CHAPTER II

UTILIZATION OF NAVAL FACILITIES IN U. K. FOR ASSEMBLY AND
 OUTFITTING OF EQUIPMENT FOR INSTALLATION ON INVASION BEACHES,
AND SELECTION AND TRAINING OF SEABEE CREWS FOR THE INVASION

	One of the principal assignments of the Construction Battalions in 
the United Kingdom was the assembly of 27 RHINO FERRIES for use in the 
invasion of France.  On 15 November 1943, the first shipment of pontoons 
had arrived, and assembly of RHF #1 was commenced at Falmouth, Cornwall, 
England.  The work was undertaken by the 81st Construction Battalion.  This 
ferry was completed shortly after 1 December 1943.  Work commenced immediately 
upon RHF #2.

	About the middle of December, CBD 1006 arrived from the Mediterranean 
Theater.  This Detachment, having assembled and operated pontoon causeways in the 
invasions of Sicily and Salerno, were well versed in many of the pontoon problems. With 
the collaboration of the 1006th CBD, the 81st CB, the 13th CR and COMLANCRAB 
11th PHIB, RHF #1 was subjected to trials and tests.  Certain changes were made to the 
original design as developed at ABD-Davisville.  The principal changes were (a) 
elimination of hinged vertical fairlead; (b) substitution of wood treadway ramps for the 60-
ton tank ramps provided; (c) utilization of one 3x7 tug in place of the two 2x7 tugs and 
(d) mounting the outboard propulsion units on the two aft quarters of the Rhino.

	The assembly yard at Falmouth was a side launching yard with a capacity of one 
1x30 string.  It had two major limitations.  Pontoon cargo arriving from the States had to 
be unloaded through the yard and, secondly, the wharfside dried out at low tide.  It 
became apparent that two more assembly yards would be required to meet the schedule.  
Accordingly, after a careful survey of all available sites, yards were established at 
Plymouth and Dartmouth.  The Dartmouth yard had the same capacity and limitations of 
the Falmouth yard.  The Plymouth yard could accommodate two 1x30 strings at the same 
time, and, although launching was not possible at low tide, it was not blocked by incoming 
cargo.  All three yards were manned by details from the 81st, the 1006th CBD and the 
111th CB; the latter having arrived from the States during February.  Inasmuch as the 
same men were to be used to operate as well as assemble the Rhinos, these details were 
shifted frequently to meet the requirements of the training program.

	The original commitment of the assembling of 27 Rhino Ferries was completed on 
April 15th, which happened to coincide with the date upon which the 25th Regiment took 
over the administration of the assembly yards from the 13th Regiment.  During this period 
of initial assembly, the tests of the Rhino proved sufficiently successful that the program 
was extended, in late April, by ten Rhinos, bringing this total to thirty-seven.  The 1006th 
CBD established a provind ground at Fowey, Cornwall, England, and conducted extensive 
tests to determine the best method of installation and operation.  The coincidence of a 
high tidal range, strong littoral current, extremely flat beach gradient and the uncertain
character of the tidal beach made this a difficult problem.

	After a series of thorough trials, it was decided to sink the causeways and provide 
them with unloading stages or blisters, to be sunk adjacent to the causeway and space 
intermittently along its entire length in such a manner that one of the stages would be 
available for unloading, irrespective of the tide level.  Accordingly, the 57 causeway 
sections, 12 causeway tugs and 32 - 4x12 blisters were assembled, outfitted and prepared 
for towing prior to 1 June.  this work was distributed proportionately among the three 
yards in accordance with the delivery of N. L. gear.  During this same period, from April 
15 to June 1, twelve warping tugs and ten camels were assembled.  The camel landing 
ramp and the offshore end was rigged with knee bumpers, chocks and suitable tackle to 
enable an LST to tie up to it.  The camel was used on yards to facilitate the loading of 
LST's.  Their use eliminated driving vehicles through salt water.  It speeded up the loading 
by providing a better gradient over which to run the vehicles and it saved wear and tear by 
eliminating the beaching of the LST.

	Prior to June 1st, five more Rhino Ferries and tugs and two Rhino Repair Barges 
were assembled.  The latter were 6x24 barges equipped with crawler cranes, machine 
shop, Quonset hut, welding equipment, spare propulsion units, engine and pontoon parts, 
and a complete se of tools.  With the exception of the camels and one Rhino Ferry and tug, which were given to the British, all of the units described above were duly alerted and 
towed to Normandy on D-Day.  (See Appendix A for towing schedule).

	On June 1st, the administration of the assembly yards reverted to the 13th 
Construction Regiment.  By reason of the distribution of pontoon equipment and the 
destination of incoming shipments, the assembly yard at Dartmouth was shut down and 
restored to its original condition.  The facilities at Plymouth were doubled by taking over 
Corporation Wharf and a temporary yard was established at Exeter.  Five more Rhinos 
and tugs were assembled, outfitted and delivered to Normandy, thus completing the full 
Rhino commitment of thirty-seven.  Twenty-five so-called Whale beetles were assembled.  
A beetle was a 3x11 pontoon structure designed by the 25th Regiment to replace the 
concrete floats for the Whale project.  Two 5x12 barges and four 4x6 docks were 
assembled for Mulberry.  One 250-ton dry dock and 100-ton dry dock were also 
assembled.  (See Appendix F for construction schedule).

	With the arrival of the 69th Battalion in the U. K., work was immediately started 
on a wharfage project for the U. S. Army to be assembled east of the Quiberon Bay area 
in France.  This involved 5880 pontoons.  Upon completion, it was made up into suitable 
tows for transit.  This was immediately followed by the assembly of a similar project for 
the Navy t be assembled in the Quiberon Bay area; this involved 2166 pontoons.  This
completed the program and the yards at Falmouth, Plymouth and Exeter were shut down, 
restored to their original condition, and all surplus gear binned, catalogued and stored in 
suitable areas established at Plymouth, Falmouth and Exeter.

	The total construction program describe herein extended over a period of two 
months, and involved 22,806 pontoons - a dead weight tonnage of 35,218, and a 
displacement tonnage of 91,225.  In addition to this, the 111th Battalion assembled three 
Rhino Ferries on the beach at Normandy.  This was unique in that the strings were 
assembled at low tide on a flat sloping beach and launched as the tide came in.

	During the period 1 January to 1 June 1944, the Royal Engineers in Southampton 
assembled 12,800 pontoons in the form of Rhinos and causeways.  The Seabees provided 
the Royal Engineers with a liaison party of ten men and two CEC officers for the purpose 
of instructing the Royal Engineers and maintaining a uniform standard of assembly and 
operation.  The Royal Marines assembled and operated four 475-ton dry docks which 
were later turned over to the U. S. Navy.

	The various DREW units assembled an undisclosed number of pontoons, but from 
the size of their stock piles at Rosneath and Cherbourg, it is apparent that the quantity 
they have assembled is a small percentage of their component.

MULBERRY A.

	Another Seabee assignment involved the installation of artificial harbors on the 
invasion beaches.  The harbors, called MULBERRIES, consisted of an outer breakwater 
formed by sunken ships, referred to as GOOSEBERRIES, and concrete cellular caissons, 
called PHOENIXES.  The WHALE element, consisting of six spud-type floating pierheads, connected to the shore by three floating bridges, was located inside the harbor.

	PHOENIX units were designed by British Royal Engineers and constructed under 
British contract.  These units were built of reinforced concrete, designed with dead weight 
of 1572 tons to 6044 tons and were built in six sizes, as follows:

						Breadth	Displacement
	Units		Height		Length		 at WL  	       Tons		Draft

	A1		  60'		204'		56'-3"		     6,044		20'-3"
	A2		  40'		204'		56'-3"		     4,773		16'-4"
	B1		  40'		203'-6"		44'		     3,275		14'
	B2		  35'		203'-6"		44'		     2,861		12'-5"
	C1		  30'		203'-6"		32'		     2,420		14'-3"
	D1		  25'		174'-3"		27'-9"		     1,672		13'

	Each unit was provided with towing gear, bollards, anchors, life saving apparatus, 
a 40-mm anti-aircraft battery and bilge pumps.  Crews quarters were provided for 
personnel during the towing operation. These units were built to be towed to the beachhead 
and sunk in place by opening the seacocks on each unit; the time of sinking varying from 
11 to 32 minutes, depending on the size of the unit.  (See Appendix E-1 for sinking 
positions of these units.)

WHALE Installation:

	The floating bridge equipment consisted of a series of 80-foot spans connected end 
to end and supported at each joint by a steel or concrete bridge float.  Each bridge span 
was steel decked, with a heavy duty roadway 10 feet in width.  Two types of spans were 
used, designed for a tank or vehicle loading of 25-ton (Mark I) or 40-ton (Mark II), 
respectively.  Two Mark I and one Mark II bridges were constructed and connected to six 
floating pierheads, as shown on Appendix E-1.  The pierhead assemblies were provided 
with electrically operated spuds on each corner to anchor the pierhead, and compensate 
for the tide variation.

	The 108th Naval Construction Battalion was assigned the task of manning, 
outfitting, riding under tow and operating the units, and therefore began accepting the 
WHALE and PHOENIX units from the British Royal Engineers in April.  The 108th 
Battalion established camps a Selsey Bill, Richborough and the Isle of Wight, and began 
the assignment and training of crews.  Each unit was outfitted for towing to and operation 
when installed on a French beachhead.

TRAINING PROGRAM.

	A vigorous training program was entered into and classes were held for all 
personnel as follows:

		Seamanship			2   days
		Rhino Operation			5    days
		Small Arms			3    hours
		Bombs and Incendiaries		2    hours
		Chemical Defense		3    hours (three times)
		First Aid			1    hour   (five times)
		Fire Fighting			1    day
		Swimming and Abandon Ship	    hour   (three times)
		Signaling			4    weeks continuous
		Aircraft Recognition		2    hours  (nine times)
		Bomb Disposal			2    hours

	Three thousand three hundred and seventy-three (3373) officers and 
enlisted men complete the above program, as follows:
					Construction Battalion
				28	81	108	111	1006	

FERRY SERVICE

	37 Rhino Ferries & Tugs	225    700		925
	 8 Causeway Tugs		64		 64
	12 Warping Tugs			64		128
	 2 Repair Barges		80		 80

CAUSEWAY							 318

MULBERRY

	Survey Party			10
	Phoenix					  354
	Pierheads				  139
	Bridging				  222								
				-----------------------------------------
			Total	225	918	  715	1197	 318

	Open beaches having a low gradient, extreme tide conditions and tidal currents 
closely resembling Omaha and Utah Beaches were selected for training purposes.  All 
training was pointed to the efficient operation of each type of unit while in the training 
area.

	Training areas for the various elements were located as follows:

	RHINOS         - Fowey, Falmouth, Dartmouth, Torquay, Plymouth.
	CAUSEWAYS      - Par Sands and Fowey.
	PHOENIXES      - Bramble Bank at Selsey and Dungeness.
	WHALE ELEMENTS - Southampton and Peel Bank on Isle of Wight.

	Training simulating conditions expected on the beaches of France, was concluded 
with exercises and drills against time.  All units were then made ready for tow to the 
assembling areas.

  • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •

Return to Operations of the 25th NCR

  • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •

SeabeeCook Publishing, Shingle Springs, CA.
Last update: August 1, 1996