Multimeter for the Boat

[kungfoo]

I'm helping a buddy of mine fix his electrical system in Japan before
he sails across the Pacific and so I put this together to help with
that endeavour. So long as I did this, though, I figured I would
share. As always, I can't solve a problem I don't know about, so
please do let me know if you spot any errors/omissions/sarcasm.


=== BLUF/TL;DR ===

* If your price-point allows it, go get yourself a Fluke 87V max or a
Keysight 1282A ($500-$800)

* If you want something cheaper, get yourself an Extech 505 (and
evaluate it at a lab-bench before you leave) or a BK Precision
2709B and a waterproof bag for it. ($100-$110)

* Make sure you have spare HRC fuses (yes the HRC part is important)
and spare (lithium for the shelf-life) batteries and leave those in
the bag with your DMM.

* Fluke also makes a nice set of silicone leads for $30 that I think
make the experience of using it much nicer.


=== Things I think are important ===

* Measurement Confidence: As an EXAMPLE, some cheap meters will start
giving you false readings when the batteries are low. If you're
fixing your electrical system in the middle of the Pacific, do you
really want to be asking whether the battery is low, or whether the
meter is out of spec, or ...? I think it's important to have a
piece of measurement equipment that you actually trust.

* Water Survivability: There are a number of "waterproof" and a few
actually-waterproof DMMs on the market.

* Manufacturing Quality: As a sortof sub-category of Measurement
Confidence, how confident are you not just that the line of DMMs is
good, but your specific DMM is good?

* Does it Explode: If you accidentally put it in a low-impedance
input measurement mode on a 470V AC signal (like the start-caps of
your air conditioner), will it break the DMM? Will it blow up in
your hands? Will it short internally and cause the leads to melt
on your hands?

* Functionality: This one almost doesn't matter. You're probably not
going to care about things like burden voltage for measuring
microamps of current, and just about any multimeter these days will
have sufficient functionality for fixing up a boat at sea. If
you're bringing up a new part and/or writing a driver for a snazzy
new pressure/temperature IC, then you probably do care about things
like micro-amps of current so you can infer device state from
current-draw...but please tell me you don't plan to do that on your
next passage...or do because you're crazy, but you're my kind of
crazy :-)


=== Source ===

My primary source of information is Dave's Blog (EEVBlog). I've seen
his videos used as training for new-hires in the space industry even.
I find his work credible and he has not let me down yet. So shout-out
to you, Dave, and please feel free to point out everything I'm saying
that's incorrect, incomplete, or misleading.

* DMM Overview and Intro:

https://www.youtube.com/watch?v=gh1n_ELmpFI

* $100-ish DMM Shootout:

https://www.youtube.com/watch?v=n3WGaiYF2sk

* Why is Fluke so expensive?:

https://www.youtube.com/watch?v=ay9wFQAW19Y

=== Options Evaluated ===

The listed prices are all from tequipment.net

* Extech 505: $110
* BK Precision 2709B: $95
* Fluke 28ii: $570
* Fluke 87V Max: $510
* Keysight 1282A: $765


=== What I Did ===

My use-case is not limited to the boat. I do some electrical
engineering and so I needed a bench-top meter for things like bringing
up new integrated circuits and custom circuit boards. For that, I
bought the Fluke 28ii*. It wasn't much more expensive than the 87V,
had more-or-less the same specs, and now I have a rugged/waterproof
DMM. I also bought a Fluke 117 for general home electrical work and as
a second benchtop meter. Next time I decide to cross an ocean, I can
always bring along my trusty Fluke 28ii which ticks all the boxes.
However, during COVID, I left the boat in its old home (San Francisco)
while we fled with the newborn infant to the lower population density
of a Portland suburb. I did buy a DMM for the boat, but its main
use-case was to be the one that's always there so that when I made a
trip down, I'd have a good DMM available in case I needed to do
anything with the electrical system.



* As an aside, I bought a Fluke 28ii right about the time the 87V Max
was coming out and had a rather fun email exchange with Fluke about
it. The 87V Max was more expensive, and seemed to have the same specs
as the 28ii. I emailed asking what I was missing and why anyone would
ever buy the 87V Max. The response was wonderfully candid, basically
indicating that there wasn't any good reason to do so. Turns out they
only did that because the 87V has a well-deserved reputation as being
a top-notch bench meter and people found that more enticing than the
28ii. These days, though, the 87V Max is cheaper than the 28ii, so
I'd recommend you go with that instead if you want a rugged/waterproof
Fluke.


=== Analysis ===

There are two classes of multimeters that were evaluated: super-good
and good-enough.

In the super-good category, the three listed above are all great and
have no need for further comment. Dave Jones has thrown these things
off of buildings/dams, and taken them through the canyons of the Blue
Mountains in Australia. They'll get the job done.

In the good-enough category, I only really ever considered two
options: the BK precision 2709B and the Extech 505. The BK (at least
WAS) made to a much higher quality standard, but isn't waterproof.
The Extech is waterproof (with some helpful silicone grease anyway),
but made to a much lower general quality standard. Again, since my
use-case only needs it to be functional at the dock, I didn't care
about waterproofing and went with the BK. If you're doing some
passage-making and can't afford the Fluke or Keysight, then I'd
probably go with the Extech and just check it out before you leave
port, or maybe get yourself a waterproof bag for storing the BK
instead. Either choice seems fine to me.

HTH,
Harrison

[SailingHarmonie]

Some very helpful features on a cruising boat's multimeter:

A clamp on ammeter that works on DC circuits. This is really helpful. Don't leave home without it

A capacitance measuring function. This is vital when you are troubleshooting AC motors.

[thomm225]

I’ve been using a $10-$15 multimeter for the last 8-10 years for troubleshooting etc on my boat.

It does the job just fine.

I have Calibrated Fluke 87’s at work that I could borrow but have never needed to.

We have a Simpson 260 also but have never needed to borrow that either. Some old school techs like those

[kungfoo]

Originally Posted by SailingHarmonie

Some very helpful features on a cruising boat's multimeter:

A clamp on ammeter that works on DC circuits. This is really helpful. Don't leave home without it

A capacitance measuring function. This is vital when you are troubleshooting AC motors.

haha, I should probably say that all of the options I evaluated will do capacitance as well as measure AC amps/volts, though obviously you'll need to put the current through a precision shunt or directly through the DMM to read that, though. Also, if you want to use a type K thermocouple you'll need to get yourself one of those adapters.

Agree about the coolness of a DC clamp meter...I've always gotten by with things like voltage drops. Any recommendations on a good DC clamp meter? Do they all use hall-effect sensors or do some of them measure the delta function as you clamp it on or ...? Do you find that the hall-effect sensors can be easily disturbed by things like magnetic fields from nearby large current draws like using a winch or something?

[kungfoo]

Originally Posted by thomm225

I’ve been using a $10-$15 multimeter for the last 8-10 years for troubleshooting etc on my boat.

It does the job just fine.

I have Calibrated Fluke 87’s at work that I could borrow but have never needed to.

We have a Simpson 260 also but have never needed to borrow that either. Some old school techs like those

I tend to view a $10 DMM the way I view DNS...it's great and it works just fine...up until it doesn't :-P

PS: For what it's worth, I have actually had the fun of using a cheap multimeter and scratching my head for a while before realizing that the battery was low and I was getting a false reading.

[GreenWave]

Wonder how the cheap vs expensive DMMs fit with the recent conversation thread on going without insurance? Hmmmm

[thomm225]

Originally Posted by kungfoo

I tend to view a $10 DMM the way I view DNS...it's great and it works just fine...up until it doesn't :-P

PS: For what it's worth, I have actually had the fun of using a cheap multimeter and scratching my head for a while before realizing that the battery was low and I was getting a false reading.

That goes for cheap or expensive.

When they don't work it doesn't matter regardless of what you paid for it.

I recently had to buy batteries (9 volt) for the Fluke 87's here at work.

Most of ours are fluke 87 III's but to be honest I still get them calibrated on schedule but we rarely use multimeters or O'scopes much anymore.

Hardware problems have gone way down these days. It's mostly software, cyber etc

And if it is hardware it's usually a circuit card that we will just replace and you rarely use meters to troubleshoot those type problems.

And these you can get for $174

https://www.ebay.com/itm/26609271897...UaAr-aEALw_wcB

[wholybee]

I have several meters of various grades and price points, including a Fluke. And I use/need that quality and precision at work.

The answer to what to get really depends on the electronics experience of the owner, and what they will be able to do themselves vs. calling someone for help. For 90% of boats, a $50 meter is fine. I probably wouldn't recommend the $10 meter, though that has worked for many boaters, and I have made a lot of repairs when that is all that was available. They break easy, and are not terribly accurate, but accuracy within 500mV is enough for 90% of repairs.

I don't believe there is ANYTHING on a boat the requires more than a $100 ish meter, and certainly nothing that requires a checkout/calibration on a lab bench. And most certainly, nothing that 90% of boaters will have any clue how to fix require that accuracy.

For the 10% of boaters that would need more than a $50 meter, they should already know what they need.

[kungfoo]

Originally Posted by thomm225

That goes for cheap or expensive.

When they don't work it doesn't matter regardless of what you paid for it.

I recently had to buy batteries (9 volt) for the Fluke 87's here at work.

Most of ours are fluke 87 III's but to be honest I still get them calibrated on schedule but we rarely use multimeters or O'scopes much anymore.

Hardware problems have gone way down these days. It's mostly software, cyber etc

And if it is hardware it's usually a circuit card that we will just replace and you rarely use meters to troubleshoot those type problems.

And these you can get for $174

https://www.ebay.com/itm/26609271897...UaAr-aEALw_wcB

The point I was trying to make is that not only is P(fluke_not_working) <<< P(cheapo_not_working) but also that P(fluke_not_working) < materiality_threshold. It may not be quite on-par with the probability of me quantum-tunneling through a wall (after all, I'm just not cool enough for that...ba dum CHING...that joke kills at physics conventions...I'm a dad, I'm allowed to be dorky) but it's pretty GD (Gauss-Derived...why, what did YOU think GD stood for?) low.

Great point about getting yourself a used Fluke. It got mine at a time when I needed it quickly, and so I didn't have any time for waiting for a good deal, or a slow shipper or, or ... but yeah, lotta good stuff there.

[kungfoo]

Originally Posted by wholybee

I have several meters of various grades and price points, including a Fluke. And I use/need that quality and precision at work.

The answer to what to get really depends on the electronics experience of the owner, and what they will be able to do themselves vs. calling someone for help. For 90% of boats, a $50 meter is fine. I probably wouldn't recommend the $10 meter, though that has worked for many boaters, and I have made a lot of repairs when that is all that was available. They break easy, and are not terribly accurate, but accuracy within 500mV is enough for 90% of repairs.

I don't believe there is ANYTHING on a boat the requires more than a $100 ish meter, and certainly nothing that requires a checkout/calibration on a lab bench. And most certainly, nothing that 90% of boaters will have any clue how to fix require that accuracy.

For the 10% of boaters that would need more than a $50 meter, they should already know what they need.

Agree and disagree at the same time...also I should clarify.

When I say checkout on a lab bench, I don't mean so that you can know if you're getting all 60k counts on your meter, but rather to make sure your specific unit does actually function as expected. So maybe make sure you got the right precision shunt resistor, for example, as opposed to making sure it's a 1% part vs a 2% part or something. So that's my clarification/agreement on that one...more of a QA check than a calibration...I spoke with an uncharacteristic lack of precision and accuracy :-P

My disagreement (other than thinking that 50mV is probably the high end of what I'd want to see so you can see things like voltage drops across cables at high current or find diodes in battery isolators or ...) is the *implication* that device reliability is unimportant (your opinion on this matter is ambiguous so happy to extend benefit of doubt here). It seems like the price-point alone is unlikely to be sufficient for a DMM. Do you have any specific recommendations in the $50 range? As I mentioned, the set of things I evaluated was pretty constrained to begin with.

There's a reason I emphasized that the feature-set is almost unimportant because any meter with decent build quality is going to be as featureful and possessing of sufficient nominal precision/accuracy for anything I can envision going down.

I also disagree (maybe...my guess is that you actually agree with me on this point) about the experience of the user. I would actually argue that it is MORE important to get a reliable meter if the user is less experienced. If I'm on the phone with my buddy in Japan helping him fix his system, I would prefer to take as many things out of the equation as possible.

[thomm225]

Originally Posted by kungfoo

The point I was trying to make is that not only is P(fluke_not_working) <<< P(cheapo_not_working) but also that P(fluke_not_working) < materiality_threshold. It may not be quite on-par with the probability of me quantum-tunneling through a wall (after all, I'm just not cool enough for that...ba dum CHING...that joke kills at physics conventions...I'm a dad, I'm allowed to be dorky) but it's pretty GD (Gauss-Derived...why, what did YOU think GD stood for?) low.

Great point about getting yourself a used Fluke. It got mine at a time when I needed it quickly, and so I didn't have any time for waiting for a good deal, or a slow shipper or, or ... but yeah, lotta good stuff there.

I didn't get myself a used Fluke.

I would never pay that much for a multimeter.

I was just letting others know that you can get a good used quality Fluke 87 III for $174 on EBay.

I wouldn't mind having an old analog Simpson 260 though. It was what we used in the 70's every morning because we had to readjust all the power supplies that had drifted.

We also troubleshot with them.

These days though you very rarely ever have to check power supply voltages. They simply don't drift

[team karst]

Originally Posted by thomm225

…
These days though you very rarely ever have to check power supply voltages. They simply don't drift

I guess ships batteries, alternators, solar panels, MPPT’s , dc to dc convertors, chargers and inverters are not power supplies?
Just started a multi month cruise and without my dc clampon ammeter etc i’d be in the dark. [emoji106]

ps: i use the 260 or the Triplett equivalent inside rf chambers. The high priced Fluke and their junk imitators go wild with rf. Put ur fluke near a portable vhf or uhf in Tx mode. [emoji43]

In the last week, i found an open solar connector, bad port alternator, and determined shading affects with a single meter.

[Lake-Effect]

I bought a Klein clamp-on multimeter (DC amps) for approx US$150, after a lesser-brand far-east (Mastech) clamp-on meter failed after a year. So that's my "good" meter. I also snap up some lesser multimeters whenever they go on sale (like for $30 instead of $70), and they're great to have. All told, I have may have 5 to 7 meters kicking around... one wherever I might want one (car, boat, workbench, knapsack, etc). I do compare them, and maintain them - contact cleaning, good leads, etc. My cheap meters have worked ok for up to 30+ years.

Advice? Don't buy the cheapest meter; look for good deals on the middle of the pack. Treat yourself to a better meter if it's going to be critical.

[thomm225]

Originally Posted by team karst

I guess ships batteries, alternators, solar panels, MPPT’s , dc to dc convertors, chargers and inverters are not power supplies?
Just started a multi month cruise and without my dc clampon ammeter etc i’d be in the dark. [emoji106]

ps: i use the 260 or the Triplett equivalent inside rf chambers. The high priced Fluke and their junk imitators go wild with rf. Put ur fluke near a portable vhf or uhf in Tx mode. [emoji43]

In the last week, i found an open solar connector, bad port alternator, and determined shading affects with a single meter.

Well darn, I forgot most of you guys have only worked on your boat's systems which usually tell you what the voltage and amp readings are.

Most times you don't need a meter for a boat's systems as 9 times out of ten it's a connector.

And the newer supplies we have at work don't need adjusting once set usually. See photo of one that we still use but isn't made anymore. 32 volt, 125 amp

When I said checking the power supply voltages was a daily requirement it was because it was the 1970's and many of our radars had tubes as well as transistors.

We troubleshot to component level back then on circuit cards and used our metters and O'scopes for that as well. Did this probably until the late 1990's early 2000's or the techs I hired did.

Our newer IFF systems late 70's were much more stable as were the new ASR -8 ASR Radar's units

Now days systems are tons better. My Victron MPPT gives me tons of info on the batteries and the solar either on my phone or laptop.

Photo is of the Precision Approach Radar (PAR) our deployable Air Traffic Control Unit had at places like Bogue Field, NC Marine Auxiliary Landing Field.

You can see the raydomes for those radars on right about half way up

[wholybee]

Originally Posted by kungfoo

Agree and disagree at the same time...also I should clarify.

When I say checkout on a lab bench, I don't mean so that you can know if you're getting all 60k counts on your meter, but rather to make sure your specific unit does actually function as expected. So maybe make sure you got the right precision shunt resistor, for example, as opposed to making sure it's a 1% part vs a 2% part or something. So that's my clarification/agreement on that one...more of a QA check than a calibration...I spoke with an uncharacteristic lack of precision and accuracy :-P

My disagreement (other than thinking that 50mV is probably the high end of what I'd want to see so you can see things like voltage drops across cables at high current or find diodes in battery isolators or ...) is the *implication* that device reliability is unimportant (your opinion on this matter is ambiguous so happy to extend benefit of doubt here). It seems like the price-point alone is unlikely to be sufficient for a DMM. Do you have any specific recommendations in the $50 range? As I mentioned, the set of things I evaluated was pretty constrained to begin with.

There's a reason I emphasized that the feature-set is almost unimportant because any meter with decent build quality is going to be as featureful and possessing of sufficient nominal precision/accuracy for anything I can envision going down.

I also disagree (maybe...my guess is that you actually agree with me on this point) about the experience of the user. I would actually argue that it is MORE important to get a reliable meter if the user is less experienced. If I'm on the phone with my buddy in Japan helping him fix his system, I would prefer to take as many things out of the equation as possible.

Because I wasn't clear on it, 500mV accuracy is really awful. I expect even the $10 meter is much better than that. I am not recommending that, only pointing out that it would work fine for *almost* anything on a boat- that any meter you buy is going to be accurate enough for 90% of the work to be done.

You definitely want to take as many variables you can out of the equation when when talking someone through something. For me, that means simplicity. The fewer functions of the meter the better. The only thing I am interested in with helping someone on the phone is measuring voltage. Anything else, and they seem to make mistakes.

Yes, generally reliability is important on anything you bring with you that you won't be able to easily replace, or that you might need offshore. I think once you get out of the $10 range, and into the $50 range, a DMM is going to be pretty reliable. Don't drop it in the drink, and keep it in a protective case. And keep spare batteries.

Fluke makes a $50 meter that is probably fine for most people.

https://www.amazon.com/Fluke-101-Mul...=1FUDS3QYF81L8

That with a clamp on Ammeter, but honestly, most boats have so many ammeters, chargers that measure current, mppt controllers that measure current etc. there is little need. And you can use a shunt if you need to.

I have one of these Klein meters in a carry bag of "stuff" I bring when I work on other people boats that works well, and isn't a big deal if I lose/forget it. That *has* happened after I am paid for my work with beer. Forgot the whole bag once. I am very happy with it. It is well made and reliable.

https://www.amazon.com/Multimeter-Au...%2Btools%2Bdvm