A PSS Shaftseal is a modern replacement for traditional stuffing boxes, and makes a nice upgrade for older boats. Most older boats were made with a short length of hose coming off a stern tube with a stuffing box on the forward end of the short hose. This was not the case with the old Cape Dory 28. As there was very little room behind the Volvo MD7A, the boatyard threaded a stuffing/packing nut directly onto a bronze stern tube. This worked well enough if the alignment was perfect, but it would never quite seal, even with green stuff packing, polished shaft surface, and a very close alignment. Some changes were in order.
The first thing to do is free up some space back there, as the PSS itself needs about 6-1/4" inches. So, haul that old motor out and get a shorter one. Now, pull the tired old bronze shaft into the boat - much easier if you remove the prop first (don't try this with the boat in the water). This is a good time to clean & paint back there.
A key to this project is the stern tube and the old stuffing nut. As this boat doesn't have a smooth stern tube, take the old stuffing nut to a machine shop and have them turn it down to 1-3/4". Toss the old locknut away. Then, put the "round stuffing nut" back on the stern tube with a strap wrench & some 4200 on the threads.
Now you have something smooth for the PSS bellows to clamp to.
It's a tight fit back there; arrange the hose clamps high so you can tighten them, and slide the bellows over the round stuffing nut. Align it straight. Get the new prop shaft and de-burr it thoroughly, so rough edges don't damage the seals in the PSS rotor or your new cutless bearing as it goes through.
Then, using soap & water as lubricant on the shaft, slide the PSS rotor over the aft end and forward on the shaft, and send the shaft aft through the stern tube. Align the bellows on the stern tube for best alignment with shaft (concentric), and tighten the clamps. Attach the PSS vent hose and put the motor back. After the motor is in place, properly aligned, and bolted to the coupling, push the rotor aft 3/4" against the graphite to make the seal, and tighten the set screws in the stainless rotor to the shaft. Add the second locking set screws. You might want to add a zinc donut immediately forward the stainless rotor to back it up. If the rotor ever worked loose, the boat would flood.
Don't forget to put your prop back on!
John ;)