It's been a couple of months since the last progress report on my Rowangarth radio controlled model tug build so I figured that an update was long overdue. To be honest, I seem to have found that I get so caught up in the actual build itself that taking photos and writing reports is the last thing on my mind so I apologise if the photos aren't as "step-by-step" as you might have liked. Anyway, on with the report...

In my previous project report, I mentioned that the next critical task that I had to perform was the installation of the running gear. More specifically, I need to fit the kort nozzles, propeller shafts, and motor mounts. This was a critical task as those three items needed to be lined up perfectly so some thought needed to go into the order in which they'd be installed.

Finding the correct positions for the kort nozzles was fairly easy as they been marked by small indentations in the hull during the moulding process. However, a double-check and exact measurement was still required to ensure that they were exactly where they wanted to be. With the mounting holes for the kort nozzles cut in the hull, it was a fairly straight forward task to install them using Isopon P-38 car body filler. However, it was important to get the first completely installed and fixed in place before attempting to fit the second one just to ensure that the mounting angles matched exactly. It would have been a disaster if I'd attempted to fix them both in place at the same time then found that moved slightly. At least if one's already solidly in place then it can be used as a reference for the other one. Personally, I found that taping lengths of 1/2" wood across the front and rear faces of the two nozzles was a good way to hold the second one in line with the first whilst it was being fixed in place.

The next thing that I did once the kort nozzles were fixed in place was cut some circular discs out of thick cardboard that matched exactly the internal diameter of the nozzles. By making a hole in the dead centre of the discs and attaching them to the ends of the prop shafts, I could then ensure that the shafts were centred exactly within the kort nozzles. That way I knew that whatever size propellers I chose to fit to the boat, they would be perfectly centred and wouldn't foul the inside of the kort nozzles.

It would also have been possible to use wooden discs for this purpose but I found that cardboard allowed me to achieve a tighter fit inside the nozzles. The slight "give" of the holes in the centre of the cardboard also meant that although the ends of the shafts were held central within the kort nozzles, I could still adjust the angle of the shafts slightly as I calculated which shaft line would give the best motor mounting position. This was an important issue as having a shaftline that was too flat would have meant that there was no way to mount the motors low enough within the hull. After a bit of trial and error (and a good dose of looking and thinking), bearing in mind that no holes for the shafts had been cut in the hull yet, I decided on a slight upwards slope for the shafts. I could now ahead and cut the shaft penetrations in the hull.

I tried to make the shaft penetrations in the hull as tight as possible so that they would be held pretty firmly in place when being fixed with filler. However, it was important to ensure that the shafts were lying naturally straight and weren't being bent at all. For this reason, I left the fixing of the shaft supports until last and just relied on the shafts being held in position by the hull penetrations and the discs in the nozzles while they were being fixed. Once the shafts had been firmly fixed in place it was a simple job to fix the shaft supports with filler. I'm now going to state the obvious here but be sure to slide the shaft supports onto the shafts and cut the mounting holes in the hull for them before fixing the shafts in place otherwise you'll never get them on afterwards.

With the shafts and kort nozzles all fixed in place, I went ahead and started adding more of the internal supporting structure to the hull. One design decision I made that isn't mentioned in the plans or the template pack from Mobile Marine Models was to fit some wooden longitudinal beams to act as a backbone for the hull. This may have been overkill but I was concerned that if the completed model was lifted with ballast and batteries in place then the weight could cause the hull to sag or flex and that strain would be put on the fixings between the plywood decks and the hull. If this caused the filler to crack then it would be a disaster so I decided to reduce the structural responsibilities of the decks.

In my last report I mentioned that I needed to buy the fittings pack in order to get the portlights that need to be fitting in the hull. I've put this off for a while whilst focussing on the internal structure but have now bought it. I've yet to fit the portlights or any of the other hull fittings though.

The rest of my time recently has been spent cutting out the decks and getting them to fit as well as fitting the access hatches and associated supporting structure. The plans that come with the hull suggest fitting a large rectangular access hatch in the aft deck to provide access to the tops of the kort nozzles but I decided to keep mine true-to-life and instead opted for the two circular hatches as on the real boat.

Speaking of the real boat, if you've been reading elsewhere on this site then you may have read about my afternoon out tugging on the Tyne onboard Rowangarth. The five hours that I spent onboard gave me a great opportunity to get a close-up look at the vessel and take a whole host of photos of the wheelhouse internal layout, which will come in handy at a later stage of the model build. This really was more than I could have ever hoped for and it certainly boosted my enthusiasm for this particular model boat project. Incidentally, my time working on Tyneside has now finished and I'm back down in Southampton so all those photos that I took of Rowangarth on the River Tyne will be even more important to me over the coming months.

Another small but significant task that I achieved with my model recently was the successful completion of the first bath test. The main purpose of this test was to prove the watertight integrity of the shaft and kort nozzle penetrations. If this test was left until later on when decks and more internal structure have been added then any leaks might be difficult to get to to seal. Luckily though, all penetrations proved to be watertight and no leaks were spotted. Some water did seep up the insides of the propeller shafts but that's only to be expected since they haven't been filled with oil or grease yet.

In order to test the watertight integrity of the hull under the most realistic conditions possible, I needed to get the boat to sit as low in the water as it will when it's completed. Luckily, a good supply of tinned food was available to use as ballast along with the sealed lead acid batteries. By counting up the number of tins used and by noting their positions with in the hull, I was also able to get a good idea of the amount of ballast that the model will require, and how it will need to be distributed within the hull. Since you ask, it took 26lbs (11.8kgs) of weight take the boat down to its correct waterline.

Tasks for the next couple of months include the installation of the motors and steering servo, and the installation of the portholes and other hull fittings. If I can get hold of all the lead ballast that I need then I can also consider finally fitting some of the decks.

Stay tuned for Part 3 of Project: Rowangarth Model Tug Boat to see how I get on.

For more information on Mobile Marine Models' Eldergarth Tug or to make a purchase, please click here.

Jason Webb

NOTE: All prices and specifications are correct at time of writing but are subject to change at the manufacturer's discretion.