It was a beautiful day on the water... until,,,

M

MikeeH

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Beautiful day on the Chesapeake yesterday....but!

The Admiral and I had been at cruise speed for an hour or so when the was a sudden, loud grinding noise at the stern, the RPMs shot up and the boat stopped its forward progress. Quickly shut it down and got towed back to our ramp where we put it back on the trailer and broke out the tools. Blown coupler.

Pulled the engine and found the fiberglass at the mounting points for the motor mounts had cracked and depressed causing the engine to go out of alignment which caused the coupler to fail. Cut out the fiberglass deck at the location and found the wood that the engine was bolted to was pretty much mush... wet, rotted plywood. PLYWOOD!!

Now, I know my Wellcraft isn't a battleship and it is 25 years old, but plywood for engine mounts??? Today I'm going to fabricate new mounts out of PT 6x6 lumber, epoxy it to the hull and glass it in. I hope to have the boat put back together by the weekend when my son comes to visit. Gonna be busy!

I'll post before, during and after pics when it's finished.
 
Sickening! Doesn't sound like you're going to sit around and sulk about it. Good on YOU!
We had a 1977 Wellcraft. That awesome V-20 (20-ft, 6") hull. A super performer but poor attention to construction details. Lots of voids rught under the gelcoat, but also in the keel lamination buildup. Transom wasn't well sealed agaist water from the Liner-to-Deck joints. Made me think of those Monday/Friday jobs built when nobody wanted to work. I was considering doing a SeaCast transom job when we decided it was time for a bigger boat. SeaCast's website features a transom job on a Wellcraft, hmmm.... Still, we ran it nearly 30 years. Wore out two JohnRude OB's.
I hope there's enough structure left to get the new work lined up just right. And No More Surprises!
 
Great that your new place is so well equipped that the engine is already out. way to go Mike.
 
Plywood, having multi-directional layers, is not only stronger but more stable than solid wood.

My motor mounts were 3/4" plywood in the shape of angle iron with foam filling in the angle. That design was weak and susceptible to water damage. I replaced it with 7 layers of 3/4" plywood, epoxied together. That design allowed for sealing the full internal structure with epoxy, preventing water migration if by chance the outer surface was compromised.

The motor mounts themselves were mounted to 3/8" SS plate bent to a large angle-iron to cover a large surface area. The 'angle-iron was lag bolted with 8 bolts installed in different angles that prevents pull-out and lateral movement from engine torque.
 
What Charlie said. Also, I thought that it was difficult to get epoxy to adhere to pressure treated lumber.
 
prefer plywood for stringers. the long slender shape can really benefit from the increased strength from the alternating directions of ply. motor mounts however are often beefier sections and depending on the application mostlyy under compression. used 4x4 VERY DRY pressure treated lumber there. plywood also has a tendency to wick water faster/further much like a sponge.

good luck you don't find further water intrusion.
 
For its dimensional stability marine grade plywood without voids is considered a good core material for sandwiching between layers of fibreglass on structural stringers in the areas where engine mounts will be located. The trick is to keep the core material dry by avoiding any unnecessary penetrations, and ensuring any required holes (engine mount bolts and anything else) are properly sealed. This can be difficult to do over 25 years of successive owners. Voids in the fibreglass during initial construction can also rupture due to thermal expansion, so even careful owners can find their boat's stringers compromised without their having done anything to them. It's true too that fibreglass technology and know-how have changed significantly over the years. What boat builders know now is a long way from what they knew 25 years ago. I have a 30+ year old fibreglass boat and, although some of the core material in the decking shows up wet on a moisture meter, the decks remain strong, and I still think fibreglass is a great material for building boats.
 
I hear what you guys are saying about plywood and I do know that proper laminated wood is stronger than dimensional lumber. However, in this case my "forensic" investigation of what came out says it was not a properly prepared surface for mounting an engine. It appeared to be a single sheet of (maybe) 3/4 plywood mounted on two blocks of wood making a sort of table that was glassed on top. The wood was not otherwise encapsulated so it rotted away under the glass surface and I have no idea if it was marine grade plywood; the wood blocks certainly were not and not of this was mechanically or chemically attached to the hull surface. I also understand that PT wood is hard to dry completely so the new glass may not adhere properly. All that said, the trimmed 6x6 I put in was pretty dry (been around a year or so) and even if the glass doesn't adhere directly to the wood I'm thinking that it will stay in place because it is glassed with chop on 4 sided and the ends and then then glassed to the fiberglass hull on the two long sides and to the deck across the top with chop topped with rove. The motor is a Mercruiser 3.7 bolted down so I'm expecting the new mount will hold up well for the type of boating we do.

Time will tell but its a 25 year old bowrider owned by a 64 year old bayrider so I'm betting it will outlast my expected boating life.
 
Mike your a Hustler when it comes to 'gittin after it'. I wish I had your direction and force.
I'd bet whatever you did will probably out last you.

I was involved with a boat that had been pitched up, vertical. Don't know how they got out of that without capsizing.
But the engine (and other stuff) tore loose from its mountings while the boat was dancing on it's tail. (that's where I came in)
A word to the wise.....
 
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