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Author Topic: St Cruiser build  (Read 21865 times)

JimG

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St Cruiser build
« on: December 30, 2014, 02:49:50 PM »

I received this kit a week before Christmas as my first boat build for around 10 years as I have been concentrating on flying for the last few years. This will be a slow build as I am not a fast builder although I am hopeing to get much of the major building done while on a 2 week break.
There were a few fittings missing which Mountfleet sent quickly when notified.
The first step was to clean up the hull then fit the stern frame. I soon found two problems with the hull, the first was a large air bubble under the gel coat in the anchor recess. This was easily filled with P38 and smoothed down. The second was that the hull had at some point been sitting on the keel before the resin had fully hardened leaving a curve in the keel with the centre depressed by around 4mm, this left the hull bottom pushed up at the keel giving a hollow contour. Unfortunately nothing can be done at this stage although as this is not seen unless the hull is upside down it is unlikely many will notice the fault.
The stern frame is a white metal casting which needed quite a lot of cleaning up as there was heavy flashing present.Once cleaned it was easily shaped to the hull and once the hull was drilled for the shaft the frame was glued in place using polyester resin. O added a couple of extra pins through the frame and hull for extra strength. The shaft was then glued in place supporting the inboard end with a 3D printed bracket. P38 filler was then used to fair the frame to the hull.
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JimG

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Re: St Cruiser build
« Reply #1 on: December 30, 2014, 03:13:06 PM »

In the previous photo the motor is just sitting in place and not fitted as I will have to make a suitable coupling first. The mount is 3D printed to fit the motor I intend to use, a 5060 outrunner 290kV with a 3S lipo. The photos are also slightly out of step as they were taken before this thread was started.
The next step was to cut two slots in the hull bottom for the bilge keels, these are 1/16 ply which I first sealed with finishing epoxy and microballoons. This both hardens and gives a smooth surface after sanding. They were then fitted and glued in place with polyester resin and glass cloth.
The inside of the bulwarks were then smoothed, first using a power file for rough sanding, then a light skim of filler and finally wet sanding. This ends up with the bulwarks thinned down from the original moulded thickness. I cut out two of the freeing ports at this stage to see how they would look, I intend to cut them all out as this will show from the inside of the bulwarks once completed. Once a line was drawn 32mm from the top the in-wales were glued inside the bulwarks. 2 layers of plastic strip were used at the bow and stern with wood strip for the rest of the hull. The wood was glued with polyester resin while cyano was used with the plastic. Once fitted a mixture of polyester resin and microfibres was used to add a fillet to the underside of the plastic strips to add some reinforcement.

Jim
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JimG

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Re: St Cruiser build
« Reply #2 on: January 01, 2015, 01:27:54 PM »

The next step was the deck beams and hatch framing. The instructions didn't say anything about camber so I included a small amount to stop the deck looking too flat. The moulded superstructure was measured to get the positions for the hatch frame.
The wash ports and mooring ports were then cut out and cleaned up.
The rudder was now fitted, this had been left off to stop damage when the hull was being moved around for the previous work. The shaft was fitted through a tube in the hull and a support moulding fitted. The bottom is mounted on a pintle fitted through the stern frame. A length of brass rod was turned down to 4.5mm and threaded, one end was then turned to 3mm and the rudder drilled to fit. The pintle was cut to length and a slot cut for a screwdriver in the threaded end. The stern frame was tapped 4.5mm and the pintle screwed into the frame, holding the rudder bottom. The rudder arm was then fitted and the rudder checked for free movement. The pintle was then fixed to the frame with one drop of cyano on the threads. I have left the rudder shaft over length for now as I may fit the steering quadrant to this above deck and have it moving with the rudder.

Jim
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Mark T

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Re: St Cruiser build
« Reply #3 on: January 01, 2015, 04:08:24 PM »

That's looking good Jim - I also like your building stand it looks very adjustable?
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JimG

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Re: St Cruiser build
« Reply #4 on: January 01, 2015, 07:46:24 PM »

Thanks Mark
the stand is from my flying side and is intended for holding aircraft fuselages. It holds the hull at a nice height for working on when standing.

Jim
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JimG

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Re: St Cruiser build
« Reply #5 on: January 02, 2015, 02:23:27 PM »

When checking the fit of the deck after cutting it to shape I thought that it looked rather low compared to the freeing ports in the bulwarks. I have the drawings from the book British Steam Tugs and this shows the deck level with the top of the rubbing strakes. My deck was going to be lower than this so I added balsa strip to all of the inwales and beams to bring the deck up to the right level.
I added an extra central beam in the bows to allow me to fit an anchor hawse pipe  to take the anchor stock and allow the anchor to sit in the recess.
All the wood was then waterproofed by painting with finishing epoxy slightly thinned with alcohol. This will soak into the wood and seal the surface. The underside of the decks were also sealed at this time.

Jim
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Fastfaz

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Re: St Cruiser build
« Reply #6 on: January 02, 2015, 02:36:10 PM »

Hi,
   Looking good, nicework keep the pics coming.
         Cheers,
              Peter.  :-))
       
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JimG

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Re: St Cruiser build
« Reply #7 on: January 02, 2015, 02:40:33 PM »

While looking at some of my photos of old tugs and some photos in books it looks like many of them had extra reinforceing plating at the bottom of the anchor recess. The hull does not show this but I thought that I would add it to mine. I used two layers of electrical tape to mask off the outside of the plate and filled it with a layer of P38. Once hardened it was sanded down to the level of the tape, finish sanded wet and the tape could then be removed. This left the filler slightly proud of the original moulding.
The rudder servo was then mounted to a wood frame mounted across the hull with central supports to the hull bottom. The linkage could then be made with 3mm rod and clevises.
The last step before fitting the deck was to set up the motor coupling to the shaft. After checking several old models that are no longer used I found a Huco double coupling in an old fast electric. This was then modified to fit the tug. The end metal inserts were threaded 5mm. The motor was fitted with an adapter to take an aircraft propeller so this had to be modified to fit the Huco coupling. This was shortened, the end turned down to 5mm and then threaded 5mm to fit the coupling. The shaft , coupling and motor could then be put in place and checked. There was around 1 - 2 mm height difference which is easily taken up by the double coupling.

Jim
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JimG

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Re: ST Cruiser build
« Reply #8 on: January 03, 2015, 01:24:01 PM »

This is definitely going to be some weight when finished!! %) I thought that I should check out the motor current draw and thrust before finalising the motor fitting. So into the bathroom test tank for testing. It took 3 12V 7Ah gel cells and around 4 1/2 Kg of other weights to bring it down near the water line. (I also had an 8Ah 3S lipo for power.
I borrowed the esc from my fast boat although it is a bit over the top at 160A but it is easily programmed to give reverse and does give good slow running. A wattmeter was fitted between the battery and esc to check the current when running. First impression was that at full throttle its time for drag racing :o . The current was still only at around 8A max and it did have good slow running up to around 1/4 throttle. The esc was then programmed to 50% forward  and this gave good performance. Max current under 4A and around 40 watts and at minimum throttle the prop revs were low so should give good low speed and a decent run time. The reverse speed was set higher as the prop seems to be much less effective in reverse.
The only problem I have found is that the shaft does let water through so will need grease or heavy oil added to stop this. It looks like I will need to retrofit an oiling tube.

Jim
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JimG

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Re: ST Cruiser build
« Reply #9 on: January 04, 2015, 07:39:24 PM »

The leak should now be sorted, I have replaced the inner plain bearing with a sealed ball bearing. These come grease filled and have metal Shields on both side so shouldn't let water through. The shaft tube was shortened slightly to allow for the bearing width and a delrin housing was turned to take the bearing and fit over the shaft tube. When the shaft is finally fitted I will add some grease to the shaft before pushing the bearing in the housing. The photo shows the bearing free and not in the housing.
I have used this method before when I replaced the shafts in a Billings Smit Nederland after wearing the originals out in 24 hour runs. I found the original chromed brass shafts were worn out after 2 events and were rattling and leaking badly. The replacement shafts with sealed bearings lasted another two events without any problems. (actually only 1 3/4 runs as one was called off due to torrential rain which left the deck awash and around 1 inch of water in the bottom of the hull after 2 hours.)

Jim
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JimG

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Re: ST Cruiser build
« Reply #10 on: January 04, 2015, 07:43:45 PM »

With the mechanics fixed it was time for fitting the deck in place. This is in two pieces as it would be very difficult if not impossible to fit a single piece deck with the large amount of sheer and the tumblehome on the bulwarks. Plenty of epoxy and clamps meant the decks fitted without any problems.

Jim
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JimG

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Re: ST Cruiser build
« Reply #11 on: January 11, 2015, 10:15:03 PM »

Once the decks were fitted and I was checking it over I saw that I had made a mistake. I had cut out the freeing ports using the depressions moulded in the bulwarks and hadn't measured them. Unfortunately this left the port side ports too low compared to the deck. So the first step was to partially fill in the lower ports and reshape them to make both sides equal. The inner bulwarks could then get a final smooth down to get them ready for painting later.
The next step was to plate the decks with pieces of art paper. No indication of size was given in the instructions so I marked out the deck initially assuming that they were around 10 foot long in full size. Printer paper was used to make templates before cutting plates from the art paper which were then stuck down with a general purpose glue. Some of the deck at the stern and bow were not plated as these areas will be covered in painted ply to represent the bitumen coating on the full size. A neodymium magnet was recessed into the deck at the bows before the plate was added, this will be used later when rigging is added.
Lastly the hatch coamings were fitted after the deck beams across the hatch opening were cut away.

Jim
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JimG

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Re: ST Cruiser build
« Reply #12 on: January 11, 2015, 10:25:04 PM »

It was now time to start detailing the inside of he bulwarks and the deck joint.
White metal riveted sections are provided to represent the deck - bulwark join. These just needed cleaning up before gluing in place, they bent to shape easily with finger pressure.
Riveted plates are then glued on the inside of the bulwarks to represent the plates over the butt joints shown by rivets on the outside.
Mouldings for the mooring hole structure could then be glued in place inside the holes previously cut and mouldings for the ends of the towing beams fitted at the stern.
Finally the inner frames for the wash ports were fitted, I have not fitted the washport doors to the outside yet.

Jim
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Fastfaz

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Re: St Cruiser build
« Reply #13 on: January 12, 2015, 09:01:48 AM »

  Hi,
     The riveted angle at the deck bulwark join looks great, when its painted I think it will look better still. Nice work keep it going.
           Cheers,
               Peter. :-))
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JimG

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Re: ST Cruiser build
« Reply #14 on: January 12, 2015, 11:19:28 AM »

Thanks Peter, its now at the stage where its been sprayed with primer before fitting the bulwark rail.

Jim
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JimG

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Re: ST Cruiser build
« Reply #15 on: January 18, 2015, 08:21:23 PM »

Still slowly progressing although I wasn't able to do much to it this week. The bulwark rails are now fitted and the insides of the bulwarks painted the final colour. The ply deck doublers have been cut out and fitted and have been painted with a black rubberised paint spray to represent a bitumen coating. They have not been glued down yet as a bit of work is needed on the superstructure first and holes will need to be cut in the deck for the deck lights.. A lot of time has been needed in cleaning up and preparing some of the white metal castings.

Jim
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JimG

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Re: St Cruiser build
« Reply #16 on: January 25, 2015, 01:32:20 PM »

Time to paint the hull now. The waterline area was first sprayed white then masked off with 6mm Tamiya tape. The yellow stripe on the bulwarks was similarly painted and masked off.
After further masking the bottom of the hull was sprayed first using halfords red oxide primer. The bottom was then masked off and the upper hull sprayed first with grey primer then with satin black. The tape on the waterline was left in place during this.
What is it about black that it shows up the slightest imperfection! After a couple more rub downs and sprays I am now satisfied, still not perfectly smooth but then how many full size tugs are. The masking tapes could then be removed leaving a white waterline and yellow stripe.

Jim
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JimG

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Re: St Cruiser build
« Reply #17 on: January 25, 2015, 01:41:05 PM »

While there are still a lot of white metal fittings to be fitted to the bulwarks and deck I decided to start doing some work on the superstructure. Unfortunately not one of the best mouldings. There were two areas of cracks in the gel coat at the front which turned out to be quite large bubbles which will need filling. The top in the boat deck area has some large blobs where there must have been holes in the mould and some of the raised sections had bits broken off. The mould join lines were rough although these have cleaned up with a carbide sanding drum at low speed. It should all work out OK although will need more work than expected.

Jim
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JimG

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Re: St Cruiser build
« Reply #18 on: January 31, 2015, 08:44:50 PM »

Fitted the motor mount  to the hull, added some white grease to the shaft inner to seal the shaft tube so shouldn't leak in use.
The next step was a lot of repetitive work. Adding the bulwark supports, 55 in total, each made up of 2 parts and needing cut to size.
Once these had all been fitted and painted the openings for the deck lights could be glazed using microscope cover slips. A ply doubler was then added to the front deck to represent the asphalt coating over the  accommodation on the original. Most of the remaining deck fittings on the fore deck were then added.

Jim
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JimG

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Re: St Cruiser build
« Reply #19 on: February 08, 2015, 09:52:28 PM »

Some more work on the details this week.
Mostly completed the anchor winch with a couple of bits of extra work needed on it. The castings generally fit together well with a couple of extra bits needed. The control rod for the break has only a short section to glue to and would be easily broken off so needed some extra work. The rod end was threaded 12BA  and the moulded thread removed from the casting. The rod could then be glued in its place giving a more secure joint. The metal castings for the outer drums were very rough and would have needed a lot of work to clean up. A replacement drum was turned up out of Delrin and this will be used to mould resin replacements.
The rear deck had some more detail added, the capstan is mostly resin with a few metal castings and goes together well. The chain drive to the steering quadrant was trial fitted but will have to wait for the copper chain to be blackened before fitting permanently.
Many of the ply parts were sealed and the grain filled with epoxy and micro balloons. While this takes a bit longer to harden it gives a good hard surface which is easily sanded smooth.

Jim
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JimG

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Re: ST Cruiser build
« Reply #20 on: February 09, 2015, 09:56:01 PM »

Made the rubber mold last night and it had cured ready for moulding by this morning. Bought a small scale accurate to 0.1g from Maplin to allow me to get the correct mix for the resin and cast 2 drums this evening. Now fitted and could now finish painting the winch.

Jim
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Mackenzie

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Re: St Cruiser build
« Reply #21 on: February 11, 2015, 10:49:33 PM »

Looking good Jim, can't wait to see in the water.


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JIm
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JimG

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Re: St Cruiser build
« Reply #22 on: February 16, 2015, 09:04:41 PM »

A few more bits added to the fore deck, basically completing this section.
The main job now for the bows is to fit the anchor into the hull recess. While the moulded anchor provided is good it would need a fair bit of work to open it up for the stock to be fitted. So I've decided to replace it with an old bronze anchor I bought around 30 years ago. Virtually the same size and shape so it should look OK when fitted.

Jim
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JimG

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Re: St Cruiser build
« Reply #23 on: February 16, 2015, 09:17:20 PM »

The main work has been to clean up the superstructure. The moulded joints were smoothed down with a carbide sanding drum at slow speed on a Dremel then finishing with a sanding stick. The holes in the gel coat and chips along the bottom opening were filled with P38 and sanded. This has lost much of the moulded rivet detail but that can be replaced later using PVA dots.
The superstructure was then fitted in place and the metal angles could be shaped and glued in place to hide the joint with the deck.
The housing for the steering engine at the rear of the superstructure was supposed to be made from a wooden block provided in the kit. Unfortunately this was way too small according to the plan so a replacement was made from plasticard.I wont glue this in place yet as it will be too easily damaged when the main structure is handled.

Jim
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JimG

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Re: ST Cruiser build
« Reply #24 on: February 22, 2015, 09:03:06 PM »

A bit more work on the superstructure moulding. The engine room hatches were cut out leaving some largish holes. The moulded hatches were cleaned up and the guards bent using the jig provided. They were then fitted and glued in with a small drop of cyano before trimming flush with the bottom of the hatch.
The hatches could then be glued to the moulding, the central brackets for the towing beams were added at this stage as well.

Jim
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