Centerboard Repair - Which method would you use?

Sep 24, 2018
2,549
O'Day 25 Chicago
I managed to convince the yard to move the blocks that were preventing me from dropping my c/b without charging me a reblocking fee. The screws came out easier than I thought they would. Someone had used silicone to "seal" them. The leading edge of the c/b cracked off a long time ago. Rusted steel plate is showing through.

  • Boat has been sitting on the hard for the past couple of years. Is that enough time for the centerboard to dry out? Leading edge was the lowest point
  • Would you use filler and then cloth or just straight cloth for this repair? It's a 3/8-1/2" SQ/IN area that's about 20 inches long
  • What would you seal the screws with? It needs to seal but still be serviceable in the future. A stuck screw could become a timely project
 
Jan 11, 2014
11,323
Sabre 362 113 Fair Haven, NY
Boat has been sitting on the hard for the past couple of years. Is that enough time for the centerboard to dry out? Leading edge was the lowest point
Most likely the interior is dry. You could drill a couple of ¼" holes to check and then fill with thickened epoxy.

Would you use filler and then cloth or just straight cloth for this repair? It's a 3/8-1/2" SQ/IN area that's about 20 inches long
Depends on the depth of the crack. You'll need to grind the glass back on the leading edge in order to maintain the foil shape.

What would you seal the screws with? It needs to seal but still be serviceable in the future. A stuck screw could become a timely project
Which screws?
 
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Oct 22, 2014
20,995
CAL 35 Cruiser #21 moored EVERETT WA
Do the "screws" go all the way up into the boat bilge or terminate in the stem keel?
If just the stem keel then you can pot them in thickened epoxy. If they go all the way through then you have an issue of water intrusion into the bilge. Most suggest 5200 for it's water sealing properties. Removable function is possible just not easy.
 
Sep 24, 2018
2,549
O'Day 25 Chicago
The screws are 1-1.25" long so they're definitely not hitting the bilge. The existing screws heads are a bit stripped with just silicone. 5200 is a death sentence for them. 4200? Sikaflex? Butyl?
 
Jan 11, 2014
11,323
Sabre 362 113 Fair Haven, NY
The screws are 1-1.25" long so they're definitely not hitting the bilge. The existing screws heads are a bit stripped with just silicone. 5200 is a death sentence for them. 4200? Sikaflex? Butyl?
4200 or 4000. You'll want caulk with moderate adhesion. 5200 is an adhesive. Silicone is the devils caulk.
 
Jun 9, 2008
1,771
- -- -Bayfield
The O'Day 25 has two stainless brackets port and starboard that hold the pivot pin in place with the additional use of two wedges on each side which wedge the pin in place. You need to support the swing keel when you unbolt the bolts that hold the brackets in place so that the keel doesn't fall (especially on you). Most likely the fiberglass keel/centerboard is dry after sitting so long, but you will know that after you start grinding into the damaged area. I haven't seen a photo of the damage, so I cannot exactly tell you how to proceed, but usually you need to grind out the area, dry it out if it isn't already dry, and then fiberglass the damage up with polyester resin and cloth or matt building it up as you go. After it is cured you grind/sand it smooth and apply some fiberglass putty and let it cure and then sand smooth. You need to clean after all your grinding/sanding with acetone before applying fiberglass, BTW. You can finish it off with whatever is on the rest of the keel (gelcoat, epoxy barrier coat, antifouling paint - whatever - again no photos to look at). I think I recall the photo had rusty bolts. Make sure you replace them with ss bolts. You should use a polysulphide caulk on the brackets. 3M101 or Life Calk, by Boat Life. They are recommended for under the waterline use (never silicone). 3M's 5200 is an adhesive and you don't want to use an adhesive caulk for such things as they are not designed to be separated every after use.
 
Oct 22, 2014
20,995
CAL 35 Cruiser #21 moored EVERETT WA
Ok ok.. no one likes to play with 5200. It is recommended for underwater use. This is his centerboard and removal and replacement is not a normal maintenance task on a yearly bases. It is highly likely that he will not be removing this in the future - unless he seriously damages it and then it is again a major repair.
  • Permanent bonding – above and below the waterline
  • Industry standard for over 50 years
  • Offers extended working time
  • Achieves handling strength in 48 hours
4000 and it's faster curing 4200
  • High performance, medium strength bonding allows for disassembly
  • Excellent UV resistance
  • Color stable sealing
  • Above and below the water line applications
  • 15-20 minute skin time helps keep jobs moving quickly
  • Medium strength - can be removed if rework or repair is necessary
5200 will more likely be a permanent fix for this task and if you want to remove there are chemical "debonding" agents as well as heat which tends to soften the caulk allowing more easier removal. It is the center board not a through hull.