Plastic Model Boat Kit
WW2 British Air Sea Rescue Launch made of vacuum formed styrene approximately Length 24″ x 7″ 1/35th semi-scale.

https://www.sarikhobbies.com/product/ww2-british-air-sea-rescue-launch-boat-kit/

The Darlington & District Model Boat Club races semi scale craft being either a pleasure craft or military craft, between 22 and 34 inches long using a 7.4v 3300mah battery, but no racing gear apart from trim tabs.

Construction is simple but the kit looked more like PT9 than a Whaleback due to the open fore cabin, which I enclosed with scrap styrene sheet.
Note PT 9 was delivered to America by the British Power Boat Company and served as the blueprint for the development of the PT boats of the USA.
To keep the boat as wide and strong as possible I didn't follow the instructions and cut the internal ribs after attaching the deck for a better fit, also cut a rib away for the battery to fit on far port side. (counter torque) and reinforce the sides of the craft with some 5mm square strips of styrene purchased separately along with some triangular running strakes under the hull.

Added rudder and water cooling pic-up and exit port today.

Please note added strakes to underside of hull this is to force water under the boat, as vacuum formed hulls like this have curved chines which can cause the hull to be held back by the suction of the water.

Also added some details such as hatches, and hand-rail effect to the cabin and painted it (stage 1) and also constructed a smaller servo cradle than the one provided.

HSL100 Type 2 High Speed Launch

63 feet
21.5 tons
39 Knots

1941 built by The British Power Boat Company and popularly known as the 'Whaleback' (as the cabin looks like a whale diving).
The craft operating in the North Sea / English Channel. Their armament consisted of any weapon which the crew could find, they started of with a single 303 in each ball turret and progressed to twin 303's, also some had two paired 303's on twin mounting posts and a 20mm on the rear deck where the life raft was originally.
Between the 15th July 1940 and October Britain lost 215, hard to replace, pilots and aircrew to the seas. Thus in February 1941, with the motto "The sea shall not have them".The Air Sea Rescue Services (ASRS) were created, which later became the RAF Search and Rescue Force.
:-

122 63ft BRITISH POWER BOAT HSL WHALEBACK
123 63ft BRITISH POWER BOAT HSL WHALEBACK
124 63ft BRITISH POWER BOAT HSL WHALEBACK
125 63ft BRITISH POWER BOAT HSL WHALEBACK
126 63ft BRITISH POWER BOAT HSL WHALEBACK
127 63ft BRITISH POWER BOAT HSL WHALEBACK
128 63ft BRITISH POWER BOAT HSL WHALEBACK
129 63ft BRITISH POWER BOAT HSL WHALEBACK
130 63ft BRITISH POWER BOAT HSL WHALEBACK
131 63ft BRITISH POWER BOAT HSL WHALEBACK
132 63ft BRITISH POWER BOAT HSL WHALEBACK
133 63ft BRITISH POWER BOAT HSL WHALEBACK
134 63ft BRITISH POWER BOAT HSL WHALEBACK
135 63ft BRITISH POWER BOAT HSL WHALEBACK
136 63ft BRITISH POWER BOAT HSL WHALEBACK
137 63ft BRITISH POWER BOAT HSL WHALEBACK
138 63ft BRITISH POWER BOAT HSL WHALEBACK
139 63ft BRITISH POWER BOAT HSL WHALEBACK
140 63ft BRITISH POWER BOAT HSL WHALEBACK
141 63ft BRITISH POWER BOAT HSL WHALEBACK
142 63ft BRITISH POWER BOAT HSL WHALEBACK
143 63ft BRITISH POWER BOAT HSL WHALEBACK
144 63ft BRITISH POWER BOAT HSL WHALEBACK
145 63ft BRITISH POWER BOAT HSL WHALEBACK
146 63ft BRITISH POWER BOAT HSL WHALEBACK
147 63ft BRITISH POWER BOAT HSL WHALEBACK
148 63ft BRITISH POWER BOAT HSL WHALEBACK
149 63ft BRITISH POWER BOAT HSL WHALEBACK
-
156 63ft BRITISH POWER BOAT HSL WHALEBACK
157 63ft BRITISH POWER BOAT HSL WHALEBACK
158 63ft BRITISH POWER BOAT HSL WHALEBACK
159 63ft BRITISH POWER BOAT HSL WHALEBACK
161 63ft BRITISH POWER BOAT HSL WHALEBACK
162 63ft BRITISH POWER BOAT HSL WHALEBACK
163 63ft BRITISH POWER BOAT HSL WHALEBACK
164 63ft BRITISH POWER BOAT HSL WHALEBACK
165 63ft BRITISH POWER BOAT HSL WHALEBACK
166 63ft BRITISH POWER BOAT HSL WHALEBACK
168 63ft BRITISH POWER BOAT HSL WHALEBACK
169 63ft BRITISH POWER BOAT HSL WHALEBACK
171 63ft BRITISH POWER BOAT HSL WHALEBACK
172 63ft BRITISH POWER BOAT HSL WHALEBACK
173 63ft BRITISH POWER BOAT HSL WHALEBACK
174 63ft BRITISH POWER BOAT HSL WHALEBACK
175 63ft BRITISH POWER BOAT HSL WHALEBACK
176 63ft BRITISH POWER BOAT HSL WHALEBACK
177 63ft BRITISH POWER BOAT HSL WHALEBACK
178 63ft BRITISH POWER BOAT HSL WHALEBACK
179 63ft BRITISH POWER BOAT HSL WHALEBACK
180 63ft BRITISH POWER BOAT HSL WHALEBACK
181 63ft BRITISH POWER BOAT HSL WHALEBACK
182 63ft BRITISH POWER BOAT HSL WHALEBACK
183 63ft BRITISH POWER BOAT HSL WHALEBACK
185 63ft BRITISH POWER BOAT HSL WHALEBACK
186 63ft BRITISH POWER BOAT HSL WHALEBACK
187 63ft BRITISH POWER BOAT HSL WHALEBACK
188 63ft BRITISH POWER BOAT HSL WHALEBACK
189 63ft BRITISH POWER BOAT HSL WHALEBACK
190 63ft BRITISH POWER BOAT HSL WHALEBACK
-
2250 63ft BRITISH POWER BOAT HSL WHALEBACK
-
2546 63ft BRITISH POWER BOAT HSL WHALEBACK
2547 63ft BRITISH POWER BOAT HSL WHALEBACK
2548 63ft BRITISH POWER BOAT HSL WHALEBACK
2549 63ft BRITISH POWER BOAT HSL WHALEBACK
2550 63ft BRITISH POWER BOAT HSL WHALEBACK
2551 63ft BRITISH POWER BOAT HSL WHALEBACK

By the end of WWII more than 8,000 aircrew and 5,000 civilians had been rescued by the service.

The role of aircraft in the ASRS was to locate downed airmen and help them, by dropping them survival equipment and stores, while they waited for an ASRS launch to pick them up.

Connect rudder to the mounted servo, servo box completed and glued into position, servo was mounted this way to leave the max height for rudder tube, as stern of the boat is narrow and when on the plane will be deep in the water. also the servo could be glued to the hull and the internal frame.

Part of coupling attached, waiting for the motor! Also note some strengthening around the frame base, with right angled scrap.

Reused cutaway plastic to make an inner sealed hatch this will be stuck down with ice hockey tape.

1. Added strakes to bow used a rectangle section of styrene as more flexible.
2. Brought a motor mount (cooled) but may also add a jacket.
3. Painted cabin will need to redo as paint cover was poor.

4. Looking to find the best brushless motor for the job, remembering these boat race on 7.4v 3300mah batteries fo 5-6 mins.
That gives a ruff consumption of 33 Amps which means the motor need to be able to handle about 250Watts.

I have pick out 4 to test
1. 2850 2650 kv, 800W, max 19v, max 52A.
2. 2860 4050 kv, 1300W,max 12v, max 108A.
3. 3650 3930 kv, 800W, max 13v, max 60A.
4. 2845 3100 kv, 800W, max 17v, max 47A.

On paper it should be between 1. and 3., 3 being the most suited ???.
So on paper motor 3. running 7.4v will give 450 watts max at (60A max current at 13v) so 7.4v should have a max a round 30A (unless stalled). giving 222W

244.2 watts target at 7.4v = 33A max for 6 mins on a 3.3ah battery if battery function is good.

33A drain will depend on the propeller size 32mm- 45mm !
A safety margin may be 30A when moving and 33A in bath.
7.4v x 3930kv = 29,082 rpm perfect for hydro, not for sub drive.

Installed hardware used brushless 2860 4050kv motor with water-cooled mount and jacket, kept prop-shaft at a low angle.

It drives really well to the extent that its too good to race so I have started again with another boat for racing.

This boat is really nice to drive it behaves perfectly and I am pleased with the craft