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Author Topic: Mystery Leak  (Read 4968 times)

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Gary Brockman

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Mystery Leak
« on: November 20, 2008, 12:26:03 PM »

When I first inspected my boat before making an offer on it, there was about ¾” of dirty standing water in the bilge.  The selling broker told me that the previous owner lived about 3 hours away from the boat and had not used the boat very much in the 3 years they owned it, and that they had only used it twice in the previous year.  The source of the water was not known but educated guesses listed rain/wash down water leaks, keel bolt leak, and/or shaft packing gland leak, none of which would be a major issue.  When the boat was surveyed, the survey stated that there was “minimal standing dirty water” in the bilge area with an unknown origin. The Notes section of the survey said to remove the water from the bilge area and clean the bilge area as necessary to detect any leaks in the vessel, which I planned to do after purchasing the boat.

When the boat was hauled out to paint the bottom, I decided to take advantage of the haul out and had the yard put in a dripless shaft system (and new SS shaft). After moving the boat to its new slip, I emptied the bilge of water and cleaned the bilge in anticipation of having a dry bilge. When I went back to the boat the next day, I was mildly surprised to find 1/2” of water in the bilge again. A systematic investigation eliminated all of the easily found leaks: keel bolts; rain water; wash downs; thru hull fittings; and hoses. My investigation found that the water seemed to be coming from the aft end of the boat and that the inside of the hull under the aft berth was moist and a small indentation would refill with water after a while when it was dried out. When the rudder post was eliminated, I removed the teak panel at the rear of the aft cabin to check the aft water tank.  I found that although the water tank did not have any leaks, the hull under the water tank was a transition point where the hull was dry to a point and then moist from there forward.  I had the manager of our local boat yard come over to inspect my boat and he confirmed my fear that the leak was coming through the hull itself. 

He said that this was not uncommon (I had never heard of this before) and that he had repaired a new Beneteau with the same problem (voids in the layup) last summer. He said that he didn’t think it was that big of a deal and that it had probably been there since the boat was new. He said that if I didn’t mind a wet bilge, I could just live with it as he didn’t think it was a structural/safety problem. If I wanted it fixed, he proposed to haul the boat, remove the aft water tank and the shelf it sits on, and to grind out the hull in the area of the leak, let it dry out, and re-glass the area. He estimated the job as a haul out, four hours labor, and material ($650±).

The boat is being hauled as I type this and I will provide an update when I know more.

 - Gary -
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Squall
1986 Hull #231
Tall Rig/Fin Keel - Elliptical Rudder
Marina del Rey, California

Ted Pounds

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Re: Mystery Leak
« Reply #1 on: November 20, 2008, 04:59:08 PM »

First - have you established whether it's salt or fresh water?  Makes a difference....
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Ted Pounds
"Molly Rose"
1987 #447

Rick Allen

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Re: Mystery Leak
« Reply #2 on: November 21, 2008, 06:50:07 PM »

I had a similar issue a few months ago and discovered that the aft deck shower hose had sprung a leak.  Took me forever to fugure out where the water was comming from!

Rick
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Rick Allen, C34 IA Commodore
Former owner of "PainKiller", 1988 C34 MKI, Sail#746, std. rig, wing keel.

Jeff Tancock

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Re: Mystery Leak
« Reply #3 on: November 21, 2008, 07:56:11 PM »

I've had and found a lot of leaks on our boat....none through the hull. I dunno but I have never heard of a leak right through the glass. If I am having trouble finding the source of a leak I use a kids marker that is water washable and draw a line around the area. The moisture leaves a trail and it becomes obvious where it is coming from.....
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Jeff Tancock
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Gary Brockman

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Re: Mystery Leak
« Reply #4 on: November 22, 2008, 12:26:42 AM »

I went over to the yard after my boat was hauled out yesterday and inspected the bottom of the boat with the yard manager.  There was a visible 2” line (crack) about 6” in front of the strut that was still dripping water as well as a line running parallel along the port side of the strut that also had a slow water drip.  Tapping of this area with a small hammer yielded both solid and dull sounds.   Although the entire area was covered in fiberglass, two areas seemed less than solid.   Fortunately, the strut itself was solid and firm.  The yard manger suggested opening up the area around the strut rather than grinding down the inside of the hull as previously planned, which I OK’d. 

When I went to the yard at noon today, they had not only already opened up the area around the strut, they were well on the way to having it repaired.  The manager told me that the area around the strut was not solid fiberglass, as a filling substance was used to fill what amounted to the area between what was the fiberglass inner hull and an outer fiberglass shell. He showed me pictures of two good sized voids they discovered in this area, one about 5” long.  Water had found its way into both voids and then seeped through a thin spot in the fiberglass hull.  Since there was nothing wrong with the strut, they ground down the area to solid fiberglass and then proceeded to fiberglass the area out to the hull lines. The yard manager said that this was an easy fix and that the area around the strut would be better than new. 

What is odd is that I had looked at the strut and the area around it with my surveyor when my boat was surveyed about 10 weeks ago, and none of these issues were apparent at that time.  The yard manager is sure that this leak had existed for a long time and was surprised that its cause was not visible at previous haul outs. 

Given what was found in the area around my strut, I suggest you closely examine and sound the area around your strut the next time you haul out.

 - Gary -

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Squall
1986 Hull #231
Tall Rig/Fin Keel - Elliptical Rudder
Marina del Rey, California

Tom Soko

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Re: Mystery Leak
« Reply #5 on: November 22, 2008, 06:04:01 AM »

Gary,
The area around the strut is a filler, by design.  Below is a picture taken during a factory tour with Gerry Douglas in 2006.  I believe that the boat/strut pictured is a C34, as the C36 molds had already been shipped to FL at the time of our tour. The inboard end of the strut is a crescent moon shaped piece, bolted to a mating piece inside the hull, which allows for precise alignment of the shaft and strut during the assembly process.  The immediate area of the skeg around the strut is not structural.  The cracks in your hull are something I've never heard of.  I'm glad they were not serious.  Hope this helps.
« Last Edit: November 22, 2008, 06:05:31 AM by Julandra »
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Tom Soko
"Juniper" C400 #307
Noank, CT

Gary Brockman

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Re: Mystery Leak
« Reply #6 on: November 22, 2008, 10:42:15 AM »

Tom -

Thanks for the information and the photo, I think it explains what happened.  The area that the boatyard took out and is glassing in looks pretty much like the area in your photo. The water that penetrated into the hull probably came in through a crack in the filler and into the hollow voids of the filler where it may have gone up a seam along the strut and into/under the mating piece you mentioned until it eventually found a way out inside the hull. It was very strange looking at a dry hull and at a certain point seeing that the hull was suddenly wet for no apparent reason.

The yard has assured me that everything is fixed and there is nothing to worry about. The boat is going back into the water on Monday. I am taking advantage of the boat being out of the water and applying new 3/4" and 1" vinyl stripes on the hull over the faded gelcoat stripes. They are supposed to be good for 7-9 years. They came in 150' rolls so I have enough to do the boat twice.

 - Gary -
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Squall
1986 Hull #231
Tall Rig/Fin Keel - Elliptical Rudder
Marina del Rey, California

Ken Juul

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Re: Mystery Leak
« Reply #7 on: November 23, 2008, 03:09:38 PM »

There is a void around the strut that will hold water.  It eventually leaks out around the strut bolts under the aft cabin floor.  Look for rust streaks.  I was surprised when I was installing a strut to prevent crab pot lines from getting stuck in the rudder/rudder strut joint.  Drilled a hole into to hull near the void and got almost a quart of water draining out.
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Ken & Vicki Juul
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tommyt

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Re: Mystery Leak
« Reply #8 on: November 23, 2008, 03:43:26 PM »

Glad that you seem to have found the problem and that it is fixed. I have to admit that what caught my eye in the original post was the $650 to fix it based on what they proposed. I quickly went back to the top of the post to see if this was a 1995 post resurrected. Keep that yard!

Good luck with the dry bilge.
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Tom Mallery, C34 #1697, 2004 MKII, Splash Dance

Gary Brockman

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Re: Mystery Leak
« Reply #9 on: December 09, 2008, 09:56:20 AM »

To update my leak problem, after my boat was returned to the water, I cleaned out the bilge one last time in anticipation of having a dry bilge for the foreseeable future.  Unfortunately, I was disappointed to find water in the bilge again when I returned to the boat two weeks later. I looked under the aft berth and again found the inside hull surface moist, but not as far back as before.

I called the yard manager and told him I still had a leak and he came over to inspect the boat.  We both agreed that the water was not coming from the same area as before but he was sure that it was related to the same type of problem.  I told him of Ken’s comment of having water pour out of the skeg area when it was drilled into and he said that could be the problem, but he would need to find where the water was getting into the area to make the proper repair. He said that they would haul my boat and repair it for no additional cost if this turned out to be the case.

My boat was hauled last Friday and he said that when he drilled into the skeg, about a gallon of water came out. I went over to the yard this morning and he said he found the problem by blowing compressed air into the hole he drilled into the skeg and observing if and where the air came out.  He found a small crack at the forward side of the rudder shaft tube into the skeg.  They have dropped the rudder and are in the process of repairing reinforcing the area this morning. Once the repair is completed, the yard plans to put the boat in the water and observe it for a few days to make sure there are no further surprises. Hopefully this will do it.

 - Gary -
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Squall
1986 Hull #231
Tall Rig/Fin Keel - Elliptical Rudder
Marina del Rey, California

Ted Pounds

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Re: Mystery Leak
« Reply #10 on: December 09, 2008, 11:08:50 AM »

Sounds like you have a great yard!  :thumb:  You might want to post their name here to let anyone else in the area know where to go for great service.
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Ted Pounds
"Molly Rose"
1987 #447

Stu Jackson

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Re: Mystery Leak
« Reply #11 on: December 09, 2008, 11:14:32 AM »

Great report, Gary, and thanks for keeping us posted.

You and others may be interested in this FAQ about rudder packing glands and the tube it sits upon:  http://www.c34.org/faq-pages/techdata-rudder-packing-gland.html  The text below the picture is pertinent.

As Ron is fond of saying: "Lotsa good material there!"
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Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  Cowichan Bay, BC  Maple Bay Marina  SR/FK, M25, Rocna 10 (22#) (NZ model)

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horsemel

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Re: Mystery Leak
« Reply #12 on: December 09, 2008, 07:10:43 PM »

Ok folks, here is my mystery leak.  The boat is out of the water on the cradle for the winter.  After hauling her out I always make sure the bilge is dry.  Inevitably there is a large amount of water that collects in the bilge over the winter.  We are talking gallons here.  I have spent hours in the spring trying to determine where the water comes from over the winter.  I have checked cockpit drains with a hose to make sure the are not leaking.  There are no leaks from the shrouds etc that I can tell. The outside of the mast where it comes through the deck appears to be water tight.  I can't tell where any water appears to be coming down through the mast, but that is the only place I figure it can be coming in.  Each winter I have to pump the bilge 2-3 times.  So far I have not had any ice damage in the bilge.  Any ideas where this is coming from?
Mark Mueller
#815 Blue Moon
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Mark & Melinda Mueller
Blue Moon, Hull #815
1988

Ken Juul

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Re: Mystery Leak
« Reply #13 on: December 11, 2008, 09:10:21 AM »

Mark,
Is the boat covered? 

Do you only get the water in the winter on the hard or is it year round?  Remember when the boat is in the water the bilge pumps are probably activated by the float switch so you may be getting the same amount, just don't realize it because the pumps are doing their job.

Sounds like you have checked the usual places.  Might want to look under the Vee Berth.  You could have a crack in the anchor well that is letting water into the bilge that way.  Might also want to do the koolaid trick.  Lay a line of powered koolaid around the edges of the bilge, any water flowing down the hull to the bilge will make a break in the line.
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Ken & Vicki Juul
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Chesapeake Bay
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tonywright

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Re: Mystery Leak
« Reply #14 on: December 11, 2008, 10:37:40 AM »

Ken : "Lay a line of powered koolaid ..."; would this be electric-powered, diesel or hybrid? 

Seriously, sounds like a good technique.

:santa

Tony
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Tony Wright
#1657 2003 34 MKII  "Vagabond"
Nepean Sailing Club, Ottawa, Canada
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