I forgot to mention that there is a crack in the fiberglass on the inside as seen in the picture. There is some sort of structural frame (aluminum?, fiberglass?) that is now bent inwards at the bulge and the overlaying fiberglass is split apart (see picture). Suggestions for repair?
That is probably a stringer (depends on the orientation, could be a frame as well). It is not difficult to repair if you can use an angle grinder and do some grp work - it is easy, you can learn quickly if you are used to tools and some handy work.
Firstly, fix the support on the outside so the is no pressure in creating the bulge. That means you have to make another arrangement for supporting the boat on land. Be creful, so this doesn't happen again.
Then, you might have to apply some preassure from the inside to correct the bulge. Doubt this will need much force, but you must have something to see to that you get the hull back in shape.
Next step is useing the ange grinder, cut away bad parts. Before that you can make some investigations with a chiesel and hammer - do not be afraid to hack away bad patches from the stringer - what is bad should go away. The hull I would be more careful with.
The damage is only in one point, but to repair you have to cover a larger area. When cutting away in the stringer, then the should be over a distance of maybe some 3-5 dm (1 -1Ĺ ft), and both ends should be tapered.
With the angle grinder you have to sand away the gelcoat of the hull in the area. Last stage is to rebuild the stringer, and to get it attached to the hull, all this with grp.
Here, I do not go inte the detail, just indicating the main steps. You have to get more detailed info from eg a book "how to repair fibreglass boats" or something.
To do this repair is neither difficult nor expensive. Use normal grp materials (not epoxy).
It could be good to invest in some thinking on why and what has caused this. It looks as the stringer was too weak, and wasn't fastened enough to the hull (?). Stringers are usually horisontal, and if you are unlucky then there has been water in the fold between stringer and hull. This water may have penetrated in between the stringer and the hull, and maybe frozen (?), and thus causing a separation. Pure speculation from my side.
Also, any suggestions regarding the rudder? A survey last September showed no cracks or outward sign of damage to the rudder but obviously now that its been draining (or freezing?) all winter, there is rust dripping visible. A google search showed that people drill into the rudder to drain the water then fill the holes up with filler. Should I do work to the rudder before putting her back in the water and if so, what? Thanks for all the help!
If you have got water in the rudder (so it seems) the drill a small hole (5-8 mm) at the lowest point where there is a void inside the rudder (light hammer, listen carefully, just light tapping). If water comes out ... OK, then you know that.
Do not fill with a filler! Use a maschine screw instead, which you then remove the following fall (and replace in the spriong and so on).
It is difficult to see in the photo, sometimes one does gets some rust coming out also from stainless - this is as stainless is not really stainless it is just rusting very slowly. But to get this process to slow down, the steel must be open for oxygen ... which will build up a thin layer of oxide. Without this, some rust may be produced.
In itself, som rust stains are not dangerous. They may be a sign of some serious damage inside the rudder - who knows what kind of steel was used?
I would recommend the small hammer again ... listen carefully. If it looks like it is just on the surface (where the rust origin is) the I recommend using a chiesel and removing bad parts, and then rebuild with new grp.
It is difficult to say if you have any serious damage in the rudder or not, based on one photo.
You may have a look on the survey, what did it actually say, and does it include some clauses on damages that were not really identified - a surveyor should give some kind of ensurance that he is worth his pay.