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Knock in stabilizer
Posted: Friday, August 3, 2012 6:17 PM
Joined: 23/08/2011
Posts: 6

Hello evrybady! I have problem- knock in stabilizer on just one side, diferent side is ok. Knock there is blade start to movie and wave at sea. I dived under water but did not see any problems. Stabilizer is Quantum.I think problem with bearing but greased bearings properly at time? It will be intresting diferent opinions.
Tedd Greenwald
Posted: Friday, August 3, 2012 10:30 PM
Joined: 26/09/2009
Posts: 8

Once had a similar issue and the fin was hitting the hull after a refit with bearing service. I used a file to lower the high spot under water. Other thoughts are air in the system or the actuator ram might be loose at it's mounts. Good luck.
Posted: Friday, August 3, 2012 10:34 PM
"Knock there is blade start to movie and wave at sea" ???? Please give more infos! [Comment edited by moderator]

Posted: Friday, August 3, 2012 11:19 PM
Joined: 17/07/2008
Posts: 26

I had a problem like that with my Quantum's last winter. If you talk to the guys at Quantum they are very helpful. We replaced the valve block and it took care of the problem. Also check your noise suppressors. Probably not the knock but they will get noisy without the nitrogen charge.
Posted: Friday, August 3, 2012 11:35 PM
Joined: 19/07/2012
Posts: 1

Bearings v/v block accumulator charge not rocket science
Posted: Friday, August 3, 2012 11:47 PM
Joined: 13/10/2008
Posts: 2

I've had a similar issue in the past as well- knock was caused by wear between the hydraulic cylinder rod-end assembly and the stabilizer arm. Tolerances are tight and over time these begin to oval out causing a knock when moving back and forth. If this is the case you should be able to see the slight movement between these parts when the fin is in motion. If you determine this is the case, Quantum should be able to supply replacement parts. Hope this helps to narrow down the source of your mystery knock.
Posted: Saturday, August 4, 2012 12:43 AM
Joined: 08/08/2009
Posts: 3

It can be a few things. First of all when was the last overhaul done? If it was more than 6000 hours ago you can expect the main bearing to go, and that will get you some knocking! But most likely it will be your spherical bearings, they go quite regularly on the quantums, to the point that we carried a bunch of spares and the tools to change them with, very easy to do if the rams are accessible. The new set ups from quantum have tapered pins the spherical bearings that allow you to tighten them up without having to change the whole bearing and therefore no need to remove the ram... It's still pretty new so not too sure how that will work out in the long run. But if you have that set up you can (carefully) tighten the pins in the bearings, that has to be done very meticulously as to not over tension or tension one side more the other. Suppressors need to be check for pressure but you normally get more of a humming noise from those when they go low. I would check the spherical bearings, put your hand on them and you will feel the which one or better yet if you have a stethoscope, that's he best. Good luck
Posted: Saturday, August 4, 2012 10:48 AM
Joined: 01/06/2008
Posts: 1061

You have bearings bushings and pins which wear. Seriously though, if you have to ask here to figure it out, you need to call a pro.
Posted: Saturday, August 4, 2012 11:12 AM
Joined: 23/08/2011
Posts: 6

Thanks a lot who answered. Yacht just 4 year. Working hours of stabiliser abourt 1000 hours probably less. I have noticed knock then sea was wave and we were in marina and fin turned left and turned right litle bit from zero position because wave push fin.I did fin in zero position, knock was removed. Stabiliser not zero speed. Hudraulics was switch off. Torday i turned right and turned left the fin and evrything ok, there are not any knock because sea was calm no wave.