DaySailer.org Forum

My DS II centerboard has two problems. It appears to be solid fiberglass but I am not certain. The S/N is XDYD77400674.

1. The bottom edge was dragged on a road surface and about 1/2'" is abraded off. It has also swelled about 1/4" in this area. My thought was to grind it down a bit, round the edge and add a layer or two of glass.

2. There is a 1/8" wide split under one of the tangs that apparently had been previously repaired. The screws fastening the tang grip solidly but the area is swelled about 1/8" due to the split. My thought here again is to grind it down to the original width and add a layer of glass and also epoxy the opening of the split.

Photos of the damaged centerboard can be viewed at www.photobucket.com/georgecenterboard

Any advise or suggestion would be most appreciated.

Hi. George. I've been doing a little looking around for this same subject since I have a bit of repair on my CB and my rudder too. I came across this article from Jamestown Distributors (Durable edges for CB and Flip up rudders - page 7) :

http://www.jamestowndistributors.com/us ... 00_448.pdf

Back in my Widgeon days I repaired a CB abrade by putting an epoxy + filler 'prosthesis' on the missing area, then applied a couple layers of epoxy saturated fiberglass cloth over it and ground it to match the original shape. It, worked, but the JD idea sounds stronger, so I'm going to try it. As far as the tangs go, your idea sounds pretty sound to me. If I have this problem, and the hold is a concern, I'll drill a hole into the CB and insert the wires in the board (similar to a '79 Widgeon rope config) and epoxy right over it. That should last longer than I do.

Regards, Bruce

3M makes a material called "High Strength Marine Filler". This consists of chopped strands of fiberglass in a creamy polyester resin matrix.

I've used this to good effect in building up edges of a centerboard. Unlike a fairing filler, this stuff is pretty tough, and I would not hesitate to build up edges up to, say, 1/2" elevation.

My preferred method for applying it to an edge is to use a strip of wax paper to be able to massage it into the desired rough shape until it's cured. For the particular section on the CB the added curvature means using several narrow strips of was paper and to plan on sanding off the ridges that will form between them. Still beats trying to form the filler free-hand with a spreader.

Don't worry if the CB ends up a bit thicker at the front than when it left the factory. The "foil shape" of the original is a bit of a joke, and in general, you'd be better off with something where the thickest point is approx at 1/3 the width and where the front edge approximates a circle between 1/4" and 3/16" diameter.

That would give you some room to apply a strip of glass to the font for reinforcement (not the rear half - the CB is too wide there already).

To approach a fair curve, you can apply a fairing compound, like SystemThree's QuickFair, between the edge and the middle of the CB. The trick there is to apply it thick with a notched spreader and sand the grooves quickly to the desired shape. Only then do you fill them and do the fine sanding.

If you use any epoxy, you'll have to paint the CB to protect the epoxy from UV.

I would encourage you to make this kind of repair first, and cut your teeth on the task of getting something like a fair curve and smooth surface. When you've gained the experience (and have a CB that is somewhat functional again) you could do worse than building a fully air-foiled one from scratch - using the excellent link in the post above.

You might find this video from Rooster Sailing has some ideas you could use for repairing the tip of your centerboard. http://www.youtube.com/watch?v=nqDHK0Vc ... ature=plcp

Thanks KC and Greenlake, I like both options better than the one I dug up!
Time fix'n><Time Sail'n=

This is a little off topic but I thought you would like to know that your CB control lines are run exactly like mine. My boat is a 1974 O'day DS II. I've not dropped the CB but after seeing your pictures I may do it if and when I paint my boat.

I forgot I had posted a diagram of the "quick fix" CB fairing I did two years ago. (The leading edge part of the diagram doesn't show the lower surface - it should obviously be symmetric. The blue stuff is added filler, except the blue circle at the leading edge is just intended to show curvature, I dd not replace that much material. The wedge at the end is unsupported high-strength filler, extending beyond the CB outline by about 1/2", actual size. Again, the diagram makes it look like I removed the existing trailing edge - instead I just added stuff around and behind it).

I did that with the boat on its side. I have since removed the CB and found massive gelcoat cracking around the head. I've ground those out, filled with the same high-strength filler I mentioned in this thread. There were also some dings on the tip of the board ("I perfectly remember there are no rocks on this beach - crack!") and other surface issues on the foil part of the blade, but the basic additions had held.

While I was at it to fix the blemishes, I decided I would try to improve a bit on the "quick fix". This mainly involved adding more fairing compound (SystemThree QuickFair) on the leading half of the CB to put the maximum thickness at about 1/3, give the whole surface a fair curve (to hide the two "corners"). I did grind away some of the gelcoat on the rear corner, but this is just a quick fix: it's still far too thick at that point compared to a real foil section.

I did add about 1/8" thickness (on each side) in the middle - I used a quick template to make sure I didn't exceed the width of the CB trunk.

It's sealed with a coat of epoxy and awaits paint. I've just repainted the hull using SystemThree's Water-based WR-LPU paint and I have some left over for this job. Otherwise, spray paint (as in the video) would look really attractive.