Until we were emptying the bilge multiple times a day and the drip had become a trickle and was threatening to become something else sooner rather than later.
We were literally sinking at anchor.
Our aim was to hold out until we next hauled out. We were a bit wary of anything that requires work on holes in the yacht while water desperately tries to invite itself onboard.
Once we realised that it was A) too expensive to haul out just to do a packing replacement and B) it would not last the next 3 months until we planned to haul, we decided to bite the bullet and replace the packing while in the water.
We made sure we did it on a week day and in close proximity to the local haul out in Prickly Bay (Grenada). Just in case!
All a bit daunting as i had never replaced packing let alone in the water!
Tools used:
Rags
Packing (over 1 ft for a 1 inch shaft)
Cable ties
Screwdriver
Pool Noodle (or something to hold the rags in place)
2 x Large pipe wrenches
Packing removal tool
Stanley Knife
Duct tape
What we did:
First, we needed to block the stern gland to prevent water from coming in while we were working
Step 1:Tear a rag into strips and coated them liberally with grease.
Step 2: Dive down and wrap the grease coated rags around the propshaft and jam them into the gap between the hull and the shaft. I did 3 separate strips and only wrapped one all the way around the shaft. The other two were used to stuff the gap above the shaft. The rags were pushed in with a screwdriver. Check that the water is no longer coming in. This can be done by loosening the stuffing box housing.
Step 3: I then cut an end off a "pool noodle" and placed it around the shaft. Securing it in place with 2 cable ties. This would hopefully keep the greased rags in place for the duration of the work. It was probably unnecessary in hindsight as the rags were in there good and proper, however I am a "belt and braces" type of guy. I also wrapped some duct tape around it too. Overkill maybe.
Step 4: You should have an idea as to the correct size of packing that your boat needs. If not buy a few other sizes. (It is cheap enough). Our Tartan 37 with a 1 inch prop shaft takes a 1/4 inch packing. This i found out from reading various forums. But some people had used 3/16 inch so i bought 2 feet of it just in case. While you have a bit of the shaft exposed between the coupling on the gear box and the stuffing box, wrap the packing around the shaft more and then using a sharp Stanley knife (Boxcutter, craft knife) cut the packing. You should get 3 strips just the right size.
Step 5: Open up the the stuffing box using large monkey wrenches or spanners (if you have the right sizes). Do it carefully to test for any water dripping out. It is not a catastrophe if you do have some water leaking as you are not trying to place the packing in the area with the water flow.
Step 6: Remove the old packing. I had a packing removal tool that looked like a cork screw. You could probably use a cork screw or a piece of wire with a hooked end.
Step 7: This was probably the hardest part. Trying to clean out all the old packing from the housing. The 3 main pieces came out but there was all sorts of bits stuck in there. If i had to do it over I would try have a spray can of compressed air and a thin long nozzle to blow into the housing to clear it of left over material. I used the packing removal tool and removed most of it.
Step 8: I inserted the first piece of packing and scratched a line on the bronze housing where the join between the two ends was. I then tightened up the nut and this forced the packing to the end of the nut in an even manner. (i.e. if i had tried to do it with a screwdriver i would have ended up pushing in one side then the other etc.). I reopened the stuffing box and placed the next piece of packing in and ensured that this was 120 degrees or so from where the first packing split was. Another mark on the housing and I tightened it up to press it in. To do the final one I reopened the housing, added the last piece of packing and ensured that the join was mid way between the other two marks on the nut and then tighten it up.
Step 9: A big one is to only HAND TIGHTEN the stuffing box. Tighten it up as much as possible to make sure it is as water tight as possible.
Step 10: Remove the greased rags one at a time. I had my partner keeping an eye on the the coupling as i removed each rag. After the second rag was removed, there was a drip happening every two seconds. I HAND TIGHTENED the nut a little more until it stopped dripping and went back in the water to remove the final rag.
Step 11: Test run the engine at anchor or in the marina by putting it astern (if on anchor) and tighten or slack off the nut until you get a bit of a drip when the shaft is turning. Better yet take your boat out and run the engine at your normal revs and adjust the stuffing box until you get the required drip. It should not (preferably) drip while at rest (read engine off). It may drip in neutral due to the vibration of the shaft in the stuffing box.
Warnings: If you over tighten the stuffing box, you introduce a lot of friction. The result will be more work for the engine and more heat applied to the packing and the stuffing box.
If you over tighten the packing, it also has a tendency to harden and can then score your prop shaft with a groove. So change your packing rather than keep tightening!
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