NT37-203 was outfitted by the factory with a ProMariner  (Model 20035) shaft brush, installed to ride on the tug’s 2” diameter shaft.  That device proved over time to be a high failure rate item, with the graphite brush attachment falling off about every year.  I eventually learned to apply an epoxy bead around the base of the graphite brush attachment to the bronze strap.  This proved to hold up well, with the last one surviving for 6 years.  Unfortunately, my marina broke the graphite brush off this year in the course of removing/reinstalling the propeller shaft (for the PSS shaft seal bellows replacement).

I have installed an on-board  spare of the ProMariner device, so all is well for now.  However, when I sought to replenish the spares inventory, I learned that the ProMariner 20035 product is no longer available.  I confirmed with the successor company (Navico Group) that the product is no longer offered.

Search for a comparable product has led only to the Electro-Guard HD-SB Propellor Shaft Wiper Brush Assembly (https://www.boatcorrosion.com/product-shaft-wiper-assemblies.html), as sold by Sure Marine Service, Inc.  But the product description indicates a limitation of shaft diameters up to 1.5”.  I confirmed with the manufacturer that the product size limitation is valid, for the reason that they consider the product to be marginally effective even at that shaft size!  (The rep told me that they only continue to offer the product because distributors say customers continue to clamor for it.)

I suspect that failure of the shaft brush assembly has been experienced by many.  But I have not found any chatter about the unavailability of a replacement.  So I would love to get some feedback on how, or if, others have addressed replacement of the propeller shaft brush assembly.

Regards.

Steve Paul

Penny-wise
NT37-203

828 Casterline Rd.
Endicott, NY. 13760

C: 607.768.4024

Steve Paul,

My original shaft brush broke as well. I replaced it with the one you cited and it has worked for several years now. I did note the 1.5” shaft size limit, but I saw no other choice. I don’t understand why it would be “marginally effective” given the tiny galvanic current.

Dave Sire

Edgewater, MD
Nordic Tug 37-171

Thanks, Dave.  Being no electrical engineer, that had been my thought as well.  But Electro-Guard said something to the effect that, at the micro-volt levels involved, the inherent resistance of the brush device substantially impedes the galvanic current.  I kind of took his recommendation against his own product at face value.  Let’s see if we get any other sage comments.

Hmmmm.  Guess I’ll have to put a multi-meter on it.
Dave Sire

Edgewater, MD
Nordic Tug 37-171