Mounting a swim platform

Hey y'all, I've got a 78' ski nautique that originally came with a ladder but has been removed and holes "filled".... I've purchased an original teak platform with brackets ($150 for anyone wondering) and I'd like to mount it to my boat but I have no holes to guide where it should mount. I'm hoping someone can give me some simple measurements as to where I should mount it and if anyone has any tips on drilling holes or hardware type to use or sealants to apply that would also be very much appreciated!!

You can put tape on the gel coat before drilling to keep it from chipping. Start with small drill & go up in size in steps.

Do you have OEM brackets? I would think they pretty much dictate position.

It appears the diaries section may be better as a for sale section. I thumbed through a few pages and couldnt find much on rebuilding, mostly just selling.

After you drill the holes for the brackets counter sink the gelcoat so it does not develop stress cracks. You want the holes to resemble this- \ / more than this- I I

For through-bolting the platform, I would use 3M marine sealants: 5200 (permanent) or 4200 (removable)

JQ

If it were mine :   I would make up some nut plates instead of just using nuts and washers. Maybe 1/4 X 2 X 2 aluminum plates.    You could even make them long enough to capture both holes in one piece. Thru drill these and use lock nuts and washers also.   These will spread out the load and help from cracking. Just one of many methods.

Would you use sealant in the holes themselves or on the inside of plates...or both?

Cool I think I got it....put boat in the water....mark where I want it to sit....drill small holes while stepping it up slowly....round over gelcoat edges to prevent cracking....use a mounting plate on inside to disperse weight evenly and use 4200 marine sealant everywhere......I think I'll have this thing on tomorrow then...just in time for the weekend fun!!