With metal propeller 1.4 x 32 mm I reached speed 43 km/h (~27 mph). Other changes to earlier configuration was that I used these for the servo:
- HobbyKing HKU5 5V/5A UBEC + Turnigy nano-tech 460mah 2S 25~40C Lipo Pack
I have also tested these Hobbyking batteries:
-
Turnigy nano-tech 1000mAh 4S 45~90C Lipo Pac
-
Turnigy nano-tech 1300mAh 4S 45~90C Lipo Pac
Unfortunately I don't have speed info available. Speed seemed to be a bit higher than with 3S. The boat is still easy to control with 4s. Battery and motor temperatures were about 40 °C (~ 104°F). It is still good to remember that the cooling water is most likely below 10 °C (50 °F).
I am very happy for the stock motor performance. I bought a Leaopard 2040 2600kv motor as spare motor but I have not needed it. During past two years I have had about five cheap, not branded chinese motors in RC cars and boats and the life time has been in best case only few batteries.
Playing with this Small bolt has been very easy. When using components that you have recommended I have not managed to break anything. I tought it is a risk to test with 4S but at least first two batteries were drained without any problems. One more thing about those 4S batteries I listed above, they fit very well under the hood.