Weird sudden loss of 12V DC.

[Nicholson58]

Good you were able to cope OK. It always a scramble when the boat goes dark. It’s also always at a bad time. We lost all power Jolly Harbor to English Harbor beating through the reef. We always have Navionics running on an IPAD as backup. It’s a good hand check under way as well.

In our case a jumper in the middle of the new battery bank failed. We have two large house banks so a switch and re-boot restored operations.

[CMO Tashina]

So glad you made it home safely. I have my own harrowing tales of being stuck in that bay and your post just brought back some memories.

[capn_billl]

It's easy to become over reliant on the electronics.

I've done this for practice.

Blank the chartplotter screen, and steered by sun, and landmarks, towers on the coast.

And steered like that for a couple hours, then checked to see how far off course.

And I consider a working compass critical equipment on any floating craft, including a cheap pocket compass duct taped to my dinghy.

And today phones, and notebooks provide effective backups, and have their own batteries.

[Cynara]

Not unless the electronics are within 3 or so feet of the compass. Even if the compass was being impacted by the electronics there wouldn't be a very big difference. Finally if you are worried swing the compass with them on and off, then note the difference

[donradcliffe]

Who needs paper? I always bring my cell phone with Navionics on deliveries, and never let it get below 80% charged. I am having an ongoing discussion with the Navionics techs about a longer averaging time on the cell phone GPS derived SOG and COG, which bounce around too much for my taste on a Samsung S21.

[opusnz]

I have been on several boats where the battery master switches failed. It is more common than people think and seeing boats loaded up with them with overly complicated electric systems gives me shivers.

On one boat I saw, the switch was not letting enough power through the worn (or burnt) contacts and the switch was getting so hot it had charred the wood on the bulkhead where it was mounted. This had obviously been happening a long time and only when components failed to operate did the problem show up to the skipper. In my opinion, they should be checked once in awhile to make sure full voltage is passing through them under load or a resistance test performed. Any long term cruising boat should carry a spare.

[Auspicious]

Originally Posted by more

because good smartphone catch all satellite for navigation + A-GPS
A-GPS , draws its information ...

That isn't how A-GPS works. The only contribution of cell towers to A-GPS is that the known location (by and transmitted by the tower) of the tower is used as a seed to the GPS location algorithms to speed initial location acquisition. Once the GPS has a position based entirely on the satellites the algorithms use the latest satellite-derived position as the seed for the next round of calculations. See https://en.wikipedia.org/wiki/Assisted_GNSS .

[sailormed]

You should of course - apart from your smartphone - think about the hand held bearing compass you have in the nav table. And even a compass equipped pair of binoculars could be used in an emergency.

[Lake-Effect]

Originally Posted by opusnz

I have been on several boats where the battery master switches failed. It is more common than people think and seeing boats loaded up with them with overly complicated electric systems gives me shivers.

On one boat I saw, the switch was not letting enough power through the worn (or burnt) contacts and the switch was getting so hot it had charred the wood on the bulkhead where it was mounted.

Interesting. This makes me wonder how many skippers first switch off the master DC breaker etc so that there's little or no current when the battery switch is changed. It seems that to many skippers, the battery switch IS the master switch.

[Cadence]

Originally Posted by Lake-Effect

Interesting. This makes me wonder how many skippers first switch off the master DC breaker etc so that there's little or no current when the battery switch is changed. It seems that to many skippers, the battery switch IS the master switch.

I would think battery switches are make before break in order to preclude arcing with a load. The excepting might be one battery bank being stone cold dead allowing arcing and in that case the burnt contacts would be on the dead battery side and would be noticed when switching back.

[wingssail]

Originally Posted by Lake-Effect

Interesting. This makes me wonder how many skippers first switch off the master DC breaker etc so that there's little or no current when the battery switch is changed. It seems that to many skippers, the battery switch IS the master switch.

Yes, the battery switch (Off, 1, Both, 2) on my Marinetics Master Control Panel is the master switch, and the only switch, for all DC power including starting amperage, alternator output, house loads, solar, and windlass.

It's been in use on my vessel for 43 years, it's inspected periodically and the terminals show no sign of heat or arching. Of course I can't see inside the switch, but I think it is fine.

I wonder why other switches fail?

[piloto]

Originally Posted by dadster3

You might consider a tablet back up for navigation purposes.



https://sailingkerguelen.com/en/best...android-apple/

My experience with tablets is that they almost always fail (in the air or at sea) when you need them most on final approach or coming into a reef or port.. ..paper

[s/v Jedi]

Originally Posted by piloto

My experience with tablets is that they almost always fail (in the air or at sea) when you need them most on final approach or coming into a reef or port.. ..paper

My iPad has never failed and that’s many years and many passages incl. nasty ones. My Raymarine GPS that I once owned did exactly what you describe. Instead of fixing it, they discontinued support for it. Switched to B&G.

[Shaneesprit]

Chart plotter and a tablet backup -. The tablet has its own battery and is kept at or near full charge. Nice and simple.

When you get near land you can see your position on Google Maps on your phone, not that I have ever used it for that.
I will be fitting a separate plotter as well this winter.
But I only have 2 batteries in the house bank and one for the engine, i could cross connect if I needed to but nothing prepared for that

[tkeithlu]

QUOTE: "But I only have 2 batteries in the house bank and one for the engine, i could cross connect if I needed to but nothing prepared for that"

A single jumper cable (you only need one - the negatives are bonded) would be useful in several situations, including finding that your starter battery is dead when you need your engine.