Install cockpit rocket launcher or chair

There should be something there unless someone ordered a boat without it.

Our 43 had a fighting chair. There is a thicker core in the area of the chair mount, but it has an external backing plate. You can see it in the photo.

I'll be back on my boat in a few days and will see if I see anything that may help you. Mine is a 1993 46'.

Maybe a stud finder will find a plate either below the deck or sandwiched inside it or since you have an inch, one of those hand held endoscopes. https://www.amazon.com/gp/product/B0CB1FPQKG/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I’m dealing with the same question right now for my 2000 42’ post. Trying to get the yard to install a pedestal for me. There’s about 6” between the top of the tank and the deck. Enough room to see there’s no backing plate there, not enough room to install one. The yard guy said it’s possible the plate is glassed in. He’s gonna check another 42’ post with an existing pedestal to locate its backing plate and see how it’s installed. I didn’t think about the stud finder. If you go that route, heads up that there is, on my 42,’ a wooden crossmember in the center of the deck. Not sure if it would set off a stud finder but make sure you don’t “identify” that instead of an actual backing plate.

interested to hear what you find - I’ll report back the same on my end if/when I figure this out.

6" should be plenty of room to add a plate if they find one is not there. I only have about 3" and my mechanic was somehow able to replace a fuel line about 12" in from the end of the top of the tank. Can't they pre drill & tap a thick aluminum plate prior to sliding into place after using it for a template to drill the deck ?

Maybe they can. The yard guy didn’t seem too worried - “we’ll figure it out.” I just put my arm in there and couldn’t reach far enough to get anywhere near the middle of the deck.

You could install an external plate in as little as an inch of space. The plate would want to be threaded so you don't have free nuts. Make sure the plate is thick enough for threads, usually 1-1/2 times the diamater of the fasteners, and thinn enough to slide in the available space. Make the plate and add two additional holes inside the main bolt pattern where some counter-sunk fasteners in the deck would not interfere. Mark 3 holes around the bolt pattern. Use the backing plate to mark and drill all the holes for the bolt pattern and the two additional holes. Countersink the two additional holes. Mark the same 3 hole positions that you marked on the backing plate on the deck. Thread long strings through the three marked holes in the deck. Push enough through so you can pul them over to where you have working room using a grabber or stick. Thread each string through matching marked hole in the backing plate. Tie them all together on the back side of the backing plate. Add a long tail so you can remove the strings from the bottom side later. Use the strings to draw the plate into position and pull it up to the undeside of the deck. Use a small pointed scribe to help fine tune the location of an open hole in the bolt pattern and thread it in loosly. Due the same for others till you have 3 holes (work better than just two) with fasteners loosly installed. Draw up all the fasteners so they lift the plate up level into position. Now thread the two countersunk fasteners into the plate and tighten. They will be perminant. You can then remove the fasteners in the mounting pattern and pull the strings out through the bottom side.

-g

this is brilliant but at the same time seems obvious after reading it. thanks

I haven't made it back to my boat yet but if you find yourself going to Panama City you are welcome to take a look at it.

Mine looks just like Gregs. 5" between the tank and sole, 350 gal tank.