Engine Mount issue 2008 R25

[dougandnancy]

I recently discovered that one of the lag bolts securing the rear-most starboard motor mount on my boat would not tighten. Upon removal, the 2 inch 3/8" bolt appeared intact but had apparently stripped whatever it was screwed into. I assumed that there was a wooden block under the fiberglass floor, but was told that, in fact, it bolt was screwed into lead. In exploring the hole the bolt came out of with a couple of probes, it seems that there is an initial 1/2 inch of fiberglass and then nothing until beyond the length of the bolt.
What gives? I'm now wondering if whatever the bolt was mounted into has fallen away or perhaps it missed the lead during construction? All the other lag bolts are tight, but the prop shaft seems to wander at times. I am really at a loss about what to do now.
TIA,
Doug

 

[knotflying]

I had the same issue on my R-27. I did not fix it myself because I was having the mounts and a few other things done at Diversified Yacht in Fort Myers. Long story short, they filled the hole with epoxy and reinserted the bolt.

 

[dougandnancy]

Thanks Knotflying. The difficulty I have with injecting resin into the hole is that my probing seemed to reveal that there is a lot of empty space under the mount, i.e., it could take gallons. Some guidance from the builders would be helpful.

Doug

 

[CaspersCruiser]

A technique that was suggested to me in case of problems with the lag bolts when I had the engine mounts replaced on my R27 was to drill the hole oversize and epoxy in a dowel and re-drill for the lag bolt. Thankfully, that was not needed on my boat.

 

[knotflying]

Thanks Knotflying. The difficulty I have with injecting resin into the hole is that my probing seemed to reveal that there is a lot of empty space under the mount, i.e., it could take gallons. Some guidance from the builders would be helpful.

Doug

Well, mix up a small batch and pour it in and see what happens.

 

[BB marine]

You have a few options. Normally there is a piece of wood laminated to the glass this is installed when the stringer is being laid up. If the builder is using the old school wood stringer support the proper way is to have a solid piece of wood span the length of the engine stringer so that the wood can be used when the proper location of the engine is set and the holes pre drilled and lag bolted. The less effective way is to laminate 4 pieces of wood in specific locations that the engine should be located at. What happens? (1) The individual pieces of wood are not laminated in the right places.(2) while doing the lay up of the stringer the wood is forgotten sometimes all four or just one. What happens if the wood anchor backing is not located properly or not there ? The engine installer drills the hole and see's that he/she never hit wood when drilling the engine mount holes. At this time the technician makes necessary repairs and these repairs are noted on the build sheet for that particular hull. Or the technician just installs the lag bolt and hopes for the best. I have a feeling you got a hopes for the best!

Ways to fix it.

(1)The stringers are filled with foam or at least should be. Filling the hole with a good mix of epoxy will normally fix the issue. Some fill the hole and thread the lag before the epoxy sets up. And others fill the hole allow the epoxy to fully cure then drill the hole to the proper size and then thread the lag into it. This normally works quite well.

(2)If there is a large void and it does not appear to be foam in the stringer. (use a stiff wire, coat hanger to probe in the hole to see how large the void is. Mix up some expandable foam and pour into the hole to fill the void. Once the void is filled and the foam is set use the coat hanger to dig out some of the foam forming a pocket for the epoxy to fill. Now follow step 1

(3) If there is no wood or foam in the location of the bolt. Locate the center line of the bolt location. Measure the thickness of the top of the stringer. You stated 1/2" there is plenty of strength in 1/2" thick fiberglass. Mark the center line on the side of the stinger using a 1" hole saw cut a hole in the side of the stringer confirming that the top of the hole is at least 1" from the top of the stinger. Once the hole is cut this will give access to install a 3/8 " SS bolt washer and lock nut. Once the bolt is tighten use a piece of thin starboard seal the bottom side with sealant and use it to cover the hole. If you ever have to replace the mount you will be able to get to the bolt.
(4) Use the method that Bill suggested. This works well when there is wood present in the stringer and the wood has stripped out. Enlarging the hole to except a larger dowel rod and then drilling it for the 3/8 lag bolt. I have used this method many times. for a 3/8 " lag I will use a 5/8 dowel rod. Drill a 5/8" hole mix up epoxy, apply a thick mixture in the hole heavy coat of epoxy on the dowel rod bottom and sides then tab the dowel rod into the hole. Leave the top of the dowel rod sitting proud about 1/4" above the hole. let the epoxy set and cure. Once the epoxy is set and cured use a sharp chisel going with the grain chisel the dowel rod flush with the stringer and the drill proper size hole for the 3/8" lag.

Good luck, it is unfortunate that this happens. In the 70's, 80's, and early 90's this is how boats were built. Thru bolting and the uses of aluminum plates took the place of the wood when no wood below the water line was the new method of building boats. Wood in stringers was never a good idea for longevity. It was inexpensive but did add a great deal of strength. The down side was rot.

Good luck with your repair.

 

[dougandnancy]

Thanks, Brian.
I think you nailed it. There was nothing about the lag or my probing that suggested a proper initial mounting. The 1/2" of fiberglass was largely compromised by the almost 1/2" inch smooth shoulder of the lag bolt. I've only had the boat for a couple of years, and had never laid a wrench on the mounts until now. There was little in the way of resistance left.
Given that the fix at this point involves a complete removal of the mount, it is beyond my DIY abilities. But you have given me some directions to steer the shop.
Thanks again,
Doug

 

[knotflying]

You may be able to have enough room to work if you just remove the other hull bolt and turn the entire mount 1/4 turn.

 

[Levitation]

At this point in time I would be having a serious conversation with the factory.

 

[Chimo]

How old is this boat?

 

[bob daily]

Original post said 2008 model, I would say 12-13 years!