In summary: 700BB motors are popular in the UK and increasingly so in the US in offshore classes.

Under rule changes proposed for Australia, they will become the spec motor for 12 cell sport hydro, offshore and out board tunnel.

This article is based on information provided by Marco Iannarelli, Walter, Marek Pleskacz, Allan Shillito of Astec and Andy Kunz of RC-Hydros. It outlines similarities and differences in the 700BB turbo 8.4v and 700 Neodymium motors which despite like model numbers are different motors.

The consensus is that they provide similar results with the 700 NEO the better choice for enduro, with the 700BB 8.4v more suited to sprint style racing and generally more robust.

The 700BB 8.4v is actually a 750-size motor. On 12 cells drawing 25 amps it puts out 225watts out and free revs at 25,000 rpm with efficiency of 75%.

A typical mono 2 boat (12 cell) with the BB motor commonly uses an Octura X445, X642 because off the high torque (but lower revs), will give a four to five-minute run time. The 700BB 9.6v is for longer run times.

The 8.4 is a much higher revving motor. For 4 or 5 minute racing the 8.4 motor is the only one worth touching. An X642 with 2400mah cells will run 5 minutes. You can push it down to 3min run time using an Octura x450 - the speed goes up too.

In the USA these motors are in their second season of sprint style racing and still going strong.

The 700 Neodymium is actually a 700-size motor. It offers higher power level over the BB version. For comparison outputs about 250 watts at higher revs with efficiency of 77%. Typically it is used for 5 min. in mono and 4 min. in hydro.

In 1997 it won the NAVIGA world championship in Mono 2 - 12 cells - 5 minutes

This motor can be run with up to 20 cells. However, unlike the 700BB it cannot be over-propped or the brushes and commutator will burn up. For 12-cell enduro the x440 is the best option. A x642 will give higher speed but is the absolute maximum and you need to run the hull loose and check the motor is not too hot.