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Sailmonkey · 22-09-2017, 10:49

Quote:

Originally Posted by Terra Nova

I have refit some Beneteaus with this water tank design. The fiberglass lids were caulked (not chalked) using clear silicone. And the lids were fastened using pop rivets. The key is to remove 100% of the old caulk, and sand and clean the surface prior to caulking. Insure there are a sufficient number of fasteners. And get some help to get the caulking and top installed very quickly so the silicone does not skin over prematurely.

This makes more sense.

I'll bet someone at some point said "it's leaking" and smeared silicone over the top of the joint.

This sloppy repair is never the right way. Like said above, disassemble, clean, and re-seal.

SSgtPitt · 22-09-2017, 12:46

Sand the bonding surfaces and Wipe it down w acetone right before caulking. I just redid mine and used 5200. I hope it works, I haven't refilled the tank yet. The PO had about 10 layers of silicone gobbed all over.

And never use "chalk".

boatpoker · 22-09-2017, 12:53

Silicone is doomed to fail.

boatpoker · 22-09-2017, 12:55

Silicone is doomed to fail.
5200 might work depending on fasteners used.
Epoxy the cover plate in place and be done with it..

hellosailor · 22-09-2017, 16:04

"why not glass the "lid" down with some thickened epoxy?"
A very bad idea. That would make it impossible to remove the lids for future repair or cleaning access. Like burning a house down in order to get rid of a mouse, there are more effective ways to do this.

Since there is some question as to what was original and correct, I would suggest calling Beneteau, who have a good reputation for keeping records and assisting owners. They will know if there is supposed to be an o-ring or gasket, and if so, they may have replacements or at least they can say what is needed.

If the answer is simply "CLEAN the lid and tank and reapply SEALANT then TORQUE DOWN ALL SCREWS EVENLY" they will say that too. Using the correct sealant, applied to properly cleaned surfaces, and applying uniform torque to all the screws (which may mean spending $20 on an inch-torque wrench and buying some new screws) should ensure a proper seal.

On what "proper" means? When materials like PermaTex form-a-gasket (similar to silicone seal) first came on the market, mechanics were given samples and because they could bother CLEANING surfaces or reading the instructions, the material failed and they wouldn't use it.

When PermaTex assembled a race car engine (Indy 500? Formula 1?) with JUST form-a-gasket, and raced it and campaigned it, and there were zero failures? People started taking more interest in the product. The only difference was in following the instructions!

To the OP: No one ever used CHALK on those tanks. They shouldn't have used CAULK either. The job calls for a SEALANT or an ADHESIVE SEALANT and they are all very different products. In order to any of them to work properly, you often need to clean the surfaces (spray and water and clean paper towels, followed by alcohol and more clean paper towels, working outwards from the clean zone to the surrounding area) and then apply the material as directed. After assembly it needs a proper time to set and cure--without getting it wet, without walking on it and bouncing around. And, if the screws are doing anything, they need to be uniformly compressed (with the torque wrench) or else the pressure on the gasket that you have made will be uneven, and it will work out of place and leak.

All simple--but all guaranteed to fail if not done correctly. And if the sealant has gone stale on the shelf (they have expiration dates, even unopened) it can fail to cure and fail to seal as well.

The devil is in the details. (And that rubric IS actually about caulk.(G)

boatpoker · 22-09-2017, 16:29

Quote:

Originally Posted by hellosailor

"why not glass the "lid" down with some thickened epoxy?"
A very bad idea. That would make it impossible to remove the lids for future repair or cleaning access. Like burning a house down in order to get rid of a mouse, there are more effective ways to do this.
(G)

What is wrong with an inspection port ? The OP stated he had one.

Terra Nova · 22-09-2017, 16:34

The inspection ports aren't large enough to thoroughly clean the tank. And the baffles are built into the lids.

hellosailor · 22-09-2017, 16:53

If there was no need for access beyond the inspection port, I think Bene would have been sharp enough to save the money on 50 screws and screw holes and just glue the tops down on Day One, no?

There may be many ways to stop the leak, all with merits, but if you give Bene some credit for having some reason for the way the tanks were built in the first place (and sometimes there is no reason, or someone's nephew had a screw business, or they prefer to have a space large enough to smuggle bricks of coca, yes) it may be worth asking them, and fixing the tanks in the same manner.

Long distance phones calls are just SO expensive these days.(G)

boatpoker · 22-09-2017, 17:00

Quote:

Originally Posted by hellosailor

I think Bene would have been sharp enough to save the money on 50 screws and screw holes and just glue the tops down on Day One, no?

After surveying hundreds of Beneteaus ........ NO!

Simply add another larger port and seal the top plate one time only with epoxy.

Suijin · 22-09-2017, 17:14

*Scratches head* I have stainless tanks and the inspection ports are caulked. I open them up every two years and never have a problem with leaks after recaulking them. I use 4000.

atmartin · 22-09-2017, 18:20

Quote:

Originally Posted by hellosailor

"why not glass the "lid" down with some thickened epoxy?"
A very bad idea. That would make it impossible to remove the lids for future repair or cleaning access. Like burning a house down in order to get rid of a mouse, there are more effective ways to do this.

Having never seen the tank in question and with no pictures posted, I'll take your word for it.

It still strikes me as a very strange and failure prone design. Silicon and pop rivets? Most metal tanks have the baffles arranged so that you can get around them to clean inside without having to remove the whole top of the tank.