You will recall we added temperature sensors to the raw water pumps on the engines, and to the exhaust water injection elbows. The concept was that this should provide early indication of a cooling issue. With a five degree F delta shown above, we decided to check the port engine pump.
We found the long life Globe impeller had tears in three of the blades, hence less water flow and more heat. So the early indication system works. This leaves a question of how long an impeller in this condition would last? With this experience validating the heat watch concept, we are going to add sensors in a variety of additional areas. We will also be installing a pair of “roving” sensors on long leads for special situations. One of these has a magnetic probe and the other has an alligator clip.
We are now working with Maretron to see what can be done to optimize their software for this type of monitoring. It will be interesting to see how it all turns out.
Posted by Steve Dashew (August 3, 2012)
August 5th, 2012 at 5:53 am
Another valuable and informative post as always but one which makes me glad of my foolproof keel coolers and dry exhausts (both much refined over the years) and the lack of complexity and cost of the electrical/monitoring installation which is better suited to the shallower pockets of many cruising folk.
August 5th, 2012 at 10:07 am
Good points, Sid, but also debatable. In terms of initial cost and complexity, some would argue that keel coolers and dry exhausts are both more costly and complex, and require just as much maintenance, albeit of a different type. We have done fine sans the N2K monitoring for the last 40 years wit wet exhausts. That said, we like the early warning capacity. The same would work with keel coolers to indicate external fouling early on.
August 5th, 2012 at 11:22 am
Were I in your position I would no doubt have gone down the same route, if only for the early warning capacity.
While certainly not wishing to re-open the old question of dry versus wet etc. you and your readers may be interested to hear of my experience with keel coolers where external fouling can indeed be a problem. Some ready-made systems are complex and expensive and difficult to keep clean. The fisherman system where you have 2 tubes on either side of the canoe body just out from the keel is appalling for a variety of reasons and this type can see astounding shell growth quite irrespective of the antifoul used.
Our present steel vessel had a similiar system which I had completely removed. Then, shallow steel boxes aprox. 200mm x 25mm x —-M were welded horizontally at the intersection of canoe body and keel. These offer minimal external resistance or disturbance of waterflow and the result after 4 years and 3,500 miles has been no shell growth whatever and minimal fouling similiar to the rest of the hull.
Young designers would do well to study and learn from this site of yours because you just cannot beat real experience.
August 9th, 2012 at 12:25 pm
Sid,
The late Luther Blount who ran a shipyard & operated cruise & dinner boats in Warren, RI told me that he had trouble with corrosion of the hull when he used steel channels welded to steel hulls as keel coolers. He thought it was because of heating up a small portion of the hull, and bilges are a very bad place for corrosion. He went back to external pipes.
August 7th, 2012 at 7:29 pm
I’m on Sid’s team re: the shallow pockets and preferring my dry exhaust with keel cooler, but certainly love to watch and learn alongside Steve and Linda. As much as I’d often do things differently, there’s little question were learning the right way to approach the whole problem by living vicariously on this blog. And just for reference, if you have really really shallow pockets you can build a keel cooler with $100 worth of 1″ copper tubing in an afternoon and have it last quite well for 15 years – so far – with almost no attention in salt water. The biggest issue so far has been explaining to one stubborn yard manager that since the cooler was made of copper, and copper is basically the active ingredient in bottom paint, he really shouldn’t have primed it over and anti-fouled it after I instructed him not to.
But I confess that I do often wonder how much quieter I could get a wet system if I switched over…
Also love to know where you’re headed in Maine, I’m near SW Harbor for the next 10 days or so and would happily bring some lobsters by for a quick handshake and a peek at the boat.