Exhaust Temperature Alarm

Flossdog

Flossdog

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After a dodgy do in Portsmouth Harbour when my Vetus waterlock melted due to a blocked water intake, I have bought a Vetus exhaust temperature alarm (and a new watertrap). Before fitting on the boat, I bench tested it and the alarm level of sound was very puny. Don't think I'll hear it underway with the engine on and wind whistling past my ears! Has anyone else got one of these? Can you hear it do you think when out in the cockpit? I am thinking of adding another louder buzzer in parallel. Anyone done this? Boat is a yacht thank goodness as we managed to sail virtually into Port Solent lock and onto the berth! Thanks in advance.
 
I had the same experience about 5 years ago on trip back from Holland. It actually happened twice on that trip. Once just outside the lock so returned and fitted new trap then again 15 miles off Harwich. I fitted a flow switch in water pipe and used the alarm already fitted that sounds when oil presure low, alternator not charging or water temp too high. Only cost about £20 in total plus an hour to fit. Very effecytive.
 
Alan, where did you get your flow meter switch, and what kind of spec are we looking at here? ie, does it come with some means of fitting into a pipe if pipe is cut? as I had thought about this after my intake blocked twice in one wk end, luckely I had an out board as a backup.
Think this would give the earliest possible warning.
Cheers, Eamonn.
 
There is a good descrption of making and fitting a flow alarm in Practical Projects on page 117 on the June 2006 PBO. Numbers for the various parts from CPC/Farnell (www.cpc.co.uk) are given. The flow switch is SN35600. Total cost for all the parts is about £25. After having two overheat situations due to a blocked water inlet I fitted it with no problems.
 
Thanks Steve, can you just fill me in on a few details? What does the actual switch fit into? and whatever it is, does it have to be coupled into the raw water pipe on hull side of pump or preasure side?
Thanks again.
 
Just fitted the system that Steve mentioned, the only place that I had room for the vertical instalation was just above the strum box BEFORE the pump, mine was 1/2" bore but they do a bigger one, need a 100 Ohmn 1/4 watt resistor in series as the valve contacts short out the buzzer (Parallel to the switch) when water flows. Didnt have 100 resistor/1/4 watt, so stuck in a 400 ohmn 1/4 instead but still loud enough with the engine running. Brilliant bit of a system,cheap and reliable.
 
Thanks Steve, seems that yours is the best solution and I've looked out that PBO and and found the article. I read the mags cover to cover but a couple of months later I've forgotten! Thanks everyone.
 
Eamonn

I fitted the switch between the inlet seacock and the raw water pump. I don't think it will matter which side of the pump it is fitted, so long as the pipe it fits into is at or near vertical so the internal flap can operate. I cut the pipe and push fitted it onto each end of the switch, making sure the switch was the correct way up. I secured the pipe with jubilee clips. There are some good pictures and details of the other components you will need in the PBO article.

Flossdog mentioned the buzzer on his exhaust alarm it not very loud. The one in the PBO article is quite loud and there is also a red LED, which I plan to mount where I can see it from the helm.
 
I fitted a Vetus alarm with the inadequate volume alarm. Maplins provided a very cheap and effective alarm to wire up in parallel.
 
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