Barry, everyone is pitching in for you here... I told you they would and before long you will get the hang of things. A small but important point worth mentioning when measuring current: When you have finished using the current reading facililty on the meter... ALWAYS take the red lead out of the 10Adc socket and put it back into the V,A, ohms socket! If you leave it there and inadvertantly try to read volts.. say your 12v drive battery, it will not like it and will blow the internal fuse rendering the Adc socket inoperable. Should you do this (we all have at some time), you can undo the small screw on the back casing and having prised it off you should find a small glass fuse in there which will have blown. The size of fuse will be stamped on one of the metal end caps so the next trip out will be off to a stockist of 20mm fuses. Buy a pack of five as you WILL do it again some time, there is no shame in this.. it's a fairly common error.
Here's a good test for your boat:
Red lead in 10Adc
Black lead in com
Meter knob set to 10Adc
Remove the red + lead from your boat battery and connect black meter lead to it.
Connect red meter lead to your meter to the + battery terminal.
With boat in bath, slowly open the throttle and watch the reading (in Amps) slowly rise on your meter scale and note how many Amps the boat is drawing from your battery at full throttle.
Now you have a maximum current reading (Amps) which is great but fairly meaningless unless you know what to do next.
Look at your battery, somewhere on it, it will state the voltage and current capacity of the pack. IE '12 Volt 5Ahr'
Now divide the battery capacity (5Ahr) by the max current reading you obtained from your meter.
If for example your meter reading was say.. 2.5Amps then 5Ahr(battery) divided by 2.5Amps (motor reading) equals 0.5. Therefore, at full throttle your boat should theotretically run for 0.5 hrs on a fully charged battery!
You may well say, "I knew that anyway, Iv'e bin running the thing for the past year!" but now at least you have the means to determine how long your boat should run on any given battery.
Another small test whilst the boat is in the bath:
Re-connect red + wire for motor to boat battery as per normal boat running set-up
Place red meter wire back into V,A,ohms socket
Set meter to read 20 Vdc (your battery is lower voltage than that on the scale so the meter will not be overloaded).
Black meter lead to Neg battery terminal.
Red meter lead to Pos battery terminal
Note the battery voltage
Now fire up the boat and go for throttle up with the meter still connected and watch the battery voltage.
You will notice it will fall off very slightly .. even on a fully charged battery.
Give the boat a good caning at full throttle for a few mins and keep an eye on the voltmeter.
If the battery is fully charged and in good nick, the voltage will not be seen to drop very much and will hold up for a considerable period. If the battery is in poor condition or low on charge, the voltage will start dropping quite dramatically.
I hope this helps with the basic idea of using your meter and even if you never bother with the other functions on the front scale, these two functions on their own will tell you most of which you need to know about your boats setup and and running times.
Sorry Barry if it all sounds a bit long winded but it's easier to do than write about.. in fact doing it takes moments when you are familiar with it. Keep us posted on progress.
REMEMBER TO TAKE THE RED LEAD OUT OF THE 10A SOCKET!!