Raboesch Prop Shaft

[Andy GreigParticipant @andygreig96027]

[Andy GreigParticipant @andygreig96027]

Bought a Raboesch Prop Shaft, but it does not appear to be very free turning.

Bottom bearing seems ok, top 'roller' as well. It is when shaft goes through seal.

Is that normal ?

Does it wear in ?

[sammykParticipant @sammyk]

Hi Andy,put some light oil on the bearings and try it ,if its the type with a seal at one end it will be a tad tight to turn.

do not run it without lubrication it will destroy the seal.regards sammyk

[CookieParticipant @cookie15923]

Andy , it sounds like that the tube or shaft is slightly bent ,this will draw extra current from your battery ,the shaft should always spin freely with your fingers . Send it back for a replacement .

Dave

[Colin BishopModerator @colinbishop34627]

I rather think Dave is right. Commercial shafts and tubes are bent rather more than one might wish!

Colin

[JeremyParticipant @jeremy15845]

The instructions for these props say "These propellor shafts are watertight and do not leak any oil. The bearing housing has a bronze self-lubricating bearing and a G ring, and the sleeve has a Delrin bearing. Lubrication is therefore totally unnecessary"

I have these shafts in my yet to be sailed Titanic. Both were slightly stiff but turn OK under power. I hope they wont leak because the motor-end is in accessible so I can't oil them now. They are below the waterline and horizontal so I am relying on them to be genuinely watertight..

Should I have ignored Raboesch's instructions?

[Chris FellowsParticipant @chrisfellows72943]

Jeremy

I've gone for Raboesch as well having read everything I could on the best method of lubricating prop shafts! Decided it was a bit hit and miss (others will disagree!) and a bit of a faff so have gone down the maintenance free route so hopefully Raboesch are right.

To be on the safe side I've gone for the ball-race ones with a higher rev limit. They are a lovely bit of kit. A replacement for the Swordsman build has just arrived as I decided it would be better to go up to 5mm. Heavy though – good job I've gone for a powerful motor!

When doing a test assembly I notice that the thread is too long i.e. with the prop and locking nut fitted and the threaded part outside of the Delrin bearing there is a gap between the prop and the locking nut. I take it this is usual with any prop shaft and just needs cutting to length?

Chris

[ashley needhamParticipant @ashleyneedham69188]

My Titanic shafts are similarly placed but accessible. They are "normal" shafts with bronze bearings and the slightest dribble comes through them after an hour and a half`s sailing. With snazzy sealed shafts I wouldn't have thought there should be an issue even if the seals were worn slightly.

​Much seems to be made of leaking propshafts, but it really doesn't matter if it is a mere drizzle, as long as the inside is not affected by a bit of damp, just manage any water ingress with dams or a bit of sponge and check/suck out every now and then. I have a shield over the couplings/propshaft end on most boats, a bit of thin stiff clear plastic (like glazing sheet) to stop flung water drops and more importantly, oil, being distributed in the ship, as oil especially might stain paint or soak in wood.

​Only one of my boats seems to be prone to leaking in any sort of quantity, the Nelson…twin shafts bot horizontal and underwater, I have tried various sorts of washers and so on to no avail. BUT even after 2 hrs it is only a few egg-cup`s full.

Ashley

​Ashley

[Colin BishopModerator @colinbishop34627]

Full size vessels leak through the prop tubes all the time but only in very small quantities. Water ingress in models can be cut right down but unless you've stuffed the tube with grease which will stifle the motor and increase current consumption, a few drops will usually get through, especially if the inboard end is on or below the waterline.

As Ashley says, the best solution is to contain any ingress by having a shallow box under the tube inboard end or a coffer dam fitted across the hull to stop water running within the hull. And yes, a guard to stop oil being flug around within the hull can be useful too.

As an aside, the prop tube is not the only way for water to get into a model, there are often plenty of above deck routes such as not quite watertight hatches though. To guard against this I usually make shallow watertight trays out of styrene in which the batteries and any other elelctrical gear that needs to be kept low down are mounted. The trays keep water out and the equipment in place.

Colin

[JeremyParticipant @jeremy15845]

I found out the hard way the need to shield the prop shaft and coupling. On Thursday, my fireboat, having run perfectly, suddenly stopped in mid lake. Water from the prop shaft had caused a short circuit.. I have now fitted a shield!

The insides of all my hulls are waterproofed with resin, except on the inaccessible areas of Titanic. I will just about be able to insert a pipette to suck out any water but I may have to accept planks in that area getting damp. Hopefully the robust outer covering will provide sufficient protection.

[ashley needhamParticipant @ashleyneedham69188]

Jeremy, the issue of "to varnish or not to varnish the inside of a boat" is an ongoing thing I believe. Several respected builders prefer NOT to seal the inside, so that the wood can dry out properly, myself, I splash it all with sealer/varnish/Eze-Kote or resin (not all at the same time) to keep the water off the wood.

Unless your rear end is swimming in water for hours, I cant see that it will make much difference.

Ashley

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