Fairing the keel


Hey all – I hope you all have gotten out on the water this spring!

I contacted Computer Keels to see about getting a template for fairing the Express 34 keel. Here’s what they said.

Regards – Greg

Thank you for your interest in Computer Keels products for your Express 34.  We do not have a Compukeel Template Kit for that boat, but having made templates for other Express boats and having talked with Schumacher, the profiles on the Universal Template kit match what the original profiles are.  Because the keel is a semi elliptical, you will probably find that one pattern or two patterns will have sufficient profiles to make  templates for multiple elevations on the keel.  I have attached further information on the Universal template kit below.

Winners understand that the shape of the keel is as crucial to boat speed and pointing as the proper sail shape. The keel provides the major reactive force that allows the power created by the sails to move the boat efficiently. Boat performance suffers from errors in either the keel or the sail shape. Cost, technology, and OSHA regulations complicate making the keel as designed. On many boats the difference between the designed keel shape and the manufactured shape is greater than the difference between the shape of a new and a worn out sail. Fairing a keel or trying to evaluate the accuracy of the shape without templates is simply guessing. Accurately controlling the keel thickness without Computer Keels Company’s patented templates is difficult and subject to errors.
Computer Keels’ patented products make it practical for you to make very accurate keel templates, and have a well shaped, symmetrically faired keel. The product design minimizes the skill and tools required to make accurate templates. Computer Keels provides patterns and detailed instructions which explain how to make templates from picture mat-board reinforced with wood strips. This construction technique produces very accurate templates that are quickly fabricated with a minimum amount of skill using a hand saw, utility stapler, ruler, and utility knife. The keel refairing instructions explain how to fair your keel, and provide tips to minimize the time to fair the keel. A power combination sander/buffer and an orbital sander are needed for the keel fairing. The easiest way to fair the keel is to plan on spending several hours per session, allowing time between sessions for materials to cure and harden.  Plan on five to ten separate sessions. Many people start the project when the boat is hauled-out, and complete grinding down the high spots when the weather is cold. Filling of the low spots and final finishing can then be done in better weather conditions before the boat is launched. Another alternative is to have your local marina or fiberglass repair shop do the work for you. Information is also included that explains how to reduce or eliminate keel blistering.

We do not presently have a Compukeel™™ Template Kit or Assembled templates for your boat. The Universal™™ Template Kit was designed to create templates for boats for which offset data isn’t available, and for boats with cast iron keels. The hydrodynamic profiles included are similar to those on many of the best performing boats and are readily adaptable to most boats.  Each pattern (chordlength) contains eight or ten profiles precisely drawn in ink on Mylar. One pattern normally is required for each template. The instructions explain how to select the appropriate profile, and turn it into a template. For simply checking the symmetry and shape of the keel a template near the top and one near the bottom of the keel works well. For fairing the keel, one template for each 10 to 20 inches of keel height is recommended. Patterns range in price from $40 for short chordlengths up to $100 for longer chordlengths.

Universal Template Pattern
If you would like help in selecting patterns for the Universal™™ Template Kit, knowing the keel chord length at the top and bottom of the keel, and the vertical distance between the two chord lengths will facilitate making the selection. To measure the chordlength, hook the end of a tape measure on the trailing edge of the keel. Pull the tape measure forward to the point of maximum keel thickness. From the point of maximum thickness forward, the tape measure should be held parallel to the centerline of the boat. Sight across the tape measure to determine the location of the leading edge of the keel.

Visit  http://computerkeels.com/uniorder/univers.htm for available chord lengths, pricing, and  to order.

Because rudders are much smaller than the keel, are made of fiberglass, and the angle of attack can be changed to get the desired response, fairing rudders has less impact on performance than the keel.  Most people find that simply rounding off the leading edge, squaring off the trailing edge and block sand or filling  any waviness or hollows provides about 80% of the benefit of fairing with templates.  Additionally, boats with a thru hull rudder often have rudder profiles that are a compromise shape because of the rudder post size and location.  If you feel you need greater performance improvements from your rudder, the Universal Template kit is your logical choice.

The following regatta results demonstrate the significance of the keel on J/24 performance. In a six race regatta, the winning skippers of each fleet (J/24, SONAR, MORC, PHRF, etc.) raced in J/24s to determine the skipper of the year. The nine boats were rotated among skippers after each race. Every race was won by a boat having a keel faired using a template. The top three boats had keels faired using Computer Keels patented templates with an average finish of 3.25. The average finish for the non-Computer Keels faired boats was 5.75. The 1987 MORC International Overall champion faired his keel using Computer Keels patented templates.  The 1990 Catalina 27 National champion faired his keel with Computer Keels patented templates.  The 1992 J/24 Mid-Winter champion faired his keel with Computer Keels patented templates.  The 2000 J80 North American Champion faired his keel with the Compukeel™ ll Templates. Many division winners at Key West Race week and NOOD regattas have faired their keels with Computer Keels patented products.  Isn’t it time that you faired your keel with templates for improved boat speed and pointing?  If you have any questions, please write COMPUTER KEELS COMPANY, P.O.Box 39757, Edina, MN 55439 or call (952) 829-5670 or visit us at http://computerkeels.com.

Again, thank you for your interest in Computer Keels products for your boat.

Copyright 1982-2014 Computer Keels Company


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s