4.4.7 EXHAUST SYSTEM MAINTENANCE:
In-board engine installations
on sailboats differ from engine installations
on power boats. The primary
difference is that the engine is usually
installed below the waterline
of the vessel.
The benefits of these locations
are that the weight of the engine
is where it will not adversely
effect trim, and that the shaft
is at an efficient angle for
powering and minimum drag when sailing.
Engine installations below the
waterline require special attention
to the design of the exhaust
system. The discharged cooling water
must be exhausted above the
waterline to avoid excessive back pressure
on the engine and prevent sea
water from traveling up the exhaust
line and entering the engine.
To exhaust the engine above the
waterline, the discharged cooling
water and exhaust gas must be
"lifted" to a level above the through
hull fitting on the transom.
In the Catalina 25, the exhaust
cooling water and exhaust gas are
lifted above the waterline by
an "aqua-lift" type muffler. The
aqua-lift muffler performs
1. It mixes
engine gas and water to cool the gas and lower
exhaust line temperature.
2. It baffles
and deadens engine exhaust noise.
It creates pressure required to lift and expel cooling
As shown in illustration 4.4.8
the inlet tube into the aqua-lift
is short and the outlet tube is
long near the aft of the tank.
As the water accumulates in the
bottom of the tank, exhaust gas
pressure builds in the top of
the tank. This forces the cooling
water up the exit tube and
through exhaust line overboard.
The system requires exhaust
pressure in the tank to function.
When the starter motor is
turning over, before the engine fires,
water is being pumped through
the cooling system by the belt driven
cooling water pump. It is very
important not to operate the starter
motor for more than 30 seconds
if the engine does not fire. Should
it be necessary to operate the
starter motor more than 30 seconds.
water must be drained from the
aqua-lift by opening the drain at
the base of the aqua-lift.
The drain valve may be opened
until the engine fires, if desired.
All Catalina 15's are equipped
with anti-siphon valves as an additional
precaution to prevent cooling
water from entering the engine.
Refer to item "B" of
illustration 4.4.8. The function of the anti-siphon
valve is to prevent cooling
water from being siphoned through the
through hull valve, through the
engine cooling system and into
the aqua-lift muffler when the
engine is not operating.
If the muffler were to fill
completely with water, water would
travel up the inlet tube and
enter the engine block.
The Catalina 25 exhaust system is basically simple and will provide
trouble free service if you perform regular maintenance and inspection.
The important points to remember are:
1. Close the engine cooling water through hull valve when
you are not operating the engine.
2. Do not operate the starter motor for more than 30 seconds
without draining the aqua-lift muffler.
3. periodically disassemble the anti-siphon valve. Be sure
the valve is not fouled with salt deposits and
opens freely under the cap.
4. Check the operation by removing the valve:
A. Put a finger over one large hole and
the other. Air should not
escape through the cap.
B. If you suck through one large hole with
a finger over
the other. air should
enter the Valve through the
5. Check the flapper valve on the transom. This prevents
water from surging up the exhaust line in a
Replace the flap as required to maintain
4.4.9 SHAFT PACKING GLAND (STUFFING BOX):
The packing gland is located under the quarter berth.
A properly adjusted shaft packing gland should drip slightly
4 to 10 per minute) with the engine off. Too loose an
will allow too much water in the bilge and engine operation
spray water from the shaft. Too tight an adjustment will rob
engine of power and the lack of water lubrication in the
gland can generate enough heat to damage the gland and/or
the propeller shaft.
1. Holding the packing nut with one wrench,
use a second wrench
to loosen the lock nut.
Turn the lock nut far enough to
keep it from interfering
with the next adjustment (2 or
2. Tighten the packing nut to obtain 4 to
15 drops per minute.
Band tightening of the
packing nut is often sufficient
to obtain this
adjustment. If this is not the case. an
additional 1/4 to 1/2
turn with the wrench should produce
the desired result.
3. Hold the packing nut in place with one
wrench, and use
the second wrench to
bring the locking nut securely against
the packing nut. Make
certain that the locking nut is
tight. Failure to do this
could allow the packing nut
to back off when the
engine is operating.
4. Operate the engine at slow speeds in
forward and reverse
and use a light to check
for excessive water at the packing
nut. Shut off the engine
and recheck packing for proper
4.4.10 SHAFT ALIGNMENT:
For proper operation of the
engine. the propeller shaft and engine
must be aligned.
Alignment is gauged at the
engine and shaft coupling. Alignment
procedures must be done with
the boat in the water after the mast
is erected, and the rig is
propeller shaft must be dimpled (1/8' deep) for two
(2) coupling set screws. The set screws must be safety
wired using the stainless steel wile provided, as illustrated
check key in key way, as it must be in place between shaft
Remove coupling flange bolts and check propeller shaft
for clearance. Adjust stuffing box to prevent excessive
seepage, yet allow shaft to spin freely.
Slide shaft away from engine and check coupling mating
surfaces. These surfaces must be clean.
Slide shaft forward to connect coupling surfaces.
Pilot on transmission flange must align with recess in
shaft coupling flange. This is an indication of correct
coupling flanges in contact, measure gap around edge
of coupling flanges with.003 feeler gauge. Maximum allowable
gap at any point is three thousandths of an inch. Take
this measurement several times....rotating shaft 1/4 turn
each time. Any gap in excess of .003 must be corrected
by changing engine position, especially fore/aft tilt.
For example. excessive gap at the bottom of the coupling
(see drawing) indicates engine is tilted too far aft (front
too high). Using a 15/16 end wrench. loosen lock nuts
on forward motor mount(s). Lower front of engine by clockwise
rotation of motor mount nuts. Re-measure gap at coupling.
A gap at the top of the coupling would require the exact
shaft backwards as in step 3. Again slide shaft forward,
rechecking axial alignment as in step 4.
Repeat steps 5 and 6 until alignment within tolerance is
Tighten motor mount lock nuts and install coupling bolts.
NOTE: Alignment should be
checked yearly. or whenever any excess
vibration is noticed. The alignment can also be affected
by changes in rigging tension.
4.5.2 GALLEY STOVE:
There is provision for a gimballed stove on
the port side of the
galley area. A two-burner alcohol stove is
the factory installation.
It comes with an operation and maintenance
booklet provided by
the stove manufacturer. A compressed
natural gas stove is available
as a factory option. Follow the
instructions for operation carefully
when using the stove. Although compressed
natural gas is among
the safest of cooking fuels, extreme
caution should be used when
cooking aboard, or handling compressed
natural gas fuel tanks.
When filling and lighting the standard
alcohol stove, please observe
the manufacturer's instructions. It is good
practice to have a
fire extinguisher within safe reach of the
galley. Alcohol fires
can be extinguished with water so it is
wise to keep a filled bucket
or container within reach of the cook.
4.5.3 POP TOP OPERATION:
If your boat is equipped with a "pop
top" hatch. the following
notes will aid in its operation.
First of all. the pop top can be used in
two different positions.
When the pop top is in the down position,
the smaller sliding hatch
serves as access to the cabin. When the pop
top is in the up position.
access to the cabin is greatly increased
and, of course, so is
the available headroom. To put the pop top
in the up position
you must go inside the cabin. The top is
raised by lifting upward
and forward at the same time. With the pop
top in the fully raised
position, reach forward to the pop top
slide lock and lock the
top to the mast.
Do not sail or motor your Catalina 25 with
the pop top in the raised
Always lower and lock down the pop top in
rough weather. When
lowered. the pop top should be locked down
using the lock down
4.6.1 RECOMMENDATIONS FOR TRAILERING:
The Catalina 25 is an easy boat to trailer when certain
have been properly heeded. The following suggestions will
1. Be sure to read the trailer
and warranty carefully,
and do not exceed the manufacturers
gross vehicle weight far
trailer boat and gear.
2. Check tongue weight. Most trailers tow
well with 7 to
10 percent of the gross
trailer and lost weight on the
tongue. If the trailer
tends to "fish tail· add tongue
weight by moving weight
forward or the trailer axles aft.
3. Test the brakes by operating the master
4. Inspect the winch cable for broken
strands or fraying.
5. Tie the mast and boom securely to the
bow and stern pulpits,
the spars should also be
supported in the middle by the
cabin top. Pad the mast
at all contact points to prevent
6. Boats should be seated properly on the
trailer: that is.
not ajar or tilted, and
with the bow properly snugged into
the rubber wedge at the
front of the trailer. Boats should
have the weight of the
boat bearing on the keel, not the
padded upright supports.
7. Follow normal trailer procedures of
connecting lights and
safety chain, and be sure
your hitch is well secured.
Always test lights before
leaving ramp area.
8. Do not allow anyone aft of the transom
or loading, who could be
injured if the boat were suddenly
dislodged from the