T&T: keel coolers
Richard Tomkinson
channel space between the hull and the inner layer for coolant. Is there a
basic chemical incompatibility between coolant and fiberglass? Is the heat
conductivity of the the hull so poor that too much area would have to be
used? Heat expansion/contraction stress too much?
Richard
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David Marchand
I don't think that there is any chemical incompatability, but all of your
other reasons seem to be in play. Plus the engine's jacket water system
operates at 5-10 psi and the channel would have to be designed to contain
that pressure, making it even thicker and more non conductive.
David
Cole
simply.
They just run a piece of 3/4" copper plumbing pipe from near the bow all
the way down one or both sides of the keel.
Twenty or so feet of copper pipe seems to have plenty of heat transfer.
Cole
John Tones
practical from a cost stand point. When you cost out a set of
manufactured coolers compared with the labor and material cost of
manufacturing "built in" coolers I think the "off the shelf" version is
going to be close if not actually cheaper and you have an installation
that you know is going to work. In my mind the keel coolers are far too
important a component to be experimenting with.
Trying to get the volume of molded in cooler inside the hull could be
quite involved when you consider all the "ribs" and fittings the average
hull has below the water line.
John Tones "Penta"
Sidney, BC
Rudy and Jill
> near the bow all the way down one or both sides of the
> keel.
If you'd like some visuals on this approach, George Buehler has drawings of this type of keel cooler in either of his books: The Troller Yacht or Backyard Boatbuilder. Doesn't get much cheaper, easier or simpler.
Steel or galvanized steel pipe, if compatable with the coolant that you'll be using, may also be considered.
Rudy
Briney Bug, Panama City, Fl
KevinR
> Steel or galvanized steel pipe, if compatable with the coolant that you'll
be using, may
> also be considered.
Rudy,
Penny pinching is sometimes a fine way to save money, but this is one area
where saving a few pennies on the cost of pipe can end up costing you big
for a replacement engine.
Galvanized steel is never used for piping in contact with salt water. It may
be compatible with the engine coolant, but it sure isn't compatible with the
salt water your proposed to use it in. Galvanization is nothing more that
zinc coating, and you know what happens to zinc in salt water!
Kevin
Glen Zwicker
>> Steel or galvanized steel pipe, if compatable with the coolant that
>> you'll
> be using, may
>> also be considered.
>
> Rudy,
>
> Penny pinching is sometimes a fine way to save money, but this is one area
> where saving a few pennies on the cost of pipe can end up costing you big
> for a replacement engine.
>
> Galvanized steel is never used for piping in contact with salt water. It
> may
> be compatible with the engine coolant, but it sure isn't compatible with
> the
> salt water your proposed to use it in. Galvanization is nothing more that
> zinc coating, and you know what happens to zinc in salt water!
>
> Kevin
> _______________________________________________
Ed,
If you use copper pipe for your keel cooler be sure to select "Type K hard"
for the pipe and the fittings. Here is a source of pipe and fittings,
including the thru-hull adapters, that I used. http://tinyurl.com/ybp87c2 .
It is a Canadian source but I am sure you can find a USA equivalent.
Glen
Rudy and Jill
> > Steel or galvanized steel pipe, if compatable with the
> coolant that you'll
> be using, may
> > also be considered.
>
> where saving a few pennies on the cost of pipe can end up
> costing you big
> for a replacement engine.
>
> Galvanized steel is never used for piping in contact with
> salt water.
I was thinking of protecting it with appropriate coatings, but your thought on doing it inexpensively bears thought. I was thinking of using gal steel on gal fastened boats, but then how many of T&Ters have gal fastened wood boats? Glad you pointed that out.
But then I got to thinking further and thought about steel boats, you don't want to use copper tubing on a steel hull without at least insulating it from the hull either, and even so, not using copper on steel is even better, insulated from it or not.
Most important I'd think is to match material and its installation to be compatable with what material the hull is made out of.
We see alot of steel and gal steel keel coolers on commercial boats around here, wood, fiberglass and steel boats. Granted, many are on the low-end shrimpers and fishing boats, but it is not unusual to see them on large, expensive commercial boats either.
I think that I'd qualify it though and mention that most of these guys are quite knowledgeable about mixing metals under water and know what to look out for, both during fabrication and installation and during haul outs.
For the ones that can afford to, they keep their engine, and its related bits and pieces in good condition, yearly haul outs are accepted as necessary. They aren't often in the mind set of seeing how long their bottom paint can go before they have to redo it, as are many recreational boaters. Doing this allows developing problems to be noticed early.
Keep in mind that when I talk to an owner, I'm also considering if he is maintenance orientated or just fixes things as they break, so the above statements reflect what I see from the maintenance minded fellas (and the few women)that I talk to.
Hope nobody ran out and bought their steel pipe yet.
Rudy
KevinR
> We see alot of steel and gal steel keel coolers on commercial boats around
here, wood,
> fiberglass and steel boats
Steel keel coolers on a steel boat, or bronze coolers on glass or wood boats
are just fine, but I would surely think that NONE of the coolers you think
you saw were ever galvanized. Other than anchor chains (at least the ones
that spend most of their life in the chain locker), zinc coated steel is
just not used in contact with salt water. If someone was so naive as to
build a keel cooler out of galvanized pipe, they would end up with a raw
water cooled engine within two years!
For some good information on keel coolers, check out:
http://flagshipmarine.com/keelcool.html
Kevin
John Tones
of 1 inch ID copper tube that are 10 feet long. At the forward end there
is a special casting (bronze) which acts as the thru-hull for both in
and out coolant pipes as well as splitting the cooling tubes into two
runs each way (fore and aft). The aft end also has a "custom" casting
that allows the tubes to again be parallel in regards to the flow. These
castings I am certain were locally made as most of the systems I have
seen seem to use identical castings so they probably came from one
foundry in this area. The normal engine cooling water pump is the only
circulating drive in the system. The hull is 36 feet long planked with
western red cedar and the engine is a 95 HP older Volvo diesel. The
coolant is at normal atmospheric pressure and the coolant expansion is
taken up in a "header tank" that is mounted higher than the highest
point of the engine. This system is common on most older wooden
work/fish/pleasure vessels here in the PNW and in my case has been
operating for about 40 years and has never caused the engine to over
heat, in fact I am certain that the cooler could be much smaller given
the nominal water temperatures in this region. A few years ago the
thermostat failed in the open mode and the engine would not even begin
to come up to operating temperature so the cooler is definitely working.
I have seen other systems where there were only two runs of tubing but
were considerably longer as well as those that were shorter but had more
tubes but I am sure they all provided relatively the same cooling capacity.
Given the higher water temperatures in the southern areas, the
dimensions for a similar keel cooler system probably would have to be
increased with regards to the length and possibly number of the tubes.
So - bottom line is, yes properly done keel coolers work, are relatively
simple compared to the normal heat exchanger systems and are basically
maintenance free provided they are properly electrolysis protected.
If anyone is interested in more information simply Google for "keel
coolers" and lots of stuff shows up.
Hope this helps the discussions.
John Tones "Penta"
Sidney, BC
Rudy and Jill
> coolers you think
> you saw were ever galvanized. Other than anchor chains (at
> least the ones
> that spend most of their life in the chain locker), zinc
> coated steel is
> just not used in contact with salt water. If someone was so
> naive as to
> build a keel cooler out of galvanized pipe, they would end
> up with a raw
> water cooled engine within two years!
Kevin, you are probably correct. I'm basing what was said on two things. First, as mentioned, there are some boats here that use galvanized pipe for coolers. All they do is go down to the local hardware store and buy what is in the plumbing section. Some buy black pipe, others galvanized.
The second reason, I used galvanized steel rudder fittings on my last boat, and as long as I kept them coated so the bottom paint would not interact with them, they did well. I replaced them 10 years later, only because I started putting bottom paint on without a protective coating on the bare metal.
I hope they don't take everything that I've said as gospel as it only pertains to the limited experience that I've had.
Rudy
Scott H.E. Welch
> At the forward end there
>is a special casting (bronze) which acts as the thru-hull for both in
>and out coolant pipes as well as splitting the cooling tubes into two
>runs each way (fore and aft). The aft end also has a "custom" casting
>that allows the tubes to again be parallel in regards to the flow. These
>castings I am certain were locally made as most of the systems I have
>seen seem to use identical castings so they probably came from one
>foundry in this area.
A couple of comments here:
1) Are you SURE that the pipes are copper? I too assumed that they were, but
when I bought the Walter cooler for my genset I discovered that the pipes wer
e actually bronze. Also, modern coolers have ridged pipes, which increases th
e cooling substantially.
2) I am guessing that the castings are actually from one of the standard mari
ne foundries (e.g. Perko, Wilcox-Crittenden, Walter, Buck Algonquin). First,
those castings are actually pretty complex. Second, I collect old marine cata
logs, plans and magazines, and even plans for fishboats 50 and 60 years ago s
pecified Walter keel-cooling fittings. From the description you give, I would
bet dollars to donuts that you have a Walter keel cooler.
Scott Welch
Chief Evangelist, Open Text Social Media Group
www.opentext.com
905 762 6101
"Things turn out best for people who make the best of the way things turn out
." - John Wooden
John Tones
alloy that has a _very high_ copper content. <grin>. Actually I am
certain they are copper due to the fact that I have scraped them clean
during haul-outs for 20 years now plus a few years back one tube got
damaged and I replaced the section of tube with 1 inch copper tube and
joined it with standard copper pipe sleeves, not household grade. I
forget the trade "grade number" but it is meant for being buried
underground and has quite heavy wall thickness.
Remember, this cooler was installed when the boat was built in 1969 so
there is nothing "modern about it.
As for the castings, I assume they are not made by a major player as
there are no names or logos cast into them but perhaps back then
manufacturers were not so concerned about getting their name on
everything they made. You may be correct about who made them but there
is nothing to indicate so.
You have to remember that this is one vessel out of probably 100's that
were built here on the west coast in years past and all of them used a
very high content of locally made hardware.
One point I forgot to make about the cooler installation on my boat is
the fact that it is installed over a copper sheet that is about a foot
bigger in all ways and is nailed to the hull before the cooler was
installed - I think for the purpose of reducing barnacle and sea life
build up between the cooler and the hull. What ever the reason I am glad
its there as it acts as a great ground plane for my HF radio system!
So - what ever, the cooler works and it is very simple !
John Tones Penta
Sidney, BC
Scott H.E. Welch
>One point I forgot to make about the cooler installation on my boat is
>the fact that it is installed over a copper sheet that is about a foot
>bigger in all ways and is nailed to the hull before the cooler was
>installed - I think for the purpose of reducing barnacle and sea life
>build up between the cooler and the hull. What ever the reason I am glad
>its there as it acts as a great ground plane for my HF radio system!
That's a darn good idea, I think that I will do this on my next haul-out. I'v
e actually thought about coppering my entire bottom, but it's a pretty large
job.
Scott Welch
Chief Evangelist, Open Text Social Media Group
www.opentext.com
905 762 6101
"Things turn out best for people who make the best of the way things turn out
." - John Wooden
Glen Zwicker
used the "that looks about right" engineering method and it works just
fine. I bought a pair of the simple bronze thru-hull castings made for the
purpose, a few lengths of 1 inch type K hard copper pipe, a U type elbow,
and a few couplings. I ran a single pipe aft from the first thru-hull along
the bottom of the hull near the full keel, did a 180 turn near the stern,
and returned to the other thru-hull, for a total exposed length of about 35
feet. I made a nice fairing block to ease the water flow over the elbow. As
I said it works just fine. The only problem is that the barnacles love it.
Not the hot end. The first ten feet or so remains barnacle free but by the
end of the season the remainder is heavily encrusted with barnacles, whether
or not I put bottom paint on it. . This leads me to believe that almost all
of the cooling takes place in the first ten feet or so because little
cooling could take place through that heavy encrustation of barnacles. The
engine, a Ford Senator 120, does come up to operating temperature normally.
There is a 180 degree thermostat and the indicated temperature stays in the
180-190 range in all modes of operation. I should add that here in Nova
Scotia the summer water temperature is on the cool side 60F
Glen
Perseverance
Yukon 36