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SailNoFo 10-19-2017 11:23 PM

Large Blister on Oday 31 Rudder
2 Attachment(s)
Bought used 1985 Oday 31 Spring '17. Took boat out for season to discover large blister on rudder (see attached)Attachment 102985

Attachment 102993. There was no blister at time of boat survey in Spring. Any suggestions/references regarding repair options? Thanks.

boatpoker 10-20-2017 09:12 AM

Re: Large Blister on Oday 31 Rudder
No way that happened without some obvious indicators that would have been caught by any half decent surveyor. Wavy-ness on lower part of rudder suggests a patch job that should have been caught by your surveyor.

JimsCAL 10-20-2017 09:21 AM

Re: Large Blister on Oday 31 Rudder
Assuming this is not just a big bottom paint bubble, I would say you are looking at either rebuilding or replacing the rudder. Start by drilling a hole in the bottom of the rudder and see how much water comes out.

Repair would involve cutting the rudder apart, fixing any corroded internal structure, and putting it back together. A new rudder can be made by Foss Foam. Here's the link.

eherlihy 10-20-2017 09:46 AM

Re: Large Blister on Oday 31 Rudder
From the comfort of my desk, that looks like a water bubble in the antifouling paint. In essence, the bottom paint was applied with inadequate preparation and water got behind it and formed a "bag."

You probably have water in the rudder of your boat. Every time that I have looked for water in the rudder post of an O'day 35 I have found it, including on my boat. I used to siphon the water out every year when the boat was hauled. Two years ago I poured a gallon of automotive antifreeze (concentrate, not the 50/50 stuff) in the rudder post. I made it through last year with no issues.

When the time comes, I'll probably just buy a new rudder from Foss Foam.

SailNoFo 10-21-2017 06:08 PM

Thanks for comments. Going to yard/boat tomorrow. Appears probable that the blister is mostly gas from foam rather than water. does that change anything with respect to treatment?

JimsCAL 10-21-2017 07:32 PM

Re: Large Blister on Oday 31 Rudder
As was noted by me and eherlihy, the first question is is this just a bubble in the paint, or is it in the laminate. The second thing to do is drill a hole in the bottom of the rudder to see how much water drains out. You can also tap all over the rudder to see if you have delamination. In delaminated areas you will get a dull hollow sound and may feel some give in the fiberglass skin. If you get a solid sound, then you still have a good bond between the foam and outer skin.

Until you do the above, there's not much we can do except guess wildly about what you are dealing with.

TQA 10-21-2017 11:27 PM

Re: Large Blister on Oday 31 Rudder
Drill hole in bottom of rudder - see how much water runs out. An egg cup or two is OK quarts are not.

Grind off blister [ start from top of vent it first.

Lock tiller or wheel and get someone to try to move the rudder [ really hard ]. while you see and feel for any evidence of internal failure.

SailNoFo 10-23-2017 06:48 PM

Re: Large Blister on Oday 31 Rudder
Again, thank you all for your comments. I went out to the yard this weekend to discover that the blisters have disappeared (which I gather translates to the blisters were in the paint* rather than the laminate). I will go out again in the next couple of weeks** to drill hole in the bottom of the rudder and measure amount of water that comes out. Is there a proper technique for drilling a hole in the rudder? I'm planning to use 1/4" drill at the lowest part of rudder going in from bottom (rather than side). I don't know the construction of the rudders but presumably I won't hit a water pipe/electrical line (or equivalent) doing that. (?)

The surveyor tapped around the rudder quite a bit during the survey. He told me about a dead spot but I gather he concluded it shouldn't be a deal breaker (or if he did, I wasn't listening).

* I would not have imagined that paint could hold that amount of water. Did this blister exist while the boat was in the water (or does it appear only when the boat is pulled)?
** I planned to drill the rudder when I was out this last weekend but putting the cover on (first time) took a little more time than I expected.

boatpoker 10-23-2017 07:00 PM

Re: Large Blister on Oday 31 Rudder
I have a hard time believing that blister is limited to the paint especially considering the unfair are below the blister.
Did you sound the rudder this time?. did you stick a knife in the blister?, Did you try to peel the paint ?

eherlihy 10-24-2017 09:00 AM

Re: Large Blister on Oday 31 Rudder
I will say this one last time; I recommend that you do not drill a hole in your rudder. Siphon the liquid out, and pour some antifreeze in.

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