Bow Thruster Bearing Replacement

amelliahona <no_reply@...>

Hi all:

While my boat is undergoing hurricane damage repair I am working on routine maintenance.  I decided to replace the open bearings in my bow thruster with SS6006-2RS sealed stainless steel bearings.  I am leaving the open bearing on the vertical shaft as it looks and feels corrosion free and runs smoothly.  However, I am replacing the two bearings on the horizontal shaft that has the bevel gear and to which the prop mounts as they both have corrosion and seem rough.  Thanks to Alexandre for his excellent photo essay on this topic.  I applied PB Blaster penetrating oil to the seals for two days prior to attempting bearing removal.  The bearing mounted to the hub of the bevel gear came off (while not easily) at least with normal effort by prying with screwdrivers.  However the gear on the prop shaft side would not budge with a gear puller applying as much pressure as I dared for fear of damaging the composite shaft.  Next I heated the assembly in an oven for 30 minutes to 260 deg. F and tried the puller and then a drift hammered circumferentially.  No movement. I didn't dare go any hotter for fear of damaging the composite shaft.   Lastly, I applied worm clamps to the hub and shaft to protect them from slips and used an abrasive disc on my Dremmel tool to gut and grind the bearing free.  It took about 1.5 hrs of grinding (very carefully to avoid damaging the underlying  shaft) to cut the bearing free.  It seems that it had been applied with some sort of sealant or locking compound.  Careful measurements of the shaft and the new bearings indicate that there is a 0.005 inch interference fit on this shaft.  I am thinking that is enough to prevent movement and am dis-enclined to put a sealant on the bearing to prevent a repeat of this hassle in the future.  I would be interested in the thoughts of anyone in the group who has done this process and/or has more of an engineering background who might be able to offer advice as to the need/desirability of applying some sort of locking material to the bearings. 

Thanks in advance, 

Gary S. Silver  

s/v Liahona     Amel SM #335   Puerto Del Rey Marina (on the hard), Puerto Rico

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