DSII CB Downhaul repair

[Nephroid]

Hey everyone, sorry I didn't mean to leave this thread hanging but a lot's happened since I started this project including a career change which has kept me busy. Have meant to finish this for a while.

Long story short, the channel seems to have fixed my CB jamming problem. After putting everything back where it belonged, I was able to consistently raise and lower the CB over a dozen times with no issues whatsoever. Here in this photo you can see the CB back in the trunk w/ the downhaul line sitting comfortably in it's groove. A huge improvement from before.

Centerboard re-installed with the downhaul neatly tucked in it's new groove

CB 1.jpg (13.7 KiB) Viewed 10913 times

I haven't taken her out on the water yet. That will be the real test but I'm optimistic that I've solved the problem.

As a sidenote, it's fascinating to see the CB mechanism in action with the boat out of the water. Couple of observations:

1. My CB won't fully retract unless I give the uphaul a swift tug and keep tension on the uphaul. The extra momentum helps get the board fully up. Otherwise there's too much "stretch" in the system to fully raise the CB. I've gone to marking the uphaul with a piece of tape so I know when the CB is fully up.

2. Likewise at full extension the CB sits well past vertical. This can be seen in the below photo where it looks to be at least 20 degrees forward of vertical.

Fully extended CB is well past vertical

CB 2.jpg (44.39 KiB) Viewed 10913 times

[GreenLake]

I don't know whether there's a situation where you'd ever want the CB forward, so you might want to mark your downhaul...

[Champlaner]

Mine is vertical with about 2" of downhaul "capacity" left. I read somewhere that the forward position might work well for heading up light air, but I had to deep-google for that and I'm not really that curious. Though I might have to figure out whether to put tension on the uphaul as well to keep it vertical (?)

[GreenLake]

The forward position would put the CLP forward, which would tend to increase the weather helm (or compensate for the CE having moved forward). I can't quite see how this works in light air, so I'll note that as a question in the "Seamanship and boat handling" section, where we might get input from others.

[AlaskaDS]

What line are you using? Seems my original was 5/16” 8mm dacron double braid, and will be replacing that.

[Nephroid]

Just a quick update if folks are considering this repair. While cutting the channel has done wonders for keeping the CB on track, it did have an unanticipated outcome that's worth keeping in mind.

By cutting a shallow channel into the edge of the CB, I effectively reduced its radius and thereby the circumference along which the uphaul / downhaul lines are wrapped. This doesn't really matter much for the downhaul but it does introduce 1/4"-1/2" of "slack" in the uphaul cable. Since mine is a braided steel cable with an eye loop at the end it makes it somewhat difficult to adjust the length. The result is that the CB doesn't fully retract into the trunk and sits maybe 1" below the hull. Not really the end of the world but I'm a bit mad at myself for not realizing its effect sooner.

In retrospect, I probably should have moved the tang back a bit on the CB to compensate. Will probably try to rig an "above deck" solution for this season as I think about a more permanent fix this fall.

[wynnron1]

My centerboard jammed yesterday in the up position and I broke the down haul trying to swing it down. This is super helpful! Question for anyone who might know…how does the end of the downhaul line attach to the centerboard edge? There is a clear pic in this post that makes it look like the rope simply disappears into a hole in the edge of the centerboard, but how is it attached? Thank you!

[RaleighRancher]

What you don't see in that picture is a second hole that has been epoxied over. The hole in the leading edge intersects a second ~1" hole through the side. The downhaul line goes into the smaller hole in the upper leading edge and is tied off in the larger transverse hole, then embedded in epoxy.

To drop the centerboard for the repair:
-unscrew the retaining plates from the bottom (exterior) of the centerboard trunk,
-scrape away all the old caulk that holds the plates in
With the plates out of the way, you now have to remove the wedges that hold the pivot in place. They are likely secured with caulk.
-Cleat off the uphaul and run a line or strap around the boat to hold up the aft end of the centerboard.
-Get comfortable on your back underneath the boat.
-with the longest utility knife you have, or a couple of sharp chisels (1" and ~3/8" worked for me), slowly dig away the caulk holding the wedges until they come out. I spent hours with a utility knife and then discovered the chisels worked much better - but you just want to use steady hand pressure, not pounding with a hammer, lest you chisel into the gelcoat & glass.
-lower the centerboard by easing the uphaul and loosening the strap around the boat.

Now you can drill out the transverse hole in order to remove the knot in the downhaul line and begin replacing it.

[steveI]

I have the same problem with the centerboard stuck in the raised position because the downhaul line comes off the edge of the nose of the CB and jams between the CB and the trunk. Pulling hard on the downhaul makes it jam even tighter. Machining a groove into the periphery of the edge of the nose for the line to ride in is way beyond my ability. There must be an easier way to prevent this from happening. Please tell me what this is. Also, how do I get the line out that is jammed really tight in the gap between the CB and the trunk?

[GreenLake]

Making a groove is actually fairly simple. I wouldn't call the process "machining". And because it's out of sight, you won't get judged on your handiwork.

The groove itself can be made by sanding with a bit of coarse sandpaper wrapped around a dowel. If you prefer a bit of assist from a tool, get what is called an "electric file". It's effectively a very narrow belt sander, but with an exposed tip. That should allow you to get the groove started, but the dowel should be the final step to get a consistent diameter.

As you probably don't want to cut into the centerboard too much , you might want to build up the edges of your groove. The material of choice is 3M High Strength Marine Filler. It's a vinylester paste that is reinforced with chopped glass fibers. You mix a bit with the catalyst and apply it to the top edge of the CB to build up the material a bit. You can use your (gloved) finger to already suggest a rough groove shape. The material is non-sagging and hardens the same afternoon. You don't need to paint it, just sand it as described to get the final shape.

For prep, you need to remove the CB from the boat (many threads discuss how this is done) and then you need to use very coarse sandpaper to roughen up the surface where you want to put the High Strength filler. That simply gives a bit of better grip.

There's very little you can do "wrong" with this fix. The groove doesn't have to be very deep, half the diameter of your downhaul is plenty. It should not be too narrow. It is fine if the top of the CB becomes a bit wider with the added material - that will help reduce the gap between board and trunk. Just as long as there's enough clearance remaining to move the board.

If your line is jammed now, removing the board will help you free it. Hopefully, with the fix, that will be the last time you need to do that.