Wing tube corrosion

Having just picked up an '86 vintage 17, I'm going over the entire boat and doing the usual (ok, maybe more than usual) tweakings and repairs. I've had great help from a close friend (who owns/races a 17), as well as from other 17 sailors in the area (kudos)!

Most of the repairs/tweakings have been rather straightforward in terms of the how to's, but I'm searching for solutions for this one...

Seems for this vintage, when they "sealed up the wing tubes" at the area where the wing tube goes into the wing socket of the boat, they plugged the tube with a solid piece of wood, about 6-8 inches long. Great for strength I'm sure, but lousy for any sort of drainage. Hence, with any water not only getting inside the tube, it couldn't get out.... so this has led to some corrosion forming inside the tube, and thus, to holes in the tubes themselves.

How do I know? I took off the plastic pieces on the bottom of the tubes, opened them up and cleaned them out. I won't go into the details, but needless to say, the wood trapped moisture in there. So now I'm trying to figure a solution to arrest any further corrosion, and to patch and reinforce the tubes.

Any suggestions? Each tube, has about 2-5 small (1/16" to 3/16") holes in it, as well as a couple of the spots (overall) that are up to about 5/16" long. What is the best way to repair and seal these holes (making flush with the outer tube surface), and what is the best way to restrengthen the tube itself? Any help would be greatly appreciated. thanks!

I think you're looking at new wings (at least the outer extrusion). If the tube is corroded all the way through, I would question its structural integrity. It could fail in a spectacular way.

Can you post a photo?

Sorry, I'm unable to post a photo here, as this forum will not allow uploads, and I have no access to post elsewhere. I could, if you wish, email some pics of the inner wing tube corrosion, and of the spots that have made it's way through the tube.

Structurally (sp?), I may be ok.... but the question is to either do a simple fix, to buy some time, or a more permanent fix. I'll be off to an aluminum welder next week with tubes in tow, to get their opinon (as they do a lot of marine work), and go from there. I'll post the details here, if anyone's interested.

'till then...

As a follow up to the wing tubes...
I looked at my options to stop the corrosion, to strengthen the tubes, and to keep any further water from accumulating inside the tubes. The solution I came up with, was to epoxy stainless tubing inside the existing tubes, and then to fill any of the places that the corrosion had made it's way to the surface, with additional epoxy.

I went with stainless, because it was the nearest outside diameter (1 5/8")I could find to fit the inside diameter (1 11/16") of the wing extrusions. This left a 1/16" gap that was coated and filled with epoxy, as the tubes were being inserted. Left to harden overnight, I'm now filling any of the spots on the wing extrusion (where the corrosion made holes in the tubes), that didn't get quite enough epoxy to the surface. They'll be ready to go tomorrow.

I can't tell you how much additional weight this added to the wings, as I didn't put them on the scale before I took out all the existing wood (which was compleately rotten and waterlogged), but I do know the stainless tubing alone added 4.8 lbs. and the epoxy is about an additional 12 ounces. So for close to 3 lbs. per side, they are now stronger than ever... and it couldn't be more than a pound or so in overall gain per side.

I went with 18" lengths of the stainless tubing, to go from the bottom of the extrusion (minus the plug height), up to the start of the outward bending (or about as far as they could go). I'll probably epoxy the bottom plugs back in, but will have a drainage hole that I can seal off, or open and close to allow any further water that get's in, to get out...

There were other options... wood dowling, pvc pipe, etc., to epoxy in, but this is the strongest by far and the most adaptable.

Hope this helps....

Many of us who sail in salt water have drilled large(1/2"-3/4") holes in the plastic plugs in order to flush out the wing tubes.
The Plugs DO NOT SEAL THE TUBES.
The pop rivets which attach the castings for the inside bar allow water into the tube.
Attempting to seal the tubes will only make the corrosion worse.

I agree with you 100%! Which is why I drilled/am keeping a drainage hole in the plastic "plug" at the bottom of the tube.

However, and to pass this on... when I spoke to the Hobie dealer about this (water getting into the tubes/corrosion), they said "the wings are supposed to be sealed watertight." So from the factory, they are assuming them to be watertight.

When I originally took the wings apart, there was so much sealant between the plug and the "wood dowling", that I had a heck of a time just getting the plug out, so obviously Hobie did seal the plugs in (and I have pictures to prove it). Also, I was going to replace the castings that hold the inner bar, and when I picked up the rivets (from the dealer), I was also instructed to use those "sheaths" that go over the pop rivet, and into the drilled hole, before riveting... the goal here they said, to seal off the unit entirely from water getting in.

This was my experience, and maybe the plugs were just sealed for that year... but as for the casting rivets, that's what I was told just weeks ago.

But as this has been my experience, I am not going to seal the tubes entirely, as I don't want the problem to happen again. I had always assumed, that aluminum does not corrode in fresh water (and this has been a fresh water boat). However, my neighbor, a retired pilot (from float planes to 747's), told me otherwise... aluminum can corrode in fresh water, if it's trapped in. I believe Hobie may have changed the wood dowling, to a wood box, that will not allow water to be trapped against the inside tube wall of the wings... which is obviously a step in the right direction. And for all I know, it could be the aluminum used for these tubes, wasn't quite right to begin with, as some of the corrosion spots, are well above where the dowling was put in. So I don't know the answer.

I had posted this question to get some real world advice, and to alert others to what my experiences were, and what I learned. I send thanks to you, for your reply.