Foam Injection for Rudder and Dinghy

[heron237]

I have two needs to inject foam. First: My dinghy has a couple of flotation chambers. It appears that foam blocks are in there with a lot of room around them, either they were originally as they now appear or they were originally larger and shrank. I'd like to fill the voids. Two: I was repairing a ding at the base of my spade rudder and had to grind through the skin-- this elicited water weepage, I subsequently drilled a few half inch holes at various points to facilitate drying out and would like to inject foam in those holes. As an aside I understand your rudder should be neutral buoyancy???or lighter, or heavier?

Can I use that closed cell house contractors foam with the probe on it? I realize there are a couple of versions of it. Should I use a two part foam? Is there a foam that will not be affected by contact with epoxy resin?

[Paul Elliott]

Sorry, I can't help with the foam, but you might want to check the rudderpost and web (framework attached to the post) for corrosion. Those conditions are perfect for stainless crevice corrosion.

[heron237]

what you're suggesting i cut the rudder in half and inspect the post? c'mon, the corrosion problem isn't a problem yet, how about the foam issue??????

[Bash]

If you're talking about the spray foam, I recommend against it merely because it can tend to waterlog over time. If it were my boat, I'd use an epoxy filler to close up the weep holes.

[Paul Elliott]

Originally Posted by heron237

what you're suggesting i cut the rudder in half and inspect the post? c'mon, the corrosion problem isn't a problem yet, how about the foam issue??????

Sorry I couldn't answer your question. You know your rudder and I don't, but how do you know the corrosion isn't a problem? Because it hasn't broken yet?

What I've heard is that to fix a leaking rudder people drill lots of holes, let it drain for a good long while, then glass over the rudder, making sure it's watertight.

And I still haven't answered your question. I'll stop now.

[Cheechako]

I have used two part foam, there is actually a mil spec foam for boat work. Not sure where you would get a small amount though. I've seen a lot of rudders with water intrusion. The current foam inside there could be "mush" at this point. The best fix would be to cut a large rectangular window in the side of the rudder with a skill saw. Peel that off and save it. Remove all the wet stuff and let it dry out good. (inspect the tabs where welded to the shaft) Glass the window back in place and fair the surface. Then fill the rudder from the top with epoxy/microbaloons mix or something similar. If you are not going offshore cruising etc..then maybe this is over kill...problem is you never know. I would imagine a lot of people are cuising out there with waterlogged rudders....they just havent drilled a hole in the rudder yet!! Not much point of injecting new foam into a wet environment that is likely still taking on water.