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Bedding thru-hulls (knotmeter)

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Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Initially Posted - 07/15/2007 : 01:44:21

Hi Guys,

When taking the boat back to the docks tonight, I had the unpleasant suprise of stepping into water (about 1/2 inch in the aft section). Once on the trailer I checked the front compartement where the thru hulls are located and it was full up to the rim.

I believe that my knotmeter thru-hull is the culprit. The Admiral and I will test this next week as we are on vacation and the boat launch should be very quiet. So we'll do some tests soon to confirm the leak is coming from there.

Searching the forums I see talks about "bedding" the thru hull with sealant like LIFESEAL or 3M 5200. I did pull out my knot-meter thru hull when I first got the boat a few months back and just put it back and "hand tightened". When I took it out again tonight I did not notice any caulking or sealant remenants. Just the normal clean plastic and rubber o-rings. I'm pretty certain sealant was never used.

Can someone explain to me what "bedding" means, and should I haved used Lifeseal when putting it back in?

Steve Blackburn, Calgary, AB
C250WB - 1999 - Hull 396

Edited by - on

britinusa
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USA
5404 Posts

Response Posted - 07/15/2007 : 06:16:34

Steve, which brand of transducer?
On JD, we have the Raymarine ST40 system which has two transducers in the pit. The speed transducer is mounted in a sleeve which is sealed into the hull (it's mounted from the outside) and the transducer itself is held in place by a ring nut. When you pull the unit out, there are a couple of flapper valves that limit the inflow of water while you insert the 'bung'.

The removable transducer itself should not be sealed with anything other than the rubber O rings.

The depth transducer is differnt, the whole thing gets sealed in place and there is a ring nut to secure it, you cannot remove the depth transducer when the boat is in the water.

Paul

Edited by - on

Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Response Posted - 07/15/2007 : 14:24:10

Paul,

Your description of the transducers seem to be exactly like mine. I have 2 separate black transducers, one for depth the other for speed. I also have an extra plug just cliped with the others that I imagine is for emergency purposes? My depth transducer is fixed and this is why I am confident the leak is not coming from there. My LCD display says Ray....something on it.

I hope with all my heart that the leak is coming from the knotmeter, as it makes sense since the pit is slightly higher than the aft section. Since the pit was full of water and overflowing towards aft (by the side indentations on port and starboard) then I'm quite sure the source is from there. Note that I have not seen water flow, since I inspect the pit whilst on the trailer. I'm hoping to see water flow from the knot meter next week when we do some dip tests.

I do not believe this leak existed a week ago, but maybe it just go worst and I just noticed. There was about about 1.5 inches of water in the bilge at it's worst. I did not hit bottom or anything else yesterday, but I did sail it a little rougher than usual (more healing, close hauled, 1-2 foot waves, 5-6 knots). So maybe the water hitting the knotmeter was just enough to cause a slight leak.

Was wondering if while leaving it on the trailer, I woudld fill up the pit and maybe I should see water dropping from the exterior where the knotmeter is? But I wonder if that is a good enough test and there is not the same presure.

Edited by - on

Nautiduck
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Response Posted - 07/15/2007 : 14:38:44

I have the same setup. Both the depth sounder and the knot meter sleeves should be bedded to the hull with 4200 or 5200 or similar item. You want bonding power in the sealant. Using the big plastic "ring nut" to hold the through-hulls is not enough. While Paul is right that the paddle wheel insert does not get caulked, the actual through-hull sleeve it goes into does get caulked.

Remove the trough-hull. Put more than what you think necessary of 5200 on the hull bottom or on the through-hull unit. Put the unit into the hole and tighten the plastic ring nut. 5200 will squeeze out all over, on the hull bottom and often even inside the hull. That is good. Clean it off and let it cure. It wont leak again.

Edited by - Nautiduck on 07/15/2007 14:40:59

Oscar
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Response Posted - 07/15/2007 : 20:02:36

I agree with the above.

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">When you pull the unit out, there are a couple of flapper valves that limit the inflow of water while you insert the 'bung'.<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

Snazzy....I need to wear diving goggles when I pull mine out.....

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Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Response Posted - 07/15/2007 : 21:22:48

Sorry for my lack of knowledge on this and misidentifications. When I said earlier that I "pulled out the knot-meter thru-hull" what I meant was that I pulled out the paddle wheel insert, not the actual thru-hull.

Fortuneatly we have a sail shop at the marina where I'm at and they should have all the neccessary materials.

Thanks for the great help guys, I'll let you know of the outcome.

More questions:
1. I imagine that since lots of talks on the subject of thru-hull rebedding exist that such leaks are not all that uncommon?

2. Using my description above (thru-hull pit full of water, and aft section with just 1.5"), do you agree that it looks like one of my thru-hulls is leaking?

Edited by - Steve Blackburn on 07/15/2007 21:30:39

britinusa
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Response Posted - 07/15/2007 : 21:49:44

1. we have one.

2. yes, the boat would have to have a lot of water in it for it to drain fwds into the pit, so I would suggest that it's the pit leak, and as you indicated that the pit is full, it's reasonable to assume it's the cause.
However, we found we get quite a bit of water leaking in from the WB valve, see my post on waterballast casing mod. I'm just finishing that.

If you have the luxury of drying out the pit and putting the boat in the water, then just check it for leaks shortly after splash time.

Replanting the thruhull sleeve for the speed transducer is something I have to figure out... how the heck do you get it out in one piece if it's been bedded in 5200 ????

Paul

Edited by - on

Nautiduck
Master Marine Consultant

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Response Posted - 07/15/2007 : 22:51:09

Paul, anti-bond, a razor and patience.

Edited by - on

Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Response Posted - 07/15/2007 : 23:04:48

What tool do you use to move the large plastic nut that holds the thru-hull? Doesn't seem to be a "turn by hand" job.

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Russ.Johnson
Commodore

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Response Posted - 07/15/2007 : 23:46:06

Steve,
There might be an easier solution to try first.
The first time I removed the knot meter insert, I re-installed it backwards and it leaked.
When it was on the trailer, I removed it and saw a slot that only fits in one direction.
It's an easy thing to check.

Also, how long was your boat in the water to get that much in the bilge?
Russ #793

Edited by - on

Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Response Posted - 07/16/2007 : 01:13:12

Russ, I did notice the slot and made sure the insert was in the right direction. Good point though.

The boat was in the water for about 8 hours.

The PO left the boat in the water at all times whereas I always store it on the trailer. We slept on the boat one evening and had no water intake like this.

One thing that is different is that now that we are getting comfortable with the boat, we tend to heal far more than before, especially this week-end. This gets me to think that I may leak water from WB valve as Paul explained? Paul do you actually see the WB valve leakage when healed over? Do you believe it possible to gain about 1" of water in the bilge healing for about 1-2 hours?

Edited by - on

Nautiduck
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Response Posted - 07/16/2007 : 09:36:09

Steve, the large plastic nut is a turn by hand thing. Other wise you'll crack it. With 5200 all around it wont leak if you get it hand tight. Of course if it is held in place by some 5200 now then see my post earlier about anti-bond, razor and patience.

If you don't think that is the place it is leaking then leave it alone. You could also pour water in that area while on the trailer and see if it leaks through the hull.

Edited by - on

kevinmac
Admiral

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USA
732 Posts

Response Posted - 07/16/2007 : 09:47:05

Guys, I have the same ST40 setup you are talking about, and I don't agree that you have to use any sealant at all if everything is normal. I hand tighten mine (not too tight, if you go too tight you could strip the threads or crack the fitting, which might be what happened here). I leave my boat in the water year round, and have a completely dry bilge.

If you are getting an inch and a half of water in eight hours, something is really wrong, and I would put the boat in the water and watch to see where the leak is coming from before doing anything else. The suggestion about the sensor being in backwards is a good one too I think...

My two cents, worth what you paid for it.

Edited by - on

Justin
Admiral

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502 Posts

Response Posted - 07/16/2007 : 10:11:48

On my C-25 I have a B&G Instruments knot meter and depth meter. I've had some recent experiences with leaking thru-hulls. When I finally put my boat back in the water a couple weeks ago I found a few inches of water in the bilge where my knot meter and freshly sealed off thru-hull from where the holding tank used to pump overboard. I sponged out all the water, and then used a paper towel to dry it as much as possible. I then saw water seeping in where the thru-hull is sealed against the hull. When I cranked on the cap, I broke the old seal against the hull. I was hauled out that night and I cleaned and resealed the thru-hull with 5200. After that, there wasn’t a drip coming in.

Then this past weekend, I anchored out overnight. When ever I use my sailboat I put in the knot meter paddle wheel plug. When docked and gone, I put in the spacer plug to prevent growth on the paddle wheel. I woke up yesterday morning and found a couple inches of water in the bilge that was not there the day before. I dried it out and noticed the top of the knot meter paddle wheel plug was wet. I dried it with a paper towel and watched it. Within a few seconds it was wet again. I found the culprit and swapped it with the blank plug and found it did not leak at all. So I need to look into what I can do to improve the seal on the one plug. Maybe new O-rings, does Vaseline also sometimes help (thought I may have read)? Steve, have you tried your blank plug as well to see if it leaks? Maybe you are in the same situation as I am.

Edited by - on

Russ.Johnson
Commodore

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836 Posts

Response Posted - 07/16/2007 : 12:37:18

Steve,
If you slept overnight and had no leak, now have water in the bilge after sailing, I don't think your through-hulls are the problem.

The ballast valve leaks when the boat is healed.
When my ballast valve leaked you could tell because the housing was wet.
Because the bilge is behind the ballast tank, it's a pretty small area.
Having 1" in the aft bilge is less that 5 gallons (more like 2).
After 1-2 hours of healing and having 1" in the bilge is about the rate of my ballast value leak.
Here's a link to Paul's posting (I also posted pictures there)-->[url="http://www.catalina-capri-25s.org/forum/topic.asp?TOPIC_ID=15801"]Waterballast Casing mod.[/url]

On a different topic, you might consider changing the bilge hose.
Here's another link --> [url="http://www.catalina-capri-25s.org/forum/topic.asp?TOPIC_ID=14927"]Bilge Pump Hose Mod for C250WB[/url]

In your first post, you mentioned you stepped into water?
My cabin sole is sealed from the bilge.
There is the bilge access in the aft berth and a cutout under the galley sink.
You would really have a lot of bilge water to get water in the cabin sole.
If your aft cushions are wet, the centerboard line hose might be disconnected or leaking.
In theory, waves could splashing up into the hose, causing a leak.
I added some PVC pipe to the end of my hose (just to be safe).

Lastly, you may have a leak in the ballast tank itself.
Once you have eliminated the ballast valve, centerboard hose, and through-hulls you could consider this post.
I don't think you have this problem, but here's a link to a related topic --> [url="http://www.catalina-capri-25s.org/forum/topic.asp?TOPIC_ID=15327"]New Owner 250 WB 2001[/url]

Russ #793

Edited by - on

Steve Blackburn
Master Marine Consultant

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1091 Posts

Response Posted - 07/16/2007 : 15:06:34

Thanks Russ and Justin, here are some answers to your questions:

Justin: No I haven't tried the plug but will soon if I see leakage like you did. By the way, why aren't you using your bilge pump to empty the water in your bilge instead of towels and sponges? Also, is your thru-hull pit completly filled with water then onced filled up the water slides back to aft? I think the thru-hull pit is at a higher level than aft but just wanted to confirm this with you.

Russ: I will do the casing mod very soon since it's such a great improvement but will be using only the "washer in expoy" method vs the Paul's puck. 2 gallons seems about right after pumping out the bilge in the parking lot. Yes I am considering putting an electric auto-bilge pump in there next week. When I was stepping in water there was only about 1/4 of an inch in between the head door and cooler (it stayed aft). The water on top of the cabin sole was coming from beneath the head sink (the small door at the bottom) and possibly below the galley sink (thank's didn't know I had a cutout there). Aft cushions were not wet. Still I'll check the centerboard line hose while under sail (after checkout all the other stuff).

Thanks to all of you, I now have an extensive checklist to go through. I will report on my results soon. I am so lucky to have this community helping out like this.

Edited by - on

Russ.Johnson
Commodore

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USA
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Response Posted - 07/16/2007 : 19:36:37

Steve,
1) Justin has a C25 so the bilge has a different design.
2) Yes, I think under the head sink has a cutout too.
3) On my 2005 model, under the galley sink has a cutout for the trash can (it should be the on your 1999 model).
Try checking the easy things before removing your transducers and dealing with re-bedding.
Russ #793

Edited by - on

Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Response Posted - 07/16/2007 : 19:44:00

Thanks Russ. Yes I do have a trash can under the galley sink and it sits in a "hole". Checking my thru-hull is not an issue since all I need to do is back it up on the launch and dip the boat (no need to even take it off the winch). We have become quite used to launching and retriving the boat now and have the drill down. Takes us only 15 minutes from the parking spot to being tied at the dock.

Edited by - on

Nautiduck
Master Marine Consultant

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Response Posted - 07/16/2007 : 20:39:28

Kevin, I think we may be talking about different things. I use 5200 on the main sleeve that goes through the hull. I do not use anything on the paddle wheel insert that goes in the sleeve. I would not rely on a mechanical-only attachment of an underwater through hull.

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kevinmac
Admiral

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USA
732 Posts

Response Posted - 07/16/2007 : 23:50:27

Then we agree. Somehow, your message gave me the impression you were proposing putting sealant on the paddle wheel sensor that screws into the thru hull. Sorry for misunderstanding you.

Edited by - on

willy
Captain

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USA
422 Posts

Response Posted - 07/18/2007 : 07:24:03

Steve,
For the last two years I have had a problem with water in my bilge also. There have been several possible explanations, from thru-hull leakage, to coaming compartment leakage to water ballast leakage and none of them was the problem on my boat. Every year at launch (I put her in for the season), I fill my water ballast not in the usual way but from a hose through the valve in the anchor locker. I made an adapter to screw on my hose, stick it in and fill. I do this because I want nice clean, fresh smelling water in there all season without putting any chemicals or bleach in. I would let it run until it backed out the top and started running out the anchor locker drain, then close the top and sail away. Turned out I was overfilling it. Pumping out the bilge every day for about a week eventually left me with a dry bilge. Worth a try.
Another way to get water in the bilge is through the centerboard cable tube. Every year for a weekend a few of my buddies come down for "boys sail". Our wives spend the weekend doing too much shopping. Anyway, these are big guys. Everyone is over two hundred pounds except for one guy who just might be three. When everyone is in the cockpit, she rides a bit low and one day in the ocean I found water running in the tube at a pretty alarming clip. I have since added about 5" to the tube with a piece of radiator hose and some duct tape, and constructed a plug from a trimmed down piece of "swim noodle". Haven't gotten a drop since.
Just some other possibilities...
Willy

Edited by - on

Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Response Posted - 07/18/2007 : 16:50:38

Thanks Willy, very much appreciated. I really like the way you extended the centerboard tube.

I fill my WB the normal way (openning the intake bottom valve and wait until no more air comes out the hose in the anchor locker). Then close the intake valve. Takes about 5-10 minutes. In the caes that you would have an overfill, where does the water come out from? I thought the WB tank was completly enclosed. The only place I can imagine water coming out is through the intake butterfly valve in the coaming compartement.

I just got a new idea that I believe will stop 100% of the water from coming out through the butterfly valve. I will be posting it in Paul's thread.

Edited by - on

Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Response Posted - 07/20/2007 : 23:58:47

RESULTS ARE IN!

Put the boat in the water with the WB valve shut, absolutely no leaks. Opened WB valve, started leaking slowly aft.

Stuck my big head in the aft access (where the bilge tube is) and looking starboard here is what I saw:

(pictures taken AFTER I dried everything down)

A 16" flaw in the fiberglass where water was slowly seeping through from 2 places.

A bit to the left of the above picture is where most of the water is coming in. Almost looks like someone poked a flat screwdriver in there.

The port side is perfectly fine. However what I want to do is to fiberglass a 4" stripe all the way across where the WB tank meets the hull. I'm thinking of applying 3 coats of resin with fiber stripes. This should reinforce everything better than original.

Is my approach OK or should I use something like epoxy putty? I tend to believe that fiberglass with generous portions of resin will bind the best and be strongest as I not only want to stop the leakage, I want to make this joint stronger.

We checked all around the boat through the various openings beneath the seats, under the garbage can etc, and found that all remained very dry. So I believe this is the only spot and am quite happy since re-bedding my thru hulls would've been much more work (and they look already bedded with adhesive).

By the way my theory on the thru-hull pit being full of water thinking that it was a higher point and that the water HAD to come from the first avered itself to be bunk.

Edited by - Steve Blackburn on 07/21/2007 00:16:26

Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Response Posted - 07/22/2007 : 18:08:43

Just finished putting in 3 layers of fiberglass over the leak area (in red). Carefully scrapped off the old ripped-out fiberglass and cleaned with acetone first.

BEFORE

AFTER

Probably not as esthetically pleasing as I would've wanted it, but function wise it should be way up to par. In fact it should be more solid than the original. Not easy to to with one shoulder down the bilge hatch and going by feel only.

Sea trials tomorrow...

Edited by - Steve Blackburn on 07/22/2007 18:29:16

Nautiduck
Master Marine Consultant

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USA
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Response Posted - 07/22/2007 : 21:46:32

Steve, looks great. Three layers of glass should make that a sturdy area now. You should consider reposting the problem and solution in a new thread with a more obvious title such as "Water Ballast Tank Leak" or something so that people can search for it and find the solution easier.

Making a fiberglass repair puts you in an elite group. Most of us have never done it!

Edited by - on

Steve Blackburn
Master Marine Consultant

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Canada
1091 Posts

Response Posted - 07/22/2007 : 23:31:58

Done. Thanks.

Edited by - on

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