Cooling Water Reduncancy....

[DrB]

I don't know how often it happens to others, but of the things on my boat that can go wrong, my worst (and most expensive) fear is to have my engine quit in the most inopportune time (moorign field, try to out run a storm, etc.) From the discussions here, the cooling system, whether it be a clogged sea strainer, broken impeller, or clogged inlet seacock seem to be the prime culprits. My engine has aways been good to me. (knock on wood...)

I was thinking of an idea of installing a back-up cooling water source to cool the engine in case something happen to the primary. To do this, I would T off the inlet port after the seacock, and put a shut-off valve on the T-ed line. On the back side of the shut-off valve, I would install a high flow water pump and then off the back of the water pump, it would re-T into the existing line.

If the sea strainer or impeller goes on the primary, I could open the by-pass valve, turn on the water pump, and get water to the engine. Yes, I'd now not have a strainer, but the fix is just temporary until I could get an anchor out, to a dock, or mooring to avid a sticky situation. and then deal with the problem. This would be for singlehanding situations.

Am I nuts?

DrB

[Pamlicotraveler]

If you do all of that the situation will never come up.

There are so many things to prepare for that creating an elaborate backup system for the water cooling would be just adding complexity to your system. You can run out of fuel and get air in the lines, have water or trash in the fuel, have a steering failure, a transmission linkage problem etc...

So I wouldn't focus on that one possible problem. Just keep the strainer clean. (and the seacock on )

[sailingdog]

I would think that a backup fuel filter, where it is parallel to the primary would be of far more importance than an alternate cooling supply. i've seen more engines stopped by a clogged fuel filter than by a clogged cooling line. If your cooling system is properly designed, with a good raw water strainer, then unless you plan on motoring through a giant seaweed patch, you're more likely to have serious fuel issues than cooling water ones.

The more complex and complicated you make the cooling side, the greater the chance of something failing there.

[sailaway21]

Dr. B,
It is good that you are thinking in the future failure analysis mode. I would recommend, rather than your plumbing plans, that you ensure you have a good quality, functioning oil temperature guage. Oil pressure doesn't hurt either, if it's a good one you can actually schedule your oil changes off of it's readings. Oil, not water, does the majority of cooling in your engine and all engines. Your first indication of trouble will be rising oil temperature. By the time you see rising coolant temperature your engine has already been stressed, if not worse.

Now if you really want to do things right, you'll also install an idiot light. The reality of guages is that we never are looking at them when they're telling us something is about to go horribly wrong. We're busy running aground or some other important maritime adventure. The idiot light, commonly used in racing cars-refuting it's name, should be hooked in to light when any of your guages are out of "normal" range. It's installation requires different sending units for each function monitored. It lights so as to draw your attention to the guages.

A solution short of this, and cheaper, is to mount your guages in a fashion that all of the needles are either horizontal or vertical when in the "normal" range. This is another race car design technique. You don't really need to "read" the guages; you just need to know they are in the "normal" range.

While on the topic, I am a big fan of VDO brand guages.

[sailingdog]

Don't forget the idiot buzzer in addition to the idiot light. Often, especially if the guages are in direct sunlight, an idiot light can be hard to see. A buzzer doesn't care about sunlight.

[SVAurora]

Doc B.. I think that is a great idea. Water pumps and impellers fail just like fuel filters get clogged. As others have said you need good maintenance and you can’t plan for every unforeseen problem. With that said engines stop unexpectedly and I would venture to say that most of the time it’s from fuel filters or the cooling system. It’s happen to me and to friends, i'm sure others as well. I have a dual Racor setup but never thought about this even though i carry a spare impellar and water pump.

A decent sized 12V self priming water pump would be the way to go. As you described it’s a very easy setup to plumb in. If you have an additional thru hull that is convenient plumb it there. This is something that should be kept very simple as it would only be used in an emergency situation.

Thanks for passing on the idea.

[cruisingdream]

if the sea strainer colgs the seacock may also be cloged alternate cooling water source should come from an alternate seacock. Now you have too many holes in your boat. stick with what you have & add a means of back washing the system if this is a common problem for you.

[camaraderie]

Doc...I don't think it is a good idea. When your impeller goes it can kick the fins into the line...if you add a second pump driven input you'll just drive them into the exchanger and then have problems digging them out. Get a big perko filter and a straight line large diameter water intake line to it and a quick release impeller cover and you can minimize delays due to clog and impeller failures.
Your fear seems to be "what if there is a failure when I NEED the engine" and I would say that :
1. Engines ALWAYS fail when you need them or they wouldn't be on.
2. Get a big honking anchor and rode that is easy to deploy quickly for such situations.
3. Make the chances for "typical failures" minimal through good design & timely maintenance (i.e dual racors, clean tanks, no bends in supply lines etc.)
4. Have the right tools & carry plenty of spare filters,belts and impellers and know how to install them.

[haffiman37]

I have in cases where people have wanted a 'quick' and easy way of fresh-water flushing engines just made a connection between the fresh-water pump (T-connector on hose from pump to galley-tap) and the inlet hose, BEFORE the pump. To flush the engine they just close the main valve, open the valve in fresh-water circuit, let the waterpump run and the engine gets flushed. Should even work in emergency for a shorter periode and at lower rpm if impeller fails.

[denby]

I don't think it's a good idea to use an eternal water pump to pump water into the engine. what happens if you pump to much water, could you back up into the engine. It's like winterizing the engine, you do not hook a garden hose directly to the water inlet.

Dennis