MRF Summary Report - August 1967
MOBILE RIVERINE FORCE SUMMARY
ComRivFlotOne / ComRivSuppron - Seven
Two cases of dog bite were inflicted on 12 August by a stray dog retrieved from
Vung Tau Harbor. The dog was found to have rabies. Treatment is currently underway with
Duck Embryo Vaccine on the two boat crew members who were bitten.
During the period 20-21 August, the Mobile Riverine Force conducted extensive search and
destroy operations in the Ben Luc District of Long An Province. The area of operation was
43 kilometers air distance from the MRB and 71 kilometers by water route. Even though no
heavy contact was made by river assault craft, the operation was noteworthy in several
1. During the planning stages, problems were envisioned in the areas of communications and
logistics. However, communications were excellent throughout the operation, both on
HF(SSB) and VHF FM. Although a communications "retrans" station was established
at Rach Kien, it was not necessary to utilize it at any time during the operation.
2. To alleviate logistics problems, six ATC's were loaded with all classes of supplies,
and were positioned at Ben Luc within 10 kilometers of the AO, as a forward supply point
for ground elements of the MRF. These supplies were fully utilized and effectively
eliminated any supply problems which might otherwise have existed.
3. During the second day of the operation, boats were refueled by a tanker truck. Due to
soft mud, the truck could not approach close enough to the river to reach the boats. To
counter this situation the truck was positioned on the route 4 bridge at Ben Luc, with
fuel hoses extended over the side of the bridge to the waterline. In spite of heavy
current, the boats were able to position themselves under the hose and conducted this
unique refueling without incident.
4. This is the greatest distance that river assault craft have conducted an operation from
the MRB. In spite of the transit distance involved, no major breakdowns occurred on any of
the units. This operation demonstrated that the Mobile Riverine Force is capable of
conducting operations up to 75 kilometers away from the MRB when the occasion demands.
During recent weeks river assault craft have employed a policy of selective use of H and I
fires against possible ambush locations while transiting water routes in sparsely
populated VC controlled areas. Since the institution of this judicious use of fire power,
there have been no attempts to ambush the craft either by automatic weapons, mining, or
recoilless rifle/B-40 rocket attacks. These procedures will be continued in order to
evaluate fully its apparent success in discouraging VC ambushes.
On 19 August a test of MDL chain link anti-swimmer net was conducted. The net consisted of
two 25 foot sections and was placed in the water at 1200 hours. As the tide began to ebb,
about 1500, the net dragged anchor and drifted rapidly down the river, becoming foiled in
Colleton's anchor chain and port accommodation ladder. The net was cut loose by divers
from the EOD team and LLC-2, and held in position south of the MRB by an ATC until
recovery could be made at the change of tide. Indications resulting from this test are
that the strong currents present in the rivers of the Mekong Delta make modifications in
the mooring of MDL chain link anti-swimmer net mandatory.
On 23 August, tests were conducted to determine the feasibility of using a 90mm RR, a LAW,
and a back pack, short range flame thrower as anti-bunker weapons on a monitor.
1. Three rounds of 90mm RR HEAT ammunition were fired at the beach with the recoilless
rifle mounted on the bow of the boat. Test objectives were to evaluate fuse arming (time
and distance), accuracy and back blast. Range to the river bank was 100 to 125 feet. All
rounds exploded high order indicating full fuse functioning. Rounds were accurately placed
in the target area. Back blast was not felt aboard the firing boat. The 90mm RR can safely
be fired from a monitor and probably an ATC. Investigation of suitable mounting and
protection for the gunner and loader is underway.
2. The Light Anti-Tank Weapon (LAW) can be fired from the position between the .50 caliber
mounts safely without excessive explosive reaction or exposure to the gunner. The small
high explosive charge does not indicate enough power for "Bunker Busting". The
use of this weapon will not be investigated further.
3. The back pack flame thrower was fired from the bow of the monitor from ranges down to
40 feet. Results of this test were poor due to limited range achieved and the fact that
this model flame thrower has limited fuel capacity. A flame thrower with 100 to 150 yards
range and increased fuel capacity is considered necessary for application within the MRF
as anti-bunker buster.
On 30 August, the 25th Infantry Division (U.S) gained heavy contact with a battalion-sized
force in the vicinity of XT 735192. Commanding General, II Field Forces, Vietnam visited
CTF-117 to determine the feasibility of employing the Mobile Riverine Force in response to
this contact. The operation envisioned was a two-day multi-battalion operation along the
Saigon river from Nhi Binh (XT 8306) to Phu Cuong (XT 8013). CTF 117 determined that
TF-117 could support the operation. Based on the above information CTF 117 began
preliminary preparations for relocating the MRB to the vicinity of Cat Lai (XS 9589). In
less than three hours, a major movement order for relocation of the MRB was ready for
distribution. Unfortunately, low vertical clearance under the bridges in the Saigon River
at XS 872969 would not permit passage of river assault craft to the desired area of
operations, so the proposed operation was cancelled. The flexibility of the Mobile
Riverine Force was amply demonstrated by its readiness to undertake a major relocation on
The RivFlot One Ordnance Officer conducted test firing of a 106MM recoilless rifle on 27
August 1967. The weapon was mounted on the bow of a monitor, firing towards the starboard
beam. The 106MM recoilless rifle weights 485 pounds and is crewed by two men. The 106MM
proportionately more damage than the smaller 90MM round tested during the last reporting
period. The accuracy of the weapon was excellent and destructive effect of the HEP round
indicated a hard hitting "Bunker Buster." However, the large propulsive charge
and resultant large back blast effects were more pronounced than the 90MM recoilless
rifle. Paint (non-skid) was peeled from the deck of the monitors and the shock of the back
blast was apparent to those operating the weapon. It is felt that this weapon is too large
for use on the monitor as configured. If mounted on the monitor for "Bunker
Busting", a proper mount with some apparatus to deflect the back blast from the rest
of the crew, is necessary. The operational test, of the 90MM recoilless rifles are
awaiting the receipt of HEP rounds from Army sources.