fig 1

 In fig 2 the groove for the propshaft can be seen. I made this by carefully grinding away using a 10mm wood drill bit.

fig 2

 In fig 3 you can see both blocks in position.

fig 3

In fig 3 & 4 you can see my alignment jig. As you may already be aware (see Installing the drivetrain - Part 2) I needed to keep the propshafts parallel, and so I made this simple jig. I measured the distance between the propshafts from both ends until they were parallel. I then drilled holes in a piece of scrap so that the shafts could be inserted. I can now easily align both propshafts simultaneously. 

fig 4

Hey, thanks to the peeps at Westbourne Models for sorting out the correct props for me, they were certainly worth waiting for. The props are really nicely made and (a first in my experience) balanced. I ran both props on a test rig and there was no vibration caused by imbalance whatsoever. 10 out of 10.

fig 1

Anyway, as you can see from fig 1 I can now double check all my measurements for the propshafts, make a real start with fixing them in place, and install the rudder.

The only thing I am unsure of at the moment is the correct rotation for the propellers. I have installed them with the port one rotating clockwise and the starboard anti clockwise (as indicated by the plans). This seems to be the correct way, but I am asking on the Model Boat Mayhem forums for more information.

I am sorry to report that there has been little progress. This is due to several factors, but mainly because I have not been feeling too well. Also I am not very good at jumping about from one area of a build to another, so although I know there is a lot of work I could be getting on with I cannot get my head around doing it. It’s just the way I do things I guess. 

In addition I need to get the propellers fitted so that I can be sure of all my measurements before gluing the propshafts in position and starting on the rudder. I have been recommended some 75mm four bladed propellers. I have ordered these from Westbourne Models and await their arrival.

Anyway, I have had some excellent advice from several modellers regarding the rudder. Some I have taken, some not. Because the rudder is a whitemetal casting on a brass spindle there is a risk of slippage, and I have decided that I will modify the rudder at a later date should that happen. Also there is no sensible way to remove the rudder should it require repair or lubrication. So I will be making my own tiller arm and modifying the upper and lower rudder bearings in order to facilitate lubrication and removal. All of the rudder components are shown below (fig 1).

fig 1

As can be seen in fig 2 the lower bearing does not fit correctly on the hull. The plan clearly shows the rudder fitted tight up to the stem (fig 3) so major modification of the lower bearing is required anyway.

fig 2

fig 3

In Part 1 I fitted the “A” frames. Now we need to drill the holes for the propshafts in the hull.

Fitting The Propshafts

The location for the propshaft holes are marked on the hull. However, on my Imara they appeared to be in the wrong place and so I only used them as a guide. The problem I had with the markings was that the propshafts would have not been parallel. The result of which would have been that the shafts were significantly further apart at the propeller end, than at the point they enter the hull. I don’t know if this was how the Imara was laid out for real (maybe someone could let me know), but I did not like it and decided to make the shafts parallel. As you can see in fig 01, the holes I made are now too wide because I had to move the shafts further away from the keel. This is not a problem, just irritating.

fig 1

To make the holes I again made a pilot hole with a 1mm drill opened out with a 4mm drill. I then used a rotary file attachment on my Dremel to open the hole to it’s finished shape. As with all things regarding glassfibre just take your time and your patience will be rewarded.

Note- Due to the propshafts low angle of entry to the hull bottom you may have to file out the interior areas where the shafts enter to get a nice fit.

Checking Alignment

Now it is time to check the alignment of the “A” frames and propshafts together. I adjusted the shafts until they were parallel then checked that the “A” frames looked correct. I marked the middle of the keel with a pencil and using my using my 24″ steel rule checked that both “A” frame shaft bearings were the same distance from that point (fig 2).

fig 2

I then checked the vertical position of the shafts to make sure they were equal (fig 3 and 4). Please excuse the improvised tool, but it did the job, and as the old saying goes “there is more than one way to skin a cat”.

fig 3

fig 4

Ok, so it has been a few days since my last post but I have been thinking about how I was going to install the propshafts and “A” frames with the minimum of fuss. I promise there has been much muttering and holding of parts in approximate positions. Anyhow the time for action has arrived and I can no longer put off drilling holes in the hull.    

Please note that quite a lot of detail will be covered here and so this will be the first of several large posts on this subject. 

Fitting the “A” frames

Firstly you need to ensure that the Port and Starboard “A” frames are on the correct side and the correct way up. If you examine the “A” frames it can be seen that there is a flat mounting plate and a wedge shaped one. The flat one goes nearest the keel (bottom plate) and the wedge shaped one nearest the waterline (top plate) with the thinnest end of the wedge facing forward. Fig 1 shows the Starboard “A” Frame.

fig 1

The “A” frames have one measurement in the instructions. The bottom mounting plate is to be located between 12mm and 16mm from the bottom of the keel. The lower the number you choose the larger the angle of the propshafts from horizontal. I chose to go for a smaller angle and so put the bottom plate at 16mm from the keel, see fig 2 to get some idea.

fig 2

Note- The smaller angle also reduces the height of the propshaft from the bottom of the hull at it’s opposite end, this may make it difficult to fit your motor. 

There are no measurements for the fore/aft location of the mounting plates and so an educated guess is required. Looking at the plan the end of the propshaft (including propeller) is level with the aft end of the stem. Using the plan and other peoples pictures I chose 16mm from the stem for the bottom plate and 12mm from the stem for the top plate. I then carefully marked out the first hole I was going to drill (one in the bottom plate). I drilled the hole straight through the hull using a 1mm drill, then opened it out using a 3mm and 5mm drill respectively. At all times I was aware of the need to keep the drill horizontal and at right angles to the hull in order that the hole would be as true as possible on both the port and starboard sides of the hull. Once the first hole was complete I put a mounting bolt through the “A” frame and then through the hull to check the alignment with the ”A” frame on opposite side of the hull. Once happy with the alignment of both “A” frames I proceeded to mark the location of the remaining holes, drill them out and loosely fit the remaining bolts (fig 3).

fig 3