savageseadog
Well-Known Member
Got a GRP laid up rudder with stainless stock and presumably stainless structure attached to stock. Would an X Ray tell me anything about the condition ? Has anyone done it?
Is X-Raying a rudder of any value?
- Thread starter savageseadog
- Start date
shamrock
Well-Known Member
don't know about x-raying but a surveyor told me that most rudders will have taken up water over the years, and if you drill a hole in the bottom, water may flow out.
If that water is brown, suspect corrosion of the stainless so locate the tangs using one of those DIY cable / joist finders and cut a hole in the side of the rudder to let you see one of the welds.
If water is clear, fill the hole with epoxy and breath a sigh of relief.
If that water is brown, suspect corrosion of the stainless so locate the tangs using one of those DIY cable / joist finders and cut a hole in the side of the rudder to let you see one of the welds.
If water is clear, fill the hole with epoxy and breath a sigh of relief.
PuffTheMagicDragon
Well-Known Member
[ QUOTE ]
Would an X Ray tell me anything about the condition ?
[/ QUOTE ]
It can be done but, unless you have free acess to an x-ray clinic (e.g. local hospital) or to a portable x-ray source, the whole exercise would probably be more expensive than a new rudder!
As has been suggested earlier, drill a hole on each side near the bottom and onother two near the top and let any water drain out. Let it drain for as long as you can and then plug the holes again with araldite (and a bit of dowel if necessary). Use an 8mm drill. I do it every time that my boat is lifted out of the water, i.e. every two years, plugging the holes a couple of days before splashdown.
IF you are suspecting that the stainless straps are detaching from the rudder stock - slight movement is noticeable, maybe? - then the easiest thing to do would be to cut the two sides of the rudder apart so that you can better assess the condition of the metalwork. Once this has been rectified, the two shells of the rudder are reassembled using foam and resin putty on the inside, followed by three layers of glass tape all round the 'cut' edges. Take a grinder to the areas where the tape will lie. Grind down any high spots after the resin has cured completely (48hours at least; depends on the temperature), prime, paint as usual.
If you are 'handy' with your hands, there is not much to it. All you need by way of tools are a small angle grinder, a 'diamond' disc for cutting and a normal one for surface preparation. Total cost should be less than STG30. Go for the cheap 'throw-away' grinders The glass tape and the resin would be around another ten pounds or so. I don't know your prices. I buy in bulk.
Good luck.
Would an X Ray tell me anything about the condition ?
[/ QUOTE ]
It can be done but, unless you have free acess to an x-ray clinic (e.g. local hospital) or to a portable x-ray source, the whole exercise would probably be more expensive than a new rudder!
As has been suggested earlier, drill a hole on each side near the bottom and onother two near the top and let any water drain out. Let it drain for as long as you can and then plug the holes again with araldite (and a bit of dowel if necessary). Use an 8mm drill. I do it every time that my boat is lifted out of the water, i.e. every two years, plugging the holes a couple of days before splashdown.
IF you are suspecting that the stainless straps are detaching from the rudder stock - slight movement is noticeable, maybe? - then the easiest thing to do would be to cut the two sides of the rudder apart so that you can better assess the condition of the metalwork. Once this has been rectified, the two shells of the rudder are reassembled using foam and resin putty on the inside, followed by three layers of glass tape all round the 'cut' edges. Take a grinder to the areas where the tape will lie. Grind down any high spots after the resin has cured completely (48hours at least; depends on the temperature), prime, paint as usual.
If you are 'handy' with your hands, there is not much to it. All you need by way of tools are a small angle grinder, a 'diamond' disc for cutting and a normal one for surface preparation. Total cost should be less than STG30. Go for the cheap 'throw-away' grinders The glass tape and the resin would be around another ten pounds or so. I don't know your prices. I buy in bulk.
Good luck.
chwarae
Well-Known Member
If you've any friends in the Royal Logistic Corps (EOD) they might do you a favour. They have or used to have portable X ray equipment. As you are in Portsmouth possibly Navy mines disposal teams might have similar kit.
Good Luck
Harry.
Good luck
Good Luck
Harry.
Good luck
William_H
Well-Known Member
Radiography is used widely in Non destructive testing of welds and critical metal parts and other parts. However it is not a catch all test that we might imagine from medical xray stories. Xray will show you I think areas of water ingress. It may also show you areas of loss of metal to corrosion. It is unlikely to show cracks in the metal or welding. It is most effective when you know where the crack is going to be and can align the source and and plate so the rays go down the crack square on. If the rays go across a crack the actual lack of metal is very small compared to the mass of good metal and xray can only show at best about 5% loss of material in the ray path.
That is a bit hard to visualise so botom line is if you are really worried tear the rudder apart as Puff describes. olewill
That is a bit hard to visualise so botom line is if you are really worried tear the rudder apart as Puff describes. olewill
savageseadog
Well-Known Member
Thanks for that everybody
ex-Gladys
Well-Known Member
A 2003 survey report recomended this for Gladys. So being a good lad, I did jsut that, two holes, top and bottom. Dry as a bone....
whiteoaks7
Well-Known Member
I bought a Sabre 27, a boat where the tangs in the rudder could have been mild steel or stainless. The surveyor suggested (and thus the insurance insisted) that I have these inspected. X-ray was too expensive (but if you go down that route get the keel bolts done at the same time) so I proceeded as follows. (1) buy a cheap detector from a DIY shop - the ones used to find wire/pipes in walls - about £10. (2) While you're there get a hole saw. (3) Use the metal detector to find the tangs then drill one side with the hole saw until you can see what's what. (4) Take photos - if you sell the boat they're good evidence, (5) plug the hole with filler paste. I was lucky, all nice stainless!
