Rudder Problems - SailNet Community
LinkBack Thread Tools
post #1 of 1 Old 02-13-2002 Thread Starter
Contributing Authors
Join Date: Jan 2000
Posts: 244
Thanks: 0
Thanked 13 Times in 6 Posts
Rep Power: 18
Rudder Problems

A small section of the metal rudder post on my boat has been deteriorating. There is a half-inch-wide section that looks bad. Can this be repaired?

Mark Matthews responds:
Thanks for the question. While it’s hard to see how bad the corrosion is from where I sit, over time all thru-hulls, shafts, props, and other submerged metal parts can lose their structural integrity. If you can’t remember the last time you changed the zincs on your boat, or if you suspect your vessel has a checkered past regarding maintenance, chances are you'll need a new rudder shaft or need to repair the one you've got. At the very least you need to take a closer look at what’s going on. 

If the boat is out of the water, tie off the tiller or wheel and then climb back down and have a look. I mention this because you'll want to determine if the rudder stock has come loose from the rudder blade. So try to move the rudder on its stock. If there’s any play at all, the rudder is likely separating from the stock and it will need repairing.

If, however, you don't discover any play when you moved the rudder with the helm tied off, then you probably just have some serious pitting in the rudder stock. I'd remove the rudder and cart the whole thing to a machinist or a welder so that they can look at it and see if they think that the structural integrity of the shaft is at all compromised.

Another thing to check if you suspect further deterioration is to look for tell-tale bubbles at the top of the rudder where the stock exits. If you've got those, it's almost unavoidable that the rudder will need to come off and be taken apart. Depending on the arrangement, you may be able to take the rudder off while the boat is in the water. (I’ll leave that up to you to decide.) If you plan to take it off while the boat is in the water, it's a good idea to keep a line tied on the rudder just in case, even though many rudders are foam-filled and thus have a near neutral buoyancy.

Most rudders are generally constructed of two halves that are glassed together. I’ve had to repair my rudder by cutting it along the central seam using either a sharp chisel, circular saw, or grinder. If your rudder is built like this, once you've got it in two pieces, you’ll be able to get a better idea of the problem and how to fix it. You may need to take the rudderstock to a machine shop for welding, which might seem like a big job, but remember, every boat crisis is an opportunity to improve things in disguise, and now is a great chance to improve the rudder design.

The rudders on many boats have a skeletal framework that is made up of short welds sticking out like unsupported fingers. This means that stress can be concentrated on several short welds rather than the entire length of the stock. Consider adding more supports to the rudder stock to strengthen it. Once you have this fixed, glass the skeletal structure into one half of the rudder. Place the other half on top of it and fill the rudder with expanding foam, and try to fill it so there are no voids. Glass the two halves back together, and after some fairing and painting you should be ready to reinstall your rudder.

You might also want to consulting either Nigel Calder’s Boatowner’s Mechanical and Electrical Manual or Don Casey’s This Old Boat before you embark on your repair. Both these books are invaluable resources for boat owners, and both are available in SailNet's on line Store. Have a go at it, and let us know how everything works out.

Mark Matthews is offline  
Closed Thread

Quick Reply

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Posting Rules  
You may not post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is Off
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome