Sail Calculator Pro v3.53

This is a new version of the sailcalculator (3.52), 4/20/07, which allows for auto conversion of metric entry data to the units (feet, pounds) used by the calculator and adds enhanced error information. Version (3.0.6), 7/30/07, corrects a "bug" in version 3.0, "Part 4", improves duplicate detection, and (in 3.0) automates the updates process. The older version is available at sailcalc1087.html. Please report any problems with this to carl@carladler.org. Note: I can no longer correct malformed or "raw data"* submissions.
*Please submit data by using the "submitIt" button below.

This space available

Welcome to

Carl's Sail Calculator v3.53.
Go to http://www.image-ination.com/sailcalc.html for the most recent update!

MacOS users some versions of IE may not function correctly with category option below, use FireFox if you have a problem
Carl's: WaterLogged
Simple Sail Game (free)
For Multihull Sailors

You can use it to look up sailboat parameters in a large database of boats, or enter your own boat and compare to the others. In addition, for any boat you can calculate a set of quantities that will help you measure how it will perform.

Version 1 of the Sail Calculator maintained a database of the calculated figures of merit submitted by the user and reverse calculated the basic data such as LOA, sometimes with a 5% error. Starting with version 2 the basic data is archived and the figures of merit are directly calculated from it. Since the basic data was not previously archived, the reverse calculated values are used for 500 of the boats included in the current database, many of these have since been corrected by users ( as of 10/29/07). Also all data included was entered by users , I do not check their entries so I cannot warrant their accuracy. . For these reasons if you see any of the basic data that you know to be incorrect for any of the boats please send the corrections to carladler@image-ination.com.

Version 2.5 adds the ability to restrict the calculator (Parts 3 and 4) to a specific category of boats. Version 2.6 adds the ability to calculate Pounds per Inch Immersion. Version 2.7 refines the function of the 'optimiser' in Part 4.

View Source for acknowledgements and open source statement.

This version was last modified on and contains boats.

Part 1: When you select a boat, its parameters display below in Part 2.
Display:

All Boats

Cruisers

Racers

Racer/Cruisers

Cruiser/Racers

Select one boat in each column above, and press to compare.

Part 1B: Enter values for your boat. Note that length overall, length of waterline, and beam are in feet, displacement in pounds, and sail area in square feet do not use , ' or " in your numbers, which should be in the form, for example, 1000.50.

!You now can enter your values in metric units (meters, square meters, and kilograms), if you follow each number entered with the letter "m" and then click on the page anywhere outside the entry box. Doing this will convert each of your entries to the native units (feet, square feet, and pounds0) used by the calculator. Thus if you enter 1000m for the displacement in kilograms, it will be converted to 2204.6 pounds, by this method.

Boat Name (e.g., Hunter 33.5):
LOA Hull Length or Length on Deck (LOD)		LWL		Beam		Disp		Sail Area: Main plus 100% Fore Triangle*

*Normally one-half the vertical distance from the deck to the point on the mast
where the jib sail attaches multiplied by the
horizontal distance from the base of the mast to the bow.

Press to see the derived quatities displayed below in Part 2.

Part 4: You can find your 'ideal' boat by doing a weighted search. For example, you can search for the boat that has the highest combined normalized scores in 'Motion Comfort' and 'Sail Area to Displacement' giving one a 60% weight and the other 40%, or whatever! You can also do low searches, for example, you can search for the boat that has the highest normalized score in 'Motion Comfort' and the lowest normalized score in 'Capsize Ratio' giving one a 30% weight and the other 70%, or whatever. A 'high' search is done as a percentage of the highest boat in the parameter. So, if the boat with the highest Sail Area to Displacement has a value of 48, a boat with a Sail Area to Displacement of 24 would receive a value of .5. For a 'low' search it is the inverse. That is, if the boat with the lowest capsize ratio has 1.3, a boat with a capsize ratio of 3.9 would receive a value of 0.33. Only boats within the specified length range and in the database chosen in Part 1 will be searched. You can also eliminate any type or types of boat from those searched by entering their names separated by commas in the first field below. For example, entering 'Herreshoff,Bolger' would eliminate any boat with either name in its name. The results (the top three boats, their scores and the average score for boats searched) are reported in the text area below.

Optout Field:
Minimum Length: \| Maximum Length:
	Capsize Ratio	Hull Speed	SA/Disp	Disp/LWL	LWL/Beam	Motion Comfort	Pounds/Inch
Weights:
Search Direction:

Part 5: Prop Sizing and More

The material here is taken from an article by Dave Gerr NA in Sail (February 2001. pp. 81-84) entitled Sailing Screws. To really understand the numbers calculated below you should consult this article or his book Propeller Handbook. A note on the Maximum Sailing Speed calculated below:

This is also from Gerr's work. He has determined that the classic formula for Hull Speed ( 1.34 Sqrt(LWL) ) does not always apply, the 1.34 is not a constant, leading to, in some cases, much higher speeds. However, Gerr observes:

"For instance, a boat with a DL or 80 might have a SL multiplier of 2.11, but it couldn't achieve that speed under sail unless it had not just sufficient sail area, but the stability to stand up to such a sail area in the wind strengths needed to deliver the required power. Not an easy task!"

To use this form, select a boat, enter a Horsepower and Prop Type.

Boat Name

Horsepower (bhp)

Prop Type

Press to see results displayed below

Classic Hull Speed	Knots	Gerr's Maximum Speed Under Sail (SL)	Knots	Gerr's Maximum Speed Under Motor	Knots
Optimum Prop Diameter	Inches	New RPM

You can use PayPal to make a a donation of any amount here:

TOP

Find all boats which have		> <
and		> <
and		> <
and		> <
and		> <

Derived quantities. (Click on each box for an explanation in the box below.)
Displacement to LWL	Hull Speed	Sail Area to Displacement
LWL to Beam	Motion Comfort	Capsize Ratio
Sailing Category		Pounds/Inch
Click on one of the derived quantities for an explanation here. After using the "compute" button send the full report to a friend's email address: by clicking here: