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A recent post by Mike Mathews on HIN's mentions a surveyor's quirky site. In his page on must-have accessories, he mentions raw water flow detectors. If your engine intake sucks up a plastic bag, this lets you know that flow has stopped before your engine has a chance to overheat seriously. I find it appealing a) because Yanmar doesn't make a temperature gauge for my engine - there's only an idiot light and b) my engine once overheated precisely because of this problem and I can't stop peering over the stern to make sure the water is still flowing. Another plus is that it's only C$60.00 - cheap insurance. Find a Canadian or US dealer on Stright-MacKay's web site.
David Weatherston
Towser, Toronto
C&C 27 Mk IV
Last edited by (2009-01-04 02:12:22)
David Weatherston
Towser, Toronto
C&C 27 Mk IV
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I second this one. Got that t-shirt too, in a previous boat. Fortunately, I had just installed a sensitive digital termperature system which save the machinery, but it is much better to be alerted sooner to a flow problem. I am just installing a completely revised cooling system, and this device is on the list.
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"New" 1974 C&C 27 Mk II undergoing refit
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1974 Mark II C&C 27
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Looked into this a bit more at my local Stright-MacKay outlet. The device is made by Aqualarm. Aqualarm's website has more detail. Requires also purchasing an alarm buzzer, figuring out how to wire the detector, purchasing a buzzer, and adjusting the device to the coolant flow rates produced in a particular boat's system. I emailed Aqualarm about our Atomic 4 and they advised their 1" model, part 10233, which will adjust down to 1.5 GPM. I'm not sure about wiring: has anyone installed one of these in a C&C 27?
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"New" 1974 C&C 27 Mk II undergoing refit
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1974 Mark II C&C 27
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Did you ask them about wiring it in? Following your message, I had a look at Aqualarm's site and found that they <a href="http://aqualarm.net/datasheets/save_your_engine_kit_one_inch_to_one_and_one-half_inch.pdf">sell a kit</a> that includes a compatible buzzer and warning light (nice). My guess is that you'd simply wire one side of the detector to the ignition switch and the other side to the buzzer and/or alarm light, then to your return buss bar, so the detector goes live whenever the ignition is on. A ten-second delay that prevents it from sounding while the engine and impeller are getting up to speed would be nice, but that's probably a bit fussy.
David Weatherston
Towser, Toronto
C&C 27 Mk IV
David Weatherston
Towser, Toronto
C&C 27 Mk IV
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Yes, I got a wiring diagram from them. The flow detector switch is normally closed and wired to the ignition switch so it is powered when the ignition switch is on. The alarm sounds until flow gets up over the set point. At first installation, the user slides the adjustable collar during idle to just below the point where the alarm sounds (switch opens). Just need to pick up a buzzer, wires, connectors and if desired an LED warning light, if that full kit is not available.
Update: I found a supplier for the complete kit David found on the Aqualarm website (same local SM outlet). Comes with a nicely labelled LED light in addition to its own little buzzer. This alarm is in addition to the oil/water temp alarm kit I've just installed. Should be quite a noisy show every time I turn on the engine now.
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"New" 1974 C&C 27 Mk II undergoing refit
Last edited by (2009-01-07 20:38:18)
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1974 Mark II C&C 27
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On my Farymann diesel engine, I had an alarm installed. 1) oil pressure and 2) engine temp. In order to avoid the problem of not seeing the alarm light I had an audible alarm (very loud!) installed which I think is a good solution.
Stéphane
Mystery, C&C27 Mark II 1972
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I installed an audio alarm for Temperature and Oil pressure from Don Moyer. It works great and it allows me to cross the lake on autopilot without any worry and even snooze. I like it better than a flow detector. It was easy to install and I think the cost is similar ($63 + S&H U$). Make sure you use a deep 6 point socket to remove the fitting from the engine). Best of all I get the buzzer if I stall out coming in at idle speed. You can't miss it.
You could have a water flow past a sensor to a broken hose/fitting that does not cool the block too. Better to detect temperature & oil - I think.
John (Weather or Not - Mark 2)
John Dallas
Weather or Not (aka: "WON")
Last edited by (2009-01-08 01:30:26)
John Dallas
Weather or Not (aka: "WON")
<a href="mailto:jedlls@sympatico.ca"></a>
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I had the Moyer alarm kit on my A4; highly recommended. My Yanmar came temperature and oil pressure warnings with an alarm. The only problem with those is that, according to most mechanics, by the time you reach the alarm threshold, a lot of the damage is starting to happen. Hence the appeal of the coolant alarm to give you warning of one common source of problems.
Thus far I've had no luck in determining if the minimum detectable flow of this device matches the raw water flow from my engine. The Canadian distributor doesn't know (no flow chart, only a value for maximum possible flow is available) and Yanmar won't say - too many variables). Perhaps I'll wait until I'm back in the water and put a bucket under the stern.
The Canadian distributor suggested an alternative, a temp sensor in the exhaust (sometimes called a pyrometer). If there's no water flow, the exhaust elbow will heat up fast (faster than the engine block) and sound an alarm. That may be an alternative.
David Weatherston
Towser, Toronto
C&C 27 Mk IV
David Weatherston
Towser, Toronto
C&C 27 Mk IV
Offline
David, is the raw water pumped by a specific water pump model? I have the flow specs for the Oberdorfer and Moyer pumps. Aqualarm might know too. 1.5 GPM is a pretty slow flow rate for engines of this size, I would imagine.
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"New" 1974 C&C 27 Mk II undergoing refit
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1974 Mark II C&C 27
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I don't know for sure about the model, but I suspect that the pump is specific to Yanmar. Japanese manufacturers like to control everything possible (particularly if there's a revenue stream from consumables like impellers) and Yanmar is big enough that it wouldn't be a stretch. I will ask the distributor again when and if I go to the Boat Show, but the national specialist says Yanmar doesn't provide a flow curve for different engine speeds, so I suspect I'm out of luck there. Aqualarm sent their wiring diagram but no recommendation about whether the minimum flow was suitable for a Yanmar 2YM15.
Is 1.5 gpm a slow rate? I don't know much about pumps but I've also sent an enquiry to a club mechanic (and asked his advice on the exhaust temp gauge). Also found an engineering site that suggests that the best way to find out coolant flow is with a measured bucket, calculator and a stopwatch.
David Weatherston
Towser, Toronto
C&C 27 Mk IV
David Weatherston
Towser, Toronto
C&C 27 Mk IV
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Is 1.5 GPM a slow rate? I guess I'll find out when I fire up the engine and energize the detector circuit at the lowest setting. The Atomic 4 water pump flow curve chart that I have show sthese flow rates for 800 RPM (I am interpolating a hand-drawn graph):
0 PSI - 2.6 GPM
8.7 PSI - 1.8 GPM
17.3 PSI - 0.6 GPM
26 PSI - 0 GPM
Since the radiator cap from Moyer is spec'd to 7 PSI (their online catalogue), then I presume the coolant system pressurizes to less than 7 PSI, which means the flow rates at idle will be greater than 1.5 GPM.
I know this doesn't help you be sure about the Yanmar diesel, but thought others may find this information of some use. Warning: I am not an expert, just a DIY amateur so, reader, verify the data yourself if you use any of this.
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"New" 1974 C&C 27 Mk II undergoing refit
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1974 Mark II C&C 27
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This is totally based on visuals, but I'd say an A4 moves a lot more water than my 2YM15, and I've just heard from my mechanic friend that he agrees with that assessment. So unless I come up with something else, you'll see me hanging over the stern with a calculator, bucket and stopwatch some time after launch.
David Weatherston
Towser, Toronto
C&C 27 Mk IV
David Weatherston
Towser, Toronto
C&C 27 Mk IV
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