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Toe rail carriage bolts

Jan 11, 2014
7,839
Sabre 362 113 Fair Haven, NY
Saltwater, aluminum, and stainless make an nice corrosion marriage, if you are lucky these nuts, bolts and toe rail will come asunder.

When you reinstall them use an anti-corrosion paste. Probably one of the best on the market is Tef-Gel (amazon link). A little goes a long way. Place it on the threads and under the bolt head, where ever the two metals touch. It doesn't take much. It seems a bit pricey, however it lasts a long time, I've only bought 2 tubs of it in about 15 years. I only bought the second tub (2 oz) after the first one leaped off the boat and tried to swim. Take note, Tef-Gel tubs do not float.

The corrosion in the photo has spread from the bolt, but the cause is the same, SS and aluminum. This bolt may have leaked helping to spread the corrosion. I'd just clean it up, being careful to not damage any of the anodizing that is still there and use Tif-Gel.
 
Sep 24, 2018
1,475
O'Day 25 Chicago
Saltwater, aluminum, and stainless make an nice corrosion marriage, if you are lucky these nuts, bolts and toe rail will come asunder.

When you reinstall them use an anti-corrosion paste. Probably one of the best on the market is Tef-Gel (amazon link). A little goes a long way. Place it on the threads and under the bolt head, where ever the two metals touch. It doesn't take much. It seems a bit pricey, however it lasts a long time, I've only bought 2 tubs of it in about 15 years. I only bought the second tub (2 oz) after the first one leaped off the boat and tried to swim. Take note, Tef-Gel tubs do not float.

The corrosion in the photo has spread from the bolt, but the cause is the same, SS and aluminum. This bolt may have leaked helping to spread the corrosion. I'd just clean it up, being careful to not damage any of the anodizing that is still there and use Tif-Gel.
Does Tef-Gel interfere with sealants such as 4200 or butyl?
 
Jan 11, 2014
7,839
Sabre 362 113 Fair Haven, NY
Does Tef-Gel interfere with sealants such as 4200 or butyl?
It might affect the bonding of the caulk to the fitting, however, only a very small amount of Tef-gel would be involved that accidentally squeezed out of the bolt threads. The caulk should have ample clean areas around the fitting and deck to seal the fitting.
 

dLj

.
Mar 23, 2017
1,830
Belliure 41 Now on the Chesapeake
I doubt it would do anything to buytl, but would the 4200...

I always wonder about switching out stainless fasteners in aluminum to aluminum fasteners...

@dlochner What are your thoughts on that?

dj
 
Apr 6, 2020
15
hunter 42 ventura
I would bet stainless steel bolts are a lot stronger than aluminum bolts. I’ve heard of T tracks ripping off like a zipper under heavy loads. I’d hate to experience that!
 
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Likes: LloydB
Jan 11, 2014
7,839
Sabre 362 113 Fair Haven, NY
I doubt it would do anything to buytl, but would the 4200...

I always wonder about switching out stainless fasteners in aluminum to aluminum fasteners...

@dlochner What are your thoughts on that?

dj
I think it would depend on the shear strength of the bolts especially at the bolt head. If the rail is used to mount genoa leads there is a lot of force put on them. What is the safety margin if one failed? Would the rail "unzip" as @wade the giant suggests?
 

dLj

.
Mar 23, 2017
1,830
Belliure 41 Now on the Chesapeake
You would win your bet.

Aluminum Bolts have very low bending moments or Shear resistance. Opps @dlochner was faster.
Jim...
Not so sure about that. 7075 has darned good mechanical properties.

Here's 7075:

1632542409065.png



Compare to 316:
1632542466098.png


McMaster carries 7075 aluminum threaded fasteners...

We use 7075 for tooling in machines for machining product. It's mighty tough stuff...

Yield strength is an important value when it comes to performance in these conditions, the 7075 is 73000 psi and 316 is 34800 psi

You may wish to rethink your position on using aluminum fasteners. Now, don't go buy them from a big box home market type store, but if you can get 7075 aluminum fasteners in the size you need, I'd be seriously considering them if I were putting them in an aluminum boat...

dj
 

RoyS

.
Jun 3, 2012
1,212
Hunter 33 Steamboat Wharf, Hull, MA
Question: What about a nylon washer under the carriage bolt head?
 
Feb 14, 2014
5,708
Hunter 430 Waveland, MS
I’ve heard of T tracks ripping off like a zipper under heavy loads. I’d hate to experience that!
Thus the SHEARing of the bolts.

You might ask yourself the question ...

"Why don't they use more Aluminum fasteners on a Sailboat?"

Actually the best bolts would be Titanium and then no galvanic corrosion either.:biggrin:
Jim...
 
Jan 11, 2014
7,839
Sabre 362 113 Fair Haven, NY
hmmm, good thought about isolation of the Stainless Steel bolt from Aluminum.
Jim...
That would work on a regular bolt. Carriage bolts have a square shape beneath the rounded bolt head. The washer would not fit and if it did the square part wouldn't be deep enough.