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Shaft Cutless Bearing
Posted by: dwkayaks (IP Logged)
Date: February 27, 2017 03:04PM
Category: Engine and propeller


Ahoy All , It's time to replace my BCC's propeller shaft cutless bearing . Has anyone installed and used a Vesconite Hilube , cutless bearing , yet ?

If so how is it lasting ? Would this bearing last longer than the Nitril rubber / Brass jacketed bearing Model # 381475 | Mfg # BLOATER from West Marine ?

Re: Shaft Cutless Bearing
Posted by: Bil (IP Logged)
Date: March 1, 2017 03:53AM
Category: Engine and propeller

A most interesting inquiry, Douglas! I can find no review comparing the usual nitrile rubber land-and-groove cutless bearing to a Vesconite Hilube bearing.

All I can offer for now is two backstories, some of which would be familiar to readers of Zygote's word list:

Story One

The first story has to start with Charles Frederic Sherwood, a mining engineer working in California, who was on duty one day when a mine pump failed. The pump was de-watering a mine shaft of gritty water so failure was critical to mine operations. Sherwood traced the failure to a soft metal journal bearing (a Babbitt metal bushing). No spares were on hand. Sherwood jury-rigged the pump by cutting a length of rubber hose and using that as the bearing.

Sherwood's fix worked. In 1921 Sherwood gained two US patents for rubber sleeve bearings, including one with a protruding spiral of rubber on the inner surface which supported the shaft.

In 1922 Sherwood and and Edwin L Oliver (of the Oliver Pump Co) formed a partnership (the Oliver-Sherwood Co) and started using the name Oliver-Sherwood Cutless Bearing, with the idea that rubber sleeve bearing with the internal spiral cut or abraded the shaft less than a metal journal bearing.

In December 1922, Sherwood and Oliver sold the patents and the company to B F Goodrich Co. "Cutless Bearing" became a trademark of B F Goodrich and it took action to protect its brand name. B F Goodrich quickly found that Sherwood's design with the spiral protusion was expensive to make and not the best. B F Goodrich abandoned the Sherwood design and came up with the land and groove cutless bearing. The land and groove design could be seen as a version, taking advantage of rubber moulding, of an older bearing made of timber slats called a stave bearing.

Other manufacturers used the spelling "cutlass bearing" to get around the actions by B F Goodrich and Duramax Marine to protect their "Cutless Bearing" brand name.

In the 1960s, engineers at Borg Warner designed a version of the rubber sleeve bearing. Borg Warner described their improved design of the rubber sleeve as "fluted" rather than "land-and-groove".

A subsidary of Borg Warner, B J Marine Products, manufactured the new design, using a facility in Florida that was called B J Rubber.

In 1971, Borg Warner wanted to move the B J Rubber facility making the B J Marine Products shaft bearings to Los Angeles.

I'm unclear what happened next. But somehow in the move from Florida to LA, B J Rubber ended up in Iowa City and became independent of Borg Warner.

Later in the 1970s, B J Rubber started calling itself Morse Rubber and Morse Marine Products (still in Keokuk, Iowa City, Iowa). That suggests that someone had bought the subsidiary from Borg Warner. I have not been able to find why the name changed.

B J Rubber/B J Marine Products continued by Morse Rubber/Morse Marine Products made more than 80 models of shaft bearings. The company used the names of fishes for each of the 80 models.

The Bloater model, named after a cured herring, is one of the smaller models: a naval brass sleeve with an Outside Diameter of 1 3/8" and a wall thickness of 1/16" with the internal rubber moulding sized to fit a 1" shaft.

In 1988, a Swedish company Svedala Industri A B bought Morse Rubber and renamed it Trellex Morse. The parent company of Svedala Industri was Trelleborg Industri A B.

A Finnish company, Metso Mineral Industry, then bought Svedala and Trellex Morse and ran the Morse Rubber facility at Keokuk, IA, until 2004.

In 2005, Patrick Boyd and John E Rector (a employee of Trellex Morse) bought the Morse Rubber facility and established Morse Rubber LLC. They continued to make the Morse Bloater, all the other 80-odd naval brass and rubber shaft bearings, plus ship fenders.

I do not know when Sam L Morse Co started using Morse Bloater bearings on BCCs. Zygote was built and launched with one. I carried a spare with me when we left the US and installed that spare a few years back.


Story Two

Somewhere in South Africa there is a gold mining town, Virginia, which deals among other things with the same problem of grit in mine water abrading bearings in pumps, the same problem that Charles F Sherwood confronted. In 1958, a couple of engineers in Virginia formed a company with the registered name Virginia Engineering Services Pty Limited. Vesco (Virginia Engineering Services Co) became their usual abbreviation. In 1968, Vesco focused their chemical engineers on a better polymer for shaft bearings and came up with Vesconite.

Questions

Have you seen a Vesconite Hilube shaft bearing, Douglas?

The only person I know of (a cruising acquaintance, a Brit currently in the UK) who has one reported no problems. His Vesconite Hilube shaft bearing has lasted at least 12 years on a cruising sail boat (I don't know how many engine hours). Alex reported that it was just a simple sleeve, i.e. not a fluted or land-and-groove structure, and that it had a 0.2 mm clearance around the shaft (which sounds about right).

Bil




Re: Shaft Cutless Bearing
Posted by: dwkayaks (IP Logged)
Date: March 2, 2017 01:48PM
Category: Engine and propeller

Ahoy Bil , T Y , always interesting to get the back ground info . My cutless bearing problems come from crust-like build-up on the prop shaft , due to in water, inactive boat storage during long winter months . This crust cuts the rubber away and scores the shaft .

Last year the May 2016 issue of www.48North.com , under "Product News" carried a bit about the Vesconite Hilube shaft bearing .

The write up says things like , "the advanced polymer that's the perfect long-lasting bearing material for this high-wear application" ,,,,, "Even in dirty or silty water .... exceptionally long wear life .....

So , I am thinking to give this new bearing a try next year. More info at : www.vesconite.com


Re: Shaft Cutless Bearing
Posted by: Bil (IP Logged)
Date: March 3, 2017 12:16AM
Category: Engine and propeller

Found it. See attached 48 N Vesconite Hilube.jpg (220 Kcool smiley.

BCC 116 Zygote,
Scarborough Marina, Moreton Bay, Queensland, Australia

Attachments: 48 N 201705 Vesconite Hilube.jpg (219kB)  
Re: Shaft Cutless Bearing
Posted by: Bil (IP Logged)
Date: March 3, 2017 03:10AM
Category: Engine and propeller

Unrelated to cutless bearings but because of Douglas referring me to 48 North, I sighted my first new BCC advert for a jolly long time: see (attached) BCC advert 48N 201702.jpg, about 190 KB )

Attachments: BCC advert 48N 201702.jpg (192kB)  
Re: Shaft Cutless Bearing
Posted by: Dioscouri (IP Logged)
Date: March 3, 2017 03:46AM
Category: Engine and propeller

That ad for the BCC appears regularly in 48 North - I hope it gets business for Cape George Boat Works!

Gary
Dioscouri #064

Re: Shaft Cutless Bearing
Posted by: Bil (IP Logged)
Date: March 6, 2017 03:29AM
Category: Engine and propeller

dwkayaks Wrote:
-------------------------------------------------------
> My cutless bearing problems
> come from crust-like build-up on the prop shaft ,
> due to in water, inactive boat
> storage during long winter months . This crust
> cuts the rubber away and scores the shaft .

No one else has responded, so I'll have a try at this. Of course it comes with the usual warning that I'm not an expert corrosion engineer/electrochemist/mechanical engineer/polymer engineer, just an interested observer.

I think two or three things are involved:

1. Precipitation of CaCO3 Calcium Carbonate on the shaft

A search of the Net using a phrase such as "precipitation of CaCO3 in seawater" finds a lump of links to pages such as this one from corrosiondoctors.com: [www.corrosion-doctors.org]

Reading that suggests that tiny changes in the pH of water, perhaps associated with the ss shaft being a cathode (and a lump of zinc acting as an anode) might be involved.

That it happens inside the shaft bearing and not on the exposed shaft suggests to me that the stagnancy of the water trapped around the shaft by the shaft bearing might also be a factor.

I try to run the engine and spin the shaft at least once a month. I met cruisers in SE Asia who were more religious: the one that impressed me most argued that the engine and prop shaft have to be turned over at least once a week (that cruiser, when at dock in Penang, ran every engine and motor (outboard, inboard auxiliary, water pumps, etc) every Monday. Monday for him was engine and pump day).

Zygote has a PSS dripless shaft seal. I've not seen it documented anywhere, but I reckon that the rotor and stator stick together (by some chemical or biological process) after about 7 days without shaft rotation. I reckon that breaking that stiction (which is tiny after one week but bigger after one month) stresses the rubber bellows. So I try to make a regular routine of entering the engine room to burp the bellows before starting the engine and rotating the shaft.

In summary, I think regularly rotating the shaft is needed. And perhaps the precipitation of the Calcium carbonate is a sign that you have good anodic protecting of the shaft/prop?

2. The nature of shaft bearings aka cutless bearings.

I figure that the engineers who designed improved cutless bearings - which means the Borg Warner engineers who came up with the shape and polymer inside Morse Marine's Bloater and the Vesco engineers who came up with the shape and polymer inside the Vesconite thingies - all focused on motor vessels running their shafts in gritty water. So they are trying to balance wear of the shaft and wear of the polymer.

I prefer them to prioritise not wearing the shaft (i.e. a softer polymer and channels that keep grit away from the shaft) and prefer to replace the shaft bearing than to replace the shaft (a shaft made skinny and weak by abrasion would be a problem, no?)

But that's different from your hassle: a chunk of limestone that has formed on the shaft inside the bearing. An engineer looking at the problem might say we have a spectrum of choices with two extremes if we just focus on the cutless bearing:

(a) let the limestone/coral rip the rubber polymer apart; or

(b) make the polymer strong enough and shaped like a scraper so it can rip the limestone off the shaft.

You can see the contradiction. A polymer strong enough to rip the limestone off the shaft will likely be hard enough to abrade the shaft. A polymer shaped to act as a scraper (in both reverse and forward rotation) might be expensive to make (and not do a good job of handling grit in water).

Of course that engineer might also say that the problem is easily solved by just running the engine and spinning the prop more frequently.

No independent authority seems to have done a comparison of the Vesconite Hilube bearings and the Morse Marine bearings. I cannot imagine that Practical Sailor or anyone else would tackle the job.

And if you look at our position in the political economic system, i.e. end users with no pricing power (we only buy and install a new shaft bearing every few years) in an imperfect market (because we don't have enough information and do not know how to balance the cost of installing a new shaft bearing against the unknown promises that any extra price of Vesconite Hilube will be compensated by a longer lived shaft bearing that is even gentler on our shaft), then we're simply stuck in the dark.

My recommendation: when in a wet berth, do everything you can to spin the prop at least every month if not every week.


BCC 116 Zygote,
Scarborough Marina, Moreton Bay, Queensland, Australia



Edited 1 times. Last edit at 03/06/17 01:17PM by Bil.



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