Before entering into the details of the dispatching of ships through the canal, it will probably be well to give a short description of the canal, setting forth some of its main characteristics.
The canal may be considered as made up of four principal features; namely, (1) the Sea Approaches, (2) the Locks, (3) the Navigable Lakes, (4) Culebra Cut. A short description of each of these features in the order mentioned will permit of a complete comprehension of the canal as a whole.
(1) The Sea Approaches are dredged channels leading from the deep water of the harbor at each terminus to the locks.
On the Atlantic side this channel is 500 feet wide and 40 feet deep at mean low water, and extends from just inside the breakwaters enclosing Limon Bay, to the foot of Gatun Locks, a distance of 5.77 miles.
On the Pacific side the channel is 500 feet wide and 35 feet deep at mean low water, and extends from the deep water in the bay to the foot of Miraflores Locks, a distance of 6.99 miles.
The difference in the depths of the two channels at mean low water is due to great range of tide on the Pacific side as compared with that on the Atlantic.
It is believed that there will be very little silting into the channels as the breakwaters at the Pacific and Atlantic ends, and the impounding of the waters of the Chagres River will have eliminated all silting currents.
The breakwater on the Pacific extends from the mainland parallel to and about 1000 yards distant from the dredged channel of the canal to Naos Island, and thence to Perico and Flamenco islands. Its full length, including the islands, is about miles, and its principal purpose is to eliminate the cross tidal currents that would otherwise silt the channel.
The breakwaters on the Atlantic side are two in number, the one on the west, extending from Toro Point 58° for a distance of 1 7/8 miles, and the east breakwater, not yet completed, extending from a mile off shore from Coco Solo Point 2940 for a distance of 1400 yards, leaving an opening 2000 feet wide perpendicular to the axis of the dredged channel.
In addition to protecting the anchorage, the breakwaters prevent the silting of the channel from the beach wash of the heavy seas breaking on the southern shore of Limon Bay.
The Locks are divided into three groups. One group on the Atlantic at Gatun consists of three locks in series, with a total lift of about 87 feet from the sea level to the level of Gatun Lake. The other two groups are on the Pacific. One group at Miraflores consists of two locks in series, with a total lift of about 55 feet from sea level to Miraflores Lake; and one group at Pedro Miguel consists of a single lock with a lift of about 30 1/2 feet from Miraflores to the Gatun Lake level.
All locks are massive concrete structures built in and forming parts of the dams, and are all double; that is, they have two parallel chambers allowing vessels to be locked up or down in the same or opposite directions at the same time.
All lock chambers are of uniform, size, 1000 feet long and no feet wide, and average, roughly, a lift of 30 feet each.
There are intermediate gates in the chambers so that they may be shortened, if desired, to economize in the use of water for lockages of small or medium size ships.
The chambers are flooded through huge culverts in the side and middle walls, and the water let in through openings in the bottom of the chambers, so arranged as to distribute the flow uniformly along the length and width of the chamber.
The valves and gates are electrically controlled, and so arranged with regard to safety that the valves cannot be opened until the gates are in the proper position ; nor can one set of gates be opened until the proper gates above or below are closed.
The sides of the lock walls are free from obstructions, and the walls are of such massive construction that they are incapable of being injured by ships in transit.
Electric locomotives, on tracks, are installed along the sides of the chambers for towing vessels through the locks, and to guide and control the vessel’s movements as desired.
The Lakes.—The dominating feature of the canal is the great body of water, Gatun Lake, covering an area of about 164 square miles, maintained at a level of about 85 to 87 feet above sea level by the great dam and locks at Gatun, on the Atlantic side, and the dam and lock at Pedro Miguel, on the Pacific side.
The lake is formed and maintained by impounding the waters of the Chagres River and its tributaries, and other streams on the northern half of the isthmus. It is very irregular in outline and full of islands heavily wooded, as is the mainland forming the borders of the lake.
The main ship channel across the lake follows closely the original bed of the Chagres River, and is 500 to 1000 feet wide, with a depth of water 87 to 45 feet, growing gradually shoaler and narrower as the upper end of the lake is approached at Gamboa.
Culebra Cut.—This is the great excavation across the Culebra Mountains, extending from Gamboa on the north, to Pedro Miguel locks on the south. The excavation forms a channel 6.97 miles long, 300 feet wide, and 45 feet deep. The sides of the hills are in places abrupt, rising perpendicularly from the water’s edge, but for the most part the hills show the signs of excavation made necessary by slides. The waters in the cut are, of course, a part and a continuation of Gatun Lake.
To the foregoing description of the main features of the canal it may be of interest to add that the total length of the canal from the entrance to the dredged channel in the Atlantic to that in the Pacific is 43.84 nautical miles, and that it crosses the isthmus in a general direction northwest to southeast, the Pacific entrance being situated 23 miles east of the Atlantic entrance.
The dispatching of ships through the Panama Canal is really a very simple matter.
All matters pertaining to the movement of vessels while in the terminal ports and during transit, the admeasurement of vessels and determination of tolls, the issuance of clearance papers, and the enforcement of the Canal Zone Navigation Rules, are under the direction of the captains of the terminal ports.
The endeavor of the canal government has been to limit the formalities preliminary to dispatching vessels to an absolute minimum. There are certain steps, however, that are required before a ship is allowed to enter the canal, and in so far as our men-of- war are concerned, the steps are the granting of the usual pratique on entering the harbor, and the determination of the vessel’s displacement in order to fix the amount of tolls. As regards pratique, the present requirement is that all vessels, even our own men-of-war from our own ports, must have a Canal Zone bill of health. This bill of health is a special form gotten out for this traffic, and blanks furnished all quarantine stations and U. S. consuls abroad. Note should be made of this requirement, as ordinarily naval vessels sailing from one to another of our own ports are not required to have bills of health. As regards the displacement upon which tolls are collected for a man-of-war, it should be pointed out that this displacement is based upon the vessel’s draft upon arrival. Any subsequent change of draft would not affect the tolls charge.
In order that the displacement tonnage may be accurately and expeditiously determined, all men-of-war, likely to use the canal, should be provided with displacement curves. The tolls rate for a man-of-war is fifty (50) cents per ton, displacement tonnage.
For U. S. Government vessels it has been arranged that the tolls be paid by means of a paper transfer of funds, the bills being sent direct to the government department concerned in Washington, so that no actual transfer of funds and no vouchers or signatures are required on the part of the commanding officer and paymaster of the vessel.
As a matter of fact in no case, either merchant vessel or man- of-war, are bills subject to verification by the captain.
Vessels bound through the canal should notify the captain of the terminal port by wireless in order to expedite dispatching her through. If expedition be desired, and the captain of the port so notified, there will be no necessity for anchoring, provided pratique be granted.
With regard to merchant vessels, upon arrival the vessel is boarded to determine her condition as to load and inspection of her tonnage certificate. If the vessel has been measured by one of the authorized officials of the United States or foreign governments, the certificate is accepted, subject to being checked and corrected for errors. If the vessel has no certificate she is measured and a certificate issued.
The correct tonnage and condition of load having been ascertained, the bills are made out in the office of the captain of the port and forwarded direct to the collector for the canal.
The toll rates are $1.20 per ton Panama Canal net tonnage for loaded vessels, and 72 cents per ton Panama Canal net tonnage for vessels in ballast, without cargo or passengers; in other words, a vessel in ballast is assessed 40 per cent less than a vessel in load.
The tolls having been ascertained, and the necessary funds deposited or otherwise provided, the vessel is dispatched forthwith.
Vessels stopping at a terminal port to take on or discharge cargo or passengers, or to take on stores, are required to enter and clear, but vessels arriving for transit only and cleared from port of departure through to final destination are not required to enter and clear. The record of a ship’s progress through the canal is kept in the captain of the port’s office, and her movements controlled by signals or wireless as found necessary.
Large arrow shaped signals on the end of the approach walls direct the movement of the ship upon approaching the locks. While proceeding through the lake from Gatun to Gamboa, there is no necessity for control by signal, but upon reaching the entrance to Culebra Cut, the ship must be governed in her movements by signals received from the signal stations. There are two signal stations in the cut, one at Gamboa, the northern entrance, and one at Empire, about midway the cut. By means of the two signal stations it is possible to keep in touch with the vessels throughout the passage of the cut.
All vessels, except those of very large tonnage, may safely meet and pass in the cut, provided they do not meet in the turns.
The high land obstructs the view around the bends so that it is necessary to indicate the positions of approaching vessels from the signal stations. Mooring dolphins and buoys are located in the reach just north of Gamboa, and mooring floats are secured to the bank near Empire, where-ships may be directed by signal to tie up when deemed necessary.
Vessels with wireless are required to keep an operator listening in at all times during the transit of the vessel, and the pilot must be given free use of the wireless on canal business. No charges are imposed for official messages.
In navigating the canal it is advisable that the captain follow closely the advice of the pilot. None of the turns are difficult to negotiate, but as the conditions are different from those of waters usually navigated, it will be well to bear in mind that the experience of the pilot, knowing the actual conditions, counts for a great deal. The charts of the lake section do not show soundings, merely indicating the channel. The most difficult feature, and the one requiring the most experience, is the approach to the lock walls. Here it is very necessary that the vessel’s engines be stopped in ample time so as to make the near approach at “dead-slow speed.” In the still waters of the canal a vessel holds her way a long distance. It is better to kick her ahead a little rather than have to back the engines upon reaching the lock entrance. On the approach the vessel should be steadied for the center line of the lock, as indicated by the middle line of the gates. If properly pointed and not too much speed on, the vessel is allowed to glide slowly into the lock chamber, the towing lines from the electric locomotives (mules) being put aboard just before the ship enters the chamber.
There are six towing lines used, specially made flexible wire hawsers, one on each bow, one on each side in the waist (just forward of the midship section), and one on each quarter. In addition, the ship should have ready for use as preventers, four heavy manila lines, with good heaving lines, two forward and two aft, at convenient chocks-clear of the wire lines. Both bow locomotive lines, and the middle wall locomotive lines are put aboard when the ship’s bow is within 50 feet of the lock entrance. The waist and quarter lines on the off side are put aboard as the ship glides into the chamber. The towing is done by the waist and bow locomotives, the bow and quarter locomotives being used to keep the vessel centered in the lock chamber. After passing sufficiently far into the chamber the waist locomotives are dropped back preparatory to checking the ship’s headway. The checking and final stopping of the ship are done by the quarter and waist locomotives.
The vessel stopped, the waist locomotives are run forward again to the towing position, and all locomotives take a strain on the lines. The preventer manila lines are run out and made fast to the bollards on the lock walls. These steps are taken to steady the ship when the water is turned on. When the flooding is done from the center and side culverts there is very little surging strain on the ship, but at times it is necessary to flood from the side wall only, and in this case there is a heavy strain due to the current rebounding from the center wall and striking the ship on the rebound. When using both sides for flooding the time required is about seven and one-half minutes, and, of course, double this time when the chamber is flooded from one side only. The chamber being filled, or emptied, as the case may be, the gates are swung open and the vessel moved ahead into the next chamber. In starting the vessel the engines are used to overcome the inertia of the vessel, and as she gathers headway the locomotives are started, and the ship’s engines stopped. The speed of towing locomotives is two knots, so that the ship’s engines must be stopped before this speed is attained.
The pulling power of the locomotives is 25,000 pounds each, and they are not capable of applying a gradually increasing strain acting continuously. To start a vessel forward by the use of the locomotive only, it is necessary to throw on and off the power until the ship has been worked up to the speed necessary to allow the power to be continuously applied. For this reason, it is better to use the ship’s engines to start her. Once started, the electric mules can easily tow any vessel and keep her centered as she goes along. The drums on the locomotives are capable of being coiled in or out on signal from the pilot, thus affording means of keeping the ship centered as desired. Checking the ship’s headway is more easily accomplished by the locomotives than starting the ship from a state of rest, due to the fact that checking is done by friction brakes which are capable of being gradually applied.
In leaving the last chamber of the locks the ship is started ahead as in the other chambers by means of the ship’s engines and towing locomotives. When centered and pointed fair, all locomotive lines are cast off by signal, and the vessel steams out under her own power. The average time required to lock a vessel through the three locks at Gatun is about one hour, for small vessels a little less, and for large ones a little greater. The lockage time for the Pacific end is considerably greater owing to the fact that the locks at that end are separated into two groups, thus requiring two separate approaches with the consequent delays thereto.
At the present time certain pilots are detailed as lock pilots, boarding the ship just before arriving at the approach wall, and leaving the ship immediately upon clearing the locks. While in the locks the lock pilot has complete charge of all the movements of the ship and locomotives, controlling the latter by means of signals given by the arms and hands. As stated above, the ship’s engines are used in conjunction with the towing locomotives.
With exception of the locks, the navigation of the canal is simply a matter of keeping to the channel, and observing certain speed rules laid down in the regulations, and the special signals received in Culebra Cut. Speed for the dredged channel from the sea to the locks, both ends, in Culebra Cut and in Miraflores Lake, is six knots. In Gatun Lake from 10 to 15 knots, depending on the width of the channel which varies from 500 to 1000 feet.
It is not within the scope of these notes to give a detailed sailing direction; however, a few salient points may be of interest.
No regular man-of-war anchorage has been assigned, and in the absence of the pilot, vessels entering Cristobal should anchor to westward of channel, south of the west breakwater.
Pending completion of the east breakwater, there is considerable swell in the harbor during the trade wind season, December to May, and it is well to anchor close under the west breakwater.
Additional anchorage room will be available to the south of the east breakwater when that breakwater is completed, possibly within the next 18 months.
In Gatun Lake there is a double range for each long reach, a front range and a rear range, so that a vessel going in either direction has a head range and a back range. The range towers are placed a little to the right of the axis of the channel so that a vessel having the head range closed will keep to the right of the channel, the idea being that vessels passing in opposite directions, each on its own head range, will pass clear of each other. The disadvantage of course is that with the head range closed, the rear range will be open, or vice versa. The range lights are all white, the front light fixed and the rear light flashing.
Lighted buoys and beacons are placed at about 1-mile intervals along the length of the canal, and also at all angles and turns. Spar buoys are placed between the lighted buoys. There are no buoys in Culebra Cut, as the banks are steep and well lighted with beacons.
All gas buoys show flashing lights, and are colored in accordance with the system in vogue in the United States. The locks at Pedro Miguel are the dividing line between the Atlantic and Pacific systems.
Upon arriving within the 15-mile limit, and until leaving the 15-mile limit of the Canal Zone, a vessel will transmit with low power not to exceed one-half kilowatt. All messages between ships at sea and ships in Canal Zone waters, must be transmitted through the shore stations at the terminal ports.