Hi Ian,
The first year 25 mk 1's such as mine (1973 hull #79) were built with a solid wood rudder. I read elsewhere on the internet that it was made out of layers of mahogany plywood. So wood is an option if you decide to replace it. I just have two bad things to say about it: my wood rudder floats to some degree, and it would bang around all night long due to slop between the hinge pin and worn gudgeons. I solved that problem by sleeving the gudgeons with bushings. The other thing is that the wood rudder can be a little maintenance intensive. I tried varnish and epoxy, even had it stripped and redone by professionals, but it would never last at the waterline where you get all the turbulence against the transom. And if you don't keep it protected, it will rot. Finally I went to barrier coat with topside paint above the waterline and it has been fine since. Putting a boot strip on the rudder is an added layer of protection at the waterline. The remaining 25 mk 1's, which is most of them, had rudders that were solid wood at the top and essentially hollow fiberglass below. The transition is a couple inches below the lower pintle. I assume there are a few inches where the fiberglass overwraps the wood. I don't know whether they came from the factory with drain holes or not. But if water gets inside the hollow portion and freezes, it will crack the rudder. So if it were me I'd put a drain hole at the bottom and a vent hole at the top. This would allow the rudder to free-flood when the boat was in the water, then let the water drain out when the boat came out of the water. But you have to keep the holes clear. In addition to the wooden rudder on my boat, I have two of the newer 25 mk 1 rudders in my garage. The first one is cracked completely in half just below the solid wood section. The boat was scrapped for it's keel, and they left the rudder on when they pushed the boat off the stands. The other rudder I took off another boat that was being scrapped for its keel. This rudder was allowed to fill with water, then freeze, so it is cracked. There was still water sloshing around inside it and weeping out the crack when I brought it home. It actually had a bolt installed in the bottom of it as if to be a threaded plug. I'm hoping it can be repaired if I ever need it. Both of these rudders came from 1974 hulls. When I look inside the two pieces of the rudder that is cracked in half, at the leading edge and the trailing edge, there are a few inches of solid fiberglass. When I look into the lower half, about 5" down, I can see a strip of plywood maybe 3/4" thick and 4" wide. This plywood strip appears to be varnished and wrapped in fiberglass. It runs down the center of the bottom 20" of the rudder and wouldn't have been attached to the solid wood at the top of the rudder in any way. So I don't think this is any kind of skeletal structure. It wouldn't be very strong. I think it either served as part of a frame to manufacture the rudder, allowing the builders to wrap the fiberglass into an airfoil shape. Or if the rudder was made in two halves, as others on the list have said, it helped to hold the halves together. I believe the 25 mk 2 rudders were identical to the mk 1 rudders, except they have a small second step where the rudder meets the bottom of the transom. My guess is that this was an attempt to prevent lines from getting caught between the rudder and the transom, which are very difficult to remove, but I don't know. So if you can get your hands on a salvaged mk 2 rudder, that would also work for you. I believe a new rudder from South Shore is about $3k. I think you can get foam rudders from Foss Foam and Phil's Foils for about half that. They make them out of blocks of foam and machine them to shape. Supposedly there's a museum in Canada that now has all the C&C drawings and will provide them for the cost of scanning or photocopying/mailing, etc.. I'm not sure if anyone on the list every got drawings for the 25 mk 1, I don't know if there's a rudder drawing, and if there is I don't know if it would describe how it was manufactured. Anyway, if you want any photos or measurements taken of my rudders, or a sketch that better describes the above, contact me off list. Thanks, Mark Dartmouth, MA > > ------------------------------ > > Message: 4 > Date: Tue, 18 Aug 2020 21:23:06 -0500 > From: Ian Tubby <ian.tu...@gmail.com> > To: cnc-list@cnc-list.com > Subject: Stus-List Rudder Rebuild on C&C 25 MK1 > Message-ID: > <cacioyhy5jwhdtepatgy0b30n2s0r-ept1kbualgcwhhkt2x...@mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > Evening Guys, > > New member here. I just bought a C&C 25 MK1 from an owner who frequented > this mailing list, who told me about this forum. What a great resource! I > searched the archives however and could not find the answer to the > questions I'm about to ask. Here goes. > > My transom hung rudder has a serious blister problem not helped by an old > leaky lower gudgeon. This leak was patched by the previous owner with Gflex > however the rudder was not opened for inspection or dried out. > > I'm away from the boat for the next week and I'd like to get ahead by > ordering what I need now to fix the rudder when I get back to the boat. I > haven't been able to find any diagrams or pictures of the rudder > construction on the 25 MK1. I've read that there is a piece of plywood > somewhere in the core and other posts that lead me to believe that below > the waterline portion is hollow, and that some have drain holes and some > don't. Does anyone have better information on the construction of this > rudder? > > I want to know because if I can safely rebuild the rudder out of some > polyurethane foam I will. I've had experience with this in the past > repairing another rudder damaged by grounding and it turned out extremely > strong and more rot resistant. But this was for a boat with a foam filled > rudder originally, so I don't know if the skeletal structure of the rudder > on the 25's would support this. > > Anyone have suggestions on what route to take? It'd be great if someone > having done this could go over what route they took. Or if foam is at all > advisable. I also don't want to upset the balance of the boat if the > original rudder structure with that hollow was an integral part of it. > > And I know that I could order a new rudder from South Shore Yachts, but I'm > guessing that's expensive. And ofcourse way less fun. > > Many Thanks, > > Ian Tubby > 1976 C&C 25 Mk1 "Icicle" > St. Petersburg, FL _______________________________________________ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. 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