Outboard Mounting Bolts

[mbrown]

I recently noticed on my '84 17ft Thundercraft the lower motor mounting bolts were loose. It appears that when trailering the motor was allowed to hop and caused the bolts to pull into the fiberglass on the inside of the transom. It appears that the lower mounting bolts were put in the area where the floor meets the transom and there was a void between the fiberglass joint and transom wood. The holes in question are the second ones down on the lower bracket of a 90 mercury. Presently the transom wood is sound w/o rot or moisture.<br />Do I fill the holes and move up to the upper mounting holes on the lower bracket? What should the holes be filled with and what should I seal around the motor bracket with to prevent water infiltration? Also what would help in the future when towing to prevent a reoccurrence?

 

[agrazela]

Re: Outboard Mounting Bolts

Ratyclaws,<br /><br />Unless the current holes have been enlarged by the loosened bolt shafts, my recommendation is to reuse the current holes, making sure to liberally fill in around the bolts (inside and outside faces of transom, as well as around the shaft of the bolt itself) with 3M 5200 sealer.<br /><br />To prevent a recurrence of the bolts pulling through the inside face of the transom, get yourself some oversized washers to spread out the force on the nut.<br /><br />To prevent motor hop, I would recommend a transom saver (though not everyone on this board agrees).

 

[mbrown]

Re: Outboard Mounting Bolts

Thank you for your reply. Would you recommend cutting one piece of 2 inch aluminum to go between the bolts? What are the concerns with the transom savers?

 

[DJ]

Re: Outboard Mounting Bolts

The 2" aluminum stock would be fine.<br /><br />Transom savers work well if; the boat is tied down well to the trailer.<br /><br />See this thread.<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=17;t=037462

 

[crab bait]

Re: Outboard Mounting Bolts

bore out original bottom holes to the largest dowel rod ( closet rod ) size with a flat/paddle/spade bit..all-the-way-thru<br /><br />epoxy rod in place.. wait for cure..<br /><br />go to good ACE/TRUE VALUE hardware or hobby shop that sells K & S tubing..<br /><br />buy a size that is two to three sizes bigger than your bolts.. but is still a common bit size..<br /><br />bore hole thru in dowel rod an install the tube all the way thru,, with epoxy..<br /><br />install bolts a shoot caulk/silcone in tube around space of bolt..<br /><br />you see .. the dowel gives you soild.. the tube isolates/seals/protects from water infusion an isolates it from EVER soakin' in the side wall of transom..<br /><br /><br />this also works for NEW transoms.. just skip the dowel rod part.. <br /><br />the dowel rod part is for exsisting transoms that rotted..<br /><br />EDIT:::<br />read this entire post.. especially below..

 

[hayhauler]

Re: Outboard Mounting Bolts

crab bait, that's brilliant. Drilling out with the spade bit will also insure that there isn't any rotten wood in that area of the transom.

 

[Boilermaker]

Re: Outboard Mounting Bolts

I hate spade bits when you need a true round hole for a tight fit! Use a FORSTNER bit>>>It will cost you more, but you get a perfect round hole.

 

[agrazela]

Re: Outboard Mounting Bolts

If you ever hire someone to work on your boat, make sure it is crab bait and not me

 

[crab bait]

Re: Outboard Mounting Bolts

thanks there, HAY.. the brillant part is the tubing.. it's very thin walled an when installed/epoxied in,,it's a permenate sleeve/liner.. that saves/isolates the transom from water but yet there's a hole goin' thru.. <br /> <br />gee AGRA,, i mess up all the time.. but i can usaully make good in the end..<br /><br />SIDEBAR>>>><br /><br />see fellas,, someone thinks i'm brillant . .. so there...