Underwater Prop Change

I've always had a suspicion my prop was undersized for the boat and the type of waterways we do and intend to use it on. The engine never seemed to be "working" which is not ideal for a diesel and is only really used at the lower rev range.

I did some research into the very black art of prop calculation, at first online with various web based calculators then with about half a dozen UK based prop manufacturers.  In all cases the maximum diameter I can swing is a 21" so this was a definite as too was the max RPM, HP, and gear ratios and the hull size and weight.

All online and all manufacturers calculations came up with the same pitch within an inch or 2,  with most pitching at the mid range of 21.  So it was decided a 21 x 21 and still a 4 blade. Up from 21 x 16.

Old and new props side by side

The initial plan was get a lift out and the back the same day at a local crane day, but the more I looked at it and them more advice I sought I decided it would be worth at least trying to do it under water. If this didn't work or something serious happened the crane was still an option.

I'm fortunate that the weed hatch on the boat is quite large and access good and Garth at the boat yard had the necessary prop puller on hand.

Weed hatch

The prop nut on a Vetus shaft is a flange nut so there would be no problem with either lining up a nut and split pin hole or having to drill a new one.  The only down side was two 2mm thick SS flanges had to be hack sawn off and hack saw movement was limited.  This part of the job took a quite painful hour or so, but once done the nut was easily removed.

Prop nut showing the flats where the flanges lock

Old prop, nut removed

Then getting the prop puller on was a bit of a fiddle but about half an hour of adjustment had it ready to start winding on the pressure.

Lots of lines attached so as not to lose anything

After a bit more tightening that sweet moment the taper broke.  The prop was off. :-)

This lot was removed and the new prop offered on the the shaft and measurements taken to establish the key wouldn't be too proud for the new prop.  I was undecided that the prop would sit entirely on the taper and not the key.  In the end I decided it was probably fine but removing .5mm would do no harm so I did this gently and ended up, once it was flat and square again, at .7mm removed.

Then it was time to fit the new prop.

All complete with shaft anode refitted

In all it took around 6 hours, and of course the only part dropped was the non ferrous prop nut which required the donning of  the wet suit and snorkel and a short dive to the river bed about 4' down to retrieve it.

All in all a good days work and a worthwhile experience. 

The purpose was to load the engine a bit more at as the 16 was not making the engine work and would easily reach max RPM of 2500 which is never needed or used. Also I wanted the fast cruise RPM to be at the top of the torque curve at 1500rpm.

RPM             Speed MPH

                   Previously 16".          Now 21".
  800            2.6                          4
1000            3.5                          4.8
1200            4.5                          5.5
1500            4.8                          6.5    Turbo now heard working
1800            6.0                          7.8    And speed building

I suspect given all the right conditions 8.5mph would be achievable.

The conditions were wind on against 2 mph (ish) flow.

Observations so far are noticeably less rudder judder throughout the range, more rudder authority, less rudder input to keep on line, turbo heard working, acceleration much better (not really required) stopping massively improved prop walk slightly more pronounced, engine ran 5°c hotter on prolonged 1800+ test but this returned to normal 85°c very quickly at 1500 and maximum rpm now 2200 so slightly over propped as expected. No black smoke at any point on the test.

In conclusion I think this has been worthwhile. I can now cruise very nicely at 1000 and fast cruise at 1500 and gallop at 1800.

These are only preliminary tests on deep water so like all things boat there are infinite variables.

The predicted all round performance/economy improvement was 20% which I think is probably about right.  Someone else can do the calculations for me if they like.

Next stop 100,000 page views?

Sneak Preview Of Current Project.

This is what I'm up to at the moment.  Seats and storage boxes for the rear deck.

More next time.

New Central Heating

Last Tuesday I set about installing a new central heating and hot water boiler.  Although the Mikuni MX60 originally fitted has done sterling service for 2 winters, it did run hard and long which is actually good for this type of heater.

I decided the replacement would be a Hurricane SCH25 as it has more function and control.

I gave my self a couple of days to do this.  First job of course was to remove the Mikuni which took about 2 hours.  

With that safely removed and packed away the next job was to drain the engine calorifier coil as I would also be installing a flat plate exchanger to recover engine heat into the radiators which the SCH25 control system is able to do.

 20 plate 44kw heat exchanger

This is placed in series with the calorifier coil. The left hand (blue) pipes are from the engine the right hand (white) go the the central heating system and the SCH25 calorifier coil.  

Once the engine water has reached 70c this aquastat switches on the circulation pump and feeds the harvested heat into the CH system but without firing the SCH25.

This of course can be used in reverse to preheat the engine from the Hurricane but this would need another pump.  There is a small amount of thermo siphon already so I might consider putting in a 1 way valve to stop this as heating the engine without the option is wasteful.

Once the system was up and running I was getting (from the engine alone) 56c of water through the CH system.  Basically free heat when cruising or charging.

Reading taken from the towel rail

After 3, yes 3 days! I had all the plumbing done, and the heater installed and the wiring put through.

I had to cut a larger hole for the exhaust.  The old one was 1 1/2" and the new one is 2".  I didn't want to put yet another hole in the boat so how to do it?  My plan was to clamp wood either side of the hole and run a new pilot. But no there's a much better way shown to me by Garth at Ely Boat Yard.  This has to be tip of the year so far. So obvious really!

Use the previous hole saw as the pilot
 by mounting both on the arbor   

How neat is that?

New exhaust fitted

As always putting in wiring neatly all takes time.  The previous room stat had only 1 pair of wires the new one needs 3 pairs + I heft a spare for an extra frost stat but probably won't be needed.  This involved taking down one of the kitchen cupboards, the one with the most stuff in it of course!

Followed by the wiring back to the control box.

There are 3 extra wires here too, one for the GSM remote for the controlling the heater by TXT, one for the extra but probably not needed frost stat, and another for a room stat in the bedroom if it proves necessary.

Then finally all connected.

And with permission from the manufacturer in Canada the GSM remote wires soldered on to supplement the  switch on the system remote panel.  Special permission to not void the warranty

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And here with the panel switch off but the GSM switch on, system working.

So that was that.  It was a bigger job than I expected and if was presented with a bill for the time it took me I would be questioning very seriously.  I would think it probably took me 30+ hours.

All I need to do now is learn how to program the room stat/timer controller.  It's too cleaver for it's own good so they provide tutorial videos on the Heatmiser website.

To come:-  The new prop has arrived.

And some new seating and storage for the stern deck.

This is the template to build to

Advanced Alternator Regulator

To finish the alternator modification I have added to the house battery system an advanced alternator regulator made by Sterling Power Products  I chose the ProD model.

Unit on the right.  The left is the MPPT

The first thing to do was to connect 2 wires to the inside of the alternator.  Only one of these wires is used but it need to be determined which.

These wires go to the brushes in the alternator.

Cap back on and wires out of a convenient hole.

With the alternator running normally its necessary to identify which type of alternator sensing you have.  Mine is a Negative sensing.

Once the right wire is found simply snip the unused one off.

This explains what they do but in a nutshell it changes the charge profile of the original regulator in the alternator without modifying it. It will fail safe to the alternators own regulator if it encounters any number of possible problems protecting the alternator and batteries from themselves as it makes the alternator & batteries and connecting cables work much harder for longer.  The full manual is here. http://www.shop.sterling-power.com/acatalog/pdar.pdf

The additional load on the alternator started to cause the belt to slip on engine start up as the ProD loaded the alternator.  I could have added more tension to the belt but this just adds extra loading the the engine front bearing and the alternator bearing. To overcome this I applied some Belt Dressing which has done the trick.

While out this week the engine clocked up 200 hours.

It's very noticeable how much quieter the engine is becoming as time goes on, and since the alternator modification how much smoother it feels.  I can offer no explanation for this tough.

I have decided to change the central heating boiler and have ordered a Hurricane CH25

The Mikuni MX60 has been and continues to be great, its done sterling service for 2 winters but I want the greater flexibility the Hurricane offers with its zoning, hot water only and the added feature of being able, with the use of an additional heat exchanger, use the the engines waste heat to heat the radiators.

More on this soon.

Another modification on the horizon:-   I have ordered a new propeller.  The current one is 21 x 16 and I shall be replacing it with a 21 x 21.  I should get this in a few weeks and have a slot booked on a local crane day but I might try to do it in the water.  I looking into the feasibility of this.

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Down The Tubes

I've decided to totally replace the flexible rubber sanitary hose because of the smell it was leaching.  I was going to just replace the long run in the saloon and kitchen but decided in for a penny etc.

Initially I thought this would be a complete nightmare, but a bit of thinking about it and a plan came together.  

The worst part was drilling a new 2" hole in the rear bulkhead.  This of course was in a very awkward position and took about an hour as I had to keep resting because of the horrible position I had to get in made me all hurty.  I lost a bit of knuckle skin in the process of course.  I wasn't able to use the original hole as I wanted to maintain the current system until I was ready to chop it out as I had no idea how it would go and I wouldn't be able to re-fit the flexible one.

A week or 2 ago I removed a bathroom cabinet and a section of wall to gain access to part of the system. Link here.

One of the main problems was going to be turning the corner to the right about 4" above where the vertical tube disappears.  I was going to simply draw the tube back and wrap it in aluminum tape to add another barrier which was suggested on the canal forum, then connect either side, Instead as I drew it back and forth I realised I could get a new piece of plastic sanitary hose round the bend.  I already had a piece of this in the system near the toilet and this hadn't developed any smell.  Indeed even when this 9" bit was removed after the previous tube purging of a dozen or so fresh water only flushes there was no smell even from the inside of the tube.

I also had to cut a 6" hole in the electric cabinet in kitchen to get my hand in to guide the the new plastic tube through the bulkhead and it's onward journey.  In doing so I shorted the Cat5 cable to the inverter against a mains wire and have damaged my inverter network bus, PC/USB interface unit and the remote panel, 1 Cat5 cable and 3 mains cables.  The cables were easily repaired as all of them were only slightly nicked, but just enough to short across the cutter :-(

Similar to this 

The new pipe was easily installed from the toilet all the way to the tank.  The whole system was replace in about 4 hours. I'ts also now easy to inspect, remove and service and only has about 2' of flexible plastic pipe throughout.

This is the only photo I took

I withdrew the old "No Smell" tube which stunk and put it outside.  To my surprise there was a lot of fine bits of lime scale grit about the size of large tea leaves inside the tube which were brown like teas leaves when wet but curiously almost white when dry.  These didn't smell at all when dry.

Next morning I noticed the smell in the saloon had completely gone and the back canopy area was where the pipe passes under the floor was also smell free.  Long may it remain.

Total cost of the replacement tube and fittings cost about £70, damage to the inverter and accessories?  I'll let you know.  

Alternator Modification

I've been having trouble getting my house batteries topped up and getting enough amperage from the engine alternators even though they are now paralleled.  Also we have an electric combi oven on board and the original idea was that the oven would run through the inverter powered entirely from the amperage supplied by the 12v alternators.

For some reason despite my best calculations this simply didn't pan out the way I anticipated, so the option was to replace the house alternator with one of a larger capacity.

A bit of digging around on good old ebay and I managed to find a 215amp alternator which is 100amps more than the one originally supplied as the house alternator.  It was also fortunate that the mounting spigot was the same 55mm as the original.  I’m thinking this might be some sort of standard.

This is what the alternator setup looked like originally.

The new larger alternator obviously requires a much larger belt to drive it due to the extra load, so I ordered it with a PK7 pulley. That was the easy part!

This extra load could not be delivered by the original single V belt and the ratio was not sufficient spin it at optimum speed in the cruise RPM range. 

I then needed to get the larger drive pulley. Originally I thought this would be a simple job of just getting one off the shelf as you can with many other types of drive pulley. However the PK standard of pulley seems to be specifically used in an automotive situation and the engine manufacturers make their own pulleys to suit.

This left me with no choice but to get one made. Once again Canal World Forum held the answer as one of the members Tim Leach of Dutton Dry Dock offered to make me one for me.

I was able to get RPM and charge data for the alternator and the max over speed rating from the supplier so I was able to work out the drive ratio. I settled on 4.5:1 as this would provide a very high charge at tick over and maximum charge at cruise revs of 1300rpm but would not over speed it at maximum RPM which in reality is never used. Knowing the small pulley diameter I worked out the large one needed to be 235mm

The first job was to get the existing pulley re-machined to take a 50mm shaft.  

This part was done by a local engineering firm as it needed welding which I did. The shaft was left long to allow for design as it had to be made up in situe. Once the design for the pulley was finalised all the parts were sent of to Tim.

As the actual belt alignment could not be predetermined exactly the best solution was to use a Taper Lock pulley and hub. This design permits the pulley assembly to be mounted anywhere on the shaft then locked off.

Old system alignment

A week or so later the pulley assembly was returned to me along with a couple of spacers I also needed. I somehow managed to lose the key which I suspect has fallen overboard so I scavenged for a but of scrap and armed with nothing more than an angle grinder and file I soon made another.

 This bit of scrap turned into the new key

All the modifications done

One thing I didn't allow for was the bolt heads sticking out from the hub face and the original ones that would have stuck out from the rear of the pulley and sitting on top of the shaft fixing bolts, so I had to use countersunk bolts instead necessitating the back of the pulley to have holes counter sunk.  

Thanks once again to Garth at The Boat Yard Ely for the use of his countersink and pillar drill.

This is what all the new parts look like.

I then bolted the new shaft into place.

Then I positioned the new pulley and hub assembly on the shaft. Only 9 x M10 bolts!

Having previously fitted and connecting the new alternator I fitted the belt, set the alignment then locked the new pulley to the shaft.

Job done!

So what has all this achieved?  Well I now have over 300amps of charge with the 2 alternators working in parallel.  This means I will be able to charge my batteries much quicker and more deeply.  There's a bit more this this as any battery expert will tell you. 

Also my electric oven draws roughly 220amps from the batteries via the inverter.  The basic maths on this is inverted power is 10v divided by the mains wattage. So 2200watts = 220amps at 12v out of the batteries.  10v is used to account for conversion losses.  It's not exact but it is pretty close and simple to do in your head. The previous setup wasn't quite able to supply this.  This means I can run my oven with the engine only and there's a hidden bonus in that any extra power from the alternators will go into the battery charging system so on initial tests I was running the oven and still getting a surplus 56amps of charge.  If the batteries are were even flatter there would be a theoretical 95amp spare available.

Conclusion is this has been a worthwhile modification. The next stage if necessary will be to add an external alternator regulator to increase the regulated charge voltage to 14.8v from the normal 14.4v  This is a better charge profile for my battery type.

Full details link

One final note.  I did a rpm check with the engine running at a shaft speed of 1035rpm the alternator was spinning at 4565rpm so the ration calculations were pretty spot on.