I'm the guy that's been running my homebuilt water jet pack off my Berkeley. In the beginning of the testing stages this summer the first few hours we had no problems with air or seizure, just a matter of time, finally had a small seizure. I've been using the standard berk white ropes. Should I use graphite? Which is the best. Since I'm using the pump in a static mode, of course I'm battling the packings overheating, I over heated them this last weekend, may need to replace the shaft again because Its getting harder to keep air out. I know this is brutal on that packing gland. If I keep them loose then we suck air in, at least I think that's where the air must be coming from. Not so good when I'm 20 feet up in the air and enough air enters the pump. Some time ago I read somewhere online of someone running a water tap off of the high pressure engine cooling line at the pump, and feeding water into the packings via a drilled hole into the packing housing. I would think one would want to have a sand/debris trap tho. Seems to me this might work somewhat especially if I keep the packings loose...? Make a hole in the packing down to the shaft might lube and replace the air with water too. I'm in a pickle here trying to make this work. This is a very interesting challenge. Like Tom at Jet Boat Performance said, I'm in uncharted territory. I'd sure like to find a way to beat this. We never turn more than 2000 rpm's. I've heard of those cartridge seals, but dont' have the funds for a new shaft just yet, maybe after tax time! And my packing housing bore has a bit of pitting so I may have problems with the outer cartridge o-ring seals. I had thought about using silicone to seal the cartridge in against the pitting. I've also read that the shaft/o-ring interface are sensitive to dirt and grime. I'd love to hear your ideas, or tell me if you think I'm crazy lol.