Chances are that at some point you will need to change numbers on a sail. Most of us buy one or more used sails along our sailor’s sailing career. New sails are only typically used at big and impactful events like National Team Trials, or International Competitions (e.g. North Americans). For our local sailing circuit NWYSC, a used sail in relatively good shape is more than enough.
Materials needed
I usually buy numbers from West Coast Sailing. They usually arrive in 2-3 days to Seattle. Remember that you need a pair of each (for each side of the sail), buy the 9” euro cut numbers on any color - the digital version is not IODA approved. You can cut your own numbers if you have the right fabric but I don’t recommend it. You wont’ save much money and you will spend a fair amount of time getting the numbers right (they have shape and thickness rules). So, now that we are done with that you will need the following before getting started.
The new numbers and/or letters (any color)
A regular pencil - you will need it to write on the sail
A yard-stick or a long batten (it just needs to be long and straight) - you will use it to mark lines across the sail
A square ruler - you will need it to measure right angle markings
A measuring tape with metric (if the yardstick does not have them) - you will need it to measure in CMs
A small bottle of adhesive cleaner - you will need it to remove the old numbers adhesive (e.g. Goo Gone, 3M Adhesive Cleaner)
I like using Goo Gone, it’s inexpensive, pretty effective, will not harm the sail, will not discolor the new sail numbers, and it’s a natural solvent made with orange peels. You can easily find it at any grocery store, Home Depot, or Lowes.
NOTE: You need to find a flat, clean and firm surface to lay down the sail (not carpet) like an untextured concrete or wood floor. It’s important because you can not step or put your weight on the sail if the surface below has any give, you will wrinkle the sail. Tables are hard because the sail does not usually fit and it’s likely to wrinkle as you move it around.
The IODA/USODA sail number rules
I will spare you a lot of research time and just say that all IODA and USODA instructions for sail numbers reference Sail Plan Sheet 4/5. However, the document is really hard to find. I was able to find one from 1994 and another version from a random uploaded file in the IODA website that seems more recent. The good news is that the the two match, so it does not seem the rules have changed much. Just to make sure, I also reviewed the dimension limits from the latest IODA Sail and Numbers Measurement Form which is used at regattas to record the inspector’s measurements. Once again, they also match.
1994 Sail Plan Sheet
IODA Website Random Uploaded file
Also part of the IODA Website Random Uploaded file
Putting your numbers on
Notice that while the Sail Plan Sheet shows the numbers aligned to the LUFF (mast or front) of the sail, however almost all sails I have ever seen the numbers are aligned to the LEECH (back or open side) of the sail. I am not sure why this is, but having been to a lot of large regattas I am yet to see a sail with numbers aligned to the LUFF of the sail. So, we will align the numbers to the LEECH of the sail. Here is an updated version of the above diagrams simplified.
PSST Sail Numbers DIY Guide
Start with the PORT side
To make sure you are on the PORT side of the sail, lay down the sail with the LUFF (mast or front) to your LEFT. The oposite way to the image above.
A. Place the Insignia (if not present)
Mark a 1,000 mm. radius semi-circle measured from the head/peak of the sail
There is no specific requirement of where to place the insignia as long as it’s within the semi-cicle
I suggest you align the ‘I’ on the insignia to the edge of the top batten
The insignias should be placed back to back on both sides of the sail
B. Mark the letter guide lines
Mark a 1st vertical guide line parallel to the LUFF and 150 mm from the edge of the sail from top to bottom
Mark a 2nd vertical guide line parallel to the LEACH and 45 mm from the edge of the sail from top to bottom
Mark a 1st horizontal guide line 45 mm below the top batten heading at the same angle as the batten towards the LUFF
C. Place the 1st country letter
Starting on the LEACH side of the sail under the top batten, place the first letter “U” along the horizontal guide 45mm from the edge
It helps to trace the corners of each letter with a pencil on the sail before exposing the adhesive
Only remove the adhesive as you place the letter avoiding any air bubbles. It’s much harder if you remove the whole adhesive backing
D. Mark the spacing between letters and place the rest of them
You need to do this one letter at a time, because the letters are different widths. Always mark the distance after you place the letter
Use the straight ruler to mark a line perpendicular to the horizontal guide at the end of the widest part of the letter you placed
If you prefer mark a box around the number using your straight edge, it's the safest way to make sure your distances are correct
Using the straight ruler mark another perpendicular line 45 mm toward the LUFF of the sail - this is the regulation distance between letters
Place the “S” letter using the 1st horizontal guide you placed and the perpendicular line. Make sure the widest part of the letter aligns with the perpendicular distance line
Switch over to the STARBOARD side
You will need to flip the sail after you place the first set of USA letters. Flip the sail so the LUFF is on the RIGHT hand side.
E. Place the starboard country letters.
Measure 125 mm distance between the end of the “U” and the "A" you are about to place
Use the square ruler to make sure your guides are parallel to each other and perpendicular to the horizontal guide
Follow the same process as before to place the rest of the letters
F. Mark the 1st number guide line
Mark a 2nd horizontal guide line below the country letters, make sure its parallel to your 1st horizontal guide line
Mark a 3rd horizontal guide line 45 mm below the 2nd line - this is the required space between rows
Letters are not always the same height, so make sure the distance from the bottom of all letters to the 3rd horizontal guide is within 40 - 50 mm
H. Place the sail numbers
Place the first number along the 3rd horizontal guide and the 1st vertical guide line parallel to the LEACH
After placing the number mark the spacing to the next number and repeat with the rest of the sail numbers
Finish with the PORT side
Flip the sail so the LUFF is on the RIGHT hand side.
F. Mark the 2nd number guide line
Mark a 4th horizontal guide line below the country letters, make sure its parallel to your 1st horizontal guide line
Mark a 5th horizontal guide line 45 mm below the 2nd line - this is the required space between rows
Letters are not always the same height, so make sure the distance from the bottom of all letters to the 3rd horizontal guide is within 40 - 50 mm
H. Place the last row of sail numbers
Place the first number along the 3rd horizontal guide and the 1st vertical guide line parallel to the LEACH
After placing the number mark the spacing to the next number and repeat with the rest of the sail numbers
Clean up the sail from any remaining adhesive using the cleaner.
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