Re: 94 Glastron SSV 175 Merc 3.0, front mount rotted? advice?
I've personally seen that type of rot spread like a drunken group of rioting partygoers all over a boat involving a 3.0L motor mount surface area like that.
First, you're going to have to find where the rot spreads to and ends. Dig and pull, and repeat until its all dry clean wood.
Usually, if this motor mount area connects to next to the gas tank area right up next to it where a thin wall is, I would bet your rot started at the drain hole that is on a fiberglassed section tied to your engine mount stringer.
Now would also be a good time to check the drain plug hole and the outer transom to make sure all areas are sealed.
If you can dig out wood or feel raw wet wood when moving your finger around the drain plug hole, you got a potential big problem.
How I know, the same mess happened to me on a 1993 Sea Ray 170BR that I currently own that this was fixed. I checked all areas for rot except for the removable gas tank section while inspecting the boat for rot, 2 weeks later I stuck a screwdriver through the 1/2 thick wall between that engine mount and the gas tank holding area, nothing but pure rot.
I had no desire to make this my next project, thus I got an estimate for the damage at 1k to fix all the applicable rot. It got fixed as estimated, checked the repair myself personally, and moved on to the important project, getting it to look restored.
I have photo of the area affected attached and comments listed on them. This is the picture before it was fixed.
View attachment 137620