Rudder filled with oil?

[Thamesbank]

I am still messing about under my steel boat. The rudder was filled with mineral oil (which smells like very old Castrol GTX). I found this out when it began leaking out of a small rusty pit as I was taking the paint off it.

Is this unusual? I figure it would be a nightmare if it starting leaking while in the water as there were ten liters or so in there.

My question: Can I fill it with sand instead? It should act as a vibration damper, which seems to be the idea of the oil, but I am unsure of this. Anyone got any ideas?

 

[Thamesbank]

Quick update

I just found a link which helps in some ways: http://www.marineengineering.org.uk/Default.htm

They write about filling the rudder with foam, which helps improve buoyancy. Interesting and perhaps better than sand, but who knows?

 

[JasB]

Re: Quick update

what sort of boat is it?

 

[Thamesbank]

It\'s a dutch sailing boat

A bit like a schouw, but with a drop keel rather than leeboards.
I think it's quite unique as there were only three made. I will upload a photo in a sec...

 

[tangofour]

Re: It\'s a dutch sailing boat

unique = 1. It either is unique or it isn't, nothing quite about it.

/forums/images/graemlins/smile.gif personal bugbear.

 

[Thamesbank]

Image of the rudder

Here:

 

[jwilson]

Quite common to fill hollow steel rudder blades with oil. Intended to avoid internal corrosion

 

[JasB]

I am sure I have read about this somewhere, Was there a thread about rudders that wobble?
I can't see much point in the oil as a damper, I would go for the foam replacement, or sawdust...or almost anything I could get in there. But if the oil IS a corrosion deterent, then maybe resin could be the answer?

 

[jhughes]

Stick a grease nipple on it and fill it full of Lard /forums/images/graemlins/grin.gif

 

[Blueboatman]

Drain the oil,flush through, grind the rust,weld/patch over ....and refill with oil-I dont see the fill plug in the top but it must be there somewhere

I can think of no easier way to repair and reliably prevent future internal corrosion.Dont start messing about with other 'fillers'.
If the rusted area is along the bottom edge consider welding a continuous sacrificial steel strip to take grounding wear.

 

[rogerthebodger]

I am currently building a steel yacht with steel rudder. I intend to fill it with oil to prevent rusting on the inside. I pressure tested my rudder and keel, fuel tanks and skeg to ensure no leaks.

What ever you do fill it with pressure to to 1 to 2 bar 15 - 30 psi and leave over night to see it pressure is lost .

If you fill with oil and it gets damaged in use you will see it if you fill with sand or foam you will not know if it leaks until it falls off.