CS17 centerboard removal & replacement

[Randy Jones]

How difficult is it to remove and replace the centerboard on a CS17?  I'd like to remove the board to make repairs but I'm wondering what I might be getting into.   

[Peter HK]

Shouldn't be hard if built to plan. Undo a few screws, prise off the ply caps, knock out the pin and remove the board (after removing lines etc). The only problem might be the bedding compound...if you didn't build it, you won't know if someone used a tough compound like 5200 or something more sensible like sikaflex. Even with a difficult bedding substance the worst situation is having to repair the doublers and redo the caps- a pretty trivial job.

Depending on what you need to repair on the board it might be worthwhile lifting the boat somehow (eg with a couple of blocks and tackle) and letting down the board to repair in situ.

Cheers

Peter HK

[PAR]

Working under the boat with goo, fabric and a bad back don't sound like fun. Assume the cap is bonded with 3M 5200 and just take a hack saw to the caulk line. With luck, you'll be able to stay between the case top and the underside of the cap. Again, the same issue with the pivot pin covers on the side of the case. Maybe a hot putty knife will work better (heat it with a torch), especially on the pivot pin covers. Once the cap and covers are off, you know what to do.

[paul_stewart]

You can view my experience with that on our CS20 at CS20DawnPatro.blogspot.com/2010/09/centerboard-refinished.html

http://cs20dawnpatrol.blogspot.com/2010/09/centerboard-refinished.html

[Randy Jones]

Thanks guys,  I didn't build it and don't even have the plans, but it looks like the cap comes off clean so I'll give it a try.  Repairs are too complex for me to do beneath the boat.  I'm going to reglass the bottom end that I damaged on a concrete ramp, feather the trailing edge to eliminate vibration, add some weight, and install some type of wear strip to tighten up the gap between the board and trunk.  I'll be back if I screw it up.

 

[Tom Lathrop]

Thanks guys,  I didn't build it and don't even have the plans, but it looks like the cap comes off clean so I'll give it a try.  Repairs are too complex for me to do beneath the boat.  I'm going to reglass the bottom end that I damaged on a concrete ramp, feather the trailing edge to eliminate vibration, add some weight, and install some type of wear strip to tighten up the gap between the board and trunk.  I'll be back if I screw it up.

 

Randy, Some years ago I started to reinforcing the leading edge of my boards with epoxy soaked Nylon or Dacron line.  It makes an essentially indestructable edge that will survive just about anything with no more than a scratch.  Instructions are on the forum somewhere.  Maybe someone can point you to it.

[hokeyhydro]

Thanks guys,  I didn't build it and don't even have the plans, but it looks like the cap comes off clean so I'll give it a try.  Repairs are too complex for me to do beneath the boat.  I'm going to reglass the bottom end that I damaged on a concrete ramp, feather the trailing edge to eliminate vibration, add some weight, and install some type of wear strip to tighten up the gap between the board and trunk.  I'll be back if I screw it up.

 

Randy, Some years ago I started to reinforcing the leading edge of my boards with epoxy soaked Nylon or Dacron line.  It makes an essentially indestructable edge that will survive just about anything with no more than a scratch.  Instructions are on the forum somewhere.  Maybe someone can point you to it.

Beefing up the outer edge of a canoe paddle with epoxy soaked nylon line does make the paddle semi-rock proof, as one can use the paddle to shove off various obstacles without splintering it. Should work on centerboards and rudders as well.

"feather the trailing edge" RED flag! Foils running in water should not be "shaped" to a feather edge, but the aft flanks of aforementioned foil should be a fairly straight run and the tender edge left square. On a CS size foil one could have a square edge close to 1/8", although I tend to hit around 3/32".     

[John Turpin]

Randy, Some years ago I started to reinforcing the leading edge of my boards with epoxy soaked Nylon or Dacron line.  It makes an essentially indestructable edge that will survive just about anything with no more than a scratch.  Instructions are on the forum somewhere.  Maybe someone can point you to it.

I put an epoxy-soaked polyprop line on the edge of both my centerboard and rudder blade.  Details are at:  http://www.svbluepeter.com/lapwing3.htm

[JeffM]

Randy, I'm not exactly sure what you mean by a wear strip, but if you beach the boat, or anchor or moor so she will dry out, beware of doing anything that will obstruct your cb slot.  I have several times been faced with a board jammed by sand and pebbles washed up into the trunk by small waves when the boat was grounded.  (It's a real bummer to be suddenly unable to sail to weather).  After nearly destroying the edge of the board hammering it out of the slot, I actually imbedded a machine screw into the trailing edge of the board near the lower end so I could hammer the board loose without destroying that thin edge.  I am not sure whether your wear strip would be a benefit by keeping stuff out of the slot, or be detrimental by holding stuff in the slot, but on balance I suspect the latter.

[Randy Jones]

I should clarify a few things.

"Feather" wasn't the correct term. The existing trailing edge of the board is about 3/8" wide with a rounded edge and I was just going to reduce it enough to kill the vibration.  I hadn't thought about squaring up the edge, but that makes sense (Can't believe I suffered through fluid dynamics in college and missed my chance to apply it).  I'll shoot for a 3/32" square edge. 

As for what I called a wear strip - I just need to close the gap between the board and the top of the trunk to keep it from banging side-to-side in light weather. I'm thinking a strip of ceder, cork, or leather near the top of the trunk where nothing will get fouled in it. I won't mess with the gap at the bottom since it works well and has never jammed.

I like the epoxy soaked nylon rope idea and will look at using that on the end of the board.

Thanks all for the great advice.

[PAR]

Remove the board and when re-installing it, fill the gap on each side of the board at the pivot with sheets of Teflon or other, self lubricating plastic sheet material. The total gap should be an 1/8" so it doesn't vibrate. Weight wouldn't be necessary with the down haul properly rigged. This said I eliminated the down haul on a CS-17 by using a weighted board. It takes about 20 pounds to weight the board enough to insure is sinks with authority. You can glue an 1/8" aluminum strip on edge, onto a slot on the trailing edge of the board, which once faired will make a nice, fairly tough trailing edge with naturally crisp edges.