How do I make Custom Buoyancy?

I've been trying to work out Custom Buoyancy with BodyForce because BodyPosition was giving me troubles.

Anyways, my problem is that my object that is placed in water bobs more and more creating a self perpetuating cycle, until it is thrown by the force.

I think I need some sort of water resistance, but I'm not sure how to go about doing that.

Here is a video of the problem https://imgur.com/a/LxkJ4rD

And here is the code that causes it:

local water = game.Workspace.Water
local waterLevel = water.Position.Y + 0.5*water.Size.Y
local BuoyantPart = script.Parent

local RotatedRegion3 = require(game.Workspace.RotatedRegion3) --Pretty much an intersection detector
local NewRegion3 = RotatedRegion3.FromPart(water)

while wait() do
    local waterHeight = water.Position.Y + (water.Size.Y * 0.5)
    local topSurfacePosition = BuoyantPart.Position.Y + (BuoyantPart.Size.Y * 0.5)
    local PartVolume = BuoyantPart.Size.X * BuoyantPart.Size.Y * BuoyantPart.Size.Z

    local BuoyantForce = PartVolume * (BuoyantPart.Size.Y - (topSurfacePosition - waterHeight) + (water.Size.Y/2 + BuoyantPart.Size.Y/2))
    --Changes based on how much the object is in the water

    if NewRegion3:CastPart(BuoyantPart) then --Returns true if part is in the water
        if BuoyantPart:FindFirstChild("BodyForce") == nil then -- Create BodyForce Instance inside of part and start the force
            local BodyForce = Instance.new("BodyForce")
            BodyForce.Force = Vector3.new(0, BuoyantForce, 0)
            BodyForce.Parent = BuoyantPart
        elseif BuoyantPart:FindFirstChild("BodyForce") ~= nil then -- Continue exerting force
            BuoyantPart.BodyForce.Force = Vector3.new(0, BuoyantForce, 0)
        end
    else --If part is not in the water stop pushing it
        if BuoyantPart:FindFirstChild("BodyForce") ~= nil then
            BuoyantPart.BodyForce.Force = Vector3.new(0, 0, 0)
        end
    end 
end

Thank you