Rudder Troubles?

As sailors who have been in the fleet since it’s conception, Jerry and I were only too aware of the number of rudder failures that occurred. When we retooled the boat we examined every area of potential failure and looked at how we could eradicate any problem areas. This article sets out some of the issues that the fleet are still experiencing and more importantly what you can do to prevent further failures. All the photos published in this article were taken last weekend whilst visiting a yacht club and are truly representative of what is seen in the fleet, check your boat to make sure not of your components look like these:

photo2 of the most common issues in this one…and an accident just waiting to happen…A2 stainless steel nuts and bolts explain the rust mark and if you look carefully you can see the crack and weld failure at the bottom of the gudgeon.

photoViewed from the other side… again showing the rust. The weld failure even more obvious and just a matter of time until it fails….

photoand the next day….(whilst not on the same boat) this is the result. Of the 5 boats I inspected on the hard (all were on keel up trailers with rudders on so easy to inspect) 4 were what I would describe as HIGHLY likely to fail within a short period of time. The problem when the gudgeon fails is that it often has the knock on effect of ripping out the upper transom gudgeon which really does turn into a bad day at the office.

photoThis is a photo of a destructive test that we carried out on a new gudgeon…we could not break the welds and could only distort the stainless plate…but the reason the gudgeons fail is due to the following:

photoHere you can see that the aft bolts have been tightened to pull in at the rear and this puts a hard spot on the gudgeon plate which, when used in this manner will eventually fatigue the edge until it eventually fails…the good news is that the cracks become obvious before failure so keep an eye out for the tell tale cracks….obviously it is better not to get the fatigue in the first place but this is down to variance in the rudder width which was experienced with the original rudder blades…these were made from a plug which enabled these changes in thickness and has resulted in the those blades requiring “packing” to ensure the blade is held square by the gudgeon …in fairness I have seen several versions out there where owners have seen the problem and acted to make a “shim” to ensure the point loading is avoided.

photoWe have now patterned some shims to fit exactly the profile of the gudgeon. These are made from 1mm stainless plate and will retro fit perfectly to the pitch of the old gudgeon so that you can pack out any old blades and hopefully avoid any gudgeon failures. They are available in stock if you require them at £4 plus VAT per shim.photoObviously it also helps if the gudgeon bearings are still there…with only 2 out of 4 being present here the feel on the rudder will not be pleasant…check your rudder regularly to ensure there is no play in the pin, the bearings or the fixings on both the rudder and transom gudgeons.

So…on to the blade itself. Our brief when we re-tooled the boat was that a rudder blade failure would not be acceptable…we started by examining failed blades to work out what was going wrong…here is a good example:

photoHere you can see that the carbon laminate has been applied near the trailing edge….we ensure that the carbon is much more where it is needed at the leading edge and we also insert a carbon tube that runs all the way through the stock and down the leading edge of the blade to further strengthen it. Added to that we cnc’ed the tooling from aluminium to ensure that the blade itself comes out of the mould with a consistent profile and the thickness of the stock is now controlled across its width to ensure a perfect fit with the standard rudder gudgeons. The blade should not stall out (straight from the mould!) and more importantly will not put a point load on the gudgeons, we are VERY happy to warranty our new blades and we are hopeful that our record of ZERO failures will continue…particularly after the thorough testing the new boats had in the Hyeres worlds. Below you can see the consistent thickness of the stock that is achieved through using cnc’ed moulds. The moulds are pictured below just after machining and prior to final polishing.IMG_4734IMG_3999So, to ensure you avoid a failure…run the following checklist through your rudder system:

1. Check the transom gudgeons are tight.

2. Check the gudgeon bearings are not worn on both transom and rudder.

3. Check the rudder blade gudgeons show NO signs of cracking at the leading edge just at the end of the stock and that the weld is fully intact.

4. Check that the rudder blade gudgeons fit the width of the blade with no “pinching in” on the aft bolt. Fixings should be A4 grade stainless only.

If you have any questions or need any parts (all in stock) do not hesitate to contact me on alan@sportsboatworld.com