TWL: Keel Cooling
Philippine boatbuilder Mike Allen has used seachests for this purpose.
Instead of a standpipe, he makes a box that begins below the waterline and
ends above the waterline. Holes cut in the hull allow free circulation of
water through the box, which forms an inner hull. From the top of the box
above the waterline he inserts a copper coil sized to fit the box fairly
snugly. Fresh cooling water is circulated through the coil, and in the
even of breakage, seawater can be used for emergency cooling. This system
undoubtedly requires more routine checking and cleaning, but it is really
cheap and easy.
Michael Rowe
I had an aluminum boat that used this system. There is an additional
advantage similar to putting an air conditioning pump in a 5 gallon pail
mentioned a few days ago. First, you eliminate the single incoming
through-hull which if it gets plugged will literally shut everything down.
Second, the water inflow into the seachest is relatively low velocity if
you have a large opening and thus weed, animals, etc. tend not to get
sucked in. The shutoff valves and strainers go on the lines exiting the
seachest and the seachest itself goes above the waterline and has a bolted
down cover which can be removed to clean it.
Tom
At 11:53 AM 4/27/2001 -0400, Michael D. Rowe wrote:
Philippine boatbuilder Mike Allen has used seachests for this purpose.
Instead of a standpipe, he makes a box that begins below the waterline and
ends above the waterline. Holes cut in the hull allow free circulation of
water through the box, which forms an inner hull.
Some of the dive boats around here have "jacuzzi" style hot tubs that double
as a large evaporative cooler. Has anyone ever seen this on a trawler?
Soaking in a nice, warm tub is a magnificent way to cruise back to port!
Doug Barnard
rebuilding a 20' Skipjack
"Fiesta Bimbo"
trawler-crawler wannabe
=Some of the dive boats around here have "Jacuzzi" style hot tubs
=that double as a large evaporative cooler.
I thought they were bait wells for the sharks.
Rick
Rick the Mouseherder - nh2f
Westsail 32 Xapic, Hull #438
Annapolis, MD
A small boat and a suitcase full of money
beats a 40 footer tied to the Bank.
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My original message elicited some humorous responses, but no real reply. I'm
not complaining, mind you...
So the question is, has anyone ever seen a small hot tub (like 2' X 4' X 4'
deep), with built-in benches, used as a "radiator" for engine cooling? Maybe
built-in integral, not much showing, up on the foredeck, just in front of
the pilothouse. Wayne from the Celestial thought that the image of driving
the boat with the autopilot remote from the luxury of the tub was pretty
darn funny, but it could happen! I figure that having to run the engine for
an hour or two daily to charge up the batteries could also warm up the tub
for a nice soak...
Is this a killer idea, or what?
Doug Barnard
rebuilding a 20' Skipjack
"Fiesta Bimbo"
trawler-crawler wannabe
Hi Doug, interesting idea. Seems to me that someone on the list is in the
process of building an aluminum boat that has a hot tub built in on the
flybridge. I remember looking at the pics. I thought it was a swell idea.
Now would it work for cooling your engines? I'm not so sure. It would
certainly act as a big heat sink for awhile, but unless there's a lot of
surface area I'm not sure that it would yield enough evaporation to get the
job done long term. You'd have to talk to a mechanical engineer who
specializes in evaporative cooling to get a confident answer I suspect.
Hate to bank on that for your only source of cooling and then be wrong.
Another problem would be temp control in the tub. A hot tub has a pretty
narrow comfort range, perhaps 10 degrees F. If it was totally reliant on
your engine cooling for heat, and that was the only source of cooling, I
doubt that the comfort window for you to lounge around with your autopilot
remote would be very long. You'd need some sort of thermostatically
controlled shunt to pull heat off of the engine as needed, but not all the
time. That means another source of engine cooling.
My thinking is that the best time for a soak is in a quiet anchorage under
the stars, and you won't want to be running your engine then. That means
another source of heat, such as a Webasto, with the appropriate heat
exchangers and thermostatic controls and pumps.
It's getting complicated, isn't it? I've seen some really slick
propane-powered hot tubs. I would bag the engine idea and just go with that
if a hot tub is what you desire. You'd be money ahead, and you would keep
things simple, which is what this group professes to.
But don't forget that a hot tub of the size you're talking about has over
2000 lbs of water, freely sloshing around as you roll - might be some
stability issues to think about, and how do you keep it filled on rough
water. Might need a big water maker to refill it..
All that being said, I love the idea of it. The implementation just might
be more trouble than it's worth...
Bob Deering
Juneau Alaska
It is an excellent idea. When we someday get Doulos II into the water, we
plan to do the same. The tub could easily be drained to save weight while
under way, but who cares how heavy you are when on the hook? Our plan is to
sink a tub into the deck, so that the cover will be flush with the deck for
when the tub is not in use.
I also plan to build in a crock pot, whereby I can slow-cook a meal with
waste heat from the engine and/or refrigeration system.
Paul Kruse
paulkruse@cfl.rr.com
-----Original Message-----
From: owner-trawler-world-list@samurai.com
[mailto:owner-trawler-world-list@samurai.com]On Behalf Of Doug Barnard
Sent: Tuesday, May 01, 2001 10:55 PM
To: trawler-world-list@samurai.com
Subject: TWL: hot tubs (was Keel Cooling)
So the question is, has anyone ever seen a small hot tub
I figure that having to run the engine for
an hour or two daily to charge up the batteries could also warm up the tub
for a nice soak...
Is this a killer idea, or what?