Which grease to waterproof a propshaft?

[JeremyParticipant @jeremy15845]

I am still having problems with water coming up the propshaft of my Vosper fire tender. I have used Lithium grease and tried to seal the upper end of the tube with a nylon washer. Black streaks on the inside of the hull at the level of the end of the prop shaft seem to confirm that something is being thrown from it.

Simple question, hopefully with a simple answer. Which type of grease should I use to help solve the problem? Lithium, molybdenum, silicone…..or what?

Jeremy

[JeremyParticipant @jeremy15845]

[Dave MilbournParticipant @davemilbourn48782]

Jeremy

The nylon washer would possibly be better positioned at the lower end of the shaft, between the thrust washer (behind the prop) and the bearing. The thrust of the prop when going ahead will push the washers up against the bearing and hopefully seal it against water ingress. In reverse, of course, it will do the opposite! I doubt you will prevent the black streak around the inside of the hull but this wipes off easily enough with kitchen roll.

Ask a dozen modellers what to put inside the prop tube and you'll get thirteen answers……… I have had some success using Waxoyl, which is sold (Halfords) as an anti-rust treatment for car bodies but has a waxy consistency and comes in a handy aerosol can with an injector tube just made for a boat's oiler tube. Now sit back and watch the other 12 answers roll in!

Dave M

[Paul TParticipant @pault84577]

Answer no 2

Lanolin

[Charles OatesParticipant @charlesoates31738]

Answer no 3.
No grease at all, too much drag, just light oil. Try Daves answer with the washer, works for me.
Just out of interest, how much water is coming in?

[Colin BishopModerator @colinbishop34627]

I find that a tight fitting washer at the prop end as Dave suggests plus motor oil works for me. Most boats take in a small amount of water if the tube inboard end is below the the waterline and this will get flung around the inside of the hull. It's nothing to worry about.

Also the bearings in many mass market tubes can often be a bit sloppy which allows water past them.

With regard to grease, I experimented with this the other day after replacing a prop tube and found that it doubled the no load power consumption compared with oil.

Colin

[ashley needhamParticipant @ashleyneedham69188]

Answer No4. As DM says. A nylon washer at the prop end. Nuts adjusted for absolutely NO PLAY at all..water lubricated nylon washer very friction free. No grease, no oil.

Black streaks, oil or grease previously used being flung about by shaft. Solution….a little "grease guard" should be fitted. As stated easily wiped off with kitchen roll.

Answer No5…previous posts a few months ago swore by packing tube with grease, said all club members used this method no probs. I didnt agree, but we dont agree on this issue in any case as prev stated by DM..

Take your pick.

For further tips plse see article in current "special" mag !!!

Ashley

[JeremyParticipant @jeremy15845]

Thanks for all the suggestions. I will put a nylon washer at the prop end and try some of the ideas. To answer Charles' question, the amount of water coming in is about two egg cup fulls after maybe half and hour of fast running.

Jeremy

[CookieOldParticipant @cookieold]

Hi Jeremy , I have put a oil seal in a housing on the end of the shaft works great.

Regards Dave

[Bob Abell 2Participant @bobabell2]

I`m surprised that nobody has mentioned the humble adjustable stuffing gland

Bob

[Colin BishopModerator @colinbishop34627]

OK for larger boats where there is room to fit one Bob but not always a practical solution for smallish scale models or those where the end of the tube does not protrude from the stern of the boat.

Colin

Edited By Colin Bishop, Website Editor on 25/05/2015 21:12:40

[Charles OatesParticipant @charlesoates31738]

Hi Bob, I’m curious as to whether that arangement is as happy at high revs as it is with a slow running shaft? I’d like to try it on my next build.
Chas

[Tony HadleyParticipant @tonyhadley]

Bob,

Your stuffing gland propshaft is most impressive, but two points I'm not sure of.

a) If the thrust washer and prop were to come up against the prop shaft's adjusting nut, there could be a possibility of the adjustable stuffing gland nut turning (hence tightening or loosening). Would it be worth fitting a locknut on the hull side of the stuffing gland adjusting nut?

b) Is this a commercially available item or would it be purpose made for those with workshop facilities, i.e. not available to us 'kitchen table' builders – those of us who lost workshop facilities when either retirement or job change occurred.

[JeremyParticipant @jeremy15845]

Nylon washer on the aft end of the prop shaft seems to have done the trick. The inside of the boat is no longer awash. Thanks for the advice.

Jeremy

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