Centerboard repair needed?

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Centerboard repair needed?

Postby jeadstx » Fri May 20, 2016 1:47 am

tinafred sent me this picture of his wedges.

John
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DS III - centerboard wedge plate.jpg
DS III - centerboard wedge plate.jpg (118.89 KiB) Viewed 7808 times
1976 Day Sailer II, #8075 - Completed the 2011, 2012, and 2013 Texas 200
1952 Beetle Boat Swan Catboat
Early Rhodes 19
1973 Mariner 2+2, #2607 - Completed 2014, 2015 and 2016 Texas 200
1969 Day Sailer I, #3229
Fleet 135; Canyon Lake, Texas
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Re: Centerboard repair needed?

Postby tinafred » Fri May 20, 2016 2:29 am

Do I need to take my centerboard off and redo the edge showing in the image?
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Re: Centerboard repair needed?

Postby Skippa » Sat May 21, 2016 8:24 pm

Mine looked just like that, I was working with epoxy on the bottom so I just painted a layer on the leading edge. Will take a look at it in the fall to see how well it holds up.
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Re: Centerboard repair needed?

Postby Alan » Sat May 21, 2016 11:13 pm

Looks just like my centerboard.

Once the board is pivoted downward into sailing position, the part of the board in the photo will be up out of the water. How does the board's leading edge look (the part that's farther aft when the board is up, that will be in the water when the board is pivoted down)?
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Re: Centerboard repair needed?

Postby GreenLake » Sat May 21, 2016 11:35 pm

A very pertinent question!

If the part that is actually in the water doesn't look substantially better there is a cheap(!) way to give it a bit of the missing profile.
  • Extend the CB.
  • Apply a goodly amount of 3M High Strength Marine Filler to the edge (it's fiber reinforced so unlike other "fillers" it can support itself even when its "proud").
  • Use wax paper or a stiff sheet of plastic to "mold" the filler into a half-circle shape.
  • Sand to taste
You can use the same technique on the trailing edge to get a nice wedge shape (that ends in an 1/8" sharp cutoff, slightly angled, that is, not 90 degrees). The use of wax paper/plastic sheet is really the secret to adding a wedge (you will add .25 to .5" and that should still be class legal and / or fit in the CB trunk)

Now, the third thing you can do:
  • apply an epoxy-based fairing compound to the front 1/2 of the CB. (West System with micro balloons or SystemThree QuickFair).
  • Apply it with a notched spreader and let it cure.
  • Sand into a continuous, fair curve with a long sanding board
  • Fill any grooves with more fairing compound
  • Sand to taste
With these three simple steps you can improve the foil shape of your CB with limited effort/expense. The goal is to get the leading edge to be round, the first half of the CB to be wider so that the max width is about at the 1/3 mark, and the remainder to narrow and taper into a wedge. You won't be able to get the full NACA foil shape, but it will be an improvement over the stock shape. I did this a few years ago and when before the CB was "thrumming" at higher speeds it is now quiet. (The stock shape is too thick in the aft 1/2 of the profile, which limits how closely you can approximate the foil shape, but there should be room in your CB trunk to make the leading half of the board a bit wider, which helps get you closet to an ideal shape).

When done, paint. You can use deck paint if you dry-sail your boat. If you plan to take it overnight, or have it on a mooring, use stuff rated for underwater use.

Then, save up for a real CB or learn how to build one from scratch, to get even better performance.
~ green ~ lake ~ ~
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Re: Centerboard repair needed?

Postby Skippa » Sun May 22, 2016 7:47 am

Not unrelated, Do you use any sealing compound under the metal wedge retainer plates ?
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Re: Centerboard repair needed?

Postby tinafred » Sun May 22, 2016 10:26 am

I am very, very new to the DS3 both sailing it and any repairs. That said, when I took those SS plates off, this is clearly a closed system. The only path for water to enter the bilge or anywhere else is where the 1/4-20 machine screws enter the hull. What I did was placed the BoatLife Calk tip in the hole, checking the inside bilge compartment ensuring a healthy amount of chalk is placed inside. With the screws inserted, I gently smoothed a cone around said screw with my hands thru the inspection port. The smaller screw in the plate never enters the bilge, just screws into the wedge which stays within the centerboard housing. Once the machine screw entry point is sealed with chalk there is no need for more chalk. Now I did back out the screws after the dried for hours to make sure I did not make them permanent inserted screws, then tightened them up. I took my boat out later that week and had no water in the bilge, dry. Prior to this PM the threads were clearly visable inside the bilge thru my inspection port with no goop with gallons of water leaking when I filled the bilge. Initially it was not clear where the water was coming from. There was a ton of old chalk all around the wedge, up into the centerboard housing but not limiting the CB travel. I scraped all this off, cleaned with acetone, and replaced with a lite coat immediately around all three screw sites, more on the 1/4 screw areas.
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Re: Centerboard repair needed?

Postby GreenLake » Sun May 22, 2016 12:52 pm

chalk = calcium carbonate (forms cliffs near Dover and creates dusts when used on blackboards)
caulk = stuff to seal boats with
~ green ~ lake ~ ~
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