This is a repost but here's how I did mine, and it's been completely trouble free and exceptionally quite.
Here's the basic components.
That's a 2" inch rubber pipe cap from Home depot. A Rule 360 bilge pump, and a modified Marelon 3/4 thru-hull fitting.
I modify all three. First I drill a 3/4 inch hole in the center of the cap and sand the end smooth on a belt sander.
I then take the Marelon (glass fibered nylon) through hull...
chuck it in my lathe reduce the height of the exterior flange end sharpen its edge and then cut in an inset for the perforated aluminum screen. I then take it out of the lathe and tighten the nut down to the flange on top of a 1/4 inch spacer, I then cut the nut and shaft off with a bandsaw leaving only the 3/8 threaded washer end.
What your seeing in the pic is the flange with 5/8 of it's shaft and threads underneath it with the screen in place and the threaded washer next to it.
I use Marlon because it's strong, I would not try this with plastic versions or straight nylon. because they can break if you make them too thin.
I go with rule pumps because the are the size I need and the 360 bilge is relatively cheap. About 12 bucks online. I also have had the plastic cases on several atwoods crack and leak. Rules have steel shafts that rust and eventually cause the pump to fail do to friction but they use better plastic then atwood that doesn't crack. Just a judgment call but personally I'd rather have a pump that overheats and dies due to a bad shaft eventually then one that cracks and fills my yak with water.
I take the pump and heat the barbed nozzle outlet with a heat gun, until it's malleable then slide on a PVC shutoff valve from Home depot. Once it cools I cover the outlet barbs with 5200 to seal it and slide the valve back on the outlet, and lock it in place with a set screw. The shut off valve allows me to control the flow or shut off the flow from the pump completely if I get a leak below the water line in the PVC tank feed line.
I then drilled a 3/4 hole in the hull where it's in easy reach from my seat both inside and outside. Mount the flange on the outside coating the contact surfaces with 5200, slide the 2 inch cap on the shaft inside turned upside down, start the washer on the shaft and turn it down tight by rotating the cap.
To install the pump you just need to put it in the cap flange and tighten the hose clamp to seal the cap to the housing of the pump like tightening a radiator line.
The advantages are: it's easy and quick to remove and put back in but also that since there is not contact from the actual pump to the hull as it floats on a cushion of the rubber cap it's also very quite.
Here's what it looks like on the outside under the hull.
The idea here with the flush screen is if it clogs I just reach down under the yak and wipe it clean with my hand.
I do not use standard hoses or clamps but instead use PVC water purification and Ice maker line and the quick disconnects that they make for it. Once again you can just get this stuff from home depot.
The advantage here is that I can easily remove the pump assembly without removing the line and since the components are nylon and stainless and since it's made for water purification systems and takes up to 60 PSI, there is usually no maintenance or leakage issues with the setup or for that matter clamps that you have to tighten to get a good seal. Just stick the tube in the fitting and your done.
I use the same connection at the rear at the tank so I can easily take the tank in and out.
It makes for a nice clean setup
I've now got maybe ten trips on this setup and have had no problems and have not made any changes to it. No airlocks no problems always fills right away... It's great to finally have a setup that always works.
Bottom line: I'm doing all mine that way in the future.
So there you have it....
Jim