Re: Installing Swimming Platform - Water Line
Here is my 0.02 on this matter...
My family's last boat was a 33' Chris Craft Sedan Bridge. It has a nice teak swim platform off the back. It was mounted very very low to the water (maybe an inch or two at rest on a calm day). We didn't think much of it until we started using it. Water was constantly hitting the platform and the platform spent a lot of time under water. It wasn't terrible, but I would have preferred it a few inches higher, to keep it mostly dry.
In your case it sounds like you will only use it for boarding, correct? If that is true, and you have the option to move it up and down, I would say an inch or two above the water might work. I have heard stories of water hitting the platform and actually splashing passenger in the back on the boat, when mounted too low.
I would also suggest getting a multi rung ladder. Makes boarding much, much easier!