Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 15-01-2014, 20:27   #1
Senior Cruiser
 
hpeer's Avatar

Cruisers Forum Supporter

Join Date: Dec 2008
Location: Philadelphia
Boat: Murray 33-Chouette & Pape Steelmaid-44-Safara-both steel cutters
Posts: 3,898
Polysulfide to seal diesel tanks

I have a steel sailboat. The deep keel is void, I want to use it as an integral fuel tank by welding on a cap. I'm not 100% sure the voids are completely watertight (95%) and want to run a sealant over the welded seams to be 100% sure no diesel will flow into the adjacent keel sections. Adjacent keel sections are filled with steel and cement.

I have the designers blessing on this idea. In essence I will be creating a double hull for that section of the keel.

I know they use two part polysulfides in aircraft for this application.

So I'm looking at Boatlife Calk as a sealant. It comes in three varieties
One part in a calk tube
Two part pourable
Two part heavy

Which of the three products (tube, pourable, or heavy) would be best suited to this application?
__________________

__________________
hpeer is online now   Reply With Quote
Old 15-01-2014, 20:41   #2
Registered User

Join Date: May 2012
Location: Halifax, NS, Canada
Boat: 47' Steel Roberts Cutter
Posts: 237
Re: Polysulfide to seal diesel tanks

I have used a gasket making product like Permatex ultra black to seal inspection hatches and the like on marine diesel tanks with great success for years. not sure how it would behave as a free-standing caulk, but it makes a heck of a good gap-filling gasket on a tank lid.

any autozone, Napa or similar store will have it in little squeezy tubes or larger cartridges. it ain't cheap, but diesel leaks suck, so I don't mind.

hope that helps.
__________________

__________________
NSboatman is offline   Reply With Quote
Old 16-01-2014, 05:38   #3
Senior Cruiser
 
hpeer's Avatar

Cruisers Forum Supporter

Join Date: Dec 2008
Location: Philadelphia
Boat: Murray 33-Chouette & Pape Steelmaid-44-Safara-both steel cutters
Posts: 3,898
Re: Polysulfide to seal diesel tanks

NS,
thanks. BTW, had the blasting done. About $3k here. Had some issues we the paint blistering though. Kinda sucks. Think I'm past that at now, I hope.
__________________
hpeer is online now   Reply With Quote
Old 16-01-2014, 06:28   #4
Guy
Registered User

Join Date: Feb 2013
Location: So. Oregon, USA
Boat: Seafarer36c
Posts: 4,308
Re: Polysulfide to seal diesel tanks

If it were like the aircraft you mentioned, you would use the 2 part heavy first and then the thin stuff as a top coat, put on with a brush to seal any pin holes you might have.
__________________
Guy is offline   Reply With Quote
Old 16-01-2014, 06:47   #5
Registered User

Join Date: May 2012
Location: Halifax, NS, Canada
Boat: 47' Steel Roberts Cutter
Posts: 237
Re: Polysulfide to seal diesel tanks

Cool - blasting done!

Now I have all kinds of questions... what blasting media? how far did you go - white metal or some other category? how did the welds look? Any plate repairs or pitting show up? how long did it take? big deal with cleanup? Did you tent the whole boat?

Did you DIY or contract out?

and of course - what paint system did you go with from bare metal...?

...ahh, so much to look forward to!

...maybe this should be a new thread. or taken to the MBS forum. but nah, there are lots of metalheads here too.

best-

bg
__________________
NSboatman is offline   Reply With Quote
Old 16-01-2014, 15:03   #6
Senior Cruiser
 
hpeer's Avatar

Cruisers Forum Supporter

Join Date: Dec 2008
Location: Philadelphia
Boat: Murray 33-Chouette & Pape Steelmaid-44-Safara-both steel cutters
Posts: 3,898
Re: Polysulfide to seal diesel tanks

Off to take another 30 hours of USCG Captains license school. Will answer when I get back.

Cheers.
__________________
hpeer is online now   Reply With Quote
Old 18-01-2014, 19:38   #7
Senior Cruiser
 
hpeer's Avatar

Cruisers Forum Supporter

Join Date: Dec 2008
Location: Philadelphia
Boat: Murray 33-Chouette & Pape Steelmaid-44-Safara-both steel cutters
Posts: 3,898
Re: Polysulfide to seal diesel tanks

NS,

I have the boat in a small DIY yard here. Had the yard staff do he blasting. We used sand, for better or worse.

I had a couple of places where there were plate issues. One in the keel where there seemed to be voids in the concrete fill, and one in her haunches were I had a persistent winter time only deck leak. The keel holes I ground out and patched (not quite done, gonna do a little exploration there) and the haunches will need a bit of plate replaced.

I painted with PPG Ameron 302 zinc primer with PPG 235 BarRust on top. Not done, still have coats to do. After applying the first two coats of 302 I got some blisters in the paint. Don't really know why.

We blasted one side, I wiped it down with acid, then with acetone, then painted. Next day did the other side. PPG gurus were nice, confusing, and not overly helpful. They think I got some contamination from salts on the surface either from the acid not being totally cleaned off of from the sand, or from the old paint, or...

Under the blister there would be paint on the hull, usually. So it almost looked like a blister between coats. Weird. Never seen this before.

The verbal paint instructions are difficult. Blast, pressure wash with water, dry with compressed air, paint before you get rust blush. If you did this it would take a LOT longer and be a LOT more expensive. When I asked about blush from washing the said "Well, ya know, a little blush is OK".

The wiping with acid and acetone was real tough, nasty. So maybe I didn't do as good a job as I could. The boat had clear plastic covers, the dust is incredible, the acid wash was not too bad. The acetone wash was bad. Freaking cold on the hands and you MUST wear a proper ventilator, fumes are horrible. Then the first coat of paint goes on under a tarp which holds the paint fumes, which are again horrible.

I can't imagine doing the process PPG recommended. You would really need a closed shop to do the work or you would have to tarp and remove each step, then there is the water run off, and disturbing the dust with the compressed air. Practically I don't see how I could have done it much different than I did.

Also, they questioned my use of the zinc primer. I explained that is what boat builders recommend. They said it was OK but not where they would use it. Damned if I know where they WOULD use it.

Anyway, I ended up sanding out blisters on maybe a quarter of the hull, touched up the paint, then found some more blisters, sanded them out, then used the 302 and (because of the different color or texture?.) found a few more blisters which I just cut out with a knife and painted.

I have no complaints with the paint. Stuff happens.

Now I have a bunch of interior work to do. The leak got water under the spray foam so some of that has to come out. Which meant I had to remove the fuel tank, in 5 pound pieces. I will convert my empty keel voids to diesel tanks. I got Ted Brewers blessing on that idea. That will provide good protection to the steel in the tanks. And essentially provide a double hull.

I also found some issues with the engine mounts I won't go into. I'll have to redo the stringer attachments. The engine is out while I treat and paint the areas underneath.

Slow going since December. Lots of family obligations and bitter cold.

Hope I answered your questions. If not ask more.
__________________
hpeer is online now   Reply With Quote
Old 18-01-2014, 20:19   #8
Registered User
 
Celestialsailor's Avatar

Join Date: Nov 2006
Location: In Mexico, working on the boat
Boat: Hallberg Rassy 35. and 14ft.Whitehall pulling skiff.
Posts: 8,013
Images: 5
Re: Polysulfide to seal diesel tanks

Quote:
Originally Posted by hpeer View Post
I have a steel sailboat. The deep keel is void, I want to use it as an integral fuel tank by welding on a cap. I'm not 100% sure the voids are completely watertight (95%) and want to run a sealant over the welded seams to be 100% sure no diesel will flow into the adjacent keel sections. Adjacent keel sections are filled with steel and cement.

I have the designers blessing on this idea. In essence I will be creating a double hull for that section of the keel.

I know they use two part polysulfides in aircraft for this application.

So I'm looking at Boatlife Calk as a sealant. It comes in three varieties
One part in a calk tube
Two part pourable
Two part heavy

Which of the three products (tube, pourable, or heavy) would be best suited to this application?
Why not do it right? If it's 95% watertight now, why not weld the 5%. I think you would be asking for a can of worms down the road. By the way aircraft use bladders.
Quote:
Originally Posted by NSboatman View Post
I have used a gasket making product like Permatex ultra black to seal inspection hatches and the like on marine diesel tanks with great success for years. not sure how it would behave as a free-standing caulk, but it makes a heck of a good gap-filling gasket on a tank lid.

any autozone, Napa or similar store will have it in little squeezy tubes or larger cartridges. it ain't cheap, but diesel leaks suck, so I don't mind.

hope that helps.
Ultra Black is silicon, I think and diesel will break it down.
__________________
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well-preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming: Wow - what a ride!"

http://wwwjolielle.blogspot.com/
Celestialsailor is offline   Reply With Quote
Old 19-01-2014, 05:47   #9
Guy
Registered User

Join Date: Feb 2013
Location: So. Oregon, USA
Boat: Seafarer36c
Posts: 4,308
Re: Polysulfide to seal diesel tanks

[QUOTE=Celestialsailor;1444009] By the way aircraft use bladders.

Why would anyone take your advice when you say something like that? If you wanted to be even a little bit correct you might have said some small planes use bladders but yes pretty much all modern planes have wet wings and if it is made from metal it uses a polysulfide sealant. If they didn't seal them up they would leak fuel out faster than you could put it in. That said they do put it on from the inside and I've never had any luck trying to seal up a leak from the outside.
__________________
Guy is offline   Reply With Quote
Old 19-01-2014, 06:18   #10
Registered User

Join Date: Mar 2010
Location: Wandering around North America
Boat: Defever 43 - Gray Hawk
Posts: 602
Re: Polysulfide to seal diesel tanks

Quote:
Originally Posted by Guy View Post
That said they do put it on from the inside and I've never had any luck trying to seal up a leak from the outside.
I was ass/u/ming the OP was putting the "gunk" on the inside of the keel. If not he's wasting his time and money.
__________________
R.J.(Bob) Evans
M/V Gray Hawk, 43 Defever Offshore Cruiser
http://www.bobandmarilyn.ca
bobofthenorth is offline   Reply With Quote
Old 19-01-2014, 06:38   #11
Registered User

Join Date: Apr 2011
Location: vancouver, canada
Boat: hunter 31
Posts: 609
Re: Polysulfide to seal diesel tanks

Is it possible to have a steel tank custom fabricated to slip into the keel void?
__________________
shorebird is offline   Reply With Quote
Old 19-01-2014, 07:16   #12
Registered User

Join Date: Sep 2013
Location: Beaufort, NC
Posts: 364
Re: Polysulfide to seal diesel tanks

Seal the tank and pressure test it.
What you are talking about is not a fix but a band aid, and a poor band aid at that.

Seal the tank and put no more than 3 PSI in the tank. Brush a soap and water mixture on the welds and look for the bubbles.

Re-weld and test any leaks.

Once the tanks have had fuel in them, they become much harder to fix.

What you are talking about doing would be a disaster.

And if you have inspection plates use nitrile gasket material. It is fuel resistance.
__________________
Capt Hugh Wilde is offline   Reply With Quote
Old 19-01-2014, 08:32   #13
Senior Cruiser
 
hpeer's Avatar

Cruisers Forum Supporter

Join Date: Dec 2008
Location: Philadelphia
Boat: Murray 33-Chouette & Pape Steelmaid-44-Safara-both steel cutters
Posts: 3,898
Re: Polysulfide to seal diesel tanks

It was obviously possible to weld the seams during construction, keel was welded up, the the plates attached so that the keel protrudes in to the hull.

You may well have been able to access the bottom seam (divider to sole) from the "top" with the keel on its side and I encumbered.

However, now the keel is in the vertical position, BatMan Could not get down there. Well, maybe Robin, but I ain't no Robin. It would require hanging upside down inside the tank.

Yes, I was thinking of pressure testing, but would obviously like to do this once. Once the lids are on all additional work will be that much harder.

It's hard to see how it would be a disaster if it is routinely done on aircraft.
__________________
hpeer is online now   Reply With Quote
Old 19-01-2014, 08:36   #14
Senior Cruiser
 
hpeer's Avatar

Cruisers Forum Supporter

Join Date: Dec 2008
Location: Philadelphia
Boat: Murray 33-Chouette & Pape Steelmaid-44-Safara-both steel cutters
Posts: 3,898
Re: Polysulfide to seal diesel tanks

Quote:
Originally Posted by shorebird View Post
Is it possible to have a steel tank custom fabricated to slip into the keel void?
She actually came with custom fit SS water tanks. The problem with that is that steel will sweat, or water will get into the void some other way, and you get corrosion with no way to maintain it. I pulled those thanks out.

I've been using the void as dry storage. I have a water bladder for that. But now I've had a issue where I needed to take out the fuel tank and don't want to replace it where it was. Again, it covered areas that may need maintenance.
__________________
hpeer is online now   Reply With Quote
Old 19-01-2014, 08:48   #15
Registered User

Join Date: Sep 2013
Location: Beaufort, NC
Posts: 364
Re: Polysulfide to seal diesel tanks

Quote:
Originally Posted by hpeer View Post
It was obviously possible to weld the seams during construction, keel was welded up, the the plates attached so that the keel protrudes in to the hull.

You may well have been able to access the bottom seam (divider to sole) from the "top" with the keel on its side and I encumbered.

However, now the keel is in the vertical position, BatMan Could not get down there. Well, maybe Robin, but I ain't no Robin. It would require hanging upside down inside the tank.

Yes, I was thinking of pressure testing, but would obviously like to do this once. Once the lids are on all additional work will be that much harder.

It's hard to see how it would be a disaster if it is routinely done on aircraft.

I am sure the product and method of application in the aircraft industry is not something that would lend itself easy application in a boat.

Pressure test first, localize the leaks, and repair them by welding.
That is the proper fix, and I am sure if you talked with a marine surveyor he would concur.

Without pressure testing up front you have no idea where any leaks are, or if you even have any, so you have no idea where needs to be repaired.

There are 6 internal tanks in the boat we are building right now, and as soon as the gasket material comes in, we are bolting the tank lids down and testing them.
Until you do that, you have no idea what you have.

The tanks can be welded to repair on the outside of the tank. Any type of coating or caulk you try to use would have to be applied on the inside of the tank to withstand the hydraulic pressure generated inside the tank by the movement of the fuel in a seaway.

Without first pressure testing you are just stabbing at it in the dark.
__________________

__________________
Capt Hugh Wilde is offline   Reply With Quote
Reply

Tags
diesel, tanks

Thread Tools
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




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 19:42.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.