motor mounts recore

[erikgreen]

Hi all.

I had an accident with my boat on its trailer where the motor shifted to starboard, shearing two motor mount bolts and pulling two others out.

I've been working on repairs to the whole boat, and today I used a hole saw on a drill to core out around the old bolt holes to removed the snapped off bolt parts. Guess what I found?

Yep, lots of dark brown powder and some good wood. Now, I know the transom is sound because A) I checked it with an awl B) I tapped it with a hammer and C) It withstood enough force in the accident to snap part of the transom plate on the inside and the bell housing on the sterndrive instead of cracking itself. The floor checks out good too, so I'm hoping the stringers either are ok or else will last a year or two.

For the motor mounts, however, I'm going to have to re-core them. I've come up with the following plan: First, use a circular saw and sawzall to remove the fiberglass on top of the old mounts - it's about a half inch thick, I think Sea Ray expects most of the strength to come from the glass. Second, I'll use a chainsaw, chisels, vacuum, and drill to remove the old wood. Third, I'll fill the hollows this creates with a chunk of solid wood bedded in epoxy putty made with wood flour. Alternatively, I could fill the space entirely with epoxy putty and skip the wood.

How does this sound for a plan? Any reinforcements or changes that would be good to do?

Erik

 

[redfury]

Re: motor mounts recore

You could recore them with 8lb or denser foam and then buy some S2 fiberglass and re-enforce the mounts with an extra layer of glass.

Alternatively, you could have some metal bent to fit over the stringers and mount the motor to that if you want to go nuts with it.

I guess it all depends on how deep you want to get into this...wrist, elbow or up to your armpits

 

[erikgreen]

Re: motor mounts recore

After getting the wood out, I found that some of it was rotten, most of it was solid, and almost all of it was wet. I also found that this wood buts up against the stringers. The sides of the stringers were wet, but not rotten (or blackened) yet, which gives me some hope that there's not a ton of water in there.

I also checked the little bit of foam I could reach from the holes, and it was pretty dry, no fungus growing.

I'm thinking I'll fill the aft part of the hollow motor mounts with floatation foam, then fill the main mount portion of the hole with hardwood pieces laminated together, bedded in and surrounded by epoxy with wood flour.

Would it make sense to put screws into the stringer, with the heads poking into the space around the hardwood laminate, so they get embedded in the epoxy, thus binding the new mount strongly to the stringer?

Here's some pics. First one is taken from the starboard - these holes are on the forward part of the motor well.

Port mount, tilted so we see the hollow going aft:

starboard mount, tilted to see the forward edge:

and also my other repair, which is a break in the top cap on the starboard side... I've cleaned the break edges up, and splinted the top of the cap, next I'll start glassing on the inside, then build a reinforcing tube with a foam core for stiffness, and finally finish the outside with marine-tex and interlux brightsides... I'll have to repaint the whole boat at some point, can't match the colors:

 

[new_boater]

Re: motor mounts recore