Thru Bolt Sealant

[JamesG161]

My life rail stanchions are bolted thru the Fiberglas (FRP) deck. I noticed "Docking Helpers" grab the stanchions to push/pull the boat. I then found some long mysterious rain leaks to be through the stanchions deck bolting. I am needing to seal the thru bolt hole. Being a Chemical Engineer I went to 3M sealants for marine applications by this link.

http://solutions.3m.com/wps/portal/...ts/~/Adhesive-Sealants?N=5510818&rt=c3&Nao=15

http://solutions.3m.com/wps/portal/3M/en_US/Adhesives/Tapes/Products/~/Adhesive-Sealants?N=5510818&rt=c3&Nao=15

The application should be more like a "O-ring" and not so much adhesive ( for all you 3M 5200 believers I would like to be able to replace/repair the stanchions in the future:naughty:).

They have several types of non-silicone (silicone is short lived, no freeze/thaw properties) sealants.

Does anyone have marine experience with their product numbers....?

755 or 760 a Hyrbrid which is flexible

555 or 560 a flexible non hardening Polyurethane

Or any non-silicone sealant you have found good in a "Stressed" application.

Thanks...
Jim...

PS: Try 3M 4200 for same sealing as 5200 but can be broken with a wrench versus a chisel.

 

[Stu Jackson]

4200 NO
5200 NEVER

This stuff: http://forums.catalina.sailboatowners.com/showthread.php?t=117172

 

[Charles Erwin]

Some time back we were presented with a boat with 52 separate leaks sources on deck - we counted them. We re-bedded 10 stanchion bases, countless other deck fittings, and six portlights.

Six years later -0 - leaks.

Obtain your material here http://www.pbase.com/mainecruising/boat_projects.

You will not regret following the advice so far given - and do pay attention to Stu's "how-to" link.

Charles

 

[bletso]

Absolutely butyl tape by maine sail.

 

[JamesG161]

Great link, Stu TYVM....

:wow: butyl tape! Who would have thought CHEWING GUM still worked that well? I am not joking.

Great idea use without much adhesion.

I just canceled my trial of 3M 560 which adds tensile strength to the flexible bond. Since I am going to use Star Board or SS backer plates with SS washers/nuts (past owner took off the nuts and plate and forgot to reinstall them:cussing that link method is professional.

Plus I will countersink the holes too.

Thanks for all inputs....
Jim...

PS: Always match metals to reduce galvanic corrosion. Plus 3M 4200 has its place in my boat repair shelf.

 

[Gunni]

While starboard is a miracle of modern chemical engineering it is not the material to use for backing a through bolt. It has the strength properties of old mozzarella cheese.

 

[JamesG161]

It has the strength properties of old mozzarella cheese.

Boy Gunni, I had to look up the compressive strength of FRESH Morzarella chesse. It is lower than the butyl rubber in the discussion, but I get your point.

Starboard is HDPE (High Density PolyEthylene), and its Ultimate Strength is rated just below acrylic and about 1/20th of steel. (Even Chemical engineers are first engineers then chemical specialty).

However...

The ultimate material to take the stanchions/cleat load is....

Fiber Reinforced Polyester (FRP or Fiberglas®)

The backing plate is intended to "spread the compressive load" across a broad FRP hull surface.

In this case 3/8 inch Starboard vs. 1/4 inch Stainless Steel material is not the issue, but the thickness and most importantly the Area of backing plate to hull contact is key.

But...

Don't use Morzerella cheese.

I love you guys and do enjoy the Sailor's points. Thats why I like experience first and engineering second (the reason modern boating normally works is both worlds).

Smooth sailing...
Jim...

PS: In the day, I made HDPE and LDPE.

 

[woodster]

if the little dutch boy in holland had of had butyl tape he would have not had to put his finger in the dyke