Yeah, normally you have to haul the boat to re-pack the stuffing box. Lots of water comes in, otherwise
. There is a procedure I read about somewhere--can't find it now--that involved packing the shaft from the water side with a "rope" of silly putty in a large baggie, that allows you to do it in the water.
Whenever you do this, you might want to consider GFO Stuffing Box Packing
. Somebody brought it up on the P30 mailing list. Says the stuff is terrific. Said that, just like the advertised claims: He installed it, adjusted once after a bit of run-time, and hasn't had to touch it in three years.