Need Advice to Complete My Steel Rudder

[captlloyd]

Yes, epoxy should fill the pin holes but if it were me I would fill the rudder with expandable foam also. What would it hurt ?

[raahell]

I'll think about that foam idea.

[Franziska]

Awesome job. Well done.

Btw. rudders are sometimes filled with vegetable oil to prevent crevice corrosion.
But that would require no pinholes.

[BlueH2Obound]

In old airplanes (think tubular steel frame and fabric (grade A cotton, or synthetic) the tubes were filled with boiled linseed oil. There were drain holes to let the excess run out. The linseed oil is and will remain sticky for years. Or you could drill a hole, pour about a a quart of really SLOW curing West System in and turn ALL directions multiple times for a long time to try and get to all the holes from the inside.
I'd avoid the expanding foam, because I've seen that stuff expand and pop spot welds on metal structures. It really exerts a LOT of pressure in the expanding process.

[raahell]

Originally Posted by BlueH2Obound

The linseed oil is and will remain sticky for years. Or you could drill a hole, pour about a a quart of really SLOW curing West System in and turn ALL directions multiple times for a long time to try and get to all the holes from the inside.
I'd avoid the expanding foam, because I've seen that stuff expand and pop spot welds on metal structures. It really exerts a LOT of pressure in the expanding process.

That'll be a good workout to turn the rudder around and around. It must weigh 60 lbs at least. Great idea though, if I could make up a 3-axis rotisserie!

I like the linseed oil idea too. I had the same concerns about foam but was thinking to do it in steps to avoid over-pressurizing.

[RaymondR]

In the long term you are going ti be better off plugging the holes with weld. Use a 1/4" drill to drill a slight countersink and either MIG or the smallest rods you can get to fill the countersink.

I would not use foam. If water gets in it may be held between the foam and the metal by capillary action and corrosion result.

The longest lasting without drying out or biological action is waxoil which is a mixture of heavy oil and parafin wax. Putting a quart in whilst leaving the rudder lie in the sun and rolling it over occasionally would probably do the job.

[raahell]

Originally Posted by RaymondR

In the long term you are going ti be better off plugging the holes with weld. Use a 1/4" drill to drill a slight countersink and either MIG or the smallest rods you can get to fill the countersink.

I would not use foam. If water gets in it may be held between the foam and the metal by capillary action and corrosion result.

The longest lasting without drying out or biological action is waxoil which is a mixture of heavy oil and parafin wax. Putting a quart in whilst leaving the rudder lie in the sun and rolling it over occasionally would probably do the job.

I have plugged all accessible pinholes as you suggested. The problem is those pinholes I can't get to with tools as per my pic in earlier post.

I'll look into waxoil. Thanks!

[Pauls]

Hi raahell,

First, ignore all the advice about filling the rudder with various compounds. A sealed rudder cannot rust internally as there is no oxygen available to cause it, with the exception of the tiny amount trapped internally.

Second, as regards the pinholes you can't fill, do NOT use West/filler. You will be painting the rudder with at least 2 coats of epoxy paint which is specifically designed to adhere to metal and seal it. The epoxy paint will do a fine job of sealing your remaining pinholes. The paint layer layer will be thin enough that it will be in no danger of cracking. The West/colloidal mix will create a much thicker layer which will greatly increase the chances of it cracking away from the steel over time. Sealing and painting steel is a highly developed technology. Use it.

Note - it is mandatory that you abrasive blast the rudder before painting. This is not optional if you want a good job. The paint you buy - I would recommend Ameron - will provide detail about the surface profile the blasting must create on the rudder surface. Any pro level paint designed for steel will give specs on this.

[raahell]

Hi Pauls,

I have in fact purchased Ameron products. Pre-primer, primer and paint, thinner and prep-wash.

I'll only use the Ameron for the pinholes, as you suggest. I nevertheless have a bit of fairing to do with the West system as I want to smooth out some minor dips in the skin due to welding deformations. I want the foil shape to be as consistent as possible. But the thickest layer will not be more than a couple mm.

I've read in the instructions that the Ameron products do take to a 60 grit sanded surface quite well, though blasting is better, as you said. I was thinking to sand to 60 grit with an orbital sander to adhere the West System to it. By that time it'll be warm enough (hopefully, up here in the North!) that I'll be able to sandblast the hull, whereupon I can blast the rudder at the same time, prior to priming.

[Manus Holm]

I would weld the leading edge and heat shrink form the plate with spot heat. Can just tack one side shape it, the remove and do the other side.
Drill large holed all along the ribs and weld through the holes to attach the plates. Bit tedious proses the shaping. But ship plating has bean formed for many years.
Id seel the inside with liquid tar. Weld in pipe fittings that can screw shut. To get the stuff in. Put in loads and slosh around to seep in all the cracks. Drain what is left for next service

[raahell]

Originally Posted by Manus Holm

I would weld the leading edge and heat shrink form the plate with spot heat. Can just tack one side shape it, the remove and do the other side.
Drill large holed all along the ribs and weld through the holes to attach the plates. Bit tedious proses the shaping. But ship plating has bean formed for many years.
Id seel the inside with liquid tar. Weld in pipe fittings that can screw shut. To get the stuff in. Put in loads and slosh around to seep in all the cracks. Drain what is left for next service

I'm guessing you didn't look through many of the previous postings or pics in this thread! Take a look. This job is pretty much done now and performed much as you describe. Still deciding what - if anything - to put inside, however. Thanks for your suggestion about tarring.

[raahell]

Well, I'm back in my little closet of a workshop after 2 wonderful weeks in my buddy's big new garage. It was hard to get motivated to get back to this project but I have no choice as I'm running out of time before boat launch day in late April.

I've started the West System slow cure epoxy with colloidal filler to fair out the rudder. Started on STBD side where the plug welds were made. These ended up being slightly depressed compared to the rest of the surface so I applied the first coat over these and sanded down with 60 grit on a long board and finished with an orbital sander.


2nd coat is just to get a thin layer on the entire side. The dried epoxy doesn't seem to feather well besides raw steel so I'm hoping I'll get a smooth finish this way. On this coat I used less colloidal filler to get a thinner, easier to apply layer.


Those dosing pumps supplied by West System sure make measuring and mixing easier and cleaner than other systems!

[raahell]

Rudder is on! Good to know the measurements I took back in October were correct. Now I'm fabricating the skeg to complete the set-up.

[Pauls]

Looking good!

[NSboatman]

Originally Posted by raahell

Rudder is on! Good to know the measurements I took back in October were correct. Now I'm fabricating the skeg to complete the set-up.

Attachment 235616

Looks great!! Well done- feels good getting real steel on the boat- you can see the end now!

Keep it going-