Actually its three questions I suppose because I first want to ask - what do you call someone who puts a steel screw in your boat and causes rust to spread above and below the hog? Words fail me...

Question 1 - How do I remove this stubborn screw where the head is nearly ruined? I've tried thumping with a hammer. I can't recut the slot with a hacksaw without cutting into the false keel. Drilling it out might not remove all the rusty bits, unless I make a big hole.

Question 2 - if I scrape the varnish off my hull, and leave it in a garage for months....will it crack as it dries out, and cause more trouble than its worth? There are a few odd cracks already (1980 cascamite, or the fact that its been in the garage for 2 years?).

Thanks all.

Q1) anything you like, but don't post it on the forum!

Q2) How big a screw? I've removed brass screws with the heads sheared off (keel-band size) by several techniques:-
a) unscrew using mole grips - you'll need to chisel a small pocket around the screw to get access - then fill afterwards.
b) if it is possible to drill into the screw shank, then a "stud extractor (LH thread with a tapered steel thread) can often do the trick.
c) using a small handheld drill (preferably not power!) drill around the screw. this makes a bigger hole. Pull out the stump, and taking the smallest size drill you can, make a clean hole. This is filled with a suitable dowel which is cut overlong, then sanded flush. I'd suggest Westing it in place.

If you are really a perfectionist, cut the dowel about 1/8 inch short, then use a "plug cutter" on a piece of wood that matches the keel - that way you'll have the grain lined up when you glue it in - rather than end grain of the dowel.

When the steel screw rusts, the rust expands the size of the screw, so I think that you'll be using method 3.

If you use a dilute solution (about 5%) of citric acid (buy it at the home-brew shop - or use a lemon!), you should be able to reduce the staining. Citric acid will complex with iron and make it soluble. Rinse with fresh water afterwards. You may need to repeat several times. A small plastic dropper/syringe (inke refill type) will be really useful.

For part 2 - I'll pass!

I have had this problem with steel screws and have found that if you work away at trying to get mole grips etc on to it the whole thing gets worse.  SO what I now do is bite the bullet and get a small drill - about 1mm and drill down the side of the screw and in several places so the screw is isolated in the centre.  Then get a soldering iron and get it really hot and place it on the top of the bit of screw you can see.  Keep it on for a good while - this helps expand the screw and I think it helps break the rust/wood joint.  I then use a pair of long nose pliers to grab the screw and push down its shaft and with a really good grip start to turn it.  Of couse it depends how long the screw is - chances are that there will be a lot of rusty dust left in the hole.  It may also snap off which is a bugger but not a lot you can do about it.  Once you get the screw shifted above the surrounding surface the vice grips can be brought into play.  The rest of the advice on stain removal is spot on.  You can also use oxalic acid as stain remover. 

I have never seen the wood crack when the varnish is removed on ply - you will want the wood dry before you revarnish/epoxy any way. Mahogany planks open and close as they dry and get wet in a clinker boat - taking up and it is a problem in those boats not sailed regularly.  Chris Barlow has a lot of advice on this.

Thanks Garry!

It based on the collected wisdon of the Morris Minor Traveller owners - they have similar problems with wood & rust stains!

Mags - drop me an email if you need to borrow plug cutter (about 1/4 inch) or stud extractor.

Colin

I do have a fantasy about turning up for a Merlin Vintage event with Secret Water towed with a Morris Traveller of a certain age!!  Preferably with personal number plate MR 111 (which I have actually seen though not on a Morris!!)

Oxalic acid is much better at removing rust stains (also from sails) - it is available as a wood bleach - just search on the net for a supplier in Southampton.

You can use a hot air gun in place of Garry's soldering iron - the technique works well especially if you do several cycles of heating and cooling.

Has anyone had any experience of the screw extractor set that they are currently advertising on TV?

Dear Garry,
Use thr Minor forum - I suspect that someone will be able to help you (I've a 2 door saloon...)

My preference for the citric acid vs oxalic acid is based purely on the fact that I've a tub of citric acid at home (used for home made wine pH adjustment). I don't fancy extracting the rhubarb leaves fr the oxalic acid.....

Good luck Mags

Colin

The problem I have found with the heat gun is that the surrounding wood can char quite easily - a problem when you revarnish - and you do need to get the steel hot.  I think too that it is the temperature differential between the steel and the wood that cracks the bond so a localised heat source is better - in my opinion that is.

Oxalic acid is available from woodwork suppliers and hence no need to boil down rhubarb leaves.  It is more chemically effective than citric acid.

I didn't consider heat becuase I thought I'd rather the screw got smaller, not expanded as it got hotter! But if that breaks the bond to the wood, I will give it a go.

Thanks everyone. Any more methods you know of, before I crawl into my garage this weekend?

Two things to try:
If any of the head is avaiable try tightening the screw first to break the bond (an old trick)
or whack the head very hard with a centre punch

When I had my 1st Morris Minor which was very rotten I used to swear by an impact driver for loosening screws but you do need something on the head for the bit to grip on.

one trick that I have used before, is to get a big fat welding rod, set the current on your stick welder a bit too low and deliberately fuse the rod to the metal you can see, and you should be able to get a good pair of grips on the rod. 
the tricky bit is earthing the broken stud, but you might be able to clamp a sharp chisel shaped drift to the earth lead and push it hard against the stud, the heat from the rod will of course help as mentioned earlier..... 

however, prevention is always better than cure, I am suprised that with screwdriver bits as cheap as they are how many ripped heads are caused by people using the wrong sized bit...

Bizarly watching UK History TV on satellite (Not a lot on today!) there was a Woolworths advertisement (Also various other outlets.) offering a "SCREW REMOVAL KIT" for GBP£9.99. So if you haven't solved the problem yet...it looked like the real thing.