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Stripped holes in engine mount stringers...

rwthomas1

Sustaining Partner
Hello All,
Had the engine hoisted back in again only to find that the three holes I tried putting the lag screws in were completely stripped. I'm more than a little pissed right now as lag screws are a poor idea in the first place to hold the engine mounts down for a few reasons. Lag screws themselves are not bad but they certainly are NOT designed for repeated loosen/tighten cycles as they will certainly strip out. They did, shame on Ericson for such a poor solution.

Why there was not stainless or at least aluminum plates in the layup to receive machine bolts is beyond me.

There are three possible solutions to the problem.

-Pour thickened epoxy in the holes, re-drill and go back to lags.

-Find a suitable stainless steel insert, McMaster has several versions.

-Inlet fabricated stainless plates and angle stock into the rails, attach with multiple lags. Backside of fabricated plates with welded on nuts, threads tapped through the topside of plate. Relieve existing fiberglass rails with router, etc. so plates are essentially flush fitting. Need to do this as engine mounts do not have enough adjustment to simply cap the existing fiberglass rails.

I am loathe to just pour epoxy in the holes and go back to lag bolts. What happens the next time I have to loosen the mounts to adjust shaft alignment? The inserts are a decent idea however I question the strength of the insert simply because the 3/8" internal thread inserts available are less than 1/2" tall. Not a lot of purchase on the fiberglass rails. The last solution, reinforcing the whole thing with inlet stainless plates is the most appealing. Its also the most time consuming, expensive and tedious.

Shame on Ericson for such a poor design compromise. The claim that Ericson is a workable "blue water" boat is severely compromised by this setup. A knockdown, or worse, would certainly allow the engine to just pull right out of its mounts. Its a safety issue essentially.

And the blasted engine has to come out. Again.

To say I'm "annoyed" would be an incredibly minor understatement. If anyone has any input I'd sure like to hear it.

TIA, RT
 
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Sven

Seglare
Rob,

Really sorry to read about the problem.

Does the engine actually have to come out or could you just jack it up enough to be able to get at the holes and go the epoxy route ?

In the end, the lady is worth it, right ?



-Sven
 

Lucky Dog

Member III
Add me to wanting know other solutions for the engine mount, I am planning rebuilding them this summer. Any and all suggestion are encouraged.

ml
 

Emerald

Moderator
I know the lag bolts may seem like a bad idea, but they really aren't that evil. Think how much fun it would be to remove 8 galled stainless fasteners some 25-30 years old! See, the lag bolts don't seem so bad after all :egrin: Just epoxy fill (thickened of course) and re-drill and move on and have a cold one. I know it sucks, but at least it's not a boat sinker.
 

rwthomas1

Sustaining Partner
After giving some consideration to this I rechecked the holes in the boat. The engine is on a three point mount, one forward/center, two aft. The two forward holes are stripped and the space below is hollow. There appears to be about 1" of material, FG laminate I assume and then hollow space.

While I am comfortable filling a blind hole with thickened epoxy a open is another issue entirely. I still have very little faith in lag bolts that are repeated tightened/loosened. If I go the "fill it and forget it" method it may work for now but what about the next time the shaft alignment is checked? If they strip out again while in the water the problem is exponentially larger.

This is a 480lb engine. Even if I felt comfortable slinging it off the boom, I'm not entirely sure that I could get it enough out of my way to drop it on the sole and then work behind it.

Lag screws are problematic is any material that is not compressible. They work great in wood since wood fibers tend to compress and then "bounce back" to some degree. FG has none of these properties. Putting lags into it and cycling them more than once or twice is asking for failure.

I'm leaning towards the stainless plate method. The engine needs to come out anyway. I can fill the holes but redrilling is not possible with the engine in the way.

Regarding the "galled or frozen fasteners" I would highly agree that that sucks to deal with. However, if the periodic alignments have been done, per every recommendation I have read, they should not have frozen in the first place. Liberal use of anti-seize compound and the correct materials negate this issue.

The last thing is I may try to make my own super-long inserts by cutting down large stainless bolts for the threaded sections. Center drill the bolts, tap them for the engine mount screws, and they become perfect inserts. I just have to make some arrangements to get some time with a Bridgeport. Cutting and tapping stainless is not a home drill press project....

RT
 
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newgringo

Member III
Another Solution

What someone did on our E32-3 surprised me when I went to change engine mounts. They took a hole saw and cut 1 1/2 inch dia holes sideways in the boat stringer about an inch or so below where each lag bolt used to go. That allowed using a bolt and nut to hold down the engine mounts. Tough to get at in the rear, but pretty effective.
 

Matey

Member III
Rob,

While the lags are a poor design .. have you considered machine screws set right into epoxy ? We mounted allot of fittings on a large wood mast & boom last summer (winches, jammers, vang plates and the like) by drilling over sized holes, pouring thickened epoxy, spraying the machine screws with pam as a release agent and popping them in the holes to set up. The next day we would pull them, clean things up and re-set them with sealant. We were working with a well respected rigger in Port Townsend who recommended the process. If you run the numbers .. I guess a machine screw/bolt beats the hell out of a wood screw for holding power. With this method .. theres no re-drilling and tapping, which might help you too.
We probably set 50 holes this way .. not one pulled out.

Just a thought .. good luck

I certainly can relate to the frustration .. sorry

Regards, Greg
 

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Rocinante33

Contributing Partner
Rob,

That's a bummer. I feel your pain!

Loren, in another post, suggested using a plug of foam rubber dipped in epoxy. Cram it into the bottom of the hole, but not so far as to push it all the way through. Let that epoxy cure, then fill the hole with a new batch of epoxy & re-drill the holes. The foam plug with the small bit of epoxy should keep the real batch of epoxy from running out the bottom of the hole. You may want to thicken it to make sure.

I thought it was a great idea from Loren....he da man!
 

Lucky Dog

Member III
I have bo idea where I found this...to much time surfing instead of sailing. Wouldn't surprise me if it came from someone here.

ml
 

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Emerald

Moderator
Lag screws are problematic is any material that is not compressible. They work great in wood since wood fibers tend to compress and then "bounce back" to some degree. FG has none of these properties. Putting lags into it and cycling them more than once or twice is asking for failure.



RT

The stringers I've messed with have been wood glassed in so the lag bolts weren't being used in straight FRP. I agree that running them only into an FRP layup is problematic. A frame as pictured from ML or some flavor of access holes and through bolting as another suggested are probably both good approaches that hopefully won't be too painful to do.
 

Maine Sail

Member III
Rob..

The fix can be done a number of ways. Catalina was also famous for this rather Mickey Mouse method of holding an engine into a boat..

I prefer to over bore the holes then attach stainless threaded rod to the mounts centered in the holes and held onto the mount with a nut on the top and bottom. The mounts are then mounted to a piece of 1/2" ply with hole centers that match the motors mounting holes, center to center, exactly.

You then judiciously wax the stud/threaded rod and put a nut on the bottom. Fill the over bored holes with un-thickened epoxy then remove it with a syringe. This wets out the wood. Next thicken the epoxy with coloidal silica (cabosil, Aerosil etc.) and inject the hole with this mixture until about half full. Then drop in your contraption of mounts and studs with a waxed fender washer under the bottom nut on the mount. Fill with thickened epoxy as necessary. Make sure it is aligned and perfectly centered and let cure. Once cured you can actually back the studs out because they were waxed. You now have an encapsulated nut and about 4" of threaded epoxy which does not even require a nut. According to Wast Systems they did this on a 2X4 and it took over 2000 pounds of force to pull the stud from the 2X4. You will likely be going more than 3-4" deep and will be very, very strong..


Pulling and replacing the engine is actually quite easy..

This is a video I made of me re-installing my 4 cylinder Westerbeke.

http://www.youtube.com/watch?v=mtJy4ytdSWY
 
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rwthomas1

Sustaining Partner
Well, the stainless plates are partially fabricated and the stringers have been inlet cut with a router to partially recess the stainless plates. Tomorrow the plates will go to the welder to have nuts welded to the bottom. The plates will be bedded in epoxy or 5200 and fastened with 4 lag screws each. The mounts will then attach to the plates with 3/8" bolts to the welded on nuts. Should be much stronger than stock and more importantly SERVICEABLE. Pics to come.

Pulling the engine is not difficult. Having to pay the yard for crane time twice is what stings.

RT
 

bigd14

Contributing Partner
Blogs Author
30+

I have the issue with the stripped holes in the fiberglass engine beds. I do not want to upsize the lag screws since that would eliminate most of the play for my shaft alignment adjustments. Since I have the motor out and following the "while you are in there" principle, I may as well do this right as per Maine Sail's method, above. In order for that technique to succeed, though, there needs to be wood underneath the mounts. Before I start drilling into things, does anyone know if there is wood underneath the mount in the 30+? Exploratory probes were inconclusive and there is no wood debris on the lag bolts.

If wood is not present I may need to drill out a big hole and install some kind of captive nut underneath so I can use threaded bolts, not lag bolts. I'm thinking of a small rectangle of steel that would be drilled and tapped to take the bolts, but would not be able to rotate when tensioned up. Kind of like a threaded backing plate.

Anyone have other solutions not previously identified?

Thanks.
 
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