Transom Knee Addition

I replaced core of a Grady Adventure 208 from the outside as design of stern section with molded seats (oil compartment & battery compartment)and cap made it impractical to work from the inside. Pic below:



This is my second transom (1st Bertram from inside) and I feel good about the new core on the GW, but I am a belt and suspenders type of person. I would like to add a single knee to the transom. I would add two, but there are 2 strainers in the way on the bottom of the hull and they are also roughly aligned with where the mounting bolt holes would come through the transom. The plan is to mount the single knee so bolts will clear it on each side. The motor is a 200 hp 424lb Yami. Can someone recommend a source of info or indicate general principles of knee dimensions/designs for me in order to add to the transom’s integrity? Certain heights and lengths relative to the overall height and width of the transom? I can’t imagine it would be less than 2” thick. It will have multiple layers of tabbing staggered to the hull bottom and transom itself. That’s my plan so far and I really appreciate any assistance on the project. Thank you very much.

 

Picture of transom from the inside hull ?

 

Sorry I don’t have any interior photos below deck at this time. The boat is now covered until spring. Accessing the bilge is very difficult. The set up of the splash-well and the access plates into the bilge do not allow me to reach inside to do any maintenance or photos. It also prevents any hope of a sight line to see what I am trying to reach. When the motor is in place it’s worse.

The first picture is looking forward and shows the splash well with its forward wall and the folding door on top. the transom makes up the real wall of the splash well.
The splash well is 32” wide.
The stringers are located about 6” outboard of the drains on each side. I

View attachment 200704

The next pic shows the access plates. The blue tape outlines the area that will be cut out for the installation of an Armstrong water tight deck hatch. The hatch will give me the ability to use both arms inside the bilge as well as a sight line to see what I’m working on.
View attachment 200711
The opening will be 9.5” x 21”

The floor of the splash well is recessed 6” below the top of the splash well rear wall where the motor bracket will be.

The distance from the floor of the splash well to the inside bottom of the hull is approximately 20” deep.

Deciding to cut the floor of the splash well was what made me decide installing a robust knee would be prudent to reinforce the new core.

Again, I’m sorry I don’t have pics, eventually I will have them
Thank You
T

 

Try connecting the stringers to the transom x 2 separate metal knees going outside the outboard screws.

 

I removed an IO and mounted an OB on an aluminum boat. I only used some aluminum square tubing bolted to the transom and through a stringer on each side. The section of yours that sits against the transom doesn't do anything, it's just extra weight. To provide any benefit the bracket would need to be through bolted with it.

So if thats the case, remove the entire thing and use two square tubing braces.