Landing Image of a Shaft Lok attached to a Borg Werner transmission

Welcome to Shaft Lok

Properly Positions, Locks

and Automatically

Unlocks the Propeller

Quickly and Easily

Without Leaving the Cockpit!

See Our Yacht List! Read Our Testimonials!

ABOUT SHAFT LOK Inc.

MILWAUKEE, WISCONSIN 53211 USA

Phone: 1-262-786-6800

Sailors enjoy sailing with the "quiet" that Shaft Lok adds to the experience. Shaft Lok locks the propeller in the most efficient position with one blade vertical. This will produce the best boat speed, quiet operation and without transmission or propeller shaft bearing wear. The propeller is held stationary regardless of the yacht speed. All that is necessary to unlock the unit is to start the engine and engage the transmission. Shaft Lok automatically unlocks.

Shaft Lok Inc. History

by Kenneth R. Nigel

July 28, 2023

Dick Badzinski and George Nigel both owned sailboats that would allow the propeller to rotate when sailing, not using the engine. This freewheeling of the propeller would slow the boat, create vibration, noise and cause unnecessary drive train wear which took the joy out of sailing. Both sailors said it was like a dripping faucet which just got on one’s nerves.

Both Dick and George decided to fix the problem! That was back in 1978. I was working at Rex Chain Belt in Milwaukee, Wisconsin at the time as a Product Marketing Manager and encouraged them to pursue the invention which they could market worldwide.

Once they decided on the concept design, they built a working model. Around the same time, we contacted a cousin of Anne’s in Boston who helped us apply for three patents. At the time we were advised to refrain from going “public” until the all the documents were in the hands of the government.

All three of us put a few dollars into the company to publish a four color bulletin, build a web site and start advertising.

We attended the Chicago Boat Show and set out to visit the Borg Warner booth. Borg Warner was building transmissions for small RV sailboats, probably under 100 feet long. We wanted to find out if BW would be interested in marketing the Shaft Lok Mod I unit. BW had invited their east and west coast dealers to the show. Those people were very receptive. In a few week’s time, we were shipping Mod I units to these dealers in 1979.

We changed from a 2V design to the Easy Lok concept which made locking the unit much easier.

U.S. Patent & Trademark Office:

Patent Number: #4389199

Patent Number: #D271583

1979

Since...

1390+

Units Shipped

50+

Boat Types

23+

Transmissions

2

Patents

Shaft Lok Mods

Mod I
Base Unit

Light Sailboats

Maximum Bore: 45mm

Mod II
Easy Lok

Medium Sailboats

Bore 1.25" and smaller...

Bore greater than 1.25"

Bore 2" or greater

Mod II Easy Lok High Torque

Medium Sailboats

Max Bore of 2.25" or greater

Mod III
Easy Lok

Large Sailboats

Bore 64mm and smaller

Mod III Easy Lok High Torque

Large Sailboats
Max Bore of 80mm

Mod IV
Max Dia. 4.33"

Million $$$ Yachts

The Maximum Propeller Shaft Diameter is 110mm (4.330”). The Mod IV was designed to enter this market. These huge yachts mostly motor vessels but a few sailing boats like the beautiful restored schooner S/Y ERNESTINA that returned to New Bedford, MA 02741 recently.
M/Y Rocket One is also a million dollar yacht, both of these boats are online.
These huge vessels with multiple power systems like to have the option of powering with only one engine at times. Having the other engine(s) shut down increase the boat's range. They need to keep the systems not being used to lock the propeller(s) from rotating. If these propellers rotate the transmission(s) will not be properly lubricated as their engine(s) are shut down. The Shaft Lok unit(s) must be designed to handle massive amounts of torque generated by the speed and propeller size.
This enormous torque can be achieved by using multiple standard short pins and spring systems in the housing to hold the very large locking pin stationary.
This design of the Mod IV is just a simple upgrade from the 1979 patented arrangement.

Mod V
Max Dia. TBD

Million $$$ Yachts

The Maximum Propeller Shaft Diameter is to be determined. The Mod V unit was designed to enter this market. These huge yachts mostly motor vessels but a few sailing boats like the beautiful restored schooner S/Y ERNESTINA that returned to New Bedford, MA 02741 recently.
M/Y Rocket One is also a million dollar yacht, both of these boats are online.
These huge vessels with multiple power systems like to have the option of powering with only one engine at times. Having the other engine(s) shut down increase the boat's range. They need to keep the systems not being used to lock the propeller(s) from rotating. If these propellers rotate the transmission(s) will not be properly lubricated as their engine(s) are shut down. The Shaft Lok unit(s) must be designed to handle massive amounts of torque generated by the speed and propeller size.
This enormous torque can be achieved by using multiple standard short pins and spring systems in the housing to hold the very large locking pin stationary.
This Mod V advances the legacy design from the 1979 patents.

Million $$$ Yachts

Mod VI
Max Dia. 6.5"

Million $$$ Yachts

The Maximum Propeller Shaft Diameter is 6.5”. The Mod VI unit was designed to enter this market. These huge yachts mostly motor vessels but a few sailing boats like the beautiful restored schooner S/Y ERNESTINA that returned to New Bedford, MA 02741 recently.
M/Y Rocket One is also a million dollar yacht, both of these boats are online.
These huge vessels with multiple power systems like to have the option of powering with only one engine at times. Having the other engine(s) shut down increase the boat's range. They need to keep the systems not being used to lock the propeller(s) from rotating. If these propellers rotate the transmission(s) will not be properly lubricated as their engine(s) are shut down. The Shaft Lok unit(s) must be designed to handle massive amounts of torque generated by the speed and propeller size.
This enormous torque can be achieved by using multiple standard short pins and spring systems in the housing to hold the very large locking pin stationary.
This Mod VI is our most robust design to handle the most torque-challenging mega-yachts.

Marine Control Cable

Marine Control Cable

This is the second option, besides the Simple Spring Locking System, to lock the Shaft Lok unit. These cables are all made to order and are available in any length. The cable prices are included in our formal quotation. The cable is attached to the cap plate on top of the unit. The cap plate is bolted to the unit. The cable can be routed to the helm station. Most live onboard sailors position the cable below deck to protect it from inadvertent use. Pushing on the black knob on the cable will move the locking pin down to contact the rotating disc. If the vessel is powering and the black knob is pushed in the long locking pin working end would be damaged.
Yes, the locking pin can be replaced but it is expensive.
These cables have stainless steel terminals. The low friction liner inside the protective casing provides easy movement of the 0.075” diameter stainless wire which is connected to the black knob. The 0.075” SS wire is also contained in the long locking pin with four set screws. This pin physically contacts the rotating disc through which the propeller shaft passes. When installing the Marine Control Cable try to keep the number of “bends” and “turns” to a minimum which will keep the force necessary to lock the unit at a minimum.
See the attached Patent Drawing.
This is a marine control cable. Specify length during order.

Marine Control Cable

Simple Spring Locking System

Replaces Marine Control Cable

This S.S.L.S is one of the two devices that lock all the Mod I thru Mod III Shaft Lok Units. It is mounted on top of the Shaft Lok Unit. Just push down on the black knob to lock.
SSLS is inexpensive, easy to install and compact.
To operate the SSLS one must enter the engine room, which may be difficult on some yachts. However, to LOCK the Shaft Lok unit, the propeller must be rotating slowly.
Shaft Lok is an excellent LOCK but as a brake “not so much”.
The SSLS operator should be able to see the propeller shaft easily. Over time the operator will become aware of what shaft rotation speed is required to lock the unit. The sailor can inform the captain if more or less speed is necessary. The Shaft Lok unit automatically unlocks when the engine is started and put into gear. The locking pin, that holds the rotating disc, travels up into the housing allowing the disc to rotate should the captain want to use the motor to move the vessel. The short pin in the housing holds the locking pin in the unlocked position. When the unit is locked the short pin also holds in the locked position. See the Patent Drawing attached: 2 pages down.

Installation

The best way to make sure the Shaft Lok unit will fit is to use a cardboard rotor template cut in half; 4 1/8 inches diameter for the Mod I Easy Lok, 6.75 diameter for Mod II Easy Lok and 11.75 for Mod III Easy Lok unit with centered hole for propeller shaft. Cut a loading slot into the cardboard equal to the diameter of the propeller shaft then use the template in the engine room where the unit is to be installed.

Shaft Lok is a simple device of few moving parts. The upper part of the Housing contains a long locking pin and a short pin with a stainless steel spring and spring assembly screw. The unit is locked with a Shaft Lok Marine Control Cable (S.L.M.C.C.) or a Simple Spring Locking System (S.S.L.S.). The cable is fastened to the top of the housing with the palm knob positioned in the cockpit or where ever the owner decides.

The SSLS replaces the Cable. It is bolted to top of the housing with the Black Palm Knob a few inches above the housing. This means one has to enter the engine room to lock the unit.

Old photo of a Mod II Easy Lok
Old photo of a Mod II Easy Lok
Full-size drawing of a Mod II Easy Lok
Full-size drawing of a Mod II Easy Lok

The lower section of the housing has a deep grove sealed ball bearing, which is maintenance free, contains the Black Rotating Disc & Stainless Steel Hub Assembly. The propeller shaft is installed into this Hub Assembly and secured with stainless fasteners.

To lock Shaft Lok when sailing press down on the Marine Control Cable or Simple Spring Locking System palm knob. The Control Cable has the long locking pin attached to the working end. The long pin engages the rotating disc locking it and hence the propeller from turning.

Inside the main housing along with the long locking pin is a spring loaded short pin that holds the long pin in locked and unlocked positions. The short pin and stainless compression spring is the heart of the unit. Shaft Lok resists the static torque generated by the stationary propeller as the yacht is sailing.

No electrical or hydraulic power required.

Sailors enjoy sailing with the "quiet" that Shaft Lok adds to the experience. Shaft Lok locks the propeller in the most efficient position with one blade vertical. This will produce the best boat speed, quiet operation and without transmission or propeller shaft bearing wear. The propeller is held stationary regardless of the yacht speed. All that is necessary to unlock the unit is to start the engine and engage the transmission. Shaft Lok automatically unlocks.

Before You Order...

Tell us about your boat.

YACHT

  1. Manufacturer:
  2. Boat Length:
  3. Vessel Name on Stern:
  4. Displacement:

PROPELLER

  1. Shaft Diameter: 55mm (2.165 inches)
  2. Diameter:
  3. Number of Blades:
  4. Fixed, Feathering or Folding:
  5. If Feathering or Folding, what is Manufacturers name:
  6. Maximum Hull Speed: (flat seas on a broad reach in 25 knots of wind):

ENGINE

  1. Make:
  2. Horsepower:
  3. Transmission Make and Model Number:
  4. Transmission ratio:

Replacement Parts

Tell us what you need...

How does a Shaft Lok work?

Shaft Lok uses a compression spring to “power” the unit. These springs have a life of several thousand cycles. Shaft Lok Inc. started shipping units in 1979 and we have yet to hear about a worn out, spring. Shaft Lok is a simple device with few parts that do not require maintenance nor any electrical or hydraulic power.

The large ball bearing is placed in the housing mold just before pouring the hot urethane. When the process is finished and cooled the bearing is secured without any fasteners. The bearing is double sealed and does not require lubrication of any kind. The entire unit is made of marine urethane that will last for decades. Urethane is strong and will absorb vibration without failing.

See attached Patent Drawing. The black rotating urethane disc with a stainless steel hub is placed on the propeller shaft secured with stainless hex head bolts. The Spring Adjustment Screw is in contact with the compression spring. A fully tightened SAS generates 100 percent of the spring’s compression force. The short pin is “pushed” into the long pin holding the unit in the locked or unlocked position via the two notches on the long pin.

To lock the unit while the sailing vessel is moving requires that the propeller is rotating slowly probably in the 2 to 3 knots range. If the rpm of the propeller is too fast just easing the sheets or head up into the wind to slow down while pushing on the black knob of the Marine Control Cable or Simple Spring Locking System which ever is installed in the yacht.

To unlock the unit just start the engine and engage the transmission, the extreme torque generated will do the trick without any damage to the disc or locking pin. The two pins are Acetal homopolymer a unique thermoplastic material for use in moving parts in which low friction and long wear life are important. It is a combination of Teflon fibers dispersed in the Delrin resin. This combination produces a material that has strength, toughness, dimensional stability and good wear characteristics.To unlock the unit just start the engine and engage the transmission, the extreme torque generated will do the trick without any damage to the disc or locking pin. The two pins are Acetal homopolymer a unique thermoplastic material for use in moving parts in which low friction and long wear life are important. It is a combination of Teflon fibers dispersed in the Delrin resin. This combination produces a material that has strength, toughness, dimensional stability and good wear characteristics.

Contact Shaft Lok

Where We Work

We'd love to hear from you!

Map to Shaft Lok

Milwaukee, Wisconsin 53211 USA

Phone: 1-262-786-6800

Email: Shaftlok@att.net

Contact: Anne Marie or Kenneth

Leave a message if the machine answers. We will return your call.

Open Monday through Friday 9am to 5pm Central Standard Time.

But, if the surf is up on Lake Michigan those hours are problematic.

For offshore inquiries please indicate exact “ship to” address including zip code with a named contact and phone number. This info is needed to estimate shipping cost.