Date: 16 February 2015. Stainless Manifold Ordered (tractor motor
adapted for boat)
The problem: how to turn the standard tractor motor into an
engine that can propel my boat. Mine, a Kubota 18hp came from
Yanmar Tractor Parts and is a gem. Progress on various fronts has
been made. The latest, how to build a cooling system, has taken time with
loads of input from a variety of sources.
Patrick and Steve move Betsy (the Kubota 18hp) into the
pilothouse via a chain hoist.
It's a boat. Everyone has an opinion. Designing a cooling
system for the exhaust of the Kubota certainly offered a ripe opportunity
for a multitude of choices.
All of us know an automobile motor is cooled via
an anti-freeze and water solution in a radiator with a big fan blowing air
on said radiator. At the other end of the car engine is your exhaust and
muffler. The exhaust is
air-cooled and the mufflers are h-o-t, far too hot to touch and certainly
not something I wanted inside my Seaweed.
My first concern is that I do not want any salt water
running through my motor. She's a tractor motor and few tractors
(none!) are designed to have salt water in their innards. I didn't want to
take a perfectly good
Yanmar Tractor Parts Kubota engine and ruin her.
Many of the problems related to motors (say "risers" if
you've a gasoline engine) or manifolds on diesels can be directly related
to salt-water. Corrosion occurs and no motor is happy with salty water
running through it. That's why many of the yacht-boats have devised closed
systems for cooling.
The final decision on the Kubota exhaust has been made.
What Just Right Marine in Carrabelle along with a welding shop in
Tallahassee came up with is a manifold attaching to the starboard side of
the motor. This item was ordered and should be ready on Monday. I'm
thrilled, though my credit card is cringing.
It's custom built, from heavy duty stainless steel... A
once-in-a-lifetime build that should last forever.
Design for Tractor Motor Used in a Boat
My sketch could be better, so let me clarify a bit.
First of all, there's a heavy duty big stainless box that
surrounds the pipes. Those pipes carry the exhaust from the
engine. Fluid, a combination of anti-freeze and fresh water,
will fill said box. The solution will flow in from the bottom
left corner and exit the top right. That water/anti-freeze
concoction will go into (and come out of) a separate tank.
A sturdy stainless box encloses the Schedule 40 (heavy, thick
walled stainless) 1.5" pipe. The
stainless pipe carries hot exhaust air through the
cooling manifold box. A nipple at
the top will deliver raw water to further cool the pipe. The
blue arrows and stars
show water and antifreeze as they flow through the stainless
box. There will be an external closed fresh water tank.
Addendum April 2015: My
drawing is a bit off from the final result. The changes you'll
note are the box (aka manifold) is now U-shaped. That will allow
better flow of the fluids through it.
Also, the coolant goes in
at #1 and exits at #2.
As you can see, no salt water will be able to get into the motor. She'll
be totally 100% fresh water and air cooled. That's why I won't be dealing
with corrosion issues. The difference between stainless pipes and elbows
as shown was just more than $100 extra over black iron. I opted for
stainless, 'cause I like it better.
The final cost of this custom built box is not yet in. We
are talking a day of labor, plus parts. It won't be inexpensive, though
this should be a one-time item. Like many others, I'd rather pay once for
a superior job. This work should last until I'm 90 years old. By then, I
just might be ready to come ashore -- but I hope not!
Tractor motors can be
Yanmar Tractor Parts
in Tennessee. Shipping is via pallet and not terribly expensive.
Just Right Marine designed the manifold and is having it
custom welded by a professional.
Side Note: Through the *coconut
grapevine I have heard that some diesels in boats have had
exhaust elbows that failed. An option for replacement is offered
Exhaust Elbow in stainless at a good
price. I've heard nice things about the quality and speed of
*Coconut grapevine is a
boater's radio net. We all listen in and it's a source of
information for cruisers.
Have you ever replaced your exhaust manifold? How
frequently has that occurred?
Was yours custom-built or off-the-shelf? If custom built I'd be curious as
to location and price paid.
In the Bilges,
Power Tools Required
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