Telescoping ladder mounting

[ConkeyX]

I bought a 4 step Windline telescope ladder to install on ‘05 250 Explorer. I’m putting it on port side entry but cannot use washer & nut to secure bolt as there’s no access to inside. My thought was to use 1/4” ss lag bolts but I don’t know the proper length to use. Anyone know how thick composite or plywood is in that area? I’m open to alternate ways to secure it if someone has experience with this. Ditching the slot ladder as it interferes with twin engines & just isn’t working well for diving. Thx in advance

[kleary4]

I use Hanger Bolts and Acorn Nuts everywhere on my boat.  1975 19-6, so I'm never sure of what I'm going into.  Home Depot has the Cad-plated stuff, but you can get Stainless at some hardware stores or McMaster-Carr - if you have the day to wait.  After install, you can monitor the nut torque and if one starts to loosen up, you can go to the next size, or add some epoxy to the threads.  Hope this helps :)

[ConkeyX]

Good info. I’ll check them out. Thanks