Hi, I reguarly launch at Bucklands Beach, the (Barracuda) Public Ramp (Any Tide with a jetski at that ramp) Many trips I have been around Rakino to the back of the Noises and frequently to the Maria's along with other trips to the Ahhaas. Realistically on my Yamaha FX HO 160,I would have know problem getting to Gannet, if I found it was worth the trip, usually there is sufficient fishing as close as Motuihe.
Typically most trips out to Maria would only use approx $25 of fuel at about 80 kph give or take sea conditions for fuel consumption, plus it is a hell of a lot of fun the journey there and back, let alone the buzz of jetskifishing.
Keep up the motivation and do not hestitate to PM me when you are ready to kit out your ski, as I am local in East Auckland and can point in the right direction of what are the most practical options for jetskifishing.