Sigma Rudder Removal

[Saracen]

I've been unable to remove a spline set into the rudder post, below the cockpit sole, which the steering quadrant locks onto.
I can't drop the rudder till the spline is removed - has anyone got any suggestions?

 

[CFarr]

Hello Saracen and welcome to the forum.
I'll just bump this back up for you.
I can't help I'm afraid but I'm sure someone will come along soon with good advice and I would be interested too for my new-to-me 362.
Which Sigma are we talking about? 33, 36, 362 or 41?

 

[Saracen]

It's a Sigma 36, your 362 will be very similar except for the below deck layout.

 

[Quandary]

Well the 33 and 36 are tiller steered so he must be asking about the 362 or 41 or perhaps the more common 38. I removed the rudder from our 33 easily but never from our 38, but if it is one of these I still have some photos and I think a Whitlock exploded diagram that I downloaded from the owners website that I might be able to find if it is established that that is the type of boat the OP refers to.

 

[prv]

By "spline", do you mean a key inserted into a slot in the shaft? I'm not a mechanic, but where I've come across these in the past they've generally been shaped such that the edge in the shaft is an arc, fitting into a matching curve in the bottom of the slot. This means that if you tap one end in towards the shaft, the whole thing slides round the curve and the other end pops up. Can't hurt to give it a try, anyway - just give a medium tap to one end with a hammer, inwards towards the shaft, and see if it moves.

Pete

 

[Saracen]

It's a 36 with wheel steering. I'd be interested to see the exploded diagram you refer to. The 36 and 38 had a lot of similar equipment fitted and it might be comparable.

 

[Quandary]

Ok to save me bother, ( I last accessed the diagram in 2009) try this first.
Google 'Lewmar Whitlock Cobra steering system', you will find answers to similar questions on YBW going back to 2009, you will also find diagrams in Lewmars archive of the Cobra system and in a further answer a series of diagrams of Cobra installations in different boats. If it is not a direct system linking the pedestal to the rudder shaft by rod, try the same search substituting 'Mamba' for Cobra, the 38 was Cobra but since the 36 was usually tiller steered they may have used a different system. There is also a company there that claims to be the specialists in parts info etc. for Whitlock Cobra (later taken over by Lewmar)
You will usually find that that Google is much better at finding answers on YBW than our own search above.

 

[Saracen]

Thanks for the tip. It's definitely a Cobra system. I couldn't find any detail regarding the key in the rudder stock and if you have any information in this regard, I'd be most grateful.
The Sigma 362 association has an owners manual, but unfortunately it doesn't discuss the key in the rudder stock.

 

[garvellachs]

Assuming the boat is ashore and it's the key fitted into the rudder stock that we're talking about, then if it's tight fit I would try putting mole grips onto it and tapping, or just tapping with an old screwdriver alternately on the sides of it to try work it out. Even tapping one end or the other into the stock may loosen it. A key like that is usually just a close fit so it shouldn't be too hard to extract unless corrosion as somehow got it tighter? Is the stock stainless or alloy? If you have to, you could even drill a hole in the key, tap it and thread something in but I can't imagine that's necessary.

 

[Saracen]

The rudder stock is stainless steel and the key is an alloy, I'd guess a phosphate bronze. There doesn't appear to be any corrosion.
The key is tight in the slot and is resisting gentle and not so gentle tapping.
I'm staring to think of taking an angle grinder to the key and getting a new key engineering when I have the rudder out.

 

[knuterikt]

The rudder stock is stainless steel and the key is an alloy, I'd guess a phosphate bronze. There doesn't appear to be any corrosion.
The key is tight in the slot and is resisting gentle and not so gentle tapping.
I'm staring to think of taking an angle grinder to the key and getting a new key engineering when I have the rudder out.

I would have tried heating and tapping and some of the other suggestions in this thread before resorting to angle grinder.

It's easy to damage the keyway or rudder stock with an angle grinder, it's supposed to be a tight fit between the key/keyway and the quadrant/rudder stock.

 

[Saracen]

A note to bring this to a finality.
I cut the key off with a hacksaw, filing down the rough edges after. The rudder slid easily off it's perch and was manhandled to the ground. Please note these are not light and we used a sling fromg the cockpit to lower the rudder.
I extracted the remnants of the key surprisingly easily with a pu ch and light hammer and have machined a fresh key in a phosphor bronze.
All this to replace a cutlass bearing!
The cutlass bearing came out quite easily once I removed the prop and sliced through the cutlass with the trusty hacksaw.
The next part of the challenge is to fit a new cutlass bearing and refit the prop and rudder.
Thanks for your comments - they all help.

 

[Quandary]

It is good when the OP comes back to report on the outcome, particularly if it has been a success. It builds the knowledge base for all the rest of us that read the thread.
Not enough enquirers take the time to report back.

 

[garvellachs]

A note to bring this to a finality.
I cut the key off with a hacksaw, filing down the rough edges after. The rudder slid easily off it's perch and was manhandled to the ground. Please note these are not light and we used a sling fromg the cockpit to lower the rudder.
I extracted the remnants of the key surprisingly easily with a pu ch and light hammer and have machined a fresh key in a phosphor bronze.
All this to replace a cutlass bearing!
The cutlass bearing came out quite easily once I removed the prop and sliced through the cutlass with the trusty hacksaw.
The next part of the challenge is to fit a new cutlass bearing and refit the prop and rudder.
Thanks for your comments - they all help.

Why did you have to remove the rudder? Is it very near the prop?

 

[cagey]

As you have done the job I can only give my solution up to the internet gods.
On a Sigma362 ashore.
My first cutless replacement, Remove prop, loosen gearbox coupling, pullshaft from boat bit of sideways lean on rudder shaft came out.
Second time, remove prop, make up extractor , socket side cut out to slip over shaft but fit through P bracket then plates to fit end of socket and another one to fit over P bracket but allow for cutless removal just pull brackets together using nuts and bolts, swap around to replace cutless.
K