Speedometer only works if the boat is moving, but it also requires a little impeller to rotate freely and they get clogged up with seaweed and barnacles. Not worth the trouble in my opinion. You can get speed off your handheld GPS so the knotmeter has been rendered obsolete again in my opinion. it is good if you are racing for instantaneous feedback on sail adjustments.
check the connections on the depth, may have some corrosion, otherwise I can't offer suggestions. Heads are not normally connected to fresh water supply for risk of contamination. Sea water tends to stink, so I use fresh water out of a gallon jug to flush the head, but you should look for a seacock to open to get seawater to the head.
Your water is either a manual pump or an electric pump. If electric you need to make sure the power is on to the pump at the panel, so when you turn on the water it will pump.
Thanks for the advice on the speedometer, although it is nice when things work (they both turn on, just the display does not change, speed is always "0.0" and depth is always "18.8"). Once we pull the boat for winter storage, we will clean both and see if that makes a difference. Are there replacements that simply fit into the existing spots without any adjustments? In other words, are there some semblance of 'standard sizes' for these instruments?
As for the faucets and head, we got both sink pumps to work, a lot of grime and dirt, but the water is coming out. The head is not there yet. Will try looking for sea water valve. we have an odd problem with the Temp gauge, where sometimes it bounces all the way to the right indicating overheating, but the exhaust water is warm and not more than 100 - 120F degrees. Is that a good way of confirming engine temp, if the gauge does not work properly? Also looking at the oil pressure, it is right in the middle. So we did not panic. Another trip out Temp gauge worked just fine (stayed in the middle). Should I worry?
Lastly, for those familiar with O'Day 272, we are keeping a spare diesel tank in the same compartment as the batteries, is that a REALLY bad idea? Is there a better place, without stinking-up the cabin?
Thanks!