Adjusting the forestay length inside a CDI Furler

It's not hard to adjust the forestay length inside the CDI, even when the mast is up.

You can do it at the dock with the mast up, which is necessary when tuning the rig to have the right amount of weakther helm. Dave and I did it about three times in an hour earlier in the summer when we decided to re-tune the rig on our P-19 "Redwing".

Redwing's rig was out of tune, because I had changed some hardware. She didn't have enough weatherhelm. So, we lengthened the forestay by about 4 turns before leaving the dock. We sailed her for about 5 minutes and she still had a slight lee helm. So we pulled into a dock, and lengthened it again by 4 turns of the turnbuckle. Ten min;utes minutes later we were back on the water sailing. The hlem was close to having the right balance, but I still wanted just a little more weatherhelm.

So we pulled into yet another dock. We lengthened the forestay by another 2 or 3 turns and in a few minutes we were sailing again. This time the helm felt just right

Here's how we do with Redwing's CDI model FF1. Before you start, review the owner's manual for your model CDI.

Step 1.
Read your CDI owner's manual.
Read the disclaimer!
Get the right tools together

Read the Owner's manual for your CDI Furler. Manuals can be downloaded at

Disclaimer: This procedure works for the way our CDI FF1 is installed, and is safe to do on our boat. It may not be safe to do on your boat. Your boat's CDI may be installed differently. Please read your owner's manual before starting this procedure. You are responsible for your own safety and the safety of your rig. This works for us -- it may not work for you. Use your own best judgement and always procede carefully and with appropriate safety precautions.

Tools and materials: You'll need a small adjustable cresent wrench, screwdriver or thin handled tool, wire cutters, spray cleaner/lubricant, cotter pins the right size for your turnbuckle, rigging tape, spare retaining cooter ring.

It's nice to have a helper who can hand you the tools as you need them, because sometimes you will only have one hand free.

Step 2. Remove the clevis pin in the neck of the drum and slide the drum up to expose the turnbuckle.

Wearing a PFD, sit at the bow with your feet dangling over each side. Observe proper safety precautions so you don't fall overboard.

Untie the foot of the sail from the drum.

Remove the retaining ring that holds the horizontal, long clevis pin through the neck of the black plastic drum. Remove the clevis pin (the pin holds the whole drum assembly from riding up the luff extrusion and keeps the extrusion from riding on the top of the turnbuckle). Slide the whole drum up the extrusion, and hold it up and out of the way.

Don't drop the long clevis pin overboard!

Step 2. Adjust the forestay length by turning the turnbuckle body, just like any other turnbuckle.

Now you can see the turnbuckle. Remove the two cotter pins from the turnbuckle. Use an adjustable wrench to keep the upper stud of the turnbuckle from turning while you turn the turnbuckle body to lengthen or shorten the forestay. The upper stud should have a flat surface machined into it onto which you can put the wrench. The turnbuckle body should turn easily by hand or with a screw driver inserted through it for leverage-- if it doesn't turn easily, you must clean and lubricate it before proceding.. Don't force the body to turn; you may destroy the threads inside the body.

After adjusting the length of the forestay, put new cotter pins in the turnbuckle studs and bend them back to keep them in place. You don't need to put rigging tape over them because the drum covers them adequately.

Step 3. Lower the furling drum and replace the clevis pin

Center the washer that sits on top of the nylon bushing inside the drum (if it's not roughly centered, it will prevent you from lowering the drum completely). Lower the drum back down the extrusion, making sure you straighten out any snags or wraps of the furling line that try to get caught inside.

With the drum lowered, lift the extrusion up so it's not resting on the top of the turnbuckle body. Replace the long clevis pin through the neck of the drum (it should be underneath the end of the extrusion). Replace the retaining ring on the end of the clevis pin.

Wrap some rigging tape around the ring and clevis pin so it can't get snagged on anything and come out.

Re-attach the foot of the sail to the drum.

Voila! You're done....

Fair winds, Judy Blumhorst, 1985 WWP-19 #266, Redwing