See full version: What is the Average Speed of a Sailboat
The second factor is the length of the boat. It's the second rule of thumb: the longer the boat, the faster it goes. Each sailboat has a maximum hull speed, which it can't exceed (in theory). The hull speed is determined by the length of the boat.
nautical miles / time = average speed necessarymore
Here are the maximum hull speeds for different monohull lengths:
2100 - 1500 = 360 minutesmore
360 / 60 = 6 hours Your average speed should be: 50 NM / 6 = 8.3 knots
This kind of speed is not a typical boat speed. The extra speed element designed for rum-runners was meant to outrun everyone as they carry on their smuggling activities.
Beaches and waterfronts do not post speed limits for boats. This is because a lot of factors can change the speed limit. Factors include the type of boat, time, type of waterway, and more. [links]
Double that speed to 30mph, and the fuel consumption will rise to 11 gallons per hour! Notwithstanding, 24-foot motorboats are capable of running at speeds of more than 45mph. [links]
Before you depart make sure that your Membership card coverage is current and that you have a working hour meter on board (if you don’t, they can be installed quickly and affordably). more
For this example we will assume the following scenario:
We are operating out of San Diego Bay in a 24’ boat with 100 gallons of fuel on board and at an average cruising speed of 22kts. more
* Author’s Note: This is the method I use to figure out the range of my boats but ultimately it is up to you, the boat operator, to accurately find the range of your own vessel.
The point here is that it’s important to measure your gallons per hour, and NOT rely solely on the fuel gauge. In fact, on my boats, the hour meters fit perfectly where the fuel gauges used to be.
______________________
I am assuming you don't have much experience at sea by the question. First of all, be careful. I strongly suggest you read @TimLymington before mine.
The duration of a crossing depends of your boat and luck with the weather. You can be lucky and get a nice 20 Knots wind, or unlucky having 0 Knots or worse 30 knots or above. You should check the dominant wind and direction on the route you want and their average speed on the time of year you're going to travel. Considering those, your sail boat efficiency and the most likely point of sail you're going to use (don't forget you will be making more miles if sailing against the wind), give all these some safety margins, and you can make a more accurate estimation.
2 persons is a small crew. There are no stops between Liverpool and Azores. It means a lot of time steering and not much sleep. more
Take supplies that will last at least twice the amount of time you calculated for the trip. If you're not at half way and you loose sails, you can always return on engine (remember that engines can also fail). Choose the supplies wisely. It's nice to take fresh fruit and vegetables, but those won't last long. Take dehydrated, canned, etc. food.