Swinging, swinging keel

Ozzie · Post by **Ozzie** » Sun Apr 25, 2010 8:29 am

Sailing over the easter break and my centre board as usual at end of season would not lower due to some minor marine growth around the slot. After a bit of scrapping and leverage with a screw driver it came down minus the pull cable.

CB is gal steel. After 6 years in the briney there is no visible rust. All i do is spray it with fish oil every haul out and anti foul on the leading edge. It gets no marine growth in the very narrow slot. I think the spot where the welded ring broke is where the movement between it and the shackle takes place.(considerable when rocking on a mooring all day.)

Question to those metalurgists / boilermakers among you. What is the best way to fix it. Just weld another ring on, repair existing ring, I cant weld a stainless ring to ordinary steel can I?. It will be treated with 2pack when finished as I don't want to remove it and have it re-galled.

Any other advice welcome.

Yara50 · Post by **Yara50** » Sun Apr 25, 2010 11:56 am

Luckily I have never had to fiddle with my centreboard, and can't get to it without taking boat off trailer, so I am speculating.

How would you weld a steel loop back on if you don't take the boat off the trailer? I imagine it would be a difficult weld, which would be less than perfect, setting up a future corrosion situation. It is in a bad corrosion spot, humid, wet and dry, etc. You could weld a stainless ring, but that would probably be worse, due to the dissimilar metals junction.
So I envisage two possible solutions:
* Take the centreboard out, clean up and do a good heavy duty weld and sandblast and re-gal the whole thing. Or maybe even replace with Stainless or aluminium like Yara.
* Drill a hole in the c/b, dollop lots of cold gal in the hole, and run a 7 X 7 (Flexible) SS cable through the hole with a swaged loop. Not perfect, but maybe more reliable until one day you drop the whole board out.

Ozzie · Post by **Ozzie** » Sun Apr 25, 2010 1:42 pm

Ta Ian
I had not thought about the second option, but I think that may be the go for now. I figured the dissimilar metals might be a problem but was not sure if the welding would be feasible. I have arc welded with stainless rods before and got a useable result, but that was stainless to stainless.

I may sleeve the wire with some plastic or rubber if it will fit to stop the abrasion of the cold gal.

You may remember my mate who bought the Court 750. He made an excellent rear stand. I was going to stand the back of the boat on that, and drive the trailer forward just enough to swing the board down. There will be ample room for clean up and weld, or drilling as now looks the case

Only thing I'm not sure of is the clearance at the side of the CB ... maybe a hole and a HD flat SS shackle may be a way around that if the clearance is tight.

I do not expect the CB to last forever, but I am impressed with the lack of deterioration after six years in the drink. Chalk another one up for the mighty little Investigator

Will photograph my progress.

Yara50 · Post by **Yara50** » Wed Oct 06, 2010 10:40 am

I will add some photos, care of Roberta (Palamida). Also the original tech report on changing centreboards. Drawing of board if you wish to replace. (Copy picture and paste in your picture editor to zoom and see the dimensions.) Yara has a light aluminium one, some people use stainless steel, others back to the original galvanised steel.

TecReportChangingCentreBoards.pdf: (209.18 KiB) Downloaded 609 times

: Washer plate; keel%20washer%20plates%5Flaminex (Custom).jpg (32.2 KiB) Viewed 9663 times

: keel%20washer%20plates%5Flaminex (Custom).jpg (32.2 KiB) Viewed 9604 times

Centre board drawing.pdf: PDF version centreboard drawing; (196.64 KiB) Downloaded 506 times

geoffr · Post by **geoffr** » Sat Oct 16, 2010 10:13 pm

Many thanks for posting the drawing of the centreplate.

When I take possession of my new (SH) Investigator in November, I may have to remove my plate and clean it.

However, there's a chance I may have to replace it altogether.

If so, I have a friend who can work such miracles in metal. I understand the choices are SS, aluminium or galvanised steel. Do you, or anyone else out there, have a preference -- if so why? Clearly there would be a weight difference between these, and a cost.

And is the plate 10mm thick?

The drawing you have attached appears to have the measurements on it, but the image is so tiny that when it's blown up the numbers are illegible. Are you able to post a higher resolution drawing please, or point me to where I could get one or download it please?

Many thanks,

Geoff

geoffr · Post by **geoffr** » Sun Nov 21, 2010 9:58 pm

Hi folks:

In my last post I mentioned a need to check a sticking centreplate on the Investigator I had just bought.

The good news is that the problem was very easily fixed, once I paid a fellow club member for the use of his hoist to lift QUMBU off her trailer.

Then I dropped the plate down to reveal a twisted swage and thimble, which I cut off and replaced with a new one on the same SS wire (which was fortunately long enough to allow me to do this).

The plate itself is made from galvanised iron with minimal rust, and only a little play in the bolt. So no need to replace!

Overall, the repair took about an hour, and gave me a good chance to also inspect the underhull area and slot.

I hope the photos are of interest to other owners.

Cheers,

Geoff

Yara50 · Post by **Yara50** » Wed Mar 16, 2011 5:07 pm

I trawled our old site and retrieved a thread by Robert on replacing his centreboard. Here it is as an attachment.

Centre board replacement.pdf: (453.74 KiB) Downloaded 653 times

Dr. Peter · Post by **Dr. Peter** » Thu Sep 27, 2012 10:52 am

It is fortunate our boats will sail quite well without the centreplate and there is that old saw about gentlemen never sailing to windward but I'm no gentleman and quite well isn't the best it could be is it?

I know this is an old topic but I am having problems with my centreplate not dropping. It is irritating because for Pip it is a real hit and miss affair. When I first got the boat it didn't work. I lifted the boat up and forced the plate with a wheel rim remover. A bunch of crap fell out but not rust. The plate looked brand new - bright red paint and swage and shiny ss wire. The plate worked OK for a while and then I needed to do a jump on the cabin sole to make it go down.

Given the relative new condition of my centreplate I think a lot of Pip's troubles are due to the centreplate slot getting packed with mud due to bouncing on the bottom. This has happened from time to time; the last time in the Werribee River. That is some real glutinous mud. My anchor would not penetrate it.

I looked carefully at the posts above and wondered something. Would it be possible to lead a small diameter line from the plate where the lifting swage is attached out the bottom of the slot and down the back of the boat where it could be used to pull the plate free of the slot? It might save a swim.

For those of you who have got close and personal with your slot could it work?

Regards,

Yara50 · Post by **Yara50** » Fri Sep 28, 2012 9:28 am

Sounds like the mud is your problem. Not good as it will grind away at everything. If you have a water blaster, maybe get into the slot at home and see how much mud comes out. One problem that has been noted, is that if you ground the c/b whilst sailing, the leeway can cause the plate to bend and then stick. If it was free before, and you have not tightened the pivot bolt, then it is not an over-tight bolt.
Wouldn't want a line back to the stern as it will vibrate and rub on your gel coat. Rather fix the cause if you can.

Not a fan of taking the ground with a T/S, as you cannot be sure of the bottom material, and can damage the gel coat. I have invested in inflatable dinghys to get ashore. (and that is a whole other story!)

Dr. Peter · Post by **Dr. Peter** » Mon Oct 01, 2012 10:08 am

Yara50 wrote:Sounds like the mud is your problem. Not good as it will grind away at everything. If you have a water blaster, maybe get into the slot at home and see how much mud comes out.

Wouldn't want a line back to the stern as it will vibrate and rub on your gel coat. Rather fix the cause if you can.

Not a fan of taking the ground with a T/S, as you cannot be sure of the bottom material, and can damage the gel coat. )

Ian,

I think mud is the cause of my particular drama and while I agree that taking the ground is not good, it is part of how I expect to use my boat. I guess it depends on what one is used to: The swing keel on my Hartley 18 was a massive object and nothing ever stopped it swinging free. My friend's boats have hydraulic rams on their drop keels and anything in the way would be pushed out; not so with the lightweight centreplate on Pip. I guess I need to adjust my expectations and plan accordingly. The water pressure idea could work between sailing although it would take modification of my trailer to ensure I could access the slot. The drama is what to do if it occurs while sailing. I don't fancy a swim which is why I suggested the other line to the stern.

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