When I posted asking for suggestions on how to change the springs, this was Matt Miller's response:
"All I can say is good luck on the spring replacement. It is difficult. "
Bob, I would love to know how you managed to make it easy. I assume you don't have an extra hatch near the centerboard well.
I don't know if trailers have different heights, but on mine I didn't have to jack up the hull to remove the centerboard, there was enough clearance below.
Jordi; and all!
It takes a helper!
On my trailer I have to lift one hull and have my helper put it on a sawhorse to remove the centerboard. I can do this by hand (or with my back) so it only takes a few seconds. I just lift from the stern.
Then I remove the centerboard pivot screws and the centerboard comes down. I don't have to remove the lifting rope but it makes handling the centerboard easier. If you need to replace the rope now is the time to do this.
The hardest part is dealing with the top spring retaining bolt from inside the hull. After numerous trials when I was going the “bungee" route I have figured this out. Get a small handed 13 year old cat sailor (one of my daughters) to remove the bolt. You may have to scrape the silicone from around the bolt first.
Attatch the new springs, with the spacer if you have one, or with a short piece of tubing that fits over the top spring retaing bolt to a length of wood or something. I used an old batten but almost anything will do. Use duct tape or other tape.
Attach the other end of the springs to the centerboard with the lifting line between the springs. Make sure you have a spacer.
Lift the centerboard as high and rearward into the centerboard slot as you can and block it there. Just leave enough space to get your stick with the springs attached up in there. Push the stick up at the same time as the centerboard so you are not twisting the springs off the stick. Lie on your back looking up into the centerboard well.
One of the big secrets! Use a strong light from the top inside the hull shining through the hole where the top bole goes. From the other side have your helper push the bolt into the top hole just enough to see the bolt from underneath(a flashlight from the bottom helps here) and using your stick push the spring spacer onto the bolt at the top. Have your helper run the bolt home and you are just about done. Make sure you have a rubber washer outside the top holes on both sides of the bolt and use a LITTLE silicon to seal. Don't over tighten the bolts here and squeeze all the silicon out. The aircraft nuts won't come out so they only need to be snug.
Twist the stick to get it off the spring/spacer (you did not use too much tape did you??)
Bring the front of the centerboard down into position without putting much tension on the springs, this take a little finesse, put the centerboard pivot pin into place and put the screws in to hold the centerboard in place.
Try to cycle the board and see that it works.
Put some silicon on the screws that hold the centerboard pivot pin (again a LITTLE silicon) and tighten them down.
Lower the boat and enjoy a beer!
I hope that is clearer than mud! It is not as hard as I make it sound.
Think this through and ask me question if you can't visualize this.