Centre plate.

[dur]

Happy New Year to all.

As you see I have dropped the plate out of the boat this winter.

It is not really in bad condition but inevitably there is a bit of corrosion along the leading edge (which suffers most from mud and grit when the boat takes the ground on her drying mooring). The area around the pivot bolt is thinest at around 5/16" thick compared with 1/2" of the rest. Plus the hole is twice the size it should be.
I don't want to put the plate back in as it is so I think my options are either to have a new plate made or to have the bottom 6 or 8" cut off and a new piece welded on. I would be grateful for any comments / experience especially as to whether welding a piece on is a good idea what with mixing metals etc. I have not priced either and it could be that there is not much in it. Either way it will be hard work as the thing weighs about 80 or 90 kg and won't go in the car.

Another thought as part of the process is to increase the thickness around the pivot bolt both so it lasts longer and to increase the bearing surface on the bolt. Maybe I should increase the thickness along the whole leading edge which would also reduce the gap slightly for mud to pack up the slot?

 

[Seajet]

My Anderson 22 has a lift keel consisting of a 3/4" mild steel plate ( originally galvanised but this scrapes off ) and a cast iron ballast bulb, direct vertical lift rather than swing like yours.

After nearly 30 years, my plate was looking pretty corroded despite a lot of attention with every steel treatment going - I keep the boat on high trestles for access to the plate.

An ex-shipbuilder chum welded the pitting for me, but it barely gave an extra season, as you suspect disimilar metals are against it.

Importantly, I have since found that zinc anodes stop the corrosion - which was appearing on my new, galvanised keel after only a couple of seasons - dead in its' tracks; there are no electrical connections or kit anywhere near the keels' internal structure, but hey it works.

In the course of investigating this, I found it's well known there is a problem with 'accelerated corrosion of steel' all the way from Chichester to Portsmouth at least; I got Portsmouth Uni' Marine Metallurgy Unit to come and look.

They were keen to do so, but looked disappointed when it didn't fit their pet theory of the time, a bacteria which excretes steel - eating stuff, so weren't much help to me ( one suggested the pitting in the steel was due to the speed of the boat through the water !!! ).

Tempting to suggest fitting the plate ( or a new one ) with a bush, the disimilar metals would probably be overcome if an anode was fitted somewhere.

If stuck I have indirect contact with the foundry near Canterbury which still makes keels for Anderson 22's so feel free to contact me; a new A22 keel, galvanised plate and 900lb ballast bulb, is around £1250.

Once you do whatever you do, I heartily recommend 'Dulux Metalshield Pro' paint; it requires it's own primer but is easy to use - don't laugh at the 'Dulux', this stuff is leagues better than anything else I've tried.

 

[dur]

Thanks for your reply...

It does sound as if a new plate is the best option if it is not too expensive.

On a previous boat (a Memory) I welded a stub of pipe through the pivot hole and made a delrin bush but sold the boat a year or two later so again don't know how well the different metals in the plate, pipe and weld lasted.

If I go fo new, I believe there are different types of steel plate with ship's plate being less prone to delaminating with the rust. Anyone know about the merits of this?

 

[Seajet]

There is BD Marine (engineering) somewhere near Shamrock Quay, they made my new keel plate and fitted it to the original ballast bulb, as at that time I wasn't in contact with the ex-M.D. of Andersons and the original keel makers.

I wasn't too happy with the keel plate they made, but as I say the addition of an anode has changed things markedly.

They claim to make all sorts of steel structures for industrial marine use, which is why I went to them.

However, just the plate - and the hassle of removing the stub of the old one then fitting the bulb with a single large pin - cost me £1,200 several years ago, while the firm in Canterbury can supply an entire new keel for very little more !

I suspect transport could be arranged, I'll get hold of their name and pass it to you, then if you give them dimensions you could at least get a quote.

BTW the Anderson keel is not just a flat plate, the leading edge is rounded and the trailing 1/3rd tapered, to give a lot more streamlined shape, something you coud consider.

The downside to that is the trailing edge of the keel having a relatively sharp edge if you run aground hard, but that's not such a problem with a swing keel anyway ( the A22 has a tufnol shock absorbing pad inside the keel case for this ).

Will ask for their name and get back to you,

seajet.

 

[Tranona]

Have it shot blasted, the hole and wasted bit welded up and fit two top hat Delrin bushes, one from each side to give a good bearing surface. Epoxy tar coat the whole thing - consult somebody like Marine and Industrial for system. Difficult to protect the edge if you regularly ground, but a sacrificial band stuck on with Sika might be worth trying.

Alternatively get a quote for a new one in 316 stainless (with delrin bushes) - might not be as bad as you think!

 

[Seanick]

Well, your right, its not really in bad condition. If you do next to nothing it will do another 30 years.

However, I agree with Tranoa, blast it, but then I would galvanise it. Galvanising is about £1.30/kg, add about £40 for blasting, plus a bit for transport.

I have to do the same to another plate next week, so feel free to chuck it in the van. Seeing as its for you I'll weld up your hole too!

It may be possible to wire the pin to an anode to help it along, but no point if you galv it, and it will blow any paint off if you epoxy it.

I would not however, put a stainless one in, as no one can predict the possible galvanic chaos that may commence with the rest of the boat. Dont mix metals, end of.

N

 

[Tranona]

There is a good article in this month's PBO on replacing (rather than repairing) a similar plate in a Barbican 33. Cost less than £200. Might give you some ideas.

 

[Seajet]

It may be possible to wire the pin to an anode to help it along, but no point if you galv it, and it will blow any paint off if you epoxy it

For interest, the keel I was referring to which suffered until I attached an anode is galvanised, from new which was about 2-3 years before.

 

[dur]

Thanks everyone. I'll give you a ring Nick!

I did speak to JW Touts in Portsmouth yesterday and they sound like the right sort of place if I did go for new. I have to send a drawing for them to price.

I'll let you know how I get on.

 

[Seajet]

In case it becomes of interest, the foundry in canterbury I mentioned is MJ Allen.