Hi Al,
Sorry I replied to your second test video before I had seen your first Test video.
As John rightly says, the Marlin doesn't like to get over the hump in shallow water. What I do if the water is that shallow is, just on tick over, head towards a little bit of exposed ground and just pop over it and it will drain the rear skirts and you're away again. The other trick for getting over the hump is to point downwind, with the wind behind you it will get over the hump a whole lot easier.
But what really concerns me is where you say:
I have 3 x 2" holes drilled along the bottom side of the rear of the plenum, so any water in the plenum, can drain out even if the bilge pump packs up.
This is not right,
At rest on the water, you are basically allowing water to enter and fill the hull and thus sinking your craft! At rest on the water a marlin floats like a boat very little if any water gets inside the hull/plenum. And any that does the bilge pump will remove. Plus, you can have a lot of water in the craft up to the weight of another person and it still operates just fine. (Don’t ask me how I know!)
PLEASE CLOSE THOSE 3 X 2’’ HOLES.
Do you have glassed in floatation foam around the rear and sides of your craft. If you do, she will float like a boat at rest on the water. If you don’t, please fit some. I had to fit it to my marlin 1’s and it made a massive difference to getting over the hump as the craft was already floating much higher in the water.
Also always take an oar or two with you when you go out. Then you can simply row back to shore if all else fails, but you won’t be able to do that if you are sinking due to three holes drilled into the bottom of your boat!