Third Lab Task

Minnow trap used to hold samples for life testing.

Cadets on floating dock inspecting samples after 48 hours in the water. Water temperature is 19^oC.

Group I of cadets and technicians will go to the floating dock behind 3rd
Company, and  (1) figure out a way of suspending the sample cage from the
inside edge of the dock.  Consider whether some line, in addition to the
cage clamp, should be used to prevent the cage from opening and spilling
the samples into the drink.  Mr. Benway has advised us that the inside edge
is the best place to deploy samples because boats alongside will not disturb
them.   (2) Collect 4 buckets of seawater to bring back to the lab.  (3)
Measure the outside water temperature with the thermocouple thermometer and
make a note of the temperature in your report.

Group II of cadets and technicians will prepare sample fixtures for life
testing.
(1) Punch a small hole for the id tag on all samples EXCEPT for the Oak Wood
and the Stainless Steel. Punch the tag on the free end (not the end where
the epoxy is applied).  Only one hole per fixture is required, so only half
the metal pieces require holes.
(2) Clean and degrease all the sample fixtures.
(3) Measure and mark the square area to be epoxied with pencil or waterproof
pen.
(4) Prepare id tags with the aluminum tags provided.  The tags are supposed
to work with a stylus and do not require ink.  A nail is provided to use as
a stylus.   Use waterproof pen for the Oak Wood and Stainless Steel fixtures,
which will not have holes for the id tags.
Today's id number will look like this:
010925FW SEA-OW
      88     SS
      911    CS
      3070   AH
      RIQ    AL

All cadets and technicians then fill the working trays with an inch or two
of seawater.
Reserve 2 buckets of seawater for later.
Prepare the samples under water.   
Leave them in the seawater while you go on to the next task.

Group I of cadets and technicians will test three NEW epoxies underwater
with our rock collection!  Empty one of the unused buckets of seawater into
a tray.  Prepare the three epoxies for test on rocks (not metal!).
Notice if any of the new epoxies will adhere to the submerged rocks.   Try
to stick a piece of plastic to the rocks, using rubber bands or Velcro
straps to press the epoxy bond to the rock.  Let the test samples sit for
about a half hour.  Record your results.  (Epoxy name, etc.)  Note the temp.
of the seawater.

Group II of cadets and technicians will remove the two storage boxes from
the refrigerator.  Drain off the original seawater and replace it with fresh
seawater from the second unused bucket of seawater.  Examine the collection
of sample fixtures and note whether any of them have failed by coming apart.
Remove any fixtures that have failed.  Make a list of their id numbers.
Note whether it is a failure of cohesion or a failure of adhesion.  See your
notes for Dr. Sichel's  tutorial on strength of materials on Sept. 20.
Return the good samples to the refrigerator.  

Group I will carry the sample test fixtures out to the dock in the covered
preparation trays.  Transfer the samples to the sample cage and leave them
outside underwater for life testing.

Group II will begin the lab clean up and stowing of equipment and supplies.
Group I will assist upon returning from the dock.