fried on most of the units (ais, chartplotter, vhf...). Since then i have canbus chips onboard and i will instal failover autopilot, completely independent from the network.
From all the equipment, AP is crucial. For the chartplotter i have several options on tablets, phone.. and for wind a windex.

Another issue with interconnected system was recently with mastervolts masterbus. They use RJ45 connectors, definitely not suitable for marine use. When one of lead-acid main engine starter batteries failed, the acidic spray in battery compartment caused shourt circuit in the connector on the one of the two service LiFePO4 Batteries and fried the communication module. Mastervolt suggested it is not safe to run battery in a 2P bank without comm module, but disconnecting it later caused additional damage since the currents on the remaining battery were now double, so the battery protection 250A fuse has blown when i touched the bowthruster.
Luckily even if we were on remote island in Polynesia, we had good weather and i was again able to find workaround.
Another question is ability of the crew to fix the issues of complicated high tech equipment. A substantial amount of people i met are not able to resolve issues of this kind. Probbably the failover should be low-tech and as simple as possible.

[tanglewood]

I think there is an important distinction between devices that are "integrated" such that they have connecting interfaces so they can share data, and devices that are "multifunction" where a single device does many things.


With integrated devices, they benefit from shared data, but if the connecting interface is lost, they can still keep running on their own. This makes it much easier to build a system with few to no single points of failure, and fewer cascading failures.


With a multifunction device, if it fails you lose a bunch of important function. This makes it much harder to eliminate single points of failure, and much harder to prevent cascading failures. In fact, both are inherent in a multifunction device.

[skipperpete]

Foreign going ships now have most of their eggs in 2 baskets, 2 completely separate ECDIS systems and no paper charts although ECDIS uses Raster as well as ENC so in the event of just a loss of satellite coverage and/or online connectivity you could still revert to celestial and change the ECDIS to manual position input. If the twin ECDIS units both failed from say .... a lightning strike or electrical fire... that would be very problematic.

[goboatingnow]

Originally Posted by skipperpete

Foreign going ships now have most of their eggs in 2 baskets, 2 completely separate ECDIS systems and no paper charts although ECDIS uses Raster as well as ENC so in the event of just a loss of satellite coverage and/or online connectivity you could still revert to celestial and change the ECDIS to manual position input. If the twin ECDIS units both failed from say .... a lightning strike or electrical fire... that would be very problematic.

Modern engines have no starter handle anymore either. There are always points of failure , in the 1700s your navigator could die from disease

Electronic navigation is all pervasive

[rslifkin]

Originally Posted by goboatingnow

Modern engines have no starter handle anymore either. There are always points of failure , in the 1700s your navigator could die from disease

Electronic navigation is all pervasive

Yup. I figure by the time you kill a couple of redundant nav systems and the can't get a GPS fix on a phone with a chart or something, there are likely bigger problems at hand than just knowing where you are.

[mvweebles]

I suspect the most common failure are: (1) low-voltage from system-wide charging failure; or (2) some sort of mechanical or physical failure (vs electronic) such as the rotor motor in the radar dome burns-out or the cable connection to the depth sounder is whacked. Sure, I've had to re-boot systems after a few days of running, but that is less common these days.

A couple years ago I purchased a new Simrad system - all the MFDs and the VHFs have onboard GPS chips so I probably have over a dozen gps sources aboard including consumer electronics. I also use charts to augment my normal navigation not for redundancy, but I find they assist in situational awareness, though I do not carry a robust set except in my home cruising grounds. My largest concerns would be - in descending order (depending on cruising grounds and conditions) - loss of of autopilot, loss of radar, loss of depth sounder.

Honestly, I see these newer systems as very reliable and frankly, fairly easy to adapt and re-wire if needed to jury rig. All nav systems these days require a reliable power source. That remains an Achilles Heel for many boats.

Peter