Which Prop = Goes Where - On Boats?

    A Lot of modelers get confused about this issue.    So I created these Moving Drawings - Below, to help ease some of the confusion.    And by the way - Guys .... "Propellers" are called = "Wheels" in Workboats, a term from steamboat days that's still respectfully used by Tradition.    And Remember .... A boat always has the tendency - to turn, in the very same direction, as its - Propeller  Is Turning.    And these drawings below, show this and how this effect can be canceled by using opposite turning wheels = props.    Just remember that these drawings show the vessel always - Going Ahead, while your looking at the - STERN!

     RH Prop torque

    Single Screw Boats, typically use a "RH - Propeller", so this means the propeller - torque will always try to turn the vessel -  Starboard or "Right".    Naturally if a the boat uses a "Left Hand" Prop, this would cause the torque to turn the vessel = to Port!

 LH-Prop torque              RH-Prop torque

    Twin Screw Boats....  use both = LH & RH Props, also called wheels, fro steamboat days.    Note how twin screw - propellers are OFF SET from the exact center line of the hull.    So each propellers - torque as it spins, has its hull torque, canceled out.    If you used a RH turning prop = on the Port side, its torque would have a drastic effect and would make the vessel steer much harder.    Therefore the use of Left / Right Hand turning props, helps to cancel these effects on vessels.    Reducing Hull - Torque, can also be enhanced by the use of special - Spit Rudders, called Contrguide Rudders.    ( See Below Info )

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  ( 1 ) LH Prop ( 2 ) RH Props

  torque                     torque

    Triple Screw Boats, use a combination of  2 = RH props, with a LH turning propeller.    And the In-board engine - is used primarily,  for additional power and not generally used when doing close-in maneuvers.    When maneuvering, pilot's more often used the two "Outboard Engines", because they apply a greater angle on the thrust provided by the boat..    But when needed, pilot's use all 3 - engines, to manhandle tows that require gentle, skillful - pressure and this means the outboard engines are the most often used on these huge towboats.

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Making Scratch - Wheels = Props!

    Hey Guys .... Remember those fancy little "Rubber Fishing Worms", that ya got hidden away in your ole Tackle Box? ......"Yeah - those little fancy tiny "Chrome Propellers" or Spinner's, that are mounted on them lil tiny rubber worm lures.    Yeah, the ones you've meant to always throw away and replace, because their - all worn out! ...... Well if you wanna make "Tiny Propellers" for a scale model boat, take a pair of those little - 2-blade spinners and cross them, and you've got a four blade = PROP! .... NEAT HUH.    Made in just seconds, using a solder gun to weld the spinners together and mount them on a length of brass tubing used as the drive shaftl - Now Ain't That A - Kick In The Head!  

Tap Drawing To Enlarge

    Purchase "Flat Brass" Sheets in about ( 3/16 to 3/32 thickness - depending on your needs.    And also purchase some - Heavy Brass - Brass Bushings, at your local hardware store.    Then trace your "Fluke" patterns, onto the brass sheets and cut them - Out.    Use a metal blade in a band saw - for example, or a Dremel tool & metal cut-off wheel.    Sand / Polish & then solder all parts - together, with a Solder Iron or Gun, or Small Torch set at low temps to avoid ruining the metal.    My own preference, is a 75/ 150 Watt - Solder Gun!    NOTE ...... The Bushing - must have "Angled Notches", cut into it, so it holds each of the 4 - flukes that make-up the wheel = Prop.    ((( Bushings are found at Bearing Suppliers, or Auto Parts )))    And I use a Dremel tool or Hack-saw, to make the notches - for each Fluke, on bushings. so their  positioned carefully to insure the wheel, will spin perfectly smooth & true.   When cutting - the notch into the  bushing, Take note of the direction you cut the notch, to determine which direction the prop -  Will Turn.    That just means you change the direction of the notches on the Bushings, so you can make Left or Right - Hand Turning - Props.    And this Idea - also easily makes 2 - 3-  4 - 5 or even 6 - bladed propellers = in versions.    And sure saves a lot of bucks, especially - if you can't find a purchased prop in the right diameter, Or Style Needed?

Tap Drawing To Enlarge

     Prop Making ..... Diagram # 2.       This drawing can be used for making props, used on Drive shafts that have Threaded Ends.     Here, Two Nuts are used to hold or clamp the brass propeller patterns - together, making up a 2 or 4 or even a 6 bladed version.    Note, the first two drawings ( L to R ), are for use in "Kort Nozzles" on modern Tugs & Towboats aqnd you can adjust the drawings size -  the drawings diameters ( increase or decrease the pattern size ), to suit your needs in any scale to fit a project!

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 Balancing a Prop & Shaft

    Regardless of the type, or size of a Drive Shaft - "It needs balancing" to reduce hull vibration.    Because that robs - shaft rpm and motor speed and power and reduces a models performance.    All this, is just as critical - in a workboat, as it would be, in a Race Boat!

   Use a 4 to 6" length of scrap - block of wood, and glue a pair of "Single or Double - Edged Razor Blades" to each end of the block, as shown in this drawing.   Making sure they are level with one another.    Then lay your Drive Shaft & Prop, across the blades, which is now the balancer, to check them ( as shown in the bottom drawing ).    The heavy side - of the drive shaft, will roll to the bottom and Indicates a need for a small amount of weight needs to be removed.    "Polish Off" a small portion of the "Solder" around the Prop or in the heavy areas of metal on the Prop.    Also check the props - fluke, are they the same pitch and same lengths, by slowly turning the prop = wheel, with an object close to them, for measuring a crooked prop.    These steps will gain a better balance to the shaft and make balancing easier.   Then rotate and recheck - balance again, to insure - its right, or repeat until correct.    NOTE ... Be sure the table your using, is also "LEVEL", before you use this system on it.    Because it can effect - Shaft balance sometimes - if your not careful.    This balancer, is not made to adjust "High Speed" props for Race Boats, but it works on much the same principle.    And its cheaper than buying one - For Sure!

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Tools Required To Make A - Prop Balancer 

#1 ... Dremel Tool & Bitts = Cut-off Wheel, Sanding Drum... to cut and shape parts.

#2 ... Solder Iron or Solder Gun, plus tip cleaning tools, or a Small Propane Hobby - Torch.

#3 ... 60/40 Rosin Core - Electronic Solder and Soldering Paste.

#4 ... 200 Grit - Sandpaper, to clean and polish brass tubing ( All Points ), prior to soldering and assembly.

#5 ... Bench Vice - to hold parts for assembly.

#6 ... Scrap block of wood, approx - 4 to 6 inches long.

#7 ... 50/50 epoxy Glue, or CA Glue to weld Razor blades to Wooden block!

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Polishing - Brass

    Naturally you want new - Props, to look their best, regardless of whether you made them or purchased them from a hobby supplier.    So here is how you can polish them - to a real professional shine.    

#1 - Small bottle of "SNOW BOWL" Toilet Cleaner. .... "CAUTION = Use Gloves & Ventilation with Acids!"

#2 - Rubber Gloves / Goggles & A small Jar = 1/2 full of Snow Bowl

#3 - An Empty - 1 Gallon Paint - CAN, with Lid ...... ( Fill - half full of = SAND )

#4 - 1 Package of "Fine Grade" - Steel Wool

#5 - A "Reversible - Variable Speed =  Electric Drill"

#6 - Johnson's - Floor Wax ( Paste ).... Adds Shine - to Brass Props - When On Display!

    STEP ONE - REMOVING SCRATCHES & POLISHING = Using an Electric Drill, to spin your wheels = props  ( Mounted on their - Drive Shafts ), with the shaft connected to an electric - hand drill.    Placing the prop slowly - as its turned, down into the Paint Can, filled with Sand and about 2/3's - full of Hot Water.    Spin the props - in both directions for short periods, checking your progress.    NOTE - The sand can be finely sifted - If desired, using some "Old Window Screen" to remove larger granules.    And to remove basic tarnish & scratches, this method works fine with ordinary sand and warm water, then dip the props into a small jar, with some Snow Bowl Toilet Cleaner.    Leave them only a few seconds, then rinse with fresh water, or they will turn black, from the acid.    USE CAUTION - With Snow Bowl, its a Toxic Acid to skin, Eys and your Nose! .....So Use Rubber Gloves and Eye Protection in a well = Vented Area!!    

        Steel Wool - can then be used on rough areas, where "Water / Sand  or Snow Bowl", didn't completely clean or polish the brass.    Then use automotive - paste wax, or Johnson's Floor = Paste Wax, to polish and shine props to much brighter luster

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Kort Nozzles

Korts as their called, are different looking on Towboats, from those used on other types of Workboats.    And below are a couple of examples, because there are several styles and they fit different applications.   Sometimes equipped with Pintle Bearings for the stern- rudder, which means they have included = rudder posts, or skid plates that hold the lower part of stern rudder as well.     And then there are Korts - That don't have such additions, and their shapes can vary greatly from what you might be used to seeing or expect - if your a Tug Modeler and Towboat are new to you.

Tap Photo to Enlarge

    The Hull of the model - Thomas K. with its tin can "Homemade" - Kort Knozzels, lined with small wood strips - glued into place, then sanded to the kort - interiors proper shape.    The kort is embedded into the hull, and filler has been used to smooth the hull & korts - mounting areas.        

    Tap Photo to Enlarge

       "Standard Korts on a towboat"    Mounted on what's called a Tunnel = or Tunnel Stern hull, which looks like a giant "Spooned Out" area in the upper hull plates, that embeds the kort further into the hull to protect it.    Note also, these korts have no stern - rudders posts, included on their rear lower points, and the rudders = Are Removed.    Here, the photo shows "Rudder - Alignment Frames", being used to "Remove Or Re-mount" the rudders during a dry-docking.    Note also that the korts ( At Their - Lowest Points ), are no deeper than the deepest part of the hull - itself.    And if you look closely, you'll see theirs no lower = Pintle Bearing or Plate to hold the rudders.    Here, the stern rudders are separate items, having no = lower bearings, which usually means their "Break Away" Rudders, which are not meant to use a lower - Pintle Bearing.

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How To Scratch Build - Kort Nozzles

    For model Towboats .... use a "Tin Can" or short length of "PVC" Plastic Sewer or Water Pipe, that's been shaped to the styles or type Kort Nozzle, your model requires. 

Tap Drawing to Enlarge

    If a Tin Can = IS USED ....  It should be lined outside with small strips of wood, then shaped with sandpaper to proper shape, then sealed with fiberglass & resin.    This insures the wood is sealed from moisture and damage, while the inner " Tin Can", holds everything solid, for added strength.    The drive shaft will also need a "Brace" to hold itself = steady inside the kort.    This is made by using two = short strips of brass, installed into 2 - Notches, cut into the top & bottom of each kort nozzle.    These braces are then glued tightly into place, once their soldered firmly to the drive shaft, so it can't move inside the kort.    Then the shaft is ready to be installed into the nozzle/ drive shaft housing and the prop or wheel installed.    Here, the kort may, or may not require a "Stern Rudder" = Pintle Bearing to hold the lower stern rudder.     If your model requires such items, they can easy be formed from brass or plastic and installed on the kort after their shaped and fitted into a small notch in the rear - lower part of the kort.    NOTE! ..... Korts must always be mounted in place, using waterproof glue, like a 50/50 Epoxy - I use, to insure they stay solid and don't break loose .... SEE BELOW!

Tap Photo to Enlarge

   REMEMBER = Always use a glue that can withstand water and moisture, and nothing beats this stuff!    It can be used for gluing hulls together or mounting = Drive Shafts / Kort Nozzles & Rudders into place on a hull or inside a Fiberglass hull.    J-B Weld is a  50/50 epoxy that auto mechanics use to seal engine blocks or cylinder heads that have cracks.    Once dry, after about 30 minuets, you can fill any gaps with "Model Plastic - Filler Putty" or use Automotive filler putty and mold parts into the hulls overall shape with sandpaper.  Available at most Hardware Stores, Hobby Shops & Auto Parts. 

WARNING! .... Don't ever use common types of 50/50 = Hobby Epoxy to mount a drive shaft or Rudder system! ..... Those brands of glue - comes loose and break down after being in contact with moisture.    Even if several coats of paint are applied over the glue, it won't stop moisture from breaking it down.    Modelers often use hobby epoxy on model boats, then a short time later, suddenly notice it falling apart???     So remember this, when using typical brands of 50 / 50 hobby epoxy glue, it just doesn't work! ......And J-B Weld = WILL NEVER FAIL!       

   I'll Add More - Later, so check back Often

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Last Updated On 06/29/23 . With