It was holding water in the fiberglass liner. Odd thing is that the handle indicated that the valve was closed but we still had water and have only filled one tank. Perhaps the valve is busted
To drill or not to drill...
- Thread starter Project_Mayhem
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To answer the question you asked, On my 88 Mk2, there is a limber hole in the liner that holds the bow tank so that it will drain to the bildge if water leaks out. Your Mk3 should probably have one as well so it could have been forgotten. If it were my boat, I would not hesitate to drill a limber hole but if any wood came out with the drillings [from a wood core in the liner] I would over-drill and fill with epoxy and then redrill.
To answer the question, you did not ask. I had the exact same problem on my Mk2 and lived with it for years but have not had a drop in the past 10. The inspection port is spin-welded to the top of the tank and is sized for a standard 3" PVC cleanout cap. I had always tried sealing it with Teflon tape and it would never seal. I finally got serious about sealing it and used PTFE pipe dope and a couple of wraps of Teflon tape over it and now it is sealed leak free. I can still remove it but it is just a bit messier. Well worth the tradeoff. To fill my tanks, I fill the bow tank until it backs up in the fill spout. I then switch to the starboard tank until the water squirts out the starboard stanchion vent. I do not stick the end of the hose into the fill because that can overpressure the tanks. I drape the hose over the lifelines so that the end of the hose is floating in the thread recess of the fill and adjust the flow of water so that it is at the rate that the fill can take without overflowing.
Bonus answer. The reason I got serious about fixing the leak was my wife found several flat-pack storage bins that were shallow enough to fit in the space between the top of the tank and hatch board. The original cap had a protruding square drive for opening it. By switching to a flush cap, I was able to fit bins over the top of the inspection port. I now carry my spare wire, tools, and NMEA 2000 supplies in the found space.
To answer the question, you did not ask. I had the exact same problem on my Mk2 and lived with it for years but have not had a drop in the past 10. The inspection port is spin-welded to the top of the tank and is sized for a standard 3" PVC cleanout cap. I had always tried sealing it with Teflon tape and it would never seal. I finally got serious about sealing it and used PTFE pipe dope and a couple of wraps of Teflon tape over it and now it is sealed leak free. I can still remove it but it is just a bit messier. Well worth the tradeoff. To fill my tanks, I fill the bow tank until it backs up in the fill spout. I then switch to the starboard tank until the water squirts out the starboard stanchion vent. I do not stick the end of the hose into the fill because that can overpressure the tanks. I drape the hose over the lifelines so that the end of the hose is floating in the thread recess of the fill and adjust the flow of water so that it is at the rate that the fill can take without overflowing.
Bonus answer. The reason I got serious about fixing the leak was my wife found several flat-pack storage bins that were shallow enough to fit in the space between the top of the tank and hatch board. The original cap had a protruding square drive for opening it. By switching to a flush cap, I was able to fit bins over the top of the inspection port. I now carry my spare wire, tools, and NMEA 2000 supplies in the found space.
Unless the hose completely blocks the fill inlet, it won't over pressure the tank as the excess water will just bubble out of the inlet and the vent. What does pressurize the tank when filling is the weight of the water in the fill and vent hoses. The CG pressure tests tanks by attaching 11.5 pipes to the inlet and vent and then fills the tank with water to the top of the pipes. Just did this on Tuesday.
On the fills on my C30, there is a 1.5" recess and then a smaller opening at the bottom that just fits the end of a garden hose. If I drop it into that recess, it leaks very little water back out and when it gets to the top of the tank, the water jets a couple of feet out from the vent. When I pull the hose out, I get a gyser out the fill that pumps maybe 1/2 gallon of water out onto the deck. Is that harmful to the tank? Probably not. My concern is that I do not like any water that touches the deck to ever enter the tank because I drink the water from the tank. The surging water from the geyser flows in all directions and then some of it flows back into the tank. Too many seagulls in my neighborhood for that!!!!
My 1983 C30 MK 1 has the same problem, water will set under the V birth but it comes from the air conditioner because the water tank was removed to make room for it.
I looked and looked and there’s no hole in mine either. I always check it before I leave and vacuum it out as well as the bulge. But it could be in a different place than yours.
I looked and looked and there’s no hole in mine either. I always check it before I leave and vacuum it out as well as the bulge. But it could be in a different place than yours.
That's why we invested $20 in a flow meter. No over flowing tanks and no water flying out of the inlet.On the fills on my C30, there is a 1.5" recess and then a smaller opening at the bottom that just fits the end of a garden hose. If I drop it into that recess, it leaks very little water back out and when it gets to the top of the tank, the water jets a couple of feet out from the vent. When I pull the hose out, I get a gyser out the fill that pumps maybe 1/2 gallon of water out onto the deck. Is that harmful to the tank? Probably not. My concern is that I do not like any water that touches the deck to ever enter the tank because I drink the water from the tank. The surging water from the geyser flows in all directions and then some of it flows back into the tank. Too many seagulls in my neighborhood for that!!!!
This is some outstanding info! This more than provides me with enough knowledge to tackle this issue
It was overflowing around the garden hose. To my surprise, the tank had bubbled at the top when it was overflowing. When it was halfway empty a few days ago, it had returned to it's normal shape
You just gave me one more use for the 20v DeWalt vacuum I just bought!
Well worth it for $20!
Our tanks have level gauges that are reasonably accurate. Typically we fill both at the beginning of the season and before any cruise and only draw from the one large tank until it is empty. The second tank can be easily be filled through the inspection port if it is partially filled. If it is very low, say 10% we will fill from outside and adjust the capacity to compensate for the water remaining in the tank.
The level senders are Kus senders connected to the N2K network Simrad N2K tank level senders. While they are pretty accurate, they can't be used to monitor the level when filling because they only send data every 10 or 15 seconds and are always behind the actual level.
Something is better than nothing. I will get that vent cleared but it won't be right away
I took a look at the tank today. The inspection port had been removed and poorly resealed. I see what appears to be the original sealant and a single layer of Teflon tape
I have not had the best luck with Teflon tape alone. I have switched to the TPFE pipe sealant with Teflon tape over it and have not had a failure since.
My C30 has a couple of tanks, both of which are only around 20 gallons. filling until the water comes out of the vent is easy and accurate and only requires that I do not push the hose down into the neck. With the hose draped over the lifeline so that it is self-supporting, I can sit inside and listen for the sound change that happens just before the tank is full then go up and either change to the other tank or shut it off.
I find it has an 80% success rate. I started keeping RectorSeal in my toolbox. I don't recall any failures and it even stands up to oil, gas and diesel