I've been on a couple boats and they were pretty slow. If the water is choppy you'll be lucky to go that fast on a small boat - I believe anyway. I don't actually like boats and I'm not sure what the average speeds are in knots, mph, or kmh... so what can I say.

When I was working in sea rescue(back on the 90's) the mates of SASEMAR get one rescue boat that makes 50 knots that is more or less about 90 km/h and that was the top speed. More than that you cannot resist in the boat(the back hurts of passengers & crew)
Right now the Armed speedboats are getting around 65 km/h. I think they can increase a little the max speed of the boats.

Mass closing ancient tickets with no activity for > 12 months; assume fixed or too trivial.

If this issue is still relevant in current dev build, please re-post.