Originally Posted by martini
I would guess 30-35 knots, maybe slightly less when you are carrying 10 people and also depends on the size and weight of the cabin you were talking about.
I think that's a bit on kind side
Your lumps have 50% more power to weight ratiocan Iask what your WOT speed.
Also the cabin's gonna act as a windbrake 10 people are gonna weigh 600 kilos 300 litres of fuel safety kit weight of the cabin there's an easy tonne ( note the ease I switched into Metric measurement there for our Eurobuddy
There is another issue when you are driving a laden passenger boat with marginal power namely the engines don't have the snap to properly power off the waves so you sometimes wind up going on and off the plane in bigger seas (not a lot of fun) and 4 strokes don't have the initial snap that 2 strokes have a struggling 4 stroke is gonna deliver power more slowly.
One other point the Artic's don't have transoms which makes it a feet wet boat, make sure your deck and glands are absolutely watertight and you have good redundancy on your bilging system cos you don't need to carry any excess weight with bilge ingress
anyway I'm off back to sea for a month so you guys will have to sort it out without me. have fun