Higher speed with drag!!

Well - tunnel boats are excellent boats for offshore. When designed for their purpose, they can be faster and more dynamically stable in the rough water than vees. The key is to have a properly designed hull. With potential for much higher aerodynamic benefits, catamarans can really perform well in ocean seas, compared to vee hulls. Either tunnels or vees will, of course, not perform well if the hull is not designed for the intended operating conditions. It is often a great topic of preferential debate, but i would never say that the "monohull is best for offshore."

 

At least in the televised offshore races I've seen (we don't have any such boats around here for more than a day or two per year), the deep-Vs rule in light weather, but the big tunnel cats are often still going in remarkably nasty stuff. They're a totally different architecture than an F1 or an Unlimited though. I have no first-hand offshore experience with these beasts, perhaps someone who does might chime in....

 

From a little bit of research I found that the average speed for the class one tunnel-boats during an offshore race are in the range of 130kn (that's average speed-top speed 150+)
Designing these is a different ballgame altogether though, lots of CFD and most importantly EXPERIENCE- you need to speak to guys who have raced and preferably your name must be Michael Peters!

 

I might have misunderstood you, Matt, but it's usually the deep V's that rule in heavier going, with the big tunnel cats hitting 185 mph + on flatter water . Always individual decisions, though. Some of the cats, as you said, can keep running pretty fast in choppy seas, and a few of the deep V's have been designed with pads aft and multiple steps and strakes that allow them to get pretty high out of the water and go fast in lighter conditions (world . Course layout plays a role, too, as the cats aren't as good at tight turns as the deep V's.

 

You very well could be right, Charlie. Now that you mention it, I think the size of the boat is probably a bigger factor though- I rarely see big V's over 35-40 feet around here, and the 40-50 foot cats seem to get more coverage than the big monos. So I'm probably biased by seeing larger cats and smaller V's.

 

Advertised as one of the fastest offshore racing boats in the world is a 46-ft. Skater catamaran powered by a 4500 hp Lycoming gas turbine with Arneson surface drive propulsion system. The rig has run 175 mph in offshore sea conditions weighing more than 10,000 lbs. empty and 1,000 gallons of fuel.

One of the better offshore catamaran designers has another boat noted as one of the fastest offshore hulls - the AMF Offshore "Miss GEICO" 2 Platinum/Skater designed by Peters. This is a Carbon/Epoxy 40 ft hull weighing 9,500 lbs, with Lycoming T-53 L13 series engines and BPM surface drives (1450X2 hp) - Performance: 185+ MPH.

Vee hulls will not reach these hulls in ocean seas.

 

4500 hp, 175 mph, 1000 gallons fuel. And how far does it go before the rendezvous with the supertanker?

 

When you can go that fast, you cover a lot of distance in a short time.

Here's a remarkable example of a high speed distance run. The average speed included fuel stops and slowing for heavy river traffic, including tugs and barges.

http://www.howardarneson.com/articles/fireonmiss.asp

I've heard unofficial reports of an offshore cat exceeding 200 mph.

Deep V builders seem not to want to be outdone, however. I found that a Fountain Racing deep v set a 1 kilometer record of over 171 mph, with a pair of Sterling piston engines.