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Maintenance..

Towards the end of our last trip, Midi in May/June (Unfortunately no autumn trip this year) several small problems needed attention.
Small oil leak from under the engine. Impossible to see location. Not unmanageable but annoying. I like bilges to be clean so that new leaks of fuel or oil can be spotted immediately.
Ingress of water past propeller shaft seal.
Spray of water into engine space from weed hatch cover when engine runs astern. This is an old problem, we have lived with it for ten years but makes other leaks difficult to spot - the shaft seal leakage for example. The problem occurs because the weed hatch cover strong back is an aluminium bar which bends if tightening screw is turned down too much. Thus compression on lid joint is insufficient. I have previously fitted two extra compression screws and also rejointed with 5mm rubber sheet, but this did not solve the problem.

Now in mid November I have eventually got around to tackling these repairs.

Stage 1.
The boat is reversed over a bank, thus giving enough clearance for the rudder and stock to be dropped out.
Tiller is released and unscrewed at top of stock. Securing nut unscrewed and rudder assembly is then free to be lowered through its steady bearings and removed.
This is necessary so that propeller shaft can be drawn outwards from stern tube.

First picture shows the original aluminium strongback and the scrap steel used for replacement. This is a hydraulic lift arm from a Ferguson Tractor, discarded because of wear in ball ends. Extremely strong.
The second picture shows steel bar cut to length, 16mm nut welded at centre for tightening screw. Two holes drilled for secondary 10mm compression screws. The steel turned out to be so difficult to work that I eventualy broke the Tap in second hole and had to abandon this idea.
Third picture shows the new strongback fitted. We will have to wait to see if it works when boat is next in the water and we make a few strong astern movements.
To illustrate the pressure under the weedhatch lid when propeller is turning astern, notice in this photo the two blanked off holes in top of weedhatch. When the boat was built the deck drainage channels drain pipes were connected in these positions into the weedhatch. This was a good idea which eliminated the need for extra holes in the hull. Obviously an advantage re strength and appearance. However when the boat was first trialed, when run astern water was projected upwards with force from the deck channels. Drains had to be turned and re routed through shell as seen.

With the boat reversed under cover in the workshop work begins in engine compartment.
Slacken off clamp bolts securing flexible coupling to the propeller shaft. Slacken two Jubilee Clips securing Crane Seal to the rotating shaft.
Propeller shaft can then be drawn out of the hull, being carefull not to damage seal. Slacken Jubilee Clip securing stationary part of seal to stern tube and lift out.

Shaft Seal removed from boat. The stationary section has the bronze surface and the rotating seal surface is some form of composition. (Tufnol)
Rotating face is lightly scored. Bronze stationary face is worn concave and has a one mm deep lip.
No possibility of a seal here. Must be renewed.
This Crane, Deep Sea Seal, cost £162 when renewed two years ago and has had only 13 weeks use since that time.
Why the wear? Comments welcome - my theories as below.

1. Due to cruising waterways with heavy silt/sand content in water. Possibly Lot - Baise - Garonne.
This is highly unlikely since stern bearing is undamage and other boats cruise in similar conditions without problem.
2. Dry running. Shaft has not been run out of the water except infrequent momentary trials ahead and astern to check operation. However does the arrangement of water supply from wet exhaust outlet allow exhaust gas to pass to the seal where it could form a trapped bubble at inboard end while water was expelled along bearing tube? Doubtful since the first seal lasted for 8years before leaking.

Ray at Sea Otter recommended replacement with a PSS seal which they now use on all new boats. Certainly these look a very good design. Unfortunately after investigation I find not possible. The PSS seal requires a minimum free shaft length between coupling and stern tube of 115mm. Distance on High Jump is 100mm - just sufficient to take the Crane Seal as seen below in photo of engine refitted but seal not yet in position.

Engine.
After disconnecting drive shaft and withdrawing outward from the stern tube bearing the engine was prepared for lifting.
It was not necessary to disconnect the flexible coupling flange, simply slacken the four clamp bolts securing coupling to the shaft and draw out prop shaft. Just sufficient room to lift the engine with flexible coupling still attached.
For purpose of access all joinery between engine compartment and cabin is removed. Wooden step, plywood bulkhead and insulation. Electric cables are tacked to underside of step and must first be released and tied up safely.

Remove raw water flex pipes and strainer for ease of access. Also air inlet filter - eases access. Exhaust flexible hose and water connection to stern seal.
Disconnect battery. Disconnect all electrical cables from engine. Red cable to starter and black earth. Alternator connections. Beta harness - one multi point connection plug. Extra wires for temperature gauge.
Disconnect jacket water flexible hose connections to calorifier.
Disconnect fuel feed and return, Two bowden control cables.
Slacken and remove four holding down nuts and finaly slacken locking bolts screwed through engine feet just below these nuts. These lock bolts secure the positioning nuts under the engine feet - try not to disturb these positioning nuts. This will make realignment easier when refitting engine.
Select suitable strong points on engine and fit lifting chain.

Fortunately my engine crane is just high enough to reach over stern of boat. First lift is straight and carefully lifts engine from flexible mountings. Set down and rearrange lift point to raise engine stern end first to clear obstructions. This boat has been retrofitted with an Eberspacher water heater and there is only just sufficient space for engine to clear heater and circulation pipes. After clearing "Engine Ole" set down again on boards and arrange strop for third lift to clear boat.

Once the engine could be inspected Source of the oil leak was clearly seen - from back of fuel lift pump flange. After removing flange it was found that the bolt holes in flange were tapered, inner edges not being of clearance diameter for bolts. The threads of the bolts were therefore binding on the flange edge and seating face was not being pulled tight against engine block. Easily remedied by drilling to size and refitting pump with new joint.
Changed engine oil, oil and fuel filters and a good clean of engine. Refitted in boat.
As well as the fuel lift pump the picture above also shows one engine mounting nut locking screw.

After the engine has been repositioned on flexible mountings the alignment with stern tube bearing must be checked. In this situation there is just not space to use usual procedure with dial gauge and feeler gauges. Proceed as follows.
With stern seal not fitted enter propeller shaft through stern bearing and fully into clamp end of flexible coupling. Harden up clamp bolts.
When alignment is correct the propeller shaft can be rotated freely by hand in stern tube bearing.
Find this position by raising or lowering engine support nuts as necessary. Then as securing nuts are carefully tightened and hardened up continue to check free rotation. Slight misalignment is easily detected by feel when rotating shaft. Adjust as necessary until nuts are secure then tighten locking bolts.

First picture above - Eberspacher water heater can be seen at bottom right with copper circulating water pipes to calorifier at top right. No insulation on circulating pipes since at 4Kw the diesel fired heater is actualy too powerful for our requirement. The problem is to lose sufficient heat to prevent cycling, which causes problems with Eberspacher control system. The pipes are continued right across the back of engine space and also supply a heated towel rail.
Second picture. With wooden step and bulkhead removed clear access to engine from cabin.

After completing reassembly and topping up oil and water, engine is run on test.
A hosepipe is inserted into the raw water inlet pipe which has been disconnected from inlet strainer. A dribble of water is then sufficient to wet the raw water ciculating pump and prevent damage to rubber impeller. Engine can then be run idefinitely - but not in gear - propeller shaft must not be run unless submerged. Shaft bearing is water lubricated.

Stationary part of seal is fitted. Rubber sleeve is pushed fully over stern tube. This stern tube, 2 inch dia, is the maximum accomodated by this size of seal and fitting is not easy. Achieved by use of washing up liquid to lubricate rubber and persverance. All operations in this area are very difficult. Being doubled up with head in the general area of knees I find that I can only work for a couple of minutes before taking a rest.
When tightening the clamps (Jubilee clips) securing stationary seal over stern tube seal must be checked to be centered. This is done by using a suitable thickness gauge to check annular space between shaft and bronze ring is same for full circumferance. Photo shows annular gap. I found that a suitable sized allen key made a good feeler gauge.
The engine coupling clamp bolts must be hardened up while this centering is taking place to ensure that shaft is lying in correct position.

Coupling bolts are now slackened off and prop shaft pulled outward. Rotating element placed in position and shaft eased gently inwards, entering through rubber sleeve.
The blue gauge shows exact longitudinal position in which sleeve is to be secured to shaft in order to give correct commpression of belows and thus correct pressure of rotating face against stationary face. In this case it can be seen that distance is correct when inner end of rotating sleeve is touching engine coupling. i.e. Seal just fits in available length with zero to spare.
Tighten clips securing seal to shaft ensuring that face rotates evenly.

Second photo shows water supply tube from cooling water outlet from engine jacket water cooler. This time I have fitted this tube with a constant fall towards seal so that water is passed in preferance to any exhaust gas which may pass up cooler outlet.
I have also fitted the Y connection supplied by Crane and a vertical vent pipe to release any air/gas trapped at inner end of stern tube.

Unfortunately there is no way of testing the seal until we next launch the boat - probably somewhere in France next Spring.
I am confident !

Trailer Wheel Bearings.

In the early days Ray advocated the fitting of a grease nipple to each wheel bearing dust cap so that a few squirts of grease could be added to the bearings before submerging for launch/recovery. This helped to prevent water entry into bearing space. However over pressurising with grease also damages the inner grease seal, thus allowing grease to enter brake drums and the practice was dropped..

I have recently come across a device which is fitted in place of the normal dust cap and keeps bearing space filled with grease, thus preventing water entry, but since the constant pressure is achieved by a light spring loading does not damage grease seal - That is the theory.

A few photos below. I have fitted one to each wheel. It will obviously be a couple of years before we know if the idea is successful. Of course if a bearing grease seal should fail the device would push a considerable quantity of grease into the brake drum. Perhaps not such a good idea - why do I always have to keep fiddling with things trying to make improvements, life would be so much simpler if I could learn to leave well alone, after all I have never had a bearing failure.
Another minus point - my wheel clamp will not now fit over the new centres.

The "Bearing Savers" were obtained from www.western-towing.co.uk at cost of £22.95 per pair.
The Plastic Protective Caps must be ordered additionaly. Cost £1.39 each.

Bearing Maintenance.
We have not had a trailer bearing failure in the ten years of Sea Otter ownership. This is probably because I am paranoid about bearing inspections and maintenance.
A few pictures below show example of what to look out for.

Forward Off Side wheel bearing, last renewed Jan 2001.

Left photo. Inner and outer roller races. Grease seal is permanently attached to inner roller race. Damage to seal can be seen. How did this occur? Could it have been during last reassembly?
Rollers when cleaned up are free and unmarked.
Centre pic shows taper tracks, inner and outer. On both tapered surfaces early signs of damage. Cracks in surface and small roughened areas. These surfaces are very heavily loaded and any imperfection will rapidly progress to full failure. Time to renew this bearing.
Right pic. Brake assembly was contaminated by grease which had passed the damaged seal. Here cleaned up and Ferodo surface abraided. Reassembly started.