Director class tug

By Trillium 20 entries 3 Sep 2014 — 24 May 2017
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19Comments
Chapter 12 / 20

20 chapters · Page 2 of 2

Trials

A couple of trial runs went well except for the fact that a small amount of water is getting into the hull. I suspect it was entering through the open ends of the aft sponson support. That's been plugged and we'll see how the next sail goes.
Most wiring has been completed. The picture shows the underside of the deck panel under the fire monitor, and the drives for the radar scanner, and for the fire monitor, the water pump and the supply hose to the monitor.
Liked by Newby7 and Dave M and

"Officially" complete

The model has now been completed, is watertight, and 'in service'. Some additional details will still be added as time permits. These will be things like cable reels, lockers, ropes and gratings, etc.
Liked by Newby7 and Dave M

Feathering paddle wheels

This model sails well but lists slightly to one side or the other when the paddle wheels start turning. I have been told this was not uncommon on full size paddlers, a phenomenon known as “digging in”. The only improvement I can think of for this is to fit feathering wheels. After waiting many months for the one remaining supplier who lists them to have them available for purchase, I concluded I'd have to make my own. So I prepared artwork for the parts using inkscape, and had PPD in Scotland photo-etch the pieces in 0.9mm thick nickel silver. The only parts not included were the paddles which I planned to make from styrene to save some weight. (The big pointy part is for something else).
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Mechanism trial

The holes in etched parts are not always as accurate as drilled holes, so some holes had to be opened out with a reamer. The pivots for the moving links were to be held together with nuts and bolts, all in stainless steel. The bolts fit through a 4.5mm length of 1/8” brass tube which acts as a bushing. The links were bent slightly to ensure that the bolt heads and nuts cleared other parts. One side wheel was assembled with its associated links and set up temporarily, using styrene fixtures made to suit, to check that it operated as planned.
Liked by Dave M

Wheel assembly

The two side wheels are held together by 5/32” outside diameter brass spacer tubes. Seven tubes were cut to the same length, one for each paddle pivot location. There is an additional central tube of 7/32” OD to fit over the drive shaft. The assembly was placed on a drill press with a 7/32” size drill through the centre to align the two wheels, and hold them at right angles to the centre shaft/drill. The pair of side wheels were first soldered to three brass spacer tubes. A drill or a piece of steel rod was used as a mandrel to align them. Unfortunately I used the wrong flux and the rods and drill were soldered in, so had to be de-soldered. They were re-soldered using a different flux and aluminum tube to align the wheels. The remaining tubes were soldered in the same way. Some of the solder found its way into the clearance space inside the brass tubes, making the aluminum tubes a tight fit. After they were pulled out this solder was cleaned out with a reamer.
Dave, Stephen says the only way (other than Youtube) to display a video was as I did.
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Wheel assembled

The paddles were cut from 0.050” styrene, the attachment points for the support arms drilled, and the support arms fitted and glued in with epoxy.
The paddles and the side wheel assembly were painted black, with small pieces of masking tape over the pivot holes in the paddle support arms, where the pivot tubes were glued to them, and painted over later. When it came to assembling the parts, the sequence was as follows:
- Fastened one end of the links to the inside face of the master rod (looks like a banjo); using #2-56 UNC bolts with the bolt heads on the outside face, a 4.5mm length of 1/8” brass tube as a bushing, and two #4 washers, and a #2-56 nyloc nut.
- Inserted a #4-40 UNC bolt and washer in the centre of the master rod from the inside, secured it with a 5/32” brass tube bushing, lock washer and nut
- Fastened the outer end of the links to the paddle arms, with the links on the outside of the paddle arms, with the bolt heads on the inside face, otherwise same as inner end of the links.
The next step is to make the support for the pivot of the feathering mechanism.
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Feathering set up

A beam was needed to support the pivot for the feathering mechanism. it was made to straddle the gap between the two sponson supports. There’s even less information available about this than there was for the feathering mechanism. My second attempt was the best solution and comprised the following parts.
- Two 3/8” lengths of ¼” brass angle; with a clearance hole drilled in the top flange near one end, to suit the small sheet metal screws I had on hand
- A length of 1/8” x ¼” rectangular brass tube to span the gap between the sponsons.
- Approx 2” length of ¼” x 0.030” thick brass strip
- A ½” length of ½” wide by 0.030”thick brass strip
- A 7mm length of 3/16” brass tube as a bushing for the pivot.
The rectangular tube was cut to length to fit across the sponson supports and inside the paddle boxes. The two pieces of ¼” angle were soldered at right angles under the ends of the 1/8” x ¼” tube. The paddle wheel and the beam were placed in position. The paddle wheel was set up while stationary to position the paddles so that one was on bottom dead centre and vertical. The axial position of the pivot point centre was marked on the beam, and the distance below the edge of the beam measured. The top edge of the ½” square strip was intended to be flush with the top of the beam, and a 3/16” hole was drilled through the former at the pivot point centre. This was soldered to the ¼” wide brass strip, and then the 3/16” tube soldered into the hole. The drill press was used to set it at right angles to the strip for soldering. The strip was joggled, to ensure the rotating paddles cleared the support beam, and with the 3/16” tube on the side nearest the hull. The brass strip was clamped to the support beam, with the complete assembly in place, and the pivot position adjusted to give the optimum motion of the mechanism. The brass strip was soldered to the support beam, and then removed and painted.
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Installation

Screw holes for holding the support beam in position were marked in the sponson supports and drilled.
At this point the assembly could be installed permanently.
- Removed the nut and washer from the centre of the master rod and attached the support beam to it; replaced and tightened the lock washer and nut.
- Slid the wheel onto the shaft until the locating holes for the support beam lined up with the screw holes in the sponson supports and fitted the screws.
- Final check of rotation on the shaft.(see video)
- Tightened the wheel drive collar onto the paddle shaft. This was a 3/16” collar drilled for a short length of 1/16” brass rod, which was soldered in and then bent to fit into one of the drive holes near the centre of the inner side wheel.
The video shows the motion for the starboard wheel. it has been operated under radio control, but even at its lowest speed it goes too fast unloaded to see the motion clearly. All that is required now is some liquid water to try it out and learn whether the objective has been achieved.
Liked by Newby7

Success

I was able to test the new paddle wheels on the water today and they have proved to be the solution to the old wheels digging in. She no longer develops a list when under way. The other advantage is that there's no longer a big wave from the paddles, and it's possible to get up to a realistic maximum speed.
Hope to have some video to post in the near future.
Liked by Newby7 and figtree7nts
Trillium Opening post 1

Director class tug

Video of the finished feathering wheels in action can be seen at: .
Roy

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