Rudder modifications

By Gil Webster
NX776 Nella Dan


The general consensus of Noelex 25 owners is that to reduce steering effort it is worthwhile altering the rudder blade angle so that when fully down the blade is vertical when the boat is on its waterline. Some owners swear by this change, for others it is ‘line-ball’. The modification reduces the effort required on the tiller to sail the boat. This is especially useful in heavy weather and in some reaching conditions. It does not reduce weather helm, but it does mask the effect by reducing the force on the tiller to overcome it. Just about every book on sailing discusses the techniques and methods to deal with the underlying causes of excessive weather helm.

The transom of the NX25 is not vertical — it has a few degrees of reverse slope. The rudder blade when fully down is parallel to the transom and hangs aft; it does not point straight down. It follows that the centre of pressure of water on the blade when steering is well aft of the pintles. A certain degree of force is required on the tiller to overcome this force on the blade. By moving the centre of pressure forward towards the pintles by moving the bottom of the blade forward, the effort on the tiller to counter this force is correspondingly reduced. Just as on a children’s see-saw if one person moves towards the pivot point the force to lift that person at the other end is reduced. In the extreme case, if the centre of pressure on the rudder blade is moved directly under the pintles, no force would be required on the tiller and the tiller would have no ‘feel’.

How do we alter the rudder system so that the blade is moved forward a bit from its present position when fully down? There are three methods that achieve this result.

  1. Pack out the top pintle.
  2. Reposition the blade’s pivot point.
  3. Remove a small amount of the blade material that hits the rudder stock preventing the blade from hanging more vertically.

The first method is fairly self explanatory, the more packing the more the force reduction on the tiller; however this may require the use of longer machine screws for fixing the pintle to the transom and the visible packing may be a bit unsightly.

The second method is probably the easiest to achieve the desired effect, merely requiring a new pivot point hole to be drilled in the blade. This allows the blade to hang vertically before it hits the rudder stock housing. The old hole may be filled with epoxy resin. Click here for a template giving guidance on where to reposition the pivot point. As a consequence of this mod. the blade protrudes a small amount from the rear of the housing.

The third method involves removing some rudder material that hits the rudder stock housing preventing the blade hanging vertically. About 8mm needs to be removed, tapering up to zero as the blade emerges out of the housing; the resultant wound on the blade needs to be sealed with epoxy resin and repainted. This work is not visible as it is inside the housing. A detailed ‘how-to’ is given here.

Thanks to Dennis Hambleton for most helpful information on this topic and supplying the template.