Centreboard maintenance

[snoopebj]

Not much consolation to those with existing C.B. problems but after reading these accounts of stuck and corroded C.B.'s and subsequent hassles in jacking up boats removing rollers etc I've taken a couple of steps in avoiding/postponing the same fate.
For the last year I have been hosing up the C.B. casing after each sail (as well as the critical trailer wheels and bearings.) I have put together an angled hose extension for this purpose.
Also whenever I change a point of sail and need to adjust the C.B. I'll drop and raise the C.B. to its' max a few times to exercise it. In fact I'll do this sometimes when boredom sets in!
Not sure if any of this helps but it's a comforting ritual.
cheers

[Andrew]

Hi Emrys, That sounds good, prevention's better than cure. I always hose everything down after a sail too, to reduce corrosion of any metal, even stainless and especially any dissimilar metals next to each other. Reckon regular use of the board would also detect any problems early on, then it could be removed easily for maintenance before it gets worse.

I noticed my board mostly rusted around the stainless pin and in the narrow crevasses where the polymer slip pads were,,the rest of the board was hardly corroded at all, it was coated with something like epoxy paint. The stainless bolt has a plastic bushing this may have helped isolate galvanic currents,,it seems that most of the problem could have occurred by the protective coating being worn down and crevice corrosion under the side pads - a tight gap that can let saltwater stay in there long after the boats out.

Guess that my board was an original one. It looks salvageable, so probably go with hot dip galvanizing it..

[snoopebj]

Hi Andrew
You're right the main enemies are crevice corrosion ( a la Ozzie) and electrolysis with dissimilar metals.
With prevention I guess hosing as mentioned up the casing to reach the crevices (pads)
With electrolysis maybe attach a thin sacrificial annode to the C.B. bottom leading edge.
Ideally of course we would all have stainless centreboards (and the whole world will live in peace and harmony!!)

[Yara50]

Yara has an aluminium centreboard, and so far it has been wonderful. Slight loss of righting moment when down, (compared to steel), but easy to lift.

[Andrew]

A small sacrificial anode sounds like an interesting idea on conventional steel plate boards. Has anyone tried one yet?

[Andrew]

Here's an update on Terias centerboard maintenance-restoration progress

Stage 1) Decided to do the pivot pin assembly first as the hole in the board had some pitting etc and had expanded beyond the original 16 mm internal diameter. Bought a new 60x10mm 316 ss bolt with washers and nut. The plastic bushing would have to be custom made. i took everything (pivot bolt and centerboard) to a small engineering firm (recommended by marine shop). They drilled out my pivot hole in the plate a bit larger. Then they machined a plastic bush to fit, it's got more beef on it than the original one, some clearance was left between bush and pivot hole to allow for the galvanizing layer to come. They also machined 2 plastic side washers. The plastic is hard white stuff (acetate?) which can be immersed, (they had made some for yacht steering assemblies before). cost $30

Stage 2) Hot dip galvanising centerboard. I prepared the plate with angle grinders-file and also some paint stripper in case any epoxy paint was left on there. Dropped the plate in at the galvanisers today, they will acid bath it before hot dip gal. quoted $55, that's the minimum lot price here (usually $2/kg for larger lots)

I did it in this order cause i don't have a 17-18mm diam drill bit to ream out the pivot pin hole in the centerboard.

Cheers
Andrew

[Andrew]

Here are some photos of Terias centerboard repairs. I also marked the lowering rope in 2 spots, one about 3/4 raised and another 1/2 raised.

Took her out sailing and it worked well. The boats performance was heaps better than without the board on the first sail. I liked the way the board balanced the rudder on different points of sail. On a broad reach the 3/4 raised position helped her track straighter in following seas and reduced weather helm allot. The 1/2 raised position seemed to work nicely on a reach.

[snoopebj]

Great job and well documented.
Very helpful
Thanks Andrew

[Andrew]

Thanks for the feed back , if anyone's interested i have a blog going about maintaining and sailing the Teria. some more details on the centerboard refit are at

http://teria563.blogspot.com.au/2014/01 ... refit.html

Posts in the blog may smooth the way for anyone thinking of repairing their boat, its indexed with post list, keywords, popular pages etc I just add to it as i go along and sometimes edit/update older posts if relevant info comes in for the old topic

Cheers
Andrew

[Seawind]

I have just read Andrew's excellent blog on his centerboard and was astounded that his board had square edges! No one has commented on this. Surely this is not the standard board for I563's? Easy to manufacture but very inefficient.
Charles