Jim, you can't go wrong with Fluke but it may be overkill.
Autoranging is nice, but on a boat you'll probably be using 12V systems and it is not hard to select the "20v" scale and just leave it there. Autoranging systems can be problematic as they hunt through scales sometimes. You'll use the 200V scale for AC and the 20V scale for ship's power...unless you need the 200V and 2000V scales to deal with 24V and 220V systems. Not a lot of switching to do in any case.<G>
The Fluke and other top names will be more accurate, yes, but I'd question whether you need that for boat work. DMM accuracy falls into two parts
, absolute accuracy, which is stated like "+- 2% for DC", and display accuracy which is stated as "+- 2 least significant digits".
The first one means, literally, that the number on the display may be off by 2% either way from reality. On a Fluke I'd expect to see 1/2% instead. Does that matter? Well, at 14.4VDC, normal alternator
output, 14.40 could show up at 14.11 (2% low) to 14.68 on a cheap multimeter. It *usually* will show up as 14.4x even though the meter isn't rated that finely. On the Fluke, if it was rated 1/2%, it might be off by .072V instead of 0.288V, so you would be sure it was 14.4x and only question the last digit.
Does that matter to you? Maybe. If it does, you need to check the specs for whatever meter you buy--many of them are in fact very good on the DC scale.
The other figure, for "least significant digits" is similar. That literally means the rightmost digit in the display may be off by 2 or 3, up or down. So 14.45 could really mean 14.43 to 14.48, as that last digits floats. Again, most meters beat their rating on this and they don't float as much as you'd think. But combine the two error factors...and you can see why folks have more confidence in a Fluke or other high quality meter.
Still, a pair or $20 meters from WalMart or Target can be more versatile, less pain if they are stolen or broken, and handy for dual readings. It's a question of what you will be more comfortable with, and what your budget
Whatever meter you get, be aware that they all use internal fuses
, especially on the amp ranges. (The cheap ones stop at 10A max, the better ones 20A max, and you'll need something else to measure higher amperages.) Those fuses
are almost always a hard to find "instrumentation" fast blow type, so have your sister bring over a box of the obscure fuses at the same time!
If you can get a meter that uses two AA cells instead of a 9V battery
for power, that's also a plus. At least, I find I have no other use for 9V cells so they're never around when I need one.<G>