Rudder Repair advice needed

[bluey]

Hi,
My boat restoration job is going well, but I thought I'd ask here for some suggestions as to what material I could use to do a major repair to my boat's rudder.

The rudder is made of Fiberglass and was originally constructed by joining together two fiberglass "shells". These two halves, when joined formed a hollow space which was completely filled with some kind of hard, dense, putty or filler material. This putty was orange in colour and made the rudder very heavy, the whole thing weighing around 15KG.

In my over exuberant efforts to repair the rudder I ended up separating the two f/glass halves and removed all of the filling material by attacking it with hammer and chisel.

I intend to repair the rudder by rejoining the two halves using West System Epoxy resin and F/glass cloth but am not sure what material or I could use to refill the hollow space. Should I use epoxy resin mixed with microfibres as the filling material? Or could anyone here make suggestions as to what product I could get to do the job? It would need to be in a liquid form to be able to pour it in and fairly dense to give the rudder some weight and rigidity.

Here are some pics of the rudder to show what I'm on about -

Cheers,
bluey.

 

[BWT]

Re: Rudder Repair advice needed

Well, the way I would tackle this would be to glass the two halves back together with the core still hollow (maybe clean up it even more to remove whatever was used originally) and cut off 1 face (roughly 2" in from the perimeter all the way around) of the rudder after everything has cured. This will preserve the original shape. Then, use a closed cell urethane foam (I get mine from us composites http://www.uscomposites.com/foam.html ) in a 16 pound density. Not sure what suppliers are avail Down Under, but I'm sure something comparable is avail. Tape off the open glass from where the pintle was mounted. Pour the foam in layers to avoid excessive heat and slightly over fill the cavity of the rudder. Cut off excess and shape then grind the 2" tabs to a taper that were left behind from the skin that you cut off and start laying up new glass to encase the new foam. I typically do the following schedule:
1 csm against the foam, 2 layers of 1608 biax then 2 layers of csm for the outer skin. Sand and shape then apply some type of barrier coat (rolled on epoxy or a commercial barrier coat product). Apply some bottom paint and all set.

It's actually a bit of a project and much more detail can be given, but that will come once you're actually doing the project; this is just a quick overview of what I would do... Hope this helps, good luck! Please continue to post so we can keep up with the progress!

 

[bluey]

Re: Rudder Repair advice needed

Hi BTW,

Your method seems to be a more commonsense way of going about it. I'll have a look around for some CCU foam or it's equivalent and give it a go. I regret to say I had not thought of doing it like that, so thanks for the good advice, I'll let you know how I get on.

Cheers,
bluey.

 

[bluey]

Re: Rudder Repair advice needed

Just one more question BTW,

What quantity of 16lb CCU foam would I need to fill the rudder? Are you able to hazard a guess from the attached photos? It's thickest point at the top would be about one and a half inches.

bluey.

 

[BWT]

Re: Rudder Repair advice needed

It's a pretty small rudder; thinking about it a little more you could probably get away with using an 8 pound foam (16 is definitely stronger but I don't know that it's necessary). As far as volume, what roughly are the dimensions of the rudder? Guessing roughly 2 feet by 4 feet? I'll need to know that to take a stab at the volume of foam needed. One thing I want to stress is that the foam needs to be closed cell (not the spray stuff you get from a general store; it will be nothing more than a sponge!!) Check the marine suppliers for this and double check the spec's. I've run into places that weren't real knowledgeable about the product and sold me the wrong stuff!! The foam needs to be closed cell and resistant to chemicals (otherwise the resin will melt it when laying up the glass!)

 

[bluey]

Re: Rudder Repair advice needed

As far as volume, what roughly are the dimensions of the rudder? Guessing roughly 2 feet by 4 feet?

You're not far off.

Overall dimensions are 45" x 19 3/4". The Rudder is 1 1/2" thick at the top and for the first 12", it then tapers down gradually to 3/4" at the very bottom.

I don't think it'll take much to fill it.

I'll bear in mind your advice about the closed cell foam.

Thanks,
bluey.

 

[Yacht Dr.]

Re: Rudder Repair advice needed

Im with BWTs way...with a twist ..

Clean both halves well .. scuff 3" around the inside perimeter. Tack glass the two halves together. Cut out one face like BWT said.

Before foaming .. Laminate the inside bond edge all the way around with a few 3 layers of 1.5 oz mat.

Carry on with BWTs suggestions.

YD.

 

[bluey]

Re: Rudder Repair advice needed

You're not far off.

???? not sure what you mean there lancer99888.


Your advice is always helpful YachtDr, thanks.


bluey.

 

[bluey]

Re: Rudder Repair advice needed

use a closed cell urethane foam (I get mine from us composites http://www.uscomposites.com/foam.html )

Hi BWT,
I wrote to uscomposites to get a quote for shipping their product to Australia and got a shock when they wrote back. The foam only costs $US21.00 but shipping would be $US84.00!!!!

The only winner out of that deal would be the postal service.nGuess I'll have to keep trying to find a dealer in Oz that has the pourable foam, most of them seem to stock it only in board form.

bluey.