Thumbnail Chart (not for navigation use) of Test Area.

TEST VESSELS:
The vessels included the twin-screw 60' (1400 Shp) commercial push-tug "Pacific Rose", which served as the main test platform.  The 50' single screw tug "California Eagle" (400 Shp), served as anchor recovery vessel.  A 39' Carver Motoryacht was chartered to provide shuttle service for guests and observers.  The 25' workboat "Grizzly Bear" provided a platform for photography and video.

SCOPE AND ANCHOR RODE:
Six prefabricated anchor rodes were prepared prior to the tests.  They consisted of one fathom (six feet) of 3/8" High Test chain, and 100' of 7/8' three-strand nylon line.  These in turn were shackled to a 14' length of 1-1/2" three-strand nylon line leading from the load measuring devices overboard to the main rode to insure that possible line-partings would always occur under water for the safety of the crew.  Total rode length was therefore 120', resulting in a range of scope from 6.3:1 to 4.2:1 depending on water depth and the state of San Francisco Bay's average of 7'-8' tides.

LOAD MEASURING:
A redundant load measuring system was used: A 4,000 lb. calibrated "Dillon" Dynometer, with a certificate of accuracy traceable to the U.S. Bureau of Standards provided primary readings.  A backup hydraulic cylinder and load gauge provided confirming readings.  A closed-circuit video camera was permanently mounted on the "Dillon" gauge, with the monitor visible to observers on the bridge during the tests.  The confirming hydraulic gauge was also mounted on the bridge.  Verbal readings were called out by an observer on the test deck through a loud hailer, and transmitted by radio to 12 two-way headsets worn by various observers.  The readings were recorded every second or so by West Marine representatives, and later confirmed by E.S. Maloney.

ANCHORS TESTED:
A primary grouping of 8 anchors, and secondary grouping of 7 anchors were tested.  The primary group, illustrated below, represented commonly available anchors from the 35-45 lb. size range.  This size was chosen for testing because it represents the size often chosen for service aboard cruising boats in the 35' to 50' range.  Generally speaking a given anchor's "performance ratio", or holding power per pound of anchor weight, can be used to determine the relative performance to be had from different sizes of the same design and model.  All anchors were obtained randomly from the stocks of various marine distributors, including West Marine, Svendsen's, Lewis Marine and Sailorman.  The secondary anchor group included experimental, prototype, or less commonly available anchors.  These included the Creative Marine "MAX" anchor, the 30 lb. Davis "Sea Hook," a revised version of Rule Industries' T-4000 Deepset Hi-Tensile, the P-1800 Danforth Deepset Plow, and a 35 lb Plastimo brand plow anchor.  Also, at the request of the Navy, larger FORTRESS FX-85 and FX-125 anchors were tested as well.

PULL LIMITS:
No load limits were imposed on these tests, as the potential for damage to an anchor in such poor holding ground was unlikely.  (Limits were imposed during the sandy bottom tests in Biscayne Bay.)

TESTING PROCEDURE:
The primary group of 8 anchors were tested in  a revolving order.  A ninth test position was reserved for testing the next anchor from the 7 member secondary anchor group, called the "wild card" anchor.  Each anchor to be tested was connected to a rode and staged for deployment from the bow of the tug "Pacific Rose".  After the tug had maneuvered into the proper test lane and direction, the rode was connected to the dynometer and the anchor was thrown into the water.  The tug would then be backed down, allowing the line to slowly pay out.  When a "set" was established, i.e.: when some load was registered on the load gauges, RPMs were increased at "Dead Slow" speed, while the loads were carefully observed and recorded, until the anchor either dragged or pulled out of the bottom, thus ending that test.  Bearings taken on 8 buoys along the test course helped observers to determine the point at which an anchor began to drag.  When a test was completed, the rode was disconnected, attached to a buoy, and tossed into the water for recovery by the tug "California Eagle".  This enabled the next anchor to be tested immediately, allowing a new anchor to be tested about every 15 minutes.  After being recovered from the bottom, the anchors were returned to the "Pacific Rose" for inspection and re-testing.

TABULATION OF RESULTS:
When the three days of testing were completed, and the results verified and compiled, each anchor's performance was then scored and rated into two categories: (1) "Average Test Pull," or, all pulls added up and divided by the number of pulls to determine an average holding power for that particular anchor.  (2) "Holding Power Per Pound of Anchor Weight" sometimes referred to as a "performance efficiency ratio" to illustrate how many times an anchor's actual weight it is capable of holding in a given bottom.  The results of these categorical tabulations can be examined in the charts on the next page.  A summary of the raw test data, as verified by Mr. E. S. Maloney, is following.

TYPE	WEIGHT Lbs.	AVG. DEPTH	MAX PULL	AVG PULL	MIN PULL	SLACK LINES	HP/LB
Bruce 44	46	25.4	300	280	250	0	6.1
CQR 45	47	22.2	525	440	400	4	9.4
Delta 35	33	24.8	625	502	200	4	15.2
H-1800	33	24.4	825	725	325	4	22.0
T-4000	30	23.0	1050	725	450	0	24.2
FX-37 32 deg.	20	22.5	1325	825	675	2	41.3
FX-37 45 deg.	20	24.8	2500	2175	2000	0	108.8
VSB-3600	28	24.6		1315	1150	2	47
WILD CARD GROUP
FX-85 32 deg.	44	21.3	1400	1200	850	0	27.3
FX-85 45 deg.	44	20.7	5150	4716	4300	1	107.2
FX-125 32 deg.	65	21.3	2500	2283	2150	0	35.1
FX-125 45 deg.	65	21.7	6600	6166	5400	1	94.9

   Note: Depth, Max, Avg, Min, Std, and Slack are based on best 5 pulls out of 6. 
   Standard deviation based on maximum reading of best 5 pulls.

CONCLUSIONS:
The test was designed to test an area of anchor performance that has had little recorded data to date:  straight line holding power in soft mud.  Since many anchorages around the world have mud bottoms, this is an important aspect of anchor performance.  The author realizes that there are many other aspects of anchor performance that need to be weighed before selecting an anchor for use.  Those performance criteria include: sand holding power, structural strength, ease of setting, ease of retrieval, ability to reset after veering, ability to penetrate vegetation on the bottom, rock hooking ability, ease of stowage and overall holding power per pound of anchor weight.

The tensions recorded in this test were substantially lower than those recorded in a similar test held in Miami with a sand bottom.  This was expected, as the sheer strengths of the two bottoms were quite different.  In comparing results from the two tests, anchors held only 11% to 33% as much tension in the mud bottom compared to the sand bottom in Miami.

The two anchors which are optimized for mud bottoms did substantially better than the traditional designs; the Nav-X  Fortress FX-37 at 45-degree fluke angles, and the Rule/Danforth VSB-3600.  These anchors held roughly four and two times the tension, respectively, of the other anchor styles.  The manufacturers of both of these anchors warn that their "mud" anchors will not reliably set in firm bottoms such as sand/clay or sand.  These anchors must only be used in soft, mud bottoms.  The convertibility of the FX-37 by changing its fluke angles makes it appropriate for both sand or mud when correctly assembled.

The NEXT Page lists each individual anchor pull, which is summarized in the table above.