Speed is important, it can get you out of harm’s way, and it makes sailing much more fun, but figuring out how fast a catamaran will be able to sail can be tricky. One important aspect is to understand maximum hull speed.

In this article, I have calculated different hull speeds for different lengths of boats; this includes both monohulls and catamarans but focuses on the latter. Here is the catamaran maximum hull speed table:

## Catamaran Max Hull Speed Calculator Table

Length on Water | Displacement Max Hull Speed | Semi Planing Beyond Max Hull Speed | |||

0% | 10% | 20% | 30% | ||

Feet | Meter | Knots | Knots | Knots | Knots |

26 | 8 | 6.9 | 7.5 | 9.1 | 11.8 |

30 | 9 | 7.3 | 8.0 | 9.6 | 12.5 |

33 | 10 | 7.7 | 8.4 | 10.1 | 13.2 |

36 | 11 | 8.0 | 8.8 | 10.6 | 13.8 |

39 | 12 | 8.4 | 9.2 | 11.1 | 14.4 |

43 | 13 | 8.7 | 9.6 | 11.5 | 15.0 |

46 | 14 | 9.1 | 10.0 | 12.0 | 15.6 |

49 | 15 | 9.4 | 10.3 | 12.4 | 16.1 |

52 | 16 | 9.7 | 10.7 | 12.8 | 16.6 |

56 | 17 | 10.0 | 11.0 | 13.2 | 17.2 |

59 | 18 | 10.3 | 11.3 | 13.6 | 17.7 |

62 | 19 | 10.6 | 11.6 | 14.0 | 18.1 |

66 | 20 | 10.8 | 11.9 | 14.3 | 18.6 |

69 | 21 | 11.1 | 12.2 | 14.7 | 19.1 |

72 | 22 | 11.4 | 12.5 | 15.0 | 19.5 |

75 | 23 | 11.6 | 12.8 | 15.3 | 20.0 |

79 | 24 | 11.9 | 13.1 | 15.7 | 20.4 |

82 | 25 | 12.1 | 13.3 | 16.0 | 20.8 |

85 | 26 | 12.4 | 13.6 | 16.3 | 21.2 |

### Table Explanation

**Length on the waterline (L.W.L.):**Length of the boat when measured on the waterline, not to be confused with length overall (L.O.A.), which is the boat’s total length (above the waterline) including bowsprit, etc.**Displacement max hull speed:**The max speed of a boat whose L.W.L doesn’t change when underway and where the vessel’s bow wave is the limiting speed factor.**Semi/Light Displacement or Semi planing hulls speed:**A boat where the bow waves speed limiting factors can be partially overcome and therefore exceed the displacement hull speed.**These hulls usually overcome hull speed by 10-30%**.

#### How to use the Catamaran Hulls Speed Table

- Choose your length on waterline in the left-most column, either in feet or meter.
- Continue reading to your right and stop either at “Displacement hulls speed” or continue to “10,20, or 30%”, depending on your estimated hull efficiency. This will be your calculated maximum hull speed for a semi-displacement catamaran.

## The Formula

First of all, we need to know the *maximum hull speed* for a displacement hull, and from that number, we will be able to calculate how much faster the semi-planing (or semi-displacement) hull will be. This is the formula for Maximum Hull Speed on a displacement boat:

Max hull speed= √((Length on Water Line x g) /(2 x pi)) x 3600/1852

Now we need to add the increased efficiency (loss of drag) of a semi-displacement hull, usually, this is somewhere between a 10-30% increase.

Semi Displacement hull speed = Maximum hull speed * 1.3

**Note:** “1.3” is the increase in efficiency, if you believe you are on the lower end of the scale this would be 1.2 or 1.1.

## How to Exceed Hull Speed

This calculator offers a theoretical perspective, but many other factors such as sail plan, weight, and sailor skill, of course, have a profound impact on speed. As we have seen, a semi-displacement hull can exceed maximum hull speed, but we can also see that it isn’t by much. The next step is to reduce drag even further by utilizing a planning hull.

If you want to better understand catamaran speed I suggest you read another one of my articles called Catamaran speed explained.

## Catamaran Hull Speed Spreadsheet

If you want more info, calculate other lengths, or see the speeds in Km/h or Mph then I suggest you check out this free spreadsheet.

Catamaran Freedom Hull Speed Calculator

Note: If you want your own copy just click, File->make a copy.

## Common Questions About Catamaran Hull Design

Below I will answer some of the questions I receive concerning catamaran hull design. The list will be updated as relevant questions come in.

### Is a Catamaran a Planing hull?

As we have discussed above, a catamaran can definitely have a semi-planing hull, but can it be designed in a fully planing configuration as well?

**Catamarans can be configured as planing hulls, although most sailing catamarans are set up as either semi-planing or hydrofoil. Due to the high speeds needed to get a boat to planing speed, this is only possible on racing sailboats or motor-powered catamarans such as high-speed ferries.**