Epoxy and Directions
Ok first
EPOXY, this is a structural member, the skin itself is structural to the rudder. Polyester does not form good secondary bonds to itself.
Second, here are the directions that I recently gave to someone that is repairing their e-39 rudder after grounding. It is relevent to all rudder repairs, and may help you.
If you have questions feel free to ask here or to PM me with your e-mail, and I will respond.
You can take the stations off of your rudder instead of using a drawing which may be hard to get. Take the stations off of the good side of the rudder. The easiest way to do this is to draw them on a piece of 1/8 inch plywood (doorskin) using a two legged compass as you would to transfer a hull pattern to a bulkhead.
If the existing foam is solid, and you can use it, then you will not need to cut new foam etc.
There are generally two things that are really bad on rudders, one is freezing with water in them, and the other is being painted black and left in the sun with water in them. Both options increase the pressure in the rudder, and cause cracking. Yours may have been left in the sun if only one side is cracked, or it could have been a bad layup at the factory, or it could have gotten more sun, hotter water on it under the water even. The list of WHYS could go on forever. So lets move on to how. ;-)
Again this was a quick e-mail fired off to an e-39 owner recently. Ask questions if it does not make sense.
The drawing is 1":1" by the way, so is Life Size! You can make your fairing section boards right off of the print. What I have done in the past is to actually glue the print to a piece of 1/8 plywood (Door Skin), cut on the line, and use that for my reference boards for fairing. This gives a nice result.
Remember take your time, make sure that the stations are correct, and that the aft edge of the rudder stays straight!!! That is important!!! Curves and s's don't work as well as a nice straight trailing edge.
The boat will sail a lot better in all airs with this rudder modification.
Your friend will want to completely take the skin off of the rudder, along with all of the foam to see what damage has been done to the rudder web. Any damage done to the web, can be repaired by a competent welder. (NOTE THAT YOU SHOULD PASSIVATE IT COMPLETELY AFTER WELDING!) The best way to do this is in a acid bath with a constant current power source, which is going to be hard to find.... Check out the local rail makers that make pullpits and push pits, sometimes they have large size passivation tanks.
If you can't find anyone to pacify it (takes less than 30 minutes of actual tank time), get a bunch of wichards wichnox stainless steel cleaning polishing gel, (Available at west marine), and use a rag to coat everything. (Be careful this is a combination of acids in a paste form. Wear safety gear! Don't breath the fumes!!!) Let is sit for a while and hose it down good. Really good, we don't want any of the acid left in the final rudder.
After passivating the rudder web and post, get some structural marine grade foam, along with the foam glue that the manufacture of the foam recommends (Don't believe anyone that tells you to use anything else. We have tried it all, and nothing works but the real stuff.) Glue the foam to the web, and through the holes in the web to the foam on the other side. Layer foam as necessary to have all of it larger that your fairing section boards. Once you have the foam on, using a Stanley Sure Form (TM) tool, gently and easily shape the foam to shape using your section boards (Note this part takes maybe a couple of hours as the sure form really cuts through the foam.)
Once you have the basic rudder shape in foam, you need to apply your glass. Use Epoxy the extra cost in this small a project is well worth the added benefits of no blisters down the line, and the extra bit of strength that it will provide. The easiest way to get the glass on the rudder is to vacuum bag the whole thing, so much easier in fact that it is probably worth getting a vacuum pump, and the stuff to do the bagging with. (Get the Gudgeon Brothers ((West systems)) little book on how to vacuum bag. It can be done without it though, do one side at a time, be patient, and careful on getting the voids and wrinkles out of the glass.
If you do the vacuum bagging then you should end up with very little fairing to do later. After the rudder has kicked, and the vacuum bagging stuff been removed, fair with micro balloons or fairing filler. Paint it with bottom paint, and put it back in.
If you want to see the process in photos, I might be able to find the photos here of a Cal 35 Rudder we did exactly this way a few years back.
Thanks,
Guy
