Island Time 1,239 Posted April 11 Share Posted April 11 Interesting pic of the failed rudder shaft, which then sank the Arcona 460 after punching a hole in the hull. 85mm alloy shaft - on a 46 ft boat? Quote Link to post Share on other sites
Island Time 1,239 Posted April 11 Author Share Posted April 11 Video: 1 1 Quote Link to post Share on other sites
waikiore 400 Posted April 11 Share Posted April 11 Alloy shaft tapered at the top 😕 I think from videos that it probably just broke the bottom bearing housing away and flooded her rather than dropping out and piercing the hull. Quote Link to post Share on other sites
waikiore 400 Posted April 11 Share Posted April 11 (After snapping below the top bearing) Quote Link to post Share on other sites
Bad Kitty 252 Posted April 12 Share Posted April 12 So Arcona obviously don't believe in watertight bulkheads? Jeez that'd be hard to watch. Hope they're all ok. 1 Quote Link to post Share on other sites
Island Time 1,239 Posted April 12 Author Share Posted April 12 5 hours ago, Bad Kitty said: So Arcona obviously don't believe in watertight bulkheads? Jeez that'd be hard to watch. Hope they're all ok. Most of the production boats don't have watertight bulkhead. Some have dams - didn't work great for the titanic! Also, an 85mm alloy rudder shaft wouldn't meet cat 1 here in NZ. Quote Link to post Share on other sites
Jon 360 Posted April 12 Share Posted April 12 1 hour ago, Island Time said: Most of the production boats don't have watertight bulkhead. Some have dams - didn't work great for the titanic! Also, an 85mm alloy rudder shaft wouldn't meet cat 1 here in NZ. Just register offshore and away you go Quote Link to post Share on other sites
Jon 360 Posted April 12 Share Posted April 12 Not exactly rough, typical to good offshore conditions alloy work hardens and will show very few external signs before breaking As a safety inspector there’s not a lot we can do other than ask the owner to check with the manufacturer or get an engineer to sign off on it/get it x rayed , they can look fine but I’d never use that as a rudder stock. But all materials have their weaknesses, stainless at least tends to crack on the surface long before it weakens in the centre, carbon will make lots of noise usually long before it lets go Biggest job of an inspector is to ask if you’ve checked / considered all the weaknesses, at the end of the day it’s only a visual inspection and I won’t be sitting in the raft with you. Still it’s surprising how we always find a few issues, can’t think of any boat that’s got 100/100, 90 is pretty normal Quote Link to post Share on other sites
Psyche 634 Posted April 12 Share Posted April 12 and anyone with a hollow SS shaft thats getting on i.e 30 plus years should get it x rayed, they were pretty popular on a lot of NZ built boats Quote Link to post Share on other sites
Zozza 293 Posted April 12 Share Posted April 12 I don't feel so bad about my old fashioned transom hung rudder on pintles and gudgeons. Quote Link to post Share on other sites
MartinRF 53 Posted April 12 Share Posted April 12 From Arcona's web on the 460 model: Quote The Arcona 460 is built to comply with the highest CE Category (A ocean) standards. It follows, it seems, that not even the highest CE Category ask for watertight bulkheads. /Martin Quote Link to post Share on other sites
Island Time 1,239 Posted April 13 Author Share Posted April 13 On 12/04/2024 at 6:47 PM, Jon said: Just register offshore and away you go My point was that the rudder shaft appears undersized, and that the NZ regs re rudder shafts are what one of our leading designers suggests are "minimums". 1 Quote Link to post Share on other sites
Bad Kitty 252 Posted April 14 Share Posted April 14 On 13/04/2024 at 8:20 AM, MartinRF said: From Arcona's web on the 460 model: It follows, it seems, that not even the highest CE Category ask for watertight bulkheads. /Martin CE is not any sort of class survey, it is more an ISO type thing that means you have systems in place. So, if the 1st Arcona sh*tbox has a weak rudder stock, all the following builds will meet the same low standard. Quote Link to post Share on other sites
John B 106 Posted April 15 Share Posted April 15 Reminds me of a certain French production cat owner who went for a swim in Neiafu ( 2017) and thought .. 'thats funny'. one rudder gone altogether , and it had slime on the broken rudder shaft ( flush with the hull). Quote Link to post Share on other sites
waikiore 400 Posted April 16 Share Posted April 16 Replaced a couple of Chico 40 rudder stocks about 22 years ago after one snapped flush with the hull North of NZ . Yes they were alloy and I dont believe that big a diameter. The first boat got towed back here and we put a new rudder on (with SS stock) then she went offshore another couple of years later and main bulkhead came away after rigging was slack so the occupants got off and I believe she washed up on a reef somewhere. Quote Link to post Share on other sites
harrytom 648 Posted April 16 Share Posted April 16 makes interesting https://noah-marineservices.com/marine-ship-rudder-stock/ 1 Quote Link to post Share on other sites
Island Time 1,239 Posted April 18 Author Share Posted April 18 On 16/04/2024 at 5:13 PM, harrytom said: makes interesting https://noah-marineservices.com/marine-ship-rudder-stock/ Great info! 1 Quote Link to post Share on other sites
waikiore 400 Posted April 19 Share Posted April 19 The only new stocks I did were of 2205 Duplex ss with tangs plug welded by a top NZ SS fabricator , now sadly deceased. Quote Link to post Share on other sites
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