How much will my boat sink if i add a jackplate

[killerpirate]

Hi! Coming weeks i will be upgrading my boat from a 115hp Merc 4 cyl to a 150HP V6 Merc. Both 2 stroke.
Also, i am adding a 6 inch jackplate on the rear (this weighs 30kg / 66lbs)
My 115 weighs about 154kg / 340lbs (?). The 150 weighs about 184 kg / 406lbs.

Now i am wondering, how far will my transom sink into the water after i add this weight? Ore more someone experienced could give me an indication of how far the mentioned amount of weight will push a boat down?
Boat is a Fletcher 16 arrowsport, about 1.8meters wide (6 feet) and has a deep V.
I once stood on the rear of the boat with a buddy (me 70kg / 150lbs) and my buddy (100kg / 220lbs) and that was on the edge of fine. No water entered the splashwell yet.

Here is my boat

[Jim Speros]

Add the estimated weight in people again. I would hope it doesn't go more then half way to the top of transom then in pic. I would suggest inspecting your splashwell for water intrusion. Seal and/or add boots to rigging. Assume at some point water will top transom. It may be when coming off plane or when boat is idle and a passing wake hits the stern. Most splash wells will be OK . Make sure yours will be too.

[Turtleherder]

Weight is weight. You want to add an extra 60kg on the transom and you weigh 70kg. Sit on your engine and see how far the stern goes down.

[rgsauger]

This may sound nuts but a bunch of us will put a beach ball in the center of the jack plate and inflate it. You’d be surprised how much buoyancy you can get just from doing simple things like that.

[tlwjkw]

i'd be more concerned with tha integrity of tha transom, kickers/stringers more than tha weight...

[killerpirate]

Im working on the transom at the moment.
4x 10mm ply with 3 layers of 450 csm in between echt of them. 2 layers 450 and 2 layers 290 woven on the inside.
All layers are overlapping to the hull.
Today i Will add transom knees and also the splashwell Will me connected to the outside transom with 450 and 290.

[rgsauger]

Looks good. I added an extra pair of knees in my build. Four total. Rock solid.

[tlwjkw]

Im working on the transom at the moment.
4x 10mm ply with 3 layers of 450 csm in between echt of them. 2 layers 450 and 2 layers 290 woven on the inside.
All layers are overlapping to the hull.
Today i Will add transom knees and also the splashwell Will me connected to the outside transom with 450 and 290.