Rudders

[Beadle]

I have a steel rudded blade

It has anodes attached but has developed some rust streaks

My intention is to remove loose rust, paint the area with phosphoric rust remover and the paint over all of the blade with 2 part epoxy paint.

Is there a better way?

Should I leave a bare area for the anodes to contact? or will the through bolt (one anode on each side) be adequate.

Any thoughts will be wecome

 

[VicS]

[ QUOTE ]
Any thoughts will be wecome

[/ QUOTE ] Follow the recommendations of your chosen epoxy coating manufacturer carefully regarding the removal of rust and suitable rust removers and I would have thought the complete removal of all old coatings, with the exception of any sound existing coating and shot blasting.

The anode question is an interesting one. If the rudder is completely coated then no anode should be necessary. If you fit anodes they must have a good electrical connection, possibly via the fixing bolts. to the rudder in order to be effective. That will mean a break in the coating.

The choice I would say was between a proper epoxy coating job and no anodes or a simple paint job and anodes.

A steel boat enthusiast like Roger Shaw may have some thoughts.

 

[oldsaltoz]

The anode MUST have a conductive to the steel in the rudder. I would look at reducing the hole size in the rudder and tapping a thread into it, then use threaded rod and nuts to ensure continuity.

Avagoodweekend......

 

[Beadle]

I'm not entirely certain how to make a hole smaller.

But thanks anyway

 

[rogerthebodger]

Yes thank Vic for the recommendation

Only real way is to dry grit blast (not sand) to get a good rough clean surface (I used slag from a platinum refinery, gold slag is too soft) and paint with 2 pack epoxy tar 3 coats before antifoul (if you can get it) within 4 hours, or better while the steel surface is still warm.

With regard to fixing anodes, weld 316 (A4) stainless steel studs direct to the bare steel rudder (yes weld stainless steel to mild steel, special arc welding rods are available) and drill the anode fixing bar to fit over the studs and fix on using A4 spring washers under nyloc A4 nuts

This is what I have done on my all steel yacht see bio for pics

 

[Beadle]

Thanks Roger. Is there an alternative to grit blasting, my boat is GRP and only the rudder is steel. Being a tight fisted Yorkshireman I'm reluctant to pay for the machinery just to blast about 4 or 5 sq feet of rudder.

OK on the rest I'll try to find a welder to do the stud thing.

Cheers

 

[DinghyMan]

I have found that some scrap yards, or recycling engineers these days, have blasting kit and will happily do a cash job. I had some glass bead blasting done a while back for £10 for a couple of hours work.

 

[VicS]

[ QUOTE ]
I used slag from a platinum refinery, gold slag is too soft

[/ QUOTE ] Now that really is one-upmanship taken to the extreme. I suppose you use waste diamond dust when you want somethig really hard. /forums/images/graemlins/wink.gif

 

[William_H]

Perhaps a better way is to bore bigger holes in the anodes and tap a hole in the rudder to suit a larger sized threaded rod.
Holes are made smaller by welding the hole closed then drilling again. Or drilling a new hole and filling the old hole.
olewill

 

[rogerthebodger]

/forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif

Thought some one would pick me up on that !!

Don't get much diamond dust in RSA most diamonds are cut and polished in the EU, but the dust is now used on diamond cutting disks.

 

[rogerthebodger]

Try any one who repairs classic cars as the body tends to be grit blasted before fixing and painting these days

 

[rogerthebodger]

I would not drill and tap into a steel rudder as the rudder would be hollow and drilling and tapping would break the seal and cause the rubber to rust from the inside.

Steel rudders must be sealed or filled with oil and sealed to prevent internal rusting.