It depends on a lot of things. To maintain on water you really need something close to a 500 liquid. That being said you can still run a fair stretch with smaller machines but you will feel yourself slowing down. The biggest thing when running long distances of water is making sure your bellypan is sealed. As soon as the spray works its way into the clutches you are going down. The other thing to watchout for if you are a first timer is a big lip/drop off onto the water. You only get a few good bounces before you go down as well unless you can get them under control.