Hi all,                                        last edited, 5-24
There is an early warning system that Alchemy has benefitted from for years. I am writing with a Valiant 42 engine installation configuration in mind, but the ideas below can be adapted to most boats.
I have long been an advocate of early warning systems: hence High-Water alarms and Smoke Detectors (for more on high water alarms, see my article at: (Google: Cruising Club of America, then follow: resources>emergencies at sea> “Planning for and Dealing with a Sinking Ship”). My engine “early warning” system is, in its essence, a quick visual indication of any leaks under the engine or any leaks “up-hill” of the dam.
On the V42 there is a section above the engine which lifts up and allows one to look in at the end of the engine and its surround. Looking straight down is the “crotch” of the hull leading down into the bilge. Right at that point, I built a low dam, maybe 2 inches high with a shallow “V” in the middle to allow and direct overflow. The “catch basin” of the dam is painted bright shiny slick white and is kept impeccably clean to show spills easily. For other boats, the dam should be located where it is easy to observe.
This dam is at the low side of the engine area. Every hour we are underway under power, I take a peek under there: takes but a few seconds. Any leak of even a few drops quickly accumulates at the face of the dam and gives indication that something is going on and may need exploration.
One might argue that there is always a “trail” for leaks, but I have been impressed over the years by how easy it is to not see trails before they become a problem: when already aware of a problem it is then easy to see the trail. If leaks are going into the bilge, one might lose a good quantity (a damaging quantity) of coolant or oil and not notice.
For years, I had a zorber type pad under the engine to catch and reveal leaks. This checked a lot of boxes but suffered as it was not easy to see the whole pad and a good quantity of liquid, particularly oil, could get absorbed prior to the leak to be easily noticed. One of the big benefits of the dam is that a quick and easy glance reveals a problem. I am a big fan of easy and inspections that take little effort are then actually done: a big advantage.
In this way I have had early warning of all sorts of engine problems. All fluids: raw water, oil, coolant, diesel have accumulated at the dam face at one time or another (or multiple times) giving early warning and allowing repair prior to it becoming an emergency or for damage to occur. Often there is no rush for repair and I could do the repair at my leisure at anchor rather than on a bouncing boat.
And the early warning was not restricted to engine leaks. I have found the rudder log seal to be leaking in this way. Also, my hot water heater pressure relief valve and multiple connections for the domestic water system reside where the dam can catch them. And, then there is the whole toilet/sanitation system with its potential for leaks as well as the thru-hulls/scupper assemblies.
I have found early warning efforts to always be a little work to institute, but to have, in the end, saved me a world of trouble.
My best, Dick Stevenson, s/v Alchemy