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Holding tank failure - 35 Mk3

unidiver

Member I
Bought boat 6+ months ago and prohibited head usage until system was checked out. Did so last weekend and discovered holding tank had leak. Removed tank and found crack that previous owner unsuccessfully tried to repair with thin layer of silicone. Repair seems unlikely but would consider if someone knows sound method. Otherwise, anyone know of replacement source. I live near boat birthplace so am hoping for SoCal solution. Really need help on this one. Thanks!
 

Sean Engle

Your Friendly Administrator
Administrator
Founder
Cracked Holding Tank: Ho Ho Ho! Time for it to go!

Silicone? For crack in the HOLDING TANK? Yuck...

Tear it out - if it were me, I would rip it ALL out during the winter and replace it. As mentioned, Ronco Plastics has the replacement (B192 for the E35-3, I believe - they can tell you - they have all the measurements.

Also - see my project on total sanitation replacement (in the projects section under my name - click on the "download entry" text - in Firefox).

Do yourself a favor - get it ALL out - a nice x-mas gift for you! :xmas_grin

Have fun! :egrin:

//sse
 

Pat O'Connell

Member III
Tank Leak

Hi Respected Owners

I agree with prior advice completely, "replace it." However... In 1982 I discovered a weep crack in our 1981 tank. plastics engineer at company I worked at referred me to plastics encyclopedia that said polyethylene or proplylene can not be patched successfully. It was June... Boat in the water and we wanted to cruise so I consulted local hardware store who said try a new product called "goop." I pushed in dry crack on top but side of the tank and it still is completely dry. Several times every summer I check crack and it is still dry. This remark is not advice and will probably curse my luck forever! I bet it might work for some skipper caught away from a tank replacement opportunity. Laughed last weekend at football game when I noticed goop patches on my old but very warm and still good ski gloves. heheh
 

Sean Engle

Your Friendly Administrator
Administrator
Founder
Crack = Failure

... I consulted local hardware store who said try a new product called "goop." I pushed in dry crack on top but side of the tank and it still is completely dry. Several times every summer I check crack and it is still dry.

Warning: Sermon Ahead.... :soapbox:

My only comment on this is that while it's nice that you've found something that you feel is working - the only issue is that structurally, when the tank cracks, it's largely because of the stresses on it - combined with age, etc. So, while sealing the crack with a flexible patch may seem to work - the failure is still there - and is subject to increased cracking, or leakage if the circumstances are right...

Ever take out guests who are new to sailboats - and don't understand that they're pumping into a tank? They keep pumping and pumping and pumping - filling your tank quite quickly. Then, they keep pumping and pumping - the pressure level rises to the point that the vent line floods outward - and then "material" from the tank gets lodged up in there - eventually drying and hardening - closing the vent line down - permanently.

Then you get more guests, pumping and pumping - and the pressure in the tank again builds - and the existing crack begins to fail anew - then expands - until the pressure in the tank is equalized. As a result, you may well end up with "holding tank fun" in your bilge - and your boat is forever changed (watch guests faces when they first come below and inhale). You can also get implosions in your tank when you suck it out dockside - as again, the vent line is occluded and no longer functions.

When I did my boat, I called one of the engineers at Ronco - and had a long talk with him about these tanks, and the one for the E35-3 specifically. The original tank had a "wing" attached to it - that wing fails after 15-20 years because the weight of the sewage in the tank, combined with the motion of the boat stresses the inside corner - and it fails. When I put the new tank in, it has no wing (you lose about 1 gallon of capacity - big deal), as a bonus the added space gives you a place to stow head-related items, spares, etc.

Best thing to do is order the tank from Ronco - and have THEM put an access port into top of it (clear is nice - so you don't have to open it to glance in there). Also have THEM attach the elbows at the bottom. They'll seal both with butyl rubber, and they will be sealed tight.

Then, once a year, put on gloves, a mask and eye protection - go to the pump out - and hose the tank out while a friend sucks it out - and be sure to get water back down the vent line - to ensure it's clear as well. If you do that - and flush your lines - every day - with fresh water - your boat will not stink at all, and you won't get "that look" from your guests when they come aboard.

Finally - the other thing I did (which I failed to mention) was to create a small placard which I had laminated, that told users how to use the head - and stressed not putting things in there "...which have not gone through you first...", and it also described where they were sending their contributions - and why they should pump the minimal amount, not pack the tank, etc. I made it very simple - very graphical - easy to read quickly. Guests are goofy about bathroom stuff - and they might find it embarrassing to ask - so they try and figure it out, and pack your vent line/stress your tank in the process. The little card helped - and it was always there on the counter next to the sink (and it's easy to clean and sanitize).

Anyhow - enough of my preaching... You would think I could have found something else to get so zealous about - but I have a very sensitive sense of smell - and getting the boat/head odor down to zero made me very happy....and my girlfriend (now wife) as well...

Good Luck!
//sse
 
Last edited:

Dan Morehouse

Member III
I concur. Pull it out and replace it. Ronco Plastics is one of the most pleasantly surprising suppliers of "stuff" I've uncovered in five years of working on my boat.

Sean, I got the tank WITH the wing because I can't get over my twitterpation with more, More, MORE capacity. My understanding is that the newer tanks are thicker walled and may not suffer the tendency to crack. I'll report back in ten years or twenty.

I did NOT know Ronco would install the elbows and an inspection port, but I'm not surprised. A port with a clear panel would be perfect for simplicity & effectiveness. It will now go on my happy list...that is, things that do or will make me happy aboard the boat.
 
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