This is not a build but a modification of a cheap Chinese boat just for fun, I got a bit bored of scratch building projects as they take so long especially as I am not retired yet.

The NDQ 757 Coastal Brother 1:25 Radio Controlled Racing Power Boat cost about £25 each from Amazon.

These boats have a basic 27mhz radio and two 380 type motors which have forward and reverse and you steer by powering one motor or both for straight ahead.

I bought two of these boats as they are light and about 24 in long, one to convert/upgrade radio, esc and brushed motors. The second was to upgrade radio, esc for brushless motors.

The brushed motor version I put in two higher rated motors (390) with cooling fans built in, but same motor diameter but longer body I had to modify the mounts, kept same couplings and shaft/propellers. I did remove trim tabs (fixed) and replaced the straight running adjuster for a racing rudder.

The brushless version is the same but has brushless motors 2x 2845 2600KV sensor less
Specifications:
KV(RPM/Volt): 2600KV
RPM: 50000
Max Current: 42A

The boats ran well but trimming needs attention, as hull is curved up at the back so trim tabs down, to prevent proposing, in-fact at one stage the boat left the water, but need to distribute weight towards the bow.

Tried on 3S (11.1v) for brushless went well but got slightly hot after 10 mins.
7.4v for brushed also got slightly hot after 10 mins., and went nearly as well as the brushless. Surprised!!