Forum - Keel and Centre Plate - Centre Plate dimensions

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Centre Plate dimensions 12Sat 06 Apr 2013 12:03:38
garyg garyg Thu 20 Dec 2012 15:28:54 Help!

I have been able to get my employers engineering dept to plasma cut a plate to the dimensions posted on this site, but we only have 6 or 10 mm plate available. I think someone has successfully used 10mm plate but need to be sure before steel is cut. I don't really want to use 6mm as I fear the plate will have too much lateral movement.

Can anyone confirm suitability of 10mm, I'd welcome opinions




Mark Mark Thu 20 Dec 2012 19:28:20 Hi Gary,

I used 10mm plate on Sophie and this was OK for me but others have suggested that this would not fit into their keels. Perhaps Sophie's keel slot has widened a bit over the years due to corrosion.

If your keel slot is accessible then the only thing I can suggest is that you measure how much clearance you have in your keel slot. Maybe use a half inch (13mm) thick bit of wood and see if it slides in and out freely.

I would also say that the dimensions on the site were the best I could do on a badly corroded plate. The one I had made needed a little bit of fine tuning with an angle grinder on the top middle bit( where it angles ) to make sure it went fully up.
garyg garyg Mon 24 Dec 2012 13:50:29 Hi Mark.

Thanks for the reply; unfortunately I will be unable to lift the boat until January and the plate, which will be taken from the attached drawing, will be cut over the Christmas period. I also thought that corrosion to the ballast keel may help but it looks like its going to be a fingers crossed exercise.

With best Wishes for Christmas and the New Year

Centre Plate dimensions
Mark Mark Mon 24 Dec 2012 18:56:11 Gary, you may need to round off the top right hand corner of the plate (the corner above the pivot). Because the pivot is 40mm back from the front edge of the plate, the top right hand edge will rise up a bit as the plate is lowered and there might not be enough clearance between the top corner of the plate and the hull when the plat is lowered.
Mekicevica Mekicevica Wed 09 Jan 2013 17:47:38 Happy New Year everyone.
I went through a centre plate replacement recently.
Here is one trick, as yet untested, that I learned from the problems I got with the new plate:
Instead of doing the front side rectangular, make it slanted back. This way you avoid the potential problems of the fitting into the front of the keel, where the fitting is tighter.
I used 8mm plate and still the new plate does not retract fully (there may be other reasons for this). And the plate still moves sideways a bit when sailing downwind. But then I just lift the damned thing.
Sometimes I wish I could convert my Mekicevica into a long keeler....
garyg garyg Wed 16 Jan 2013 21:40:03 Mark / Luis.

Thanks for your replies. The plate has been cut from 10mm plate and I have followed your recommendations to diagonally cut the corner above the pivot point. With snow forecast this weekend I do not think I will be venturing outside to start the strip down but I will let you know how I get on.

Many Thanks and Regards

garyg garyg Sat 23 Feb 2013 14:22:14 I am struggling with the removal of the old very rusty center plate on my boat - to be named Dekho Na in memory of my Father who died last month. Removal is not helped by the seizure of the 8mm plate bolt. I am therefore considering the removal of the keel and going for a full refurbishment as Luis has done.

Removal of the bilge keels which need minor repairs should not be am issue as the bolts are accessible from under the berths, however the bilge is completely glassed over and I am not sure if this is as built or something done by a previous owner.

So that I may avoid pitfalls I'd appreciate comment regarding the glassed in keel bolts and approach taken by anyone who has dropped the keel on their boat.

One belated note of thanks to Luis as I did not realise that the drawing I used for cutting the centre plate was originally drawn by him, hope I haven't transgressed copyright!!
Mekicevica Mekicevica Mon 25 Feb 2013 18:00:08 Hi, Gary:
It is normal that there is some filling of the bilge covering the keel bolts. That stops them from rusting by being in the bilge water all the time. It should be soft stuff that can be removed with chisel and hammer without damaging the fibreglass underneath. At least it ws in my case.
To remove the keel you need to find eight bolts:
front one on the small bilge under the potti;
two pairs in the main bilge
one pair only accessible by drilling holes on the centreplate box. These are the ones that get really rusty because unless they were covered with fibreglass, they are in the water all the time;
one other bolt just behing the centre plate box.
Good luck, it is a hell of a job. I got professionals to help me in this one.
PS: the drawing of the centre plate was actually posted by Mark
garyg garyg Mon 25 Feb 2013 22:04:56 Luis.
Thanks for the comment. I read your blog regarding keel removal and, from the pictures you posted, it looks like the three bolts at the rear of the keel sheared off on removal, was that the case. However, as you had the keel re-tapped to take 10 mm bolts shearing may not have been a major issue. Also, on reassembly were you able to do anything to protect the three exposed bolts.
Finally, did you have any problems removing the plate bolt as the one on Dekho Na is badly seized and I will be making judicious use of a blow lamp next weekend.
Your blog is appreciated as it is reassuring to know I am not the only one prepared to undertake an insane refit.
Mekicevica Mekicevica Wed 27 Feb 2013 22:14:11 Hi, Gary.
Removing the old, rusty bolts was indeed hard work. When eventually I got them out I had to make wider tapered holes. I used the opportunity to change to metric.
For the new bolts don't use stainless stell, because that would cause galvanic corrosion. Just plain soft steel, and cover the bolts with plenty of epoxy and glass fibre.
It was reassuring that the guy in the boat yard said: "You'll never be able to get that keel out again!" That was exactly the idea.
Removing the centre plate pivot bolt was no problem at all.
Check also Jakob's blog. He also did a keel refit amd posted very useful photos.
garyg garyg Fri 05 Apr 2013 17:15:12 Hi Luis / Mark
We have had quite severe weather here for some weeks which I am glad to say is passed. This means I am able to start keel removal and I was glad to see that the builder placed red plastic covers over the five fwd keel bolts which are visible through the translucent fibre glass in the bilge. However this is not the case with the three bolts at the stern end of the keel. To find them, with a guesstimate of position based on Luis and Jakob's photos of removed keels, I will have to dig out all the glass around the hollow post (fairing) which supports the bridge deck and through which the centre board lifting chain passes. Before I do so can you confirm that these bolts are positioned one on each side of the post and the aft one behind it. I am hoping they will not be underneath the post as this will mean care to not damage it and also some surgery to re-secure it.
As ever thanks for your advice.
Mark Mark Fri 05 Apr 2013 22:32:50 Hi Gary,

I've never taken the keel off of Sophie and the bolts are so thickly glassed over that I can't tell where they are. Sorry about that.

Hopefully Luis can provide you with the info.
garyg garyg Sat 06 Apr 2013 12:03:38 Thanks Mark.
I have been reading Luis' blog and his description of keel removal has answered the question - a bit of trial and error to locate the bolts.

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