WHP Ref. No.: PR6
Last updated: 3 May 1994

I.  CRUISE REPORT: Repeat Hydrography on Line P

1.  Cruise Narrative

a.  Highlights

WOCE Section:	PR6

EXPOCODE:		18DD9401/1
Chief Scientist:	Ron Perkin, IOS BC
Ship:			John P. Tully
Port of call:		Esquimalt, B.C. 
Cruise dates:		February 7 to February 18, 1994

   With the Tully having just completed a major overhaul, the cruise began with 
some testing of engines, sounders and generators while proceeding to Esquimalt 
on a sunny and cold February morning. At Esquimalt, the WOCE survey 
winch(Lantec), was loaded using the large crane at the Esquimalt Graving Dock. 
Since the last cruise, the Lantec winch had been equipped with a new .322" 
dia., 8000 m cable and new controls allowing finer adjustment of the winch 
speed. Once again, a system of "bungee" cords was installed to afford a measure 
of heave compensation.
   One Rosette cast to the bottom was competed at Station P4 on Feb. 8, but 
shortly thereafter the ship came under the influence of a North Pacific low 
with wind speeds of 30 knots, building to 45 knots and up to 60 knots in 
squalls. Initially, it was possible to do a few CTD casts but the seas soon 
built to such a state that it was dangerous to put anything over the stern. The 
low stalled over the northern British Columbia coast for the next few days and 
deepened somewhat giving us consistent head winds and opposing seas to the 
point where the Tully, in seas up to 15 m, was making little more than one knot 
toward Station P26 (Station Papa). By Feb. 13, it became apparent from weather 
forecasts that we would not be able to do the planned experiments at Station 
P26 even if the ship could reach it in time. We therefore did the upper ocean 
sampling and CTD cast to the bottom at a position between stations P23 and P24 
on Feb. 13, and started the return leg, picking up missed stations as weather 
permitted on the way back. By Feb. 18, we were able to complete 18 CTD 
stations, 2 with Rosette water samples, and enough upper ocean sampling to 
allow completion of much of the upper ocean chemistry and productivity studies.
    All of the CTD data and water samples were collected with a Guildline 8737 
"WOCE CTD" in combination with a 24 bottle G.O. rosette equipped with digital 
reversing thermometers. For this trip, a transmissometer was added to the CTD's 
suite of sensors. New logging and processing software was tested and modified 
according to users' requests during the cruise. Nutrients, including ammonia 
for productivity studies, salinity and oxygen were analyzed on board. Net 
hauls, nitrogen cycle and productivity measurements were made.

2.  Cruise Summary Information

a. Cruise track
     The cruise took place along Line P (PR6) beginning at the mouth of Juan de 
Fuca Strait on the Canadian West Coast, and extending westward 1200 km toward 
Station Papa (MP26, 50o N, 145o W) but, this time, reaching only as far as 49o 
07 N, 132o 40 W. The return leg, was along the same track.


c. Floats and Drifters deployed
- no drifters or floats could be safely deployed because of bad weather.

d.  Principal Investigators:

Measurements		Principal Investigator	Institution
----------------	----------------------	---------------
CO2			C. S. Wong		IOS BC
Productivity		Philip Boyd		UBC
Nutrients		Frank Whitney		IOS BC
Ocean Circulation	H. J. Freeland		IOS BC

IOS BC - Institute of Ocean Sciences, 9860 West Saanich Road, 	Sidney, B.C., 
Canada,  V8L 4B2
UBC - University of British Columbia, Vancouver, B.C.

3. Preliminary Results

a. Narrative
    The ship left the dock at IOS on the morning of Feb. 7 and proceeded with a 
series of shakedown tests of the refit(engines, generators, sounding equipment) 
in Saanich Inlet and in transit to Esquimalt. After loading the Lantec winch at 
Esquimalt Graving Dock, the cruise proceeded to Race Rocks to calibrate radio 
location gear then to the Straits of Juan de Fuca to begin the sampling 
program. After a good first day of sampling , mainly at station MP04, a period 
of high winds opposing seas began; up to 60 knots in squalls and up to 15 m 
wave height. This condition persisted until, on Feb. 13, it became apparent 
that the ship would not reach Station P in reasonable time and that the planned 
experiments could not be deployed. At some risk, sampling was done at the point 
of farthest progress, between station MP23 and MP24. The ship then returned, 
picking up the sampling program along Line P as conditions permitted. More 
moderate conditions on the return leg allowed completion of a large fraction of 
the scientific program. After unloading the Lantec winch and UBC equipment at 
Esquimalt, the ship returned to IOS on the evening of Feb. 18.
     Although the cruise failed to reach Station P, most of the objectives of 
the cruise were met. A line of CTD/Rosette stations was done almost as far as 
station MP24; productivity experiments were completed; continuous sampling with 
the SAIL and RDI systems was done; trace metal, net tow, PAR and Tucker Trawl 
programs were at least partially accomplished; extra sampling for other 
researchers (Holdsworth, Strom and LaRoche) was done.
      Our plans to intensify sampling and modify procedures for a WOCE one time 
survey in 1994 have been aided by this cruise. Thanks to our sea-going 
programmer, many improvements to the logging program were implemented. On-board 
analysis and processing of chemical and physical data will streamline the 
production of data reports and archive files. The transmissometer and back-up 
CTD were tested. Winch control was excellent and the Lantec performed well, 
even to the point of automatically slowing intake of line when wave motion 
generated large stresses.
       The stern of the Tully is very active in a heavy sea, moving up and down 
by some 40 feet with the waves experienced on this cruise. Observations in 
heavy seas of the handling characteristics of the CTD/Rosette system and ship 
dynamics gave us confidence that we would be able to at least do a CTD cast in 
almost any weather. The technique of letting the ship settle into the wave 
troughs and keeping the ship under way by about 1 knot relieved part of the 
line stress associated with the wave motion.

b. Major Problems
       Station P could not be reached in a reasonable time because opposing 
wind and heavy seas reduced ship speed to 1-2 knots. 

c. Other incidents
  None.


