Hi, Jami.

Yes, those bulky hinges were meant to sit on the transom. I was thinking of a free spade rudder.
As for bearing, I was thinking of trying with plain epoxy bearings first. I would lock the pintle rod to keep it from rotating. Any wear would then just be on the rudder gudgeons. In case there proved to be any wear there, it would be easy to remove the rudder, drill up the holes again and glue in metal bushings to get a metal to metal bearing. (That bushing could start life as a full length tube between the hinges to ensure alignment, and then be cut off after the epoxy had set.).

Arne

If everything fails, try plywood...

Hi Jami.
Over the years, I have used plywood for all sorts of small jobs. I find plywood to be strong and easy to work with. In case you fail to find good rudder hinges from metal to an affordable price, here I have drawn up a plywood type of rudder hinge from plywood. They may look awfully big and bulky at first glance, but when they have been fitted on the boat, they will appear to have shrunk quite a bit. Once you have made a pattern for the rudder part and transom part, and glued together some plywood to about 40-50mm thickness, it will be a quick job with a bandsaw to cut out the bits...
I would first drill the holes for the pintle rod oversize. Then I would fill the holes with epoxy, before drilling them to the rod’s size.

Anyway, I hope a new rudder will sort out the control issues you have had with your boat.

Arne

Jamie wrote:

Oh, that sounds quite different than dinghy-size then! Thank you, I’ll look a bit closer.

I think for your size of boat, and with the loads you are talking about you would probably need 'u' shaped gudgeons on the transom, which the rudder gudgeon fits between, and with a pin/bolt which passes all the way through. 

Another option is to make/have made the 'u' shaped transom gudgeons (brackets), out of stainless steel, and then do the composite flanges/gudgeons on the rudder as part of the rudder construction. That would be strong, simple, and probably not very expensive, If you could find a suitable size stainless box section extrusion with a wall thickness of 4 to 6 mm you could make the gudgeons by cutting off one face of the extrusion, Aluminum would be easier to work with, but probably not so good if a gudgeon was to be mounted below the waterline. 

Anonymous wrote:

Thanks, but ”... small to midsize dinghies and daysailers” doesn’t sound too convincing.

Yes, the text is not convincing, but  seems to be a standard phrase in toplicht's offerings. Take a look at the dimensions of the pintle (13mm!) and the weight of all items (nearly 2kg). The width is 44mm for thick rudders. Considering this you get the sturdiness. To my opinion, price is ok. If you go to a welder, you will have to pay the same (in Germany). If you want to make the fittings yourself, you should perhaps open up a new theme. Your question has been "...find...fittings in the EU?"

Jamie wrote:

The plywood-carbon fiber on the other hand would be well in my comfort zone. Is anyone able to say about the strength of it? We’re talking about a 1600kg 22ft monohull with a large junk sail and a larger rudder than the original plus I’m moving it some 40-50cm aft to the transom.

This is where someone with some engineering knowledge would come in handy. When building my rudder fittings I aimed to equal the thickness of the designed stainless steel fittings, which was 4 mm. Given that carbon fiber is supposed to be as strong as steel I figured I was in safe ground. It took a lot more layers of carbon than I expected to build up the thickness. I used a mix of woven cloth as the first and last layers, and then some double bias for thickness buildup, and some unidirectionals for strength. If it were me I would aim for a thickness of 6mm for the transom brackets, probably about 8 mm bolts for attachment to the transom, and 12 mm through bolts for the pins. I think I would want the thickness of the flanges on the rudder to be at least 50 mm with probably at least 6 layers of unidirectional carbon fiber wrapped around them. I used a proper laminating roller for laying up the carbon, and I used peel ply over the final layer to give a smooth finish.

Certainly if you can build the rudders then you have the skill to make carbon rudder fittings. It probably does not need to be carbon fiber, but if you just used normal glass cloth to make these the fittings would need to be so much thicker to get the strength.

If you build in some balance area on the rudder blade forward of the rudder gudgeons you will decrease the load on everything and the boat will be a lot easier to steer.