Cobra 850 Rudder crack

[BigStu]

Hi all

I've had a survey done on a Cobra 850. All is good apart from a crack about an inch down horizontally from the top of the rudder all around. The surveyor recommends opening it up to check and rebuild. Has anyone experience of what to do here? I'm not keen to lift, take rudder off, open up, etc etc unless I really have to. How are they built? What would be the best course of action?

Cheers

Stu

 

[LP1]

I had a survey done on a cobra 850 and it was so bad all round that I walked away. The rudder was so badly affected by osmosis that it was ruined. The survey was done by an excellent contributor to YBM and I was advised that the construction of the rudder was stainless tangs welded onto a stainless shaft, foam filled for shape then fibreglassed. On the one I had surveyed, the rudder would have to be split in half longitudinally, died out, osmotic blisters bled and washed out, the welds checked, and the whole thing reassembled and presumedly reglassed?

I am assuming this is a time consuming and laborious task that could be done done by a competent DIYer with any structural defects inspected by a surveyor or other expert.

HTH

 

[BigStu]

Hi

That sounds like what I thought. Luckily this boat is in very good order- no osmosis anywhere, and no other problems- just this crack in the rudder. It's just a pain to do as I think you need a lift to get the rudder off?

Stu

 

[LP1]

sounds like you either get a lift into slings to get it off then back into the water allowing you the time to sort it, or out onto the hard and then time = money so the pressure's on. You'd have to be organised if that's the case. Obviously something to factor in if negotiating with the owner or not if you already own it.

HTH.

 

[BigStu]

She is on the hard already- but I guess these need a lift to get the rudder off anyway. I've negotiated a fair bit down for this as well.

 

[corbu]

She is on the hard already- but I guess these need a lift to get the rudder off anyway. I've negotiated a fair bit down for this as well.

Hi, there is a link on the cobra\ seawolf forum to a rudder rebuild. I can't remember if mods allow external links on this forum but here goes:

http://www.randpsystems.co.uk/seawolf/rudders.htm

We have an 850 and its been great fun and very easy to maintain. Good luck.

 

[Dipper]

Hi, there is a link on the cobra\ seawolf forum to a rudder rebuild. I can't remember if mods allow external links on this forum but here goes:

http://www.randpsystems.co.uk/seawolf/rudders.htm

We have an 850 and its been great fun and very easy to maintain. Good luck.

That's my rudder rebuild on a Seawolf 26.

Someone in my club has a Cobra 850 and his tangs failed at the end of last season. I was talking to him earlier this week and he has split his rudder around the edge into two halves which is the more usual way to do it. There were two stainless steel tangs one top and one bottom. They had a curve cut out of the end and the curve was welded onto the stock with a mild steel weld. The bottom weld had failed a long time ago and the tang was not fully encased in GRP. The top tang was completely covered in GRP and the weld showed recent failure.

For some reason, rudder design on a single model of boat often varies markedly so the OP's rudder may not be the same. Perhaps the rudder construction is contracted out and the contractors vary over the production run. Seawolf 26 rudders show quite a difference over the years.

 

[aquaholic]

Depending on what your boat is sitting on you might want to consider jacking it up with an acro? I did mine a few weeks ago......
https://youtu.be/gShc2J6v-ok

 

[Steve_N]

Depending on what your boat is sitting on....]

Or digging a hole - I've dropped my rudder twice this way but clearly not relevant to tarmac, concrete etc.

 

[30boat]

Don't let it stop you from buying an otherwise good boat.Rebuilding the rudder is not dfficult just some hard work.Avoid foam if you can and rebuild the blade in good marine plywood glued with epoxy.It's much more pleasant to work than fiberglass and the veneer layers will help you achieve an even shape as you sand or plane the plywood down.A final sheathing with a light roving in epoxy and you'll have a strong and durable rudder.