TSS DEVELOPED SEMISUBMERSIBLE SKIFF

• Document Type: FOIA
• Collection: FOIA Collection
• Document Number (FOIA) /ESDN (CREST): 0005578298
• Release Decision: RIPPUB
• Original Classification: U
• Document Page Count: 18
• Document Creation Date: June 24, 2015
• Document Release Date: November 2, 2011
• Case Number: F-2010-01480
• Publication Date: October 8, 1959

APPROVED FOR RELEASEF] DATE
27-Oct-2011
Sa/DOB/59/ 4 i
ATTENTION
Extremely quiet
Low silhouette
Minimum radar pickup
Ballast easily flooded to present
silhouette or radar pickup.
1. Per your request for information concerning the subject skiff,
the following information and recommendations are submitteds
a. For specific and/or technical information, recommend you
contact TSS/WAD, on extension 3840.
b. Check for desired specific information in the "SKIFF -
OPERATING AND INSTRUCTION MANUAL" which may be obtained from TSS/WAD.
SR/DOB has a copy of this Manual which you may borrow if you wish.
c, Based on certain personal information gained through
training and operational use, the undersigned would prefer the Skiff
as an operational vehicle in many maritime operations over other means
of transportation. Obviously, consideration must be given each specific
operation and its peculiar needs; however, generally speaking, it is
felt the Skiff has many points to its credit.
d. In comparing the Skiff with Rubber boats and silenced
outboard motors (in general), the following points are submitted:
DOCUMENT NO. No CHAfiaa ; ~t.;.ss. ^ (8)
CLA!3
N_ AY
AUTH: H"' 2 z ~10)
Ballast easily pumped to obtain more
critical areas.
remaining in critical landing areas
Personnel and equipment arrive dry
Long range possible due to adequate
capacity.
Warm for personnel
Weight limits rapid deviation in
due
 Disadvantages
(1) Relatively slow speed
(2) Limited visibility
(3) Bulk and weight presents problem of getting Skiff
to launch point
(lt) Requires relatively calm seas to operate and navigate
(under o')
(5) Definite personnel, cargo and weight limitations.
2. In summary and from a layman viewpoint, the undersigned feels
that the Skiff definitely has many operational possibilities.
 REFERENCE: Your memo, same subject, to Chairman,
In-Exfiltration Panel, TRB dated 18 August
1959
1. The In-ExfiLtration Panel, TRB discussed the reference
memo at its 30 September meeting and agrees that the skiff in its
present form' is inferior to other vehicles for the purpose. There
is no objection on the part of the Panel to the disposal of the re-
2. I I SR representative on the Panel is of
the opinion that the concept of such a craft is still valid although
the item produced in response is not satisfactory. His ideas re-
garding future development effort along these lines will be the sub-
ject of a separate memorandum after r,4iew bqcthe Panel.
Chairman, In-ExfiLtration Panel
Technical Requirements Board
 18 August 1959
Chairman, Technical Requirements Board
In/Eeiltraticn Panel
1. T55S/WAD previously developed and completed two (2)
in/exfiltration craft, called the Semi-submersible Skiff. This craft
is listed in WAD Class A Project Booklet, Water Project W-9.
2. One of these boats was shipped to FE for operational use. It
is understood that it was never used operationally, and has since been
scrapped in the field. The other boat has been stored and maintained
by WAD and recommissioned ca two occasions for actual operations. The
boat was shipped to the field, but on both occasions, the operation was
cancelled.
3. TSS/iAD recently has reviewed the characteristics of the semi-
submersible Skiff relative to those of the RB-12 powered by an 18 HP
Special Outboard engine. The following is a brief summary of comparative
characteristics of these two in/exfiltration craft: ?
Characters sti es
Pay - load
Maximum: operator
& 2 passengers, plus
12!) lbs. of equipment.
Maxim=: Four men with
equipment up to 1100 lbs,
total
Speed 2 to 5 As depending on
load, submersion, and
state of sea.
5 to 12 kts depending on
load and state of sea.
Range approx. 110 miles in Approx. 12 miles per can of
calm seas. (Full load) gasoline in calm seas. (Full
load)
 Radars Sonar
Detestability
Sn
Acceptable sea keeping
qualities.
Fair, due to cramped
space, restricted vision
of operator, the small
rudder, the single screw,
and the low power available.
Restricted to deeper water
since propeller is fixed.
U=IL
Good sea keeping qualities,
but wet in rough seas.
Excellent. Greater speed
makes for better maneuvering.
Shallow draft permits smaller
turning circle. Good vision
all around. Can be beached
and operated in unknown, shoal
waters since engine is hinged
& can swing up.
Operation of gasoline he hazard as long as normal
engine in enclosed space precautions are observed in
is hazardous. A serious handling gasoline in
explosion is possible if"- containers in the:=open.
operator does not follow
purging procedures.
Requires caching in calm Simple to hide or cache on
water of adequate depth to shore. Easy to relocate &
saver Skiff throughout rise reinflate. Ground cache
and fall of tides. Ravi mm more reliable; boat & engine
caching depth of Skiff is should be dry, it properly
30 ft. which is also depth cached in dry ground above
trained man can dive without water-level,
aqua lung. Two anchors are
required to hold boat in
position on bottom plus a
retrieving line to beach
which must be hidden. Through
personnel or material failure
Skiff can be flooded. If
flooded, engine would be
impossible to start. Caching
beat off shore requires
operators to have small RB
available for transporting
themselves h equipment to
shore.
 Initial Costs Large development and
construction cost -
Approx. t5O,C0O/unit
Maintenance Costs High and continuous
while boat is in camm-
ission in the water.
Overseas Shipping Requires huge crate,
cranes & large truck to
bsndle, special reserv-
ations for ship trans-
portation, subterfuge in
labeling, etc.
Boat - 3000 lbs.
Boat in crate with
accessories - 7800 lbs.
'Spares &accessories Large spare part &
accessory list.
Launching from Mother- Requires slinga & crane
craft as well as skill & good
seamanship. Chance of
damaging boat always
present.
Comparatively cheap -
Boat - $1200, Engine - $1270
Small awe permits easy
handling & shipping. Boat &
engine can be shipped
separately. Can be shipped
as recreational equipment.
Boat 150 lbs.
Engine 125 lbs.
Easily accomplished under mos
any end all circumstances.
Chance of damaging boat small
technician in field with
Skiff. (TSS/WAD technician
accompanied Skiff to area
on both overseas operations)
Extensive training is required. Coly nominal training
Good practical engineering required to insure reliable
ability needed by the inflation, caching of boat
operator. Operator also must and operation of the engine
be a trained swimmer and
capable of diving to 30 ft.
and searching for Skiff in
pitch dark water. Operation
of Skiff blowing & Trimsdng
down system requires training,
familiarisation and continual
association to insure reliable
operation.
 Chara_ er ics Stiff 83-13
Potential for Very limited Very versatile. Can be
maritime operation used in may types maritime
operations.
5. It is requested that the TR3 Panel review the above and that the
requirement for the semi-submersible 'Skiff be reassessed so;that a conclusion
may be made regarding the retention or disposal of the remaining developmental
Skiff.
DIsm.IBUTIOB:
Orig & 1 - addressee
1 - TSS/SRB
3 - TSS/tlAD
 stD#pRA l Y` as Q ief, /7
, 11011
1. In accordance with verbal nest frogs a repreaentstive of SF/j
the following information is supplied:
a. Siml;ls are long eaves caused by distant wind di$turtattCes.
Wind eaves are short in length end are caused by local slinda.
c. For flat or nepfly flat sae ca iitioas, where mace he- 1942"t
does not ezaeed one foot and wind is under 10 knot a, the curves
roe the buoyant and semi-wed condition (figure 5, lcxer
e*.art, "Zkifr' fOperatia; and lratauction Manual) are ccneer ative.
115kiff" can be expected to make the speeds shown by the c3:rveo, for
each ram selected.
d. For sea ecudittons wiaere ds are 10 to 15 knots and -
height cf waves are 1 i/2 to 3 fast, the "Skiff" speed may be
reduced about l/L knot when running with or across the seas, and
possibly as much as one knot when running into the seats,
e. For heavier than ordinary sea conditions, where the h"t
of waves is 3 i/2 to 5 feat, retnaented by winds as high as 18 -
20 knots, the speed ma~r be expect-ad to be reduced by nearly one
knot, when running, with or acre" the seas, and mill be reduced by
about 2 knots when running into the seas,
f. When winds are above 20 knots and height of seas over 5
feet, it is recd t1hat use of the "Skiff" be delayed until
conditions :moderate.
g. On the assunw.tien that the mother ship win be 80 to 100
feet in length, we do not extend launching in seas over 3 feet
(15 knot wind), in order to be conservative.
h. It is noted that a recent Air Maritime Divi,ion study dated
8 June 1956 of the areas under consideration indicates that during the
 summer months, winds seldom exceed 8 to 12 statute miles per hour.
From this data it appears that moderate winds and seas will prevail,
if the launching time is planned over a period of 2 to 3 days.
Distribution:
Orig & 1 - Addressee
1 - TSS/SRB
2 - TSS/WAD
 18?.. June 1956
SVBJBCT: a. Re-ballasting of "Skiff" No. I
b. Installation of Heavy-duty Pulll s and Belts on "Skiff"
No. I
1. Between 12/14 June 1956 the permanent ballast arrangement on
"Skiff" No I was changed, as follows,
a. 27 lbs. was removed from after part of middle ballast
tank, port side, 25" aft of gas tank bulkhead.
52 lbs, was removed from after part of middle ballast
tank, port side, 25" aft of gas tank bulkhead.
c.
282 lbs. was removed from after part of middle ballast
tank, port side, 12" aft of after bulkhead of gas
tank.
d.
25 lbs. was removed from after par
tank, starboard side, 13" aft o
t of middle ballast
f gas tank bulkhead.
e.
28 lbs. was removed from after par
tank, starboard side, 28j" aft
t of middle ballast
of gas tank bulkhead.
f.
6 lbs. was removed from after part
of middle ballast
tank, starboard aide, 12" aft of after bulkhead of
gas tank.
2. The two supposedly 100 lbs, lead pigs in the forward part of
middle ballast were removed and 432 lbs. of lead was cut from each. The
remaining, 55 lbs. (9821bs. actual initial weight), was re-installed with
the starboard 55 lbs. using the original forward securing hole and the
port 55 lbs. using the aft original securing hold. This avoided changes
in the mn longitudinal position of the two weights.
3.- One additional small piece was removed from the forward middle
ballast tank by0
a. The above arrangement was to provide for removing 200 lbs.
of soak up of the wood in the "Skiff" during the past l2 and 2
years and for 2-mein, 687 The of equipment, including 5 gals. of
additional gas in the compartment, 5 gals. in deck over
the engine compartment, and certain additional weights such as
extended gas ftlliM line. DIC, ,r ,:, . 110. 2 %
 b. On 15 June 1956 heavy-duty pulleys and new heavy-duty
belts were installed on the water pump of "Skiff" No. I. The new
pulleys were standard steel types, the one on the propeller shaft having
20 teeth, bored for 1" shaft, with the keyway cut to 1/4" width and
1/8" depth. The pulley on the pump had 28 teeth bored to 3/4" diameter
with the keyway being cut to 3/16" depth. Bored pulleys were cadmium
plated in Baltimore, prior to installation. The belt is a Gilmer timing
belt, made by New York Belting and Packing Company, Passic, N.J., but
with the Timing Belt Division at TaconW, Philadelphia 35, Pa. The belt
is known as No. 420-H -100 "Timing" Belt. The pitch of the teeth is 1/2"
instead of 3/8" pitch. We have been using this pitch on the light-duty
drive. In installing the new pulley and belt along with two spares
along the propeller shaft, it was not necessary to make a new bracket
for the water pump. The distance between the propeller and pump shafts
remained almost exactly the same as before.
 /h~0`O /apy /Q~ 7oc 3140
foeb /wo nFcu idoa /B'00 %-owe
 S~I~fi E 'I V vs\ 04
to To a5 mPW Ctwow. THE W10 hk
%%6F-(ll -
c%o p e'? - "tv,
`vta siRRTcrt - 1335'
~.~ f,~ E S 3.
05 Nr,.Q) JE USES ~.~~ QvA2..
Spet~ Ru~.1z
SPer
a_1 44'F
~- St?
svc. ,~L 1
%SI.O Tt
2000 ?.?K~
V4 f.1
 C
Sea conditions - very alight chop, 8 knot wind.
Runs conducted off measured quarter mile which
will be resurveyed before computing speeds from
the time below.
Skiff No* ii 51-175 against current
!1-55 with current
51-315 against current
liu-6s with current
Above times were made at 2000 RPM, semi-submerged
heavy condition, stern planes installed.
Skiff Boo 2s (Practically no current)
3M-h$S down stream
3M-43S up street
312-465 down stream
Above time were made at 2000 RPM, semi-submerged
heavy condition; no stern plane
31-175 down straaaa, practically zero _ 4
current as above, 2500 RPM, seffi-submerged heavy
condition*.
 Office memorandum -UNITED STATES GOVERNMENT
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