Raw Water Flow Detector

[Loren Beach]

20064-LF Save Your Engine Kit - LOW FLOW, 12 volt [] - $119.95 : AQUALARM, Warning Systems For Land And Sea

Save-Your-Engine Kit Works fo Save-Your-Engine Kit, LOW FLOW, 1/2" or 3/4" Hose, 12 volt Works for Raw Water Hose sizes 1/2" and 3/4" . Designed for smaller engines with lower flow rates. Monitors Raw Water Flow and sounds audible alarm and lights red light warning panel if cooling water flow is

aqualarm.net

I just ran across a reccomendation for this product on another sailing forum, from a contributor that I have found to be credible. Have any of you used it? I have not (yet) had a sudden clog in the intake, but whenever we are motoring thru/around patches of seaweed do worry about it.

Thanks!

 

[nukey99]

Loren - Our previous large boat was a 48 foot express cruiser with 2 430 cummins diesels which required a mountain of water to keep them cool. What we used were thermistor gauges on the exhaust hose to indicate a sudden increase in temperature. That was pretty inexpensive to purchase and was a handy man due it yourself job. I looked at paddle wheel type sensors in the line, and didn't like the idea of another set of couplings in the cooling system. I will say, those large turbocharged after cooled diesels are always running on the edge of a heat disaster. If my recollection is correct, each engine had a 2 inch raw water intake and a massive pump.

I'm relieved to have a natural aspirated diesel at 24 HP.

How far do you typically motor?

 

[Loren Beach]

We either motor a little, like 20 minutes, to go out for a sail. Or all or a major part of a day if heading down or upriver for a cruise. Then there's the odd trip up the WA coast, 26 hours at a stretch.

Seeing this product, I contemplate whether it's better to catch a raw water problem at the input side or at the exhaust temperature part of the circuit. (?)
Hmmm......

 

[nukey99]

That's a tough on to decide on. On our express cruiser with the big diesels, we had grates on the thru holes and large strainers before water entered the pumps. With that infrastructure, it is tough for a plastic bag to get into the system. I tended to dive the boat myself the day before or the day of a longer trip to check the running great and all that stuff. In a perfect world it is better to check upstream. We also every engine start, had a person checking for water flow on each engine at start time. I don't know how many belts and suspenders you can use!

Right now, we are dealing with a DEF error code on our diesel pusher RV, cummins in its infinite wisdom will derate the engine to 5 mph if you don't fix the issue. The part which is an ambient temperature sensor cost 2500, and then you get the installation penalty. To me it seems like a total scam.

 

[Elgyn]

Right now, we are dealing with a DEF error code on our diesel pusher RV, cummins in its infinite wisdom will derate the engine to 5 mph if you don't fix the issue. The part which is an ambient temperature sensor cost 2500, and then you get the installation penalty. To me it seems like a total scscam.

Got to love those emission codes that mess up your day (and wallet) and have nothing to do with how your engine is running...

 

[frick]

I just look off the stern for the water coming out of my exhaust

 

[Pete the Cat]

We either motor a little, like 20 minutes, to go out for a sail. Or all or a major part of a day if heading down or upriver for a cruise. Then there's the odd trip up the WA coast, 26 hours at a stretch.

Seeing this product, I contemplate whether it's better to catch a raw water problem at the input side or at the exhaust temperature part of the circuit. (?)
Hmmm......

I have an Aqualarm sensor on the exhaust elbow for this reason. I think it is probably better to sense heat there rather than monitor raw water. There are a host of things that could cause overheat even if there is good flow in raw intake. FWIW.

 

[Kenneth K]

I thought about installing that LOW-FLOW detector when I rebuilt my exhaust system but decided against it. One, it looks like it's made of PVC, which is not good either below the waterline or too close to the engine (due to heat). Two, it looks like it might restrict water flow all by itself. And, three, I thought it looks like it might be a bit "delicate" to survive for long in the engine compartment.

I installed a manifold temperature sensor instead: https://aqualarm.net/index.php?main_page=product_info&cPath=5&products_id=7

 

[Loren Beach]

Another good idea. Where did you mount the sensor? (One of those old manifold bolts might be rather difficult to withdraw, seems like... )

 

[Kenneth K]

Another good idea. Where did you mount the sensor? (One of those old manifold bolts might be rather difficult to withdraw, seems like... )

I did this as I was replacing the old alternator bracket, so I already had all the nuts off of the manifold studs.


I think a single stud & nut would probably be fine to mount the plate (you can drill additional holes in the plate). It just has to rest firmly against the manifold. It's probably more important that there's no rust or un-evenness between the two surfaces than it is that they're bolted tightly together.

 

[BlueCanoe]

My neighbor has an outboard water pressure gauge screwed into the heat exchanger drain plug (I think, might be tapped or the pump). Something like this https://www.westmarine.com/sierra-white-premier-pro-series-water-pressure-gauge-kit-outboard-14658777.html?utm_medium=cpc&utm_source=google&utm_campaign=[ADL][PLA] Most Categories_Test&gad_source=1&gbraid=0AAAAAD_lEeoyCEMZBn2BwOfOyMmASugPG

 

[Tooluser]

I contemplate whether it's better to catch a raw water problem at the input side or at the exhaust temperature part of the circuit. (?)
Hmmm......

This isn't sailing specific, but I always try to monitor the actual thing that matters. That is, a heat detector will alarm if the heat is too high for any reason. After all, that is what you want to know.

A second concern is that instrumentation whenever possible should not affect the process. Especially when something in the line (to measure) is potentially going to exacerbate the problem.

The ideal value to measure is a perfectly correlated value that is outside the process or a product of the process you want to monitor.

My 0.02, exceptions of course occur, ymmv, void where prohibited, etc.

All in all, I'd measure downstream.

 

[Bolo]

This just popped up on Practical Sailor about raw water flow.