My GRX is way slower than a Zapcat - it doesn't have that insane acceleration. No suprising as I went for heavier denier hypalon, have a bow, carry a lot of kit (anchor, spare fuel, tools, etc, etc) and have a 93kg 40hp engine, with a plastic prop.
Tops out at 30kts with 2 onboard and all the gubbins. In the surf I trim the engine right in, put doelfins on the engine and drop the pitch on the prop - better acceleration at the cost of top speed.
Surf on sat was a messy 6-8ft. Having a superb time up until it went wrong! Started when I landed awkwardly, ended up out of the boat, clambered back in, restarted and kept on going. Hadn't realised that the fuel line had severed at the mid point. Engine sucked in water rather than fuel coughed and died.
Got the sea anchor out and started the drift back through the surf to the beach. Took on alot of water, but the boat drained really quickly despite the lack of open transom. Incredible force in the waves and was really impressed by the sea anchor's performance. All came a croper about 40m of the beach where the waves were dumping. Backflip, and an upside down boat on the beach.
Not too much damage - scaped outboard cowl, lost compass, vhf dodgy now?
Biggest concern is that the righting strap parted when I tried to right the boat on the beach! Glad it didn't happen offshore!