Lag Bolts of Mass Destruction

[maxingout]

When I repowered my Privilege 39 catamaran, I removed the old lag bolts from the engine mounts.

What I discovered was "Lag Bolts of Mass Destruction".

These are photos of lag bolts that were holding the engines in place.

Fortunately we are a catamaran which sails flat, and I suspect that the engines were partly held in place by gravity and the fact that the boat did not heel over.

When I had my Westsail 32, the boat would routinely heel over at 30 degrees when sailing to windward hard on the wind. I am not sure these lag bolts would have held the engine in place with that much of an angle of heel.

So one of the benefits of not heeling on a yacht is that the engines stayed in place even with lag bolts in this condition.

Maybe we were just lucky and the sea gods were smiling on us!

[JPA Cate]

Oxygen deprivation wastage, I presume?

Good catch, Dave. Fwiw, our engine mounts are shackled to the engine beds.

Ann

[Jim Cate]

Hi Dave,

What material are those ex-lag bolts? Interesting how different the wastage is between the examples. At any rate, you have now identified one non-arguable advantage of cats over monos!!

So glad you found those before they showed themselves voluntarily.

HOpe the refit is going well... we await your speedy return.

Jim

[maxingout]

Refit complete finally.

We had to delay our departure because I had some surgical adventures. The refit on my body is nearly complete. Hopefully!

[maxingout]

Originally Posted by JPA Cate

Oxygen deprivation wastage, I presume?

Good catch, Dave. Fwiw, our engine mounts are shackled to the engine beds.

Ann

Interesting. Do you have pictures of the shackle arrangement?

[fernandosmooth]

Why are they not stainless steel? (is it normal on boats for them to be like that? )



Where else in your boat do you have these screws?

[Snowpetrel]

Originally Posted by fernandosmooth

Why are they not stainless steel?

Stainless can be one of the worst materials for this type of job. The heads can look perfect, while the hidden parts waste away.

[sigmasailor]

I vote for number 4; the prettiest by far!

[MV Wanderlust]

Just gotta say... wow.

[billknny]

This is actually completely normal for stainless steel lag boats into wood that is damp, especially with salt water. All because the boat builder didn't think it worth an extra $10 for bronze lag bolts. Or maybe they are just ignorant of the properties of stainless steel? Either way---scary.

If you find something like this, how do you not worry about the other ten thousand value decisions that went into building the boat???

"Heck, they'll last at least until the warrantee period is over!"

There are many good ways to mount engines, even into wood stringers. Any kind of ferrous metal lag bolt is NOT included in the "good" ways.

[maxingout]

Originally Posted by fernandosmooth

Why are they not stainless steel? (is it normal on boats for them to be like that? )



Where else in your boat do you have these screws?

The lag bolts on both the port and starboard engines had a similar appearance.

The lag bolts were 25 years old when removed.

[SailRedemption]

I don't think it's unreasonable to use stainless lag bolts. How old are those lag bolts?(edit: I see they were 25 years... Long time not to have looked at mounts) Why are they in wood saturated enough to cause that type of corrosion in the first place? Wet wood stringers could have let go before any flavor lag was used.

Bronze lags are twice the price of 316 ss.

$10/ea - 3/8"x6" bronze
$5/ea - 3/8"x6" 316 stainless

Engine mounts and their hardware are part of regular (though not yearly) maintenance. Mounts wear out and should be changed so should their hardware. Don't blame the bolts, the wet stringers are the problem the corrosion was a side effect.

[SV Bacchus]

Crap! That wasn't on my list for this month and now it is.

[a64pilot]

When I changed the bolts on my 30 yr old IP they were in perfect shape and I reused them. However the stringers are dry.
The mast step I pulled last yr, the bolts were perfectly fine and reused too.
I do not think what you have is normal. If the wood stringers are wet, are they rotten?

[stnick]

i sure would want to know why the stringers were damp .Im a replace the stringer guy ! take no chances at sea !
Put a deflated basket ball under the engine and blow it up ! when it rises remove the mount and saws-all the stringer out replace and reglass with Roving and mat paint white and re install the mount. May have to move the basket ball 4 times . But sure does the job !