Due to their structure and design they can float even with a.
Will i get seasick on a catamaran. I say let the poor kid relax on the beach while you go out on an hour catamaran. That was on a much smaller boat though. Before you make your final decision on catamaran vs monohull make sure to go out sailing in at least 20 knots of wind on both a cat and a mono.
Sydney Harbour is however a dynamic environment and a working harbour so guests should expect to experience some movement. Some people get seasick on monohulls others on catamarans. The more determining factors are the ocean conditions and whether you are taking anti-nausea medicine.
I get sea sick as well and on board a boat is never the time to find out all these well intended recommendations dont work. However itll take extreme tides to misbalance a catamaran. Since we use a specially designed catamaran we have had very few guests get seasick on our trips.
Our non-rolling catamaran is especially nice on the ocean following whales dolphins and sea-lions. Some people may not know or believe that they are prone to seasickness and therefore did not take any proactive measures. They also sell a hard candy with ginger so I would look for that in Hawaii.
I remember one of my early offshore deliveries from Fort Lauderdale to Annapolis on a Lagoon 440 and how I hoped I would avoid seasickness on a catamaran after many experiences on monohull. The boat deos move but not a ton in my opinion. In a mono-hull vessel you are more likely to have a strong rolling effect with the waves.
If you are easily prone to seasickness we would recommend trying a herbal ginger tablet prior to boarding the cruise. It all depends on your body and what its used to. Our boats simply dont roll around like all single hulled boats.