Cruisers Forum
 


Join CruisersForum Today

Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 24-11-2018, 14:54   #1
Registered User
 
Jerry Woodward's Avatar

Join Date: May 2008
Location: Punta Gorda/Kentucky
Boat: PDQ 32 LRC
Posts: 415
Help: punctured water tank

I did a real bonehead maneuver. I was drilling a pilot hole (5/32) for a screw through some glass/core under the settee and went to far, puncturing the water tank on the other side. I have since cut away a square access port and have access to the hole. It is near the bottom of the tank. It is a 47 gal polyethylene tank. I am trying to decide how best to repair it, knowing that not much sticks to polyethylene. But it is just a small hole and it seems that there should be something I can fill it with.

1. fill with an epoxy or adhesive. I have 5200 and I bought some JB Weld Plastic Bonder 2-part urethane adhesive. Does 5200 stick to polyethylene?

2. Use some sort of hot knife and fill with a blob of molten plastic

3. drill, tap and screw a nylon machine screw into the threaded hole with some sort of thread sealant.

Any other ideas?


Thanks
__________________

__________________
s/v Terrapin
May the four winds blow you safely home
Jerry Woodward is offline   Reply With Quote
Old 24-11-2018, 14:58   #2
Registered User

Join Date: Oct 2015
Posts: 1,420
Re: Help: punctured water tank

Polyurethane will not stick.

You can weld polyethylene. Try a youtube search. You'll find lots.
__________________

billknny is online now   Reply With Quote
Old 24-11-2018, 15:28   #3
Registered User

Join Date: Dec 2007
Location: Duluth,Minnesota
Boat: Lindenberg 26 & Aloha 8.2
Posts: 1,126
Re: Help: punctured water tank

Yes you can weld polyethelene and for a hole that size it may be the best solution. You can buy a cheap welder and supplies at Harbor Freight, should be adequate for something like this.

Steve.
clockwork orange is offline   Reply With Quote
Old 24-11-2018, 18:22   #4
Registered User

Join Date: Jan 2017
Posts: 12,121
Re: Help: punctured water tank

West Systems has repair kits, based on their G/flex. Surface prep is everything.

Small enough hole, mechanical plug (cork rubber?) tapered from the inside?

https://www.practical-sailor.com/iss...s_12522-1.html

Welding works, but only if you match the material. Danger is, structural weakening, especially low down.
john61ct is online now   Reply With Quote
Old 24-11-2018, 18:30   #5
Registered User

Join Date: Jan 2017
Posts: 12,121
Re: Help: punctured water tank

3M Scotch-Weld DP8005

TAP Poly-Weld*

Loctite All-Plastic Super Glue

**not** JB Weld
john61ct is online now   Reply With Quote
Old 24-11-2018, 19:32   #6
Writing Full-Time Since 2014
 
thinwater's Avatar

Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 6,495
Re: Help: punctured water tank

I interviewed the engineering departments of the two largest manufacturers for an article. They both suggested installing a small bulkhead fitting. That is the advice they give installers when they do that--you are NOT the first one, it is apparent quite common.


That said, I've put self-tapping screws in tanks like that and they held for ages. No need for sealant, it won't help. I once had a large PE chemical tank delivered, and the freight company had stapled the BOL to the tank! If it ever leaks, put a gasket on both sides.


Although welding and adhesives can be made to work, they are not the best answer for a clean, round hole.
__________________
Gear Testing--Engineering--Sailing
http://sail-delmarva.blogspot.com/
thinwater is offline   Reply With Quote
Old 24-11-2018, 19:33   #7
Writing Full-Time Since 2014
 
thinwater's Avatar

Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 6,495
Re: Help: punctured water tank

https://www.practical-sailor.com/iss...s_12522-1.html


A short primer on PE tank repair.
__________________
Gear Testing--Engineering--Sailing
http://sail-delmarva.blogspot.com/
thinwater is offline   Reply With Quote
Old 25-11-2018, 04:57   #8
Registered User
 
Jerry Woodward's Avatar

Join Date: May 2008
Location: Punta Gorda/Kentucky
Boat: PDQ 32 LRC
Posts: 415
Re: Help: punctured water tank

Thanks for the suggestions guys. Drew, your article in practical sailor is very timely, but welding seems pretty extreme for a small hole. Your idea of a self tapping screw is similar to what I was thinking, drilling and tapping, but a self tapping screw sounds like it would work. Do you think I need a "self tapping" screw or would a regular machine screw work? I would assume just get the size where the threads extend just beyond the diameter of the hole, stainless of course.



John, those adhesives you recommend, do you have any experience with them, or are those just manufacturers claims?
__________________
s/v Terrapin
May the four winds blow you safely home
Jerry Woodward is offline   Reply With Quote
Old 25-11-2018, 05:07   #9
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 26,826
Help: punctured water tank

I like your idea of a nylon screw, plastic on plastic is I think the way to go, no corrosion ever, and no thermal expansion issues either, and your only enlarge I guess the hole a tiny bit so you donít lose anything if it doesnít work, but Iíd bet money it will work, and last.
There just isnít much pressure is why I think it will work, and work well.

Just donít tap the threads completely, make it an interference fit. If you overtap maybe a wrap or two of Teflon tape.

My worst bonehead move with a drill was helping a friend install a car stereo in an old air cooled VW. He was drilling a hole in the dash, and suddenly gasoline started pouring from the hole.
We had both forgotten that a Bugís gas tank was just in front of the firewall, thankfully he stopped drilling with the old 110V sparky drill just before the gas appeared, or I donít think I would be here.
a64pilot is online now   Reply With Quote
Old 25-11-2018, 05:22   #10
Registered User
 
Jerry Woodward's Avatar

Join Date: May 2008
Location: Punta Gorda/Kentucky
Boat: PDQ 32 LRC
Posts: 415
Re: Help: punctured water tank

Yes, the nylon bolt sounds good, but the threads would be straight and the nylon bolt would be straight and they probably wouldn't form a tight seal. I like your idea of wrapping with teflon tape, this would probably seal it. On the other hand, a tapered metal screw would cut new threads and the taper should create a tight seal. Yes, corrosion is a concern, but it is fresh water. I can always check and replace if necessary after a season.
__________________
s/v Terrapin
May the four winds blow you safely home
Jerry Woodward is offline   Reply With Quote
Old 25-11-2018, 05:23   #11
Moderator
 
Pete7's Avatar

Cruisers Forum Supporter

Join Date: Aug 2009
Location: Solent, England
Boat: Moody 31
Posts: 12,117
Images: 14
Re: Help: punctured water tank

Quote:
Originally Posted by Jerry Woodward View Post
Thanks for the suggestions guys. Drew, your article in practical sailor is very timely, but welding seems pretty extreme for a small hole.
Its welding but not with a gas axe, that will probably make a horrendous mess.

We used to repair gouges in skies with the plastic rings beer cans come tied together with. Using a cigarette lighter melt a small strip of beer can plastic and drip into the gouge. Allow to cool and file flat. Done properly it would last the season easily.

Also used the idea to repair a cracked plastic trailer mud guard, with additional heat from a soldiering iron. Ended up with a long spilt welded together with a series of little rings along the crack similar to a continuous weld before it is ground down.

Btw, I have a steady hand but am no a welder, tried it once, made right bloody mess.
Pete7 is offline   Reply With Quote
Old 25-11-2018, 06:40   #12
Registered User

Join Date: Dec 2007
Location: Duluth,Minnesota
Boat: Lindenberg 26 & Aloha 8.2
Posts: 1,126
Re: Help: punctured water tank

I just remembered that about a week after I bought the truck im driving now it developed a fuel tank leak. It was caused by something getting between the tank and one of the straps that hold it up. I repaired it with an epoxy kit that I bought at an auto parts store sold for fixing plastic tanks. That was about 3 years ago and so far so good and I had forgotten about it. I have also rebuilt a Yakima rocket box (Roof rack box) which I got for free because someone forgot it was on their suv and drove into the garage causing extensive damage. I used epoxy and glass with proper prep and again, worked fine, probably abs plastic though which glues well. For your problem though I think I would probably do as others have suggested and use a ss sheetmetal screw. I would use a pan head with some butyl tape or similar under the head for good measure. Actually I saw recently on a plastic tank site where they suggested silicone for installing fittings so maybe a dab of that under the head.
clockwork orange is offline   Reply With Quote
Old 25-11-2018, 07:09   #13
Registered User
 
Terra Nova's Avatar

Join Date: Apr 2007
Location: Marina del Rey, California
Boat: Mako 248
Posts: 4,089
Re: Help: punctured water tank

Quote:
Originally Posted by clockwork orange View Post
...use a ss sheetmetal screw. I would use a pan head with some butyl tape or similar under the head...
This. A #10 should do the job.
__________________
1st rule of yachting: When a collision is unavoidable, aim for something cheap.
"whatever spare parts you bring, you'll never need"--goboatingnow
"Id rather drown than have computers take over my life."--d design
Terra Nova is offline   Reply With Quote
Old 25-11-2018, 07:20   #14
Writing Full-Time Since 2014
 
thinwater's Avatar

Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 6,495
Re: Help: punctured water tank

Nothing that complicated. No sealant or tape. No tapping. No plastic screw. Just a tight fit. It's probably that simple.

If it leaks someday, I'd replace it with a through bolt with gaskets on both sides. That can't leak if done properly.

BTW, sealant or tape is NEVER recommended for PE tanks. Ask the manufacturers. Just clean threads. You only use sealant if the threads have worn... which happens.


If you must use sealant, I'd try a drop of Sika 291 (not 3M products--not as good on PE) under the head only.




__________________
Gear Testing--Engineering--Sailing
http://sail-delmarva.blogspot.com/
thinwater is offline   Reply With Quote
Old 25-11-2018, 08:17   #15
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 26,826
Help: punctured water tank

Quote:
Originally Posted by Jerry Woodward View Post
Yes, the nylon bolt sounds good, but the threads would be straight and the nylon bolt would be straight and they probably wouldn't form a tight seal. I like your idea of wrapping with teflon tape, this would probably seal it. On the other hand, a tapered metal screw would cut new threads and the taper should create a tight seal. Yes, corrosion is a concern, but it is fresh water. I can always check and replace if necessary after a season.


Well the Stainless crowd has a following, but if you only lightly tap the threads it will be an interference fit for a plastic screw, similar as to npt in function, donít fully run the tap through.
I donít like sheet metal screws for something like this because the threads are so coarse, but I bet it would work.
It wonít take much to seal, there is no significant pressure.
__________________

a64pilot is online now   Reply With Quote
Reply

Tags
water

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Dinghy punctured multiple times from fish Captaintim1 Challenges 8 11-11-2013 18:49
Repairing Punctured Fenders holmek Construction, Maintenance & Refit 10 12-09-2012 21:24
Converting a Water Tank to a Holding Tank royelshort Powered Boats 0 16-11-2011 16:06
Fuel Tank to Water Tank jkleins Construction, Maintenance & Refit 8 23-06-2010 17:49
Converting a Water Tank to a Holding Tank Ray Tarr Plumbing Systems and Fixtures 3 21-02-2010 17:39

Advertise Here


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 07:19.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
×

ShowCase vBulletin Plugins by Drive Thru Online, Inc.