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Old 03-06-2013, 19:38   #1
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Wet closed foam rudder

Our closed cell foam rudder has a fair amount of water inside and the closed cell is not solid (was it ever or is it crumbling?). The fiberglass man who did the core sample drained the water and said it was not rusty. He recommended we plug the holes he made and continue to use the rudder.

As far as we can tell, delamination is not an issue. For now we intend to sail only inshore on the Chesapeake Bay but eventually we plan to take the boat bluewater cruising.

Should I worry about fiberglass delamination from the inside? Is there a test like ultrasound that can check for internal problems? At the moment, I'm thinking we can just check it during our annual haulout and replace it before we go out to bluewater.

Fyi the boat is a 1999 Bavaria 38 ocean.
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Old 03-06-2013, 19:43   #2
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Re: Wet closed foam rudder

Sounds like your "fiberglass man" is probably right.
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Old 03-06-2013, 20:08   #3
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Re: Wet closed foam rudder

Your fiberglass guy is probably right ..... but remember that water expands by 8 percent when it freezes and if there is enough water in there it can split your rudder. Drill a hole in the bottom of the rudder at winter haulout (if you do haul out) and let the water drain before it freezes each year.
You can patch the hole with epoxy each spring.

If you are really concerned hire a surveyor to put a moisture meter on it and do percussive sounding. Using these two methods is a bit of an art form but an experienced surveyor will give you a sense of how bad it really is.

I've inspected a few thousand rudders and have come to the conclusion that closed cells in the foam only close after the water is inside each cell.
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Old 04-06-2013, 08:13   #4
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Re: Wet closed foam rudder

You can dry the core without taking the rudder apart. Cut a two inch hole through the skin and using a vacuum pump, thick plastic and gorilla tape for a seal, apply a vacuum to it along with heat from some halogen lights or a propane heater (forced air type). Leave it on for 24 hours, remove and let the surface foam dry. Glass it back up.

We dried the core in a Lagoon 400 keel this way recently for a repair.
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Old 04-06-2013, 08:36   #5
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Re: Wet closed foam rudder

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Originally Posted by CharlieCobra View Post
You can dry the core without taking the rudder apart. Cut a two inch hole through the skin and using a vacuum pump, thick plastic and gorilla tape for a seal, apply a vacuum to it along with heat from some halogen lights or a propane heater (forced air type). Leave it on for 24 hours, remove and let the surface foam dry. Glass it back up.

We dried the core in a Lagoon 400 keel this way recently for a repair.

What did it read on the meter when you finished? At the start?
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Old 04-06-2013, 10:34   #6
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Re: Wet closed foam rudder

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Originally Posted by CharlieCobra View Post
You can dry the core without taking the rudder apart. Cut a two inch hole through the skin and using a vacuum pump, thick plastic and gorilla tape for a seal, apply a vacuum to it along with heat from some halogen lights or a propane heater (forced air type). Leave it on for 24 hours, remove and let the surface foam dry. Glass it back up.

We dried the core in a Lagoon 400 keel this way recently for a repair.
What kind of vacuum are we talking about? Vac cleaner or refrigeration vacuum pump? How many hg?
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Old 04-06-2013, 11:51   #7
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Re: Wet closed foam rudder

Hmmmm. I'd be more concerned about rust than delamination. The way that rudders are generally constructed is that the shaft has several tangs or even a plate welded onto it. The rest of the rudder is then constructed around this. If water gets into the rudder as it appears to have done in your case the danger is that the welds holding the plate or the tangs to the shaft will rust through. Once these welds go, the shaft will rotate independently of the rest of the rudder, essentially rendering it inoperative. I'm currently in Bermuda out of the water and a boat came into the yard last week having lost an entire side of it's rudder plus the bottom foot and a half because of a blow-out from water-ingress. They were very lucky not to lose the whole thing and find themselves floating around helplessly in the middle of the Atlantic.

For sailing around inshore i'd be tempted to do as suggested above, biut for offshore sailing i'd personally want to know that my rudder is sound. It's quite easy to inspect and repair this problem. Take an angle grinder and make a cut all the way around the circumference of the rudder. You may also need to run a hand-saw down the middle but the two halves should separate nicely since you have a foam core. You can then get access to the interiour, inspect the welds, treat any rust and bond the two halves back together again, sealing the whole thing up again properly as you do it. All it takes then is a 2" fibreglass tape around the edge that you cut, a little bit of fairing and she'll be as good if not better than the day she was built.

At any rate it seems to me that you need to address the problem (i.e. dry it out and stop water from getting in) otherwise it's only going to get worse over time until it eventually fails...........
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Old 05-06-2013, 21:33   #8
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Re: Wet closed foam rudder

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What did it read on the meter when you finished? At the start?
30% and then 12%
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Old 05-06-2013, 21:34   #9
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Re: Wet closed foam rudder

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What kind of vacuum are we talking about? Vac cleaner or refrigeration vacuum pump? How many hg?
A standard vacuum pump used for vac bagging. I'm not sure what this 4.4 CFM pump pulls.
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Old 05-06-2013, 22:10   #10
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Re: Wet closed foam rudder

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Originally Posted by CharlieCobra View Post
30% and then 12%


Not bad. Heat source?
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Old 06-06-2013, 00:04   #11
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Re: Wet closed foam rudder

Some years ago we lost our rudder and, potentially could have lost our boat. We had had the rudder inspected by 2 separate shipwrights who had pronounced it fine, the glass looked ok and the stainless steel shaft looked fine too. When it broke, it snapped the stainless steel shaft 2 or 3 inches inside the blade... apparently some water had been getting in over a long period of time and the stainless steel shaft was badly cracked and corroded... but this was invisible in a normal visual inspection.

I guess what I am saying is that water in the foam blade of a rudder is never a good thing. The fiberglass man who recommended you continue to use the rudder is not putting his rudder, boat and, potentially, life on the line.
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Old 06-06-2013, 00:20   #12
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Re: Wet closed foam rudder

Always plan for a jury-steering scenario. A sculling oar, a prepared hatch that easily can become a rudder, anything. But prepare - before it happens. Never mind whatever guarantees, quality or survey.
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Old 06-06-2013, 08:06   #13
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Re: Wet closed foam rudder

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Originally Posted by minaret View Post
Not bad. Heat source?
2400 watts of Halogen lights about a foot away.
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Old 06-06-2013, 08:49   #14
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Re: Wet closed foam rudder

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Originally Posted by Weyalan View Post
Some years ago we lost our rudder and, potentially could have lost our boat. We had had the rudder inspected by 2 separate shipwrights who had pronounced it fine, the glass looked ok and the stainless steel shaft looked fine too. When it broke, it snapped the stainless steel shaft 2 or 3 inches inside the blade... apparently some water had been getting in over a long period of time and the stainless steel shaft was badly cracked and corroded... but this was invisible in a normal visual inspection.

I guess what I am saying is that water in the foam blade of a rudder is never a good thing. The fiberglass man who recommended you continue to use the rudder is not putting his rudder, boat and, potentially, life on the line.
Bingo....

You can probably repair for light use if you plan to rebuild it correctly in the near future... I honestly wouldn't trust your recommended repair for any weather, overnight coastal, or offshore....
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Old 06-06-2013, 09:13   #15
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Re: Wet closed foam rudder

if you want a watertight rudder, try a solid metal one. even wood rudders of old are waterlogged. also, nothing last forever, how long should a fiberglass rudder last? keep inspecting yours for cracks along the edges when hauled, then repair if cracks are seen. never go fast in reverse, high stresses on rudders.
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