# Maximum Velocity of a Sailboat **URL:** \ **Category:** Factual Questions\ **Created:** [March 19, 2016, 11:15pm UTC](https://boards.straightdope.com/t/maximum-velocity-of-a-sailboat/749591 "2016-03-19T23:15:26Z")\ **Posts on this page:** 7\ **Page:** 2
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [March 23, 2016, 7:48am UTC](https://boards.straightdope.com/t/maximum-velocity-of-a-sailboat/749591/21 "2016-03-23T07:48:44Z")
Yeah, Dogzilla (aka USA-17) is probably one of the most amazing boats, and I do suspect one of the most efficient. Sadly it is unlikely she will ever sail again. She could never survive the winds and speeds the later AC-72s, and the new AC-50’s sail in, so would never reach the absolute speeds they do, but in her own right, very hard to match. Optimization for the precise course to be sailed has reached astounding levels of sophistication. Oracle have used large scale GA and ensemble sims to optimise their hull shapes, modelling the impact of everything from the weather to the rules of racing and their impact. And indeed, the fastest absolute shape was not the one best to win the race. ---
**Author:** ![CableCutter](https://avatars.discourse-cdn.com/v4/letter/c/35a633/32.png) [@CableCutter](https://boards.straightdope.com/u/CableCutter)\ **Post date:** [March 23, 2016, 9:31am UTC](https://boards.straightdope.com/t/maximum-velocity-of-a-sailboat/749591/22 "2016-03-23T09:31:00Z")
> [@Francis\_Vaughan](#): > > Yeah, Dogzilla (aka USA-17) is probably one of the most amazing boats, and I do suspect one of the most efficient. Sadly it is unlikely she will ever sail again. She could never survive the winds and speeds the later AC-72s, and the new AC-50’s sail in, so would never reach the absolute speeds they do, but in her own right, very hard to match. Here a neat size comparison: [![](https://sailinganarchy.com/wp-content/uploads/2015/03/size-matters.jpg) ](https://sailinganarchy.com/wp-content/uploads/2015/03/size-matters.jpg) ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [March 23, 2016, 8:16pm UTC](https://boards.straightdope.com/t/maximum-velocity-of-a-sailboat/749591/23 "2016-03-23T20:16:33Z")
> [@Ethilrist](#): > > Looks like overall, the determining factor is actually hull length, as in, the longer the hull, the faster the boat can sail. Boats in a race are probably limited in how long the hull can be, so then the determining factor would be wind speed. I believe that holds for all surface boats. Even the biggest ones, like aircraft carriers (or supertankers). Even if you added a couple more nuclear power plants to the _USS Nimitz_, you still would have a maximum speed limit. ---
**Author:** ![Hail\_Ants](https://avatars.discourse-cdn.com/v4/letter/h/dc4da7/32.png) [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)\ **Post date:** [March 24, 2016, 12:21am UTC](https://boards.straightdope.com/t/maximum-velocity-of-a-sailboat/749591/24 "2016-03-24T00:21:21Z")
> [@t-bonham@scc.net](#): > > I believe that holds for all surface boats. Even the biggest ones, like aircraft carriers (or supertankers). Even if you added a couple more nuclear power plants to the _USS Nimitz_, you still would have a maximum speed limit. It should be noted that the key technology that allowed for such dramatic increases in sailing speed with those ultra-modern boats like USA-17 was building them out of carbon fiber. Carbon fiber has a strength-to-weight ratio much higher than any metal or fiberglass etc. The main ‘sail’ is not a fabric sheet but a rigid-wing like on an airplane (with a mast 220 feet tall\*!\*). And they are catamarans or trimarans which means both not having to have a large hull displacement nor the sail balanced by a heavy lead keel. Its sort of comparable to battery-powered hovering drones. Before Lithium-ion designs there was no battery/motor with a power ‘density’ (power-to-weight ratio) that was even close to being able to lift its own weight. ---
**Author:** ![donkeyoatey](https://avatars.discourse-cdn.com/v4/letter/d/e47c2d/32.png) [@donkeyoatey](https://boards.straightdope.com/u/donkeyoatey)\ **Post date:** [March 24, 2016, 1:17am UTC](https://boards.straightdope.com/t/maximum-velocity-of-a-sailboat/749591/25 "2016-03-24T01:17:13Z")
Is that an African or a European sailboat? ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [March 24, 2016, 1:18am UTC](https://boards.straightdope.com/t/maximum-velocity-of-a-sailboat/749591/26 "2016-03-24T01:18:51Z")
Another thing about the catamarans used in the recent America’s cup is that they don’t obey the hull speed equations given by Stranger. They can go much faster than the same length monohull boat. > **[Advantages of Catamarans and Catamaran Hull Speeds Calculation](https://www.brighthubengineering.com/marine-history/83095-advantages-of-catamarans/)** > > Catamaran hull speeds are very high due to several factors. The advantages of catamarans are great, resulting in fast speeds. Open bridgedeck catamaran hull speeds are not the limiting factor on speed, and many catamarans routinely exceed the hull... ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [March 24, 2016, 5:02am UTC](https://boards.straightdope.com/t/maximum-velocity-of-a-sailboat/749591/27 "2016-03-24T05:02:40Z")
Carbon is a pretty important component, but the place it was a game changer was probably in the foils. You can build a very strong composite cat from a great many materials, and even wood is capable of being used for a very light and strong result. For instance the C class cat Miss Nylex was a game changer (and arguably the progenitor for the US-17 and the AC-72s). But her wing was made of wood. (Not they they didn’t already acknowledge how important weight was, and the impact of carbon fibre would have in the future.) The loads on the foils are silly, and the foils are almost heroic in strength and construction. Dogzilla’s wing was bigger even than the Spruce Goose, and a heck of a lot lighter. Of course none of these were the first wing masted multi-hulls in the AC. That milestone goes to Dennis Conner’s Stars and Stripes. Even he built two cats, one with a wing, one with a conventional sail. Just in case. And a key designer of that boat (Morelli) was involved with Dogzilla and the AC72s (albeit for the Kiwis in the last AC.) Both Stars and Stripes are still sailing (but neither with a wing.) What is interesting about Dogzilla is that its design deliberately exploited the Deed of Gift rules to get a very long water line length. Sitting upright in the water the armas (outriggers) were only just touching the water, and the centre hull took the weight. The centre hull was designed with a 90 foot LWL. So it fitted the DoG rule. But the armas were closer to 120 feet long, and very skinny. One powered up only the leeward arma was in the water, so the boat suddenly had a massive increase in LWL, and a corresponding increase in displacement limited speed. No that such exploitation has not been part of the design of boats for decades. The [magnificent J-class](http://www.jclassyachts.com/galleries) (although not DoG boats, they still had a 90’ LWL) but once heeled their huge overhangs extended the length very significantly. [Previous page](https://boards.straightdope.com/t/maximum-velocity-of-a-sailboat/749591.md?page=1)