Ohio Class, Ballistic Missile Nuclear Powered Submarine, USS Kentucky SSBN737

Sail, control surfaces, propeller & bow thruster:

The sail:
Now it's time to make the sail. Again, use your drawing and build it as you see it, only a bit higher than it is on the drawings. (App. 1/4" (6mm)). It need to go into the missile deck later on. The sail will be kind of crowded, housing mechanical stuff, lights, and dive plane controls. Do consider this before deciding to build in resin and fiber cloth alone..

   I decided to form the sail in aluminum. Reason being, that this would give me the most space within, as material thickness could be reduced. The top of the sail is wrapped in masking tape, and pure resin is poured in while the sail rests up side down. Then, after curing, the resin is filed into shape, and the entire sail is coated a few times in pure resin to allow engraving. The coating also ensures that the sail will not corrode. This approach also makes it way easier to place the navigational lights, the mechanical link to the dive planes, and the scope(s) incl. mechanism if chosen. The entire shaping was done by hand in 1.5mm (0.06") thick plating.

   The dive planes inner most ends (stationary) are normally filed to match the sail, and then glued on to the side of the sail. However, this would mean that all of the forces introduced by the dive planes would go into the thin coat of resin, and since the entire weight of the sub might rest here, I doubt if that would hold. Instead, I choose to file a hole in the sail, all the way through the resin coat and the aluminum, and then fix the inner most stationary part of the dive planes in the aluminum core. This should ensure that the forces from the dive planes are absorbed and transferred to the hull by the core, and not the thin resin coating. It also gives a much stronger construction, and should prevent the dive planes from breaking off in case of an accident.

Use your drawings to copy the hatches as shown on this image, and take a look at the images of the sail in the pictures section for inspiration. Remember that the sail is one of the most visible parts at all times, so do take your time getting it just right... it'll be worth it!

This is a small test fitting of the three operable scopes, made by straws pressed oval. Please see the section about scope building for further details.

The dive plane shaft and control mechanism blocks the smaller rectangle hatch and the bridge, so neither of these are open on my sub.

The two holes with a little red liner on the edges, will not be operable on the final sail. They will only have a fake top of a scope, but to make it look "as if" they'd work, I decided to file them anyway, make five scopes, and just put the very top of two of them in these two holes. This will end up looking like they are there, but are only retracted. Making five operable scopes are an option, but might look "too much", so I decided not to. ("Less is more"?)

The remaining three holes will have operable scopes fitted later, as shown on the image above.

Holes for the scopes are drilled and filed (Notice that they are oval). Finally the navigational lights are fitted, and sealed. Notice the clear one facing forward, this is a white LED. Missing is only the top light, but it'll follow shortly.

This completes the sail, and we can move on to making the control surfaces, before we mount it all on the main hull.

The beginning:

  The piece of plastic material is marked, the initial control surface work can begin.

The rudders and dive planes are all made from looking at the drawing, and filing them into shape in some material that is nice to work with
. Originally I intended to make the surfaces using the mold method, but as I found this material, I decided to build the pieces in one process.
The material is a plastic, simulating wood, and normally used for making prototypes of objects. It's very easy to work, can endure water, and does not crack. I put a piece in water for three weeks, and no change was noted, I then glued two pieces together using epoxy resin, and repeated the test. Even after three weeks submerged in water, and subjected to sun light, it was still not possible to break them apart, nor had they changed shape as a result of any water being absorbed.

Sail dive planes:

Function: The function of these control surfaces, is to control the dive angle of the sub, e.g.. up- or downwards direction of travel. These control surfaces are controlled by the remote, and in second priority, the later fitted automatic pitch controller.

  Here's the raw blocks that will become the dive planes on the sail. Only the raw outline as seen from above are marked, as the other views will follow when the blocks have been cut to a closer fit. More images will follow as work progresses.

top view shape of these two control surfaces are based on pictures alone, as they were not on the drawing I bought of the Ohio sub. All measurements was based on scaling images, and may not be 100% correct.

   Here you see the finished dive planes, which are exact copies of each other. The holes to the shaft have been drilled, and they are almost ready to be fitted on the sail. The two dive planes will go on the same shaft, extending all the way through the sail between them This ensures mechanical stability.

  The dive planes will need to be cut across to fit to the sail. The sail is curved, and you cannot have another curved surface rotating right up against it. To solve this, the first 1/4" of each dive plane are cut from this piece, and fixed on the sail, leaving a straight line for the dive plane to align with, when in neutral position.

Important: Drill the hole prior to cutting, as this ensures that the moving part will be 100% correct aligned later, when hinged on the shaft.

Now the two surfaces have been cut as described above, and the two small strips have been glued on to the sail as described in the section about the sail construction. The surfaces have been temporary mounted on the sail. Notice that they rotate around their center axis.

You want to start with the dive planes prior to the sail, as the stationary parts go on the sail before this can be completed. 

This is the completed sail from below. Light, scopes and linkage are in place, and works!

Fitting it all was difficult, there's not much space for anything. (Rule no. 2 in subs...)

Here's the completed sail with extended scopes. The "737" was made on a machine that cut them out in in a material similar to stickers, but very adhesive!

On real subs, these numbers are magnetic sheets, that are only applied when docking.

Here's the completed sail with scopes tugged away.

(Manual operation for the time being.)

Close-up of the completed sail. Please look under "Navigational lights" for a few shots where the nav. lights are on, and the amber top light flashes an "S" (Three short ones, and a pause..)

Aft dive planes:

Function: The function of these control surfaces, is to control the dive angle of the sub, e.g.. up or downwards direction of travel. These control surfaces are controlled by the remote only.
  Here's the two aft dive planes, including the two vertical stabilizers. The stabilizers have not yet been fitted to the dive planes, as these need to have the hole drilled for the shaft, and have the moving part cut out first. The parts are exact copies of each other.

The shaping was done using first a saw, then a sanding belt machine, where the belt is fixed, and you hold the parts in your hand. This was very messy, but proved to be the best way to form the objects. The final sanding was done by hand.

  Here you can see the future cut in the moving part, when this is cut shortly. The arc indicates where I need to sand, so that the moving part can rotate freely around the shaft, later fitted. Also, you can see where the center of movement are to be.

Important: Drill the hole prior to cutting, as this ensures that the moving part will be 100% correct aligned later, when hinged on the shaft. (The shaft will extend from within the hull, through the moving part, and into the stationary part at the far side. Please see section below for further details on this procedure.)

The shaft are mounted as illustrated here. When done, fit the entire part to the hull.
Mark the places where you need a shaft or guide pin to go into the hull, and drill the holes.
Then fit the parts with each other (movable and
stationary) and push the shafts through the movable part, and into the stationary part. This ensures that the movable part is properly hinged. Then check the clearances while temporary fitting the parts. When it can move freely with no grinding, pull the shaft back out until it sticks into the movable part only a bit further than the depth of the hole in the stationary part on the outwards end. Then apply a drop of resin to the shaft, and push it a bit further in. Then another drop, a little further in, and so on until the shaft reengages with the hole thus hinges the movable part. The idea here is that the glue should only be pulled along and into the movable part, but not all the way through and into the hinge.

   Here you can see the whole thing put together, ready to go on the sub. The parts have been test-fitted several times, and last minute adjustments have been carried out, to ensure a perfect fit to the hull, and an easy and smooth movement of the moving part. (Important!) Notice the nylon bearing where the shaft will rest on the far side, in the stationary part.
Now fit the aft dive planes to the hull, using epoxy resin, but only at the
stationary parts! Ensure that it is all aligned correctly at all times, and secure it well, before leaving it to cure. Observe: Once the shaft is glued, and the two parts are mounted on the hull, then there's NO way to separate the stationary part and the moving part without destroying one, or both.

Once the stationary part, and the moving part, have been fitted, then the vertical stabilizer is fitted. It proved to be easier to mount the vertical fins once it all was on the hull. The tiny nail holding it while curing, was later cut and sanded, so it wouldn't show under the paint.
The stabilizers was fitted using resin, and a cotton pick was used to fill any gaps.


Function: The function of these control surfaces, is to control the sideways movement of the sub, e.g.. turns to port or starboard.

  Here the finished aft rudders are shown. The two are exact copies of each other. The top one will have a tunnel for the navigational light drilled later, and both will of cause have the shaft mounted shortly.

As the top rudder has a navigational light on top, the hole for this has been drilled as well. The shaft in the top rudder will be a hollow shaft, allowing wires to run down and into the sub this way. This puts only a minimum of mechanical stress on the wires, and are the only way to do it. The hole for the nav. light, and the hole for the hollow shaft, has been interconnected within the rudder, here seen from the lower side. Notice the hole in the shaft, right below the Teflon bearing.

The nav. light is a white, sealed L.E.D.

The finished result should look something like this.

Please see the section on fitting rudders etc. for a detailed w
alk-through. Click here


  A word of consideration: The propeller is one of the most visible parts on the outside, which everybody gets close to for a closer view. Therefore, do consider buying the propeller as a ready-made product, rather than making one your self. The price tag is only around $40.. I bought my propeller (in picture) from LoyalHannaDockyard which I can highly recommend! Outstanding world wide service, and product range!
Also, do observe the max. RPM rating. It is dangerous to exceed this, as a blade braking off travels at high velocity in a random direction, easy taking out an eye. Consider limiting the RPM at the remote, and NEVER stick your fingers close to the prop while the sub is turned on! Something might cause it to spin without warning, and you need all of your fingers in the future, right? The receiver in your sub is a very sensitive thing. Someone miles away might trigger it, someone might touch your remote, or even switch it off before the sub is switched off! (This will cause the receiver in the sub to go apes...)

  The very end of the aft and, the shaft hole. The center hole is much bigger than the shaft, as the shaft will rest in bearings within the hull, and NOT in the hull it self. The white stuff you can see inside, is the mock-up not yet removed, as the hull has not yet been split in this image.

The outer diameter of the hull at this place is 1.14" (29mm), but the core of the propeller is only 0.79" (20mm)
Therefore, I had to figure out how to make those two fit in a nice manner.

  The idea I came up with was to make a cone in black nylon, and then put it between the hull and the propeller. The nylon was shaped on a lathe, and the center hole was drilled just a fraction too small, so the cone would have a tight grip on the shaft.

Why BLACK nylon? Well, the sub's gonna be black later on, so now I can leave this part as it is, not having to paint it.
The gap between the cone and the shaft is only there to illustrate the orientation. The gap will be reduced to almost nothing when finally mounted.

  The shaft exits the hull through a hole in the very back. The bearing used for this, is an oil-bronze bearing.
In order to prevent the oil from soaking into the resin and fiber cloth, I had a small stainless steel pipe made to work as a lining for the hole.
Notice the two 'tracks' in the lining. They serve to give the resin a secure grip.
ce the steel lining is glued in place using resin, the oil-bronze bearing will be fitted using Locktite.
The black nylon cone will slide right up against the hull, and the propeller will follow next.

This also makes it possible to replace the oil bronze bearing, if need should arise.

  This shows the actual fitting of the stainless steel lining, held in place by the actual shaft while resin cures.

Almost needless to say, the alignment of this bearing is important, and great care should be taken!

  This shows the prop shaft connected to the engine shaft. Due to very good alignment, and the flexibility of the long shaft, no flexible coupling has been used initially. Both shaft ends has "flat-spots" so the bolts has a flat spot to stand on, preventing the shafts from sliding. The weight of the bolt heads are compensated by the flattening of the coupling, thus giving a fine balance.

  This shows the prop shaft with the flat spot, preventing the shaft from sliding out during operation, which would be BAD. The bolts are further more secured with nail polish to lock those into position.

  This image shows the "flat-spot" at the prop end, similar to the one mentioned above. The pinol-bolts rests in these, and even IF they come loose, then the things will not come apart right away. Checking the drive train prior to sailing should reveal if something is loose, without you having to buy a new prop every time...

  This image shows the now fitted propeller, with it's nylon spacer between it, and the hull.

Turning it is VERY easy, in fact easier than I had hoped, thus only VERY low friction.

Bow thruster:

The bow thruster is not the average bow thruster normally used for R/C models. Why not? Well, they're too big. In stead I found a pump from Pandan (UK) which used <1A, but is a high performance pump. As all bow thrusters, it takes water from one side, and jets it out the other.
My thruster is controlled by the side-to-side movement of the throttle stick, and can be mixed with the rudder channel as well to automate the thruster function. The rudders of the model is not effective enough to do the turning alone, so the thruster will aid them at normal sailing.

When traveling on reverse though, the thruster will have to invert it's function, and thrust the other way around. This is the reason why I have the ability to control the thruster in a separate stick, as well as hooking it up on the rudders on auto mode.

  The actual controller that drives the ABP pump, is an RS-5 "reverse-off-on" remote controlled switch from Pandan (UK). Because this unit was too big in it's original shape, I had to partly remove it's housing.
  The thruster ports are placed as close to the middle of the side as possible to avoid that the sub creates a list to the side, when the thruster is active. (Some where between the center of weight, and the hydro-dynamic center of the hull.)

Holes drilled, cobber knees held in place with close-to-hand things, and using resin they're mounted in place.
  This nice overhead view gives a nice indication on where they're fitted. The pump will need some housing before going on to the hoses, and the cable coming from the controller within WTC1.

The ports are located as far in front as I could get them, thus as far from the center of weight as possible, giving me a bigger "arm" to push the sub. (Effect = power applied x arm)
  Though maybe hard to see, the ports sit juuuust a fraction under the upper edge of the lower hull part. The little black dot in the resin is actually a piece of plastic used to hold it all in place while curing.

The angle of the jet if 90 degree on the length axis, so
that the sub will not travel back nor forth when thrusting, only port to starboard, or starboard to port.

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