which battery and speedo

[chkm8]

Hi,
Please bear with me. I am both fairly new 2 boats (2nd season) and have a limited diy knowledge but am determined to do as much work as possible on my boat myself. I have a Finnsport 650 with mercury 110 outboard engine.
First question there are 2 batteries 1.domestic and 2.engine with a single isolation swich with 4 settings. I understand the both and the off (not totally stupid lol) but how do I know which number refers to the engine battery and which the domestic battery as regardless of which I isolate the seems to be no difference in ability to operate items on the boat.
Secondly the speedo though wired up is not registering. Now I know there is a thread on this just below mine but I was quickly lost in the technical jargon so any chance someone could explain in real laymans terms what I need to check to find the fault.

Many thanks,

John.

 

[drewpster]

Re: which battery and speedo

Sounds like your battery switch is connected properly. An easy way to determine which battery is number 1 and which is number two is to disconnect one of them and operate the switch. The number on the switch that has power is connected to the battery you left alone.
If both batteries are the same type then it does not matter which one you use. (1-2-both, your choice) If one battery is a start battery type and the other is a deep cycle type then the deep cycle is typically used as a domestic or house battery while the start is used to start the engine exclusively. This leaves your start battery with a full charge when needed.

Hope this helps, hope to visit Ireland one day!

 

[Silvertip]

Re: which battery and speedo

Your speedo is probably a very generic pitot (pronounced "pit-oh") style which works on air pressure. Yes -- air pressure. The pitot (pickup) is either a separate unit hanging off the back of the boat, or it's built into the lower unit of the drive or outboard. As the boat moves through the water, water pressure acting on a small hole in the pitot compresses air in a simple tube that runs up to the speedo. The faster you go, the higher the pressure in the tube, and hence the speedo reads higher. If the unit doesn't work, either the speedo is bad, the tube is kinked or plugged or the pitot is plugged. The problem is usually the latter.