Water Pressure Gauge quesiton
 

I'm doing some planning for my plumbing and thinking about water pressure monitoring. I am planning to put small gauges in the engine bay that I can monitor but really only at idol. I am also planning a gauge on the dash. I have only a single space on the dash but at least it will give me some insight while under way. Here are a few questions:

1. How much risk is there in running a mechanical water pressure gauge line up to the cockpit? Should I run braided ss? Should I run an isolator like it were a fuel pressure gauge?
2. How crazy would it be to connect both engines' cooling systems and run a single line up to the dash for a single gauge? I figure if I have an issue with too much pressure, it would still show?
3. When you say #2 is crazy, how about just monitoring one engine? I can switch between them when I get the boat going for the first few runs just to make sure things are operating properly.

This isn't the kind of gauge I would think I would need to monitor all the time so I'm trying to make one gauge at dash and two in the engine bay work out. Maybe a terrible idea?

IMO
The water pressure gauge is the one that should be at all helms, right next to temp and oil pressure.
Use a mechanical gauge and 1/8 air brake line. If line gets cut or melts there is not going to be very much water coming out

I Tee'd mine off the block drain

Having a gauge in the engine compartment is a waste

1 gauge, 2 engines?
 

Thanks for the advice. Small amounts of water, I agree. What about a tee situation sending pressure from 2 engines to 1 gauge?

2 to 1, I wouldn't do that, to small a volume. Which ever has more pressure will display on the gauge. One could be real low and gauge will still look good

If your unable to get the second gauge, then could use a mechanical valve to switch feeds. That said, how often will the valve be turned

My block drains plug every year and had problems with gauges there. There is an 1/8" NPT port on most oil coolers or put it in your intake manifold. I agree it is one of the most important gauges in the dash and useless in the engine bay. And the 1/8" nylon hose that they come with works just fine.

I think where to put the pick up will make a difference in your readings. There are many opinions of where you should put it. I ended up installing mine in the intake manifold. It just depends on your engine and set up.

Al Dodge is right, you want the gauge on the dash.

When installing it, be careful not to bend or crimp the line as it will be no good. The 1/8" plastic line bends easily.

If your running open or closed cooling system will also affect where you put sensor. On closed cooling, you need it on the raw water side.

I used air brake hose on mine run to the cockpit but I don't like using the block drains, too much sediment ends up heading to the gauge when mounted there. On mine I picked up at the back of my bellhousing cooler and so far I have not had a problem.

Water pressure gauges barely move at idle so having them in the bilge really does little to no good. On my Pantera, the hose was connected to a block drain. It clogged all the time. On my AT the hoses are in the Tstat housings and have never clogged. I can tell by water psi gauges if I sucked up just a little debris and its stuck at the oil cooler. PSI will be 5-10# less depending. I'd find a way to install 2 gauges.

My hoses are just 1/8 inch poly tubing.

I had a client that ALWAYS had WP gauge on all the boats after burning up an engine (warning horn was ignored by everyone until it was too late to tell dad)....he was a "do-it-yourself'er" and worked with what he had... one boat had it on the pass through to the bow, one boat had it on the drivers side panel and the other had it on the passenger side panel just below the windshield @ the dash.

NOT ideal locations but with the high viz orange needle on the mechanical gauges, he said all he needed to see is where the pressure was reading at a glance and knew if he had issues.