The 4.2 litre
class is based on the 1970's Holden V8. Except for the camshaft
which may be of any make or grind, only standard Holden replacement
parts are permitted. The cylinders may be overbored a maximum
of 0.040 inches. Compression may be raised by the removal of metal
from the block or heads. (no domed top pistons) with a minimum
combustion chamber volume of 53ccs. The standard intake manifold
must be used with one four barrel carbie, either Rochester or
Holley. Porting, polishing or larger valves are not allowed, nor
is magneto ignition. Balancing, stronger springs and dry sumpimg
are permitted. Fuel is restricted to pump petrol. Though 320 bhp
has been registered on a dyno by a legal motor, 300 is generally
quoted. Engines will run safely up to 7200rpm.
The kilo record
is 200 kph (124.4mph)
A 4.2 litre
litre & 6 litre
The 5.2 &
6 litre classes are restricted only by engine capacity and av
gas or methanol may be used. Super/turbo charging is allowed,
but a penalty applies. A factor of 1.7 is applied to actual capacity
to determine the class capacity. Thus a 3 litre supercharged engine
would make it the equivelant of 5.1 litre (3 x 1.7 = 5.1), and
therefore run in the 5.2 litre class.
for the 5.2 litres is 214 kph (133.3mph)
The record for the 6 litre class is 230.4 kph (143.2mph)
6 litre boat Mistic
GP hydro is
the only class where dimension and weight requirements are specified
(though a general rule allows a maximum length of 9.14m / 30 ft
for all hydros). The maximum length of a GP is 8 metres (26' 3")
and if supercharged the boat must weigh no less than 1080kg (2380
lbs). Engines must not exceed 510ci (8.26 litres), there being
no penalty for supercharging, be iron block, two valves per cylinder,
with methanol allowed.
cockpits are now required on all new hulls, those built prior
to this rule may still be raced. A hydro field may thus comprise
of Rear Seaters and Cabovers with and without reinforced cockpits.
Inboard tunnel hulls (also known as KTs) are generally raced with
hydros except in a hydro championship event. All hydroplanes must
be driven by a propeller acting against the water. Nitrous Oxide
and nitro fuels are allowed only in Unlimiteds.
many hydros running in Australia which do not meet the above class
requirements. These compete in non-class events, as indeed do
the class specific boats from timr to time.
has a long and colourful history of hydroplane racing, dating
from stepped hulls of the early 1900s. The NSW Hydroplane Club
continues the tradition by fostering new boats and drivers.
to boat menu
GP boat Latimer
with a reinforced cockpit
Older rear seater
Swap, without a reinforced cockpit