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Old 07-24-2017, 09:46 PM   #7
Aquabelle
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City: sydney
Country: australia
Vessel Name: Aquabelle
Vessel Model: Ocean Alexander Flushdeck
Join Date: Jun 2012
Posts: 916
Some progress and new learnings: the prop shop called me having examined the original props and compared to new, to say the old props sat well back on the shaft taper and that the new would be much further forward. Was I sure there was enough distance between original props and the aft skeg to accommodate this? I had the slipway guys measure up and reported a 48mm (~2”) gap available; happily the prop shop said this would be OK. The keyways of the original & new props were also different, so now as well as re-tapering to 16 & making up bronze spacers, they’ll also make up new keys. Props will be prop-scanned and balanced/matched also.
Meanwhile back at the slip, the team seemed to have no problems getting the Port shaft out….all 3.9m x 58mm (12.8’ x 2 ¼”) of it. As expected, pretty severe corrosion on the stuffing box end but good everywhere else. Photo below shows 200mm (7 3/4”) corroded section but only 45mm (1 ¾”) of this is within the packing area of the stuffing box; the balance made for an unattractive but harmless view between SB & trannie. This corrosion was obviously the explanation for the Port SB’s steady drip despite re-packing over the last 10 years; and the deterioration in the cutlass bearings since the last haul-out 2 ½ years ago must have exacerbated this by letting the shaft sit out-of-centre through the SB.
The shaft is double-tapered and so would usually have been reversible…but for some reason, the thread on the prop end is 1 ½” but only 1 ¼” at the trannie end. The yard kindly lent me their truck so with the prop shaft & coupling loaded, it was off for the 2-hour drive from Sydney’s eastern edge to an industrial area to the west, to meet up with a spray-welding outfit. When they saw my interest in the process, I was given a full tour of the facility. Pretty amazing, they spray-weld all kinds of coatings, not just the stainless I need: including hi-tech ceramics.
With the shaft removed, the worn cutlass bearings x2 were removed…and we found the ‘spares’ left on board by the previous owner 10 years ago didn’t fit! Also, there is a bearing behind the stuffing box itself in the stern tube and this had almost entirely disappeared. (The SB is bolted direct to the aft engine room bulkhead….no rubber hose….and right behind this is the stern tube with this newly-discovered bearing.) The slipway guys feel this bearing is redundant, as the shaft is supported by two bearings on the hull and by the SB itself…but since we’ve come this far, I told them to go ahead and replace the shaft tube bearing as well, so the SB operates just as a gland. I have to believe this will allow the SB to do as little work as possible.
The slipway team got the new anti-fouling done (but not PropSpeed). Now, while we wait for work on the props and the shaft to catch up, Aquabelle has been un-slipped and is sitting out on a mooring.
Attached Thumbnails
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Name:	To the Spray Welder.jpg
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