Propeller shaft seal & cutlass bearing replacement.

Marc_Langbroek · 2021-01-27 17:06:24

Dear friends,

When leaving port someday this autumn I had that undefinable feeling that Grace Darling (Frances 26 with a BETA16 H.P. engine) was suffering from some power loss. Meaning that she didn't come to full speed when asked for and while maneuvering she didn't react as quickly as usual. There were initially no unfamiliar sounds nor any suspicious odor. Also the engine revvs were in good order, so my thoughts went into the direction of some sort of obstruction in the propeller area. A quick look when moored again gave no solution, so the thing was forgotten due to all the activities that comes with closing a long day of day sailing with the family.

Next time we went out, again I noticed the loss of power. This time the performance deteriorated that fast that I had to be towed back into the marina again. Also an alarming shrieking sound was audible, not heard before. Thanks to the friendly Navy Patrol, we were quickly towed back into our berthing. That is without propulsion.

A thorough inspection of the drivetrain showed me that the connection between the exit flange of the coupling/damper and the shaft was not holding. This flange pinches or clamps the shaft by means of two hex bolts.

The shortest solution in that situation was to tighten the clamp connection between flange and shaft by means of a hex key lengthened by a small piece of pipe (force X arm). Off we went again, all in working order. Till we were on the engine back to the marina, and she started to lose power again. With a soft moaning as well. The sign to stop improvising, and start making some serious repairs.

So last week Grace Darling was hauled ashore for some serious shaft modifications.

I took the rudder off, removed the propeller and disconnected the shaft from the coupling flange. Slowly I pushed the shaft that far outward so I could remove the Volvo seal. Without the aid of the special guiding tool the now visible heavily scratched shaft end had to pass thru the seal, probably damaging the inner double seal. After the seal came off I went outside to retract the shaft completely. Overall the shaft was in good condition, except the shaft end that was heavily worn in by the loose coupling flange.

Also the cutlass bearing was now within reach. Although the bearing showed very little play I decided to change that one as well (with Exalto 25X40X48 rubber/bronze). I sawed 2 small slots in the protruding bearing to give it a gentle nudge with a copper punch. Be careful, the bearing bush deforms easily and take note that the bearing is secured by 2 (!) hardly visible small hex bolds.It came out easily. When inspecting the Volvo seal, the actual seals inside were really thin by wear, so that had also to be replaced. Instructions by the manufacturer states replace after 500 hours or 5 years, what comes first. So, this seal had seen its years as well as its hours I suppose, due to trailing while sailing.

Inspecting the shaft and the flange in the workshop showed that the amount of force to get a a good reliable connection was due to wear impossible. I.e. it was clampable, but with a max load it wouldn't hold. So I decided to add a key way / key in the shaft / flange coupling to get rid of it for once and forever. The work was done by a small shipyard / winch manufacturer for under 70 pounds.

So last weekend I rebuilded the whole, with a new seal and a new cutlass bearing. Before placing back I polished the shaft with Scotch Brite polish pads (green for paint removal) to give the contact surfaces with the seal and the bearing a superb smooth finish. Do not take the abrasive red one, that might ruin the surface! The damaged shaft end with the now new key way was sanded with a piece of sanding belt to finish it as smooth as possible. Point of interest was that the old Volvo seal was clamped on the shaft tunnel by means of a stainless steel hose clamp instead of the original clamp band with 2 hex screws/nuts. This original clamp band connection was thus weak that when fully clamped the seal was still able to slip off the tunnel. So off with the original clamp band, and back to the hose clamp.

Working upside down in the confined space of the pilot bunk while trying to secure a coupling where two hands are needed is a challenging exercise. Dropping tools in the bilge is a known phenomena that can easily been avoided by securing a thin line with duct tape to your tools, and ty it to your wrist. Placing the key had to be done very cautiously. Drop it and its gone, unreachable in the bilge and while key steel is non magnetic no chance of fishing it back with a magnet. Buying a spare one to afford to lose one might be a good idea. Also be very secure with the special plastic insert for placing the seal on the shaft. You might need it later,
and it's hard to get without buying a whole seal.

So the whole drivetrain is back in place except for the propeller. That has to be polished and protected with anti-fouling spray.

Thinking of the trailing and the useless wear of the Volvo seal, that might be a justifiable reason to go and look for a variprop!

When interested in additional information, just let me know.

Marc Langbroek
S/Y Grace Darling

Last edited by Marc_Langbroek (2021-01-27 17:11:50)

Duncan_Hill · 2021-01-28 08:49:27

Nice work, and definitely less intrusive than what had to be done to Blue Opal

Dingeman_Boogert · 2021-02-08 16:13:44

Beste Marc,
met bewondering je verhaal gelezen. Wat betreft de aanschaf van een variprop o.i.d., vraag ik me af hoeveel dat oplevert. Ik zet mijn tweebladsschroef altijd vast en haal dan nog rompsnelheid. Bij langere wedstrijden, zoals de 24-uurs, zet ik hem verticaal achter de kiel. Daartoe heb ik een merk aangebracht op de schroefas. Even een duik in de hondenkooi en de bemanning melden wanneer ie goed staat en het is voor elkaar. Als ik solo zeil begin ik er niet aan. Eén keer geprobeerd en toen direct naar het ziekenhuis voor hechtingen. Dir bouten in de flens achter de versnellingsbak zijn vlijmscherp.

Groet, Dingeman

#1 2021-01-27 17:06:24

Propeller shaft seal & cutlass bearing replacement.

#2 2021-01-28 08:49:27

Re: Propeller shaft seal & cutlass bearing replacement.

#3 2021-02-08 16:13:44

Re: Propeller shaft seal & cutlass bearing replacement.

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