Prop Guard Marine Prop Guard 11" 25-35 HP - Safety Orange

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Prop Guard Marine
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Ships: In 1 Business Day

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Prop Guard® is made to surround the propeller like a nozzle. This designed nozzle action moves water with a controlled directional force which gives the boat improved handling and more power. This nozzle action is accomplished with no moving parts to adjust or replace. Whether you have an outboard or stern drive, Prop Guard® will increase propeller efficiency, decrease fuel consumption and improve boat handling while reducing hull and engine stress. Technical testing of the Prop Guard® has proven that the performance of pleasure crafts are actually enhanced by the installation of the Prop Guard®.

How does the Prop Guard® increase propeller efficiency?

Optimum performance of any vessel is dependent upon the design match between the type of engine, its propulsion system and the type of hull. The delicate balance can easily be upset with an under powered or over powered engine. Even a perfectly well designed propeller may perform miserably if that propeller is placed behind an oversized or overloaded hull. Any problem with these elements can result in poor performance and handling for a vessel.

However, Prop Guard® , even with a technically unbalanced craft can increase the thrust of the propeller. The loss of kinetic energy due to rotational flow in the water downstream of the propeller can be partially recovered by the guide vanes of the Prop Guard® as it creates a counter rotation vortex, reducing the torque effect of the rotating propeller. The hydrofoil nozzle configuration of the Prop Guard® creates forward thrust, which overcomes its own drag and also provides an effective trim without drag. Nozzle propellers produce more thrust than open propellers as the nozzle produces greater dynamic lift for the boat and permits it to achieve faster acceleration and planing.

Prop Guard® eliminates the need for existing or additional drag producing trim devices. In a steep turn, boats tend to turn on their center of gravity and the propeller loses its bite in the water creating uncontrolled rev-ups, as the stern of a boat and the prop moves tangential to the center of gravity of the boat. This is eliminated as the greater lateral area of the nozzle produces a larger effective rudder area. Prop Guard® increases the thrust significantly to overcome handling problems.

How does the Prop Guard® increase boat handling?

In tests, vessels with Prop Guard® installed were put through tight figure 8 turns. The handling characteristics were greatly improved, as greater lateral area of the nozzle produces a larger effective rudder area. There is significantly greater steering control at high speeds, when the vessel made 360 degree turns in 30 to 40 feet compared to 60 to 80 feet with an unguarded propeller. The stopping ability of the boat is also dramatically increased as the nozzle presents a greater blockage area.

How does the Prop Guard® reduce hull and engine stress?

Prop Guard® allows a vessel with a planing or displacement hull to be trimmed so efficiently that porpoising or pounding of the hull can be greatly reduced. The fact of less pounding on the hull should reduce hull stress. When a boat is porpoising, sometimes the upper portion of the propeller will be in and out of the water allowing the engine to rev and release. The improved handling can also help reduce this type of engine stress.

How does the Prop Guard® make a vessel safer?

There are no “minor” propeller accidents. Installation of the Prop Guard® on all propellers would greatly reduce prop blade injuries to humans and marine life. The added thrust also allows for better handling control of the vessel. The Coast Guard, life guards and military vessels are preparing to order Prop Guards® because of the greater propeller safety factor and increased vessel control that they can achieve.

In a statement from the celebrated Philadelphia court case of Fitzpatrick vs. Madonna & Outboard Marine corporation, Dr. Robert Taggart states that, “the Schultz nozzle is a basis of a near optimum additional device to provide protection from outboard motor propellers.” Prop Guard® combines the majority of the recommended features into a structurally and hydrodynamically sound design.

Current Federal and State lobbying groups predict a mandatory propeller guard law to be mandated in the very near future. Florida predicts the prop protection law could be passed in the near future to protect the manatees and humans. Marine insurers are offering premium reductions for policy holders who install safety devices on their vessels now, with further incentives for propeller guards coming.

What is a Prop Guard®?

Prop Guard® is the next patent generation of propeller protection from the noted engineer and inventor Wilderich Schultz. Mr. Schultz has spent his life creating products that improved safety and performance for many aircraft and marine products. Mr. Schultz’s father invented the first propeller nozzle guard, the “Kort Nozzle” for canal and river boats in the early 1930’s. Mr. Schultz took this well proven product and used present technology and hydrodynamic principals to adapt it to the needs of today’s boating industry. Now with the joint engineering and design modifications between Mr. Schultz and Mr. Morrell, the new Prop Guard®

Prop Guard® is a two piece plastic injection molded cage that will completely cover the propeller. The Prop Guard® is attached by a specially designed clamp system and bolts. The Prop Guard’s® two halves are attached like a clam shell to the cavitation plate and the skeg of any outboard or stern drive motor. The easy installation can be accomplished by anyone with simple tools in about 20 minutes.

How is the Prop Guard® different from other propeller h3guards?

The differences of the Prop Guard® over the current market propeller protectors are many. First, the Prop Guard® is made out of a light weight but strong, high impact, flexible injection molded plastic. This allows the guard to work without having the heavy weight and danger of the metal guards that are on the market today. Metal guards can corrode, and with a hard hit, the metal guard can be pushed into the propeller causing possible propeller damage. Besides propeller damage, the metal cage can break into metal fragments that could cause personal injuries and gear box damage.

The one major difference that the Prop Guard® has over any other guard is the Prop Guard® will improve the performance of the propeller. What this means is that if you can improve the efficiency of the propeller, you will improve the performance of the boat. The Prop Guard® is the only product not only designed to protect, but to improve the handling of a boat.


The purpose for the Prop Guard® is to provide a product that will protect a family from deadly propeller accidents and give the boat owner the excitement and enjoyment of improved performance. The Prop Guard® provides important benefits for the boat owners throughout the world. Boat safety and performance is a world wide need, not just an American issue. Boating accidents happen worldwide, therefore, the Prop Guard® is a truly global product.

As you can see, the Prop Guard® is a well designed product which offers many benefits to the boating industry.

Installation Instructions

1.Place the Prop Guard® on the underside of the cavitation plate. Align the guard so that equal distance exists between the guard and the prop when the propeller revolves inside the guard. The Prop Guard® should be positioned as far forward on the cavitation plate as possible. Note: The mounting surface of the guard should remain flat against the cavitation plate. The use of a hand file may be needed to remove any imperfections in the lower surface of the cavitation plate and the lower skeg. ALIGN TRIM TAB UNDER CAVITATION PLATE IN A STRAIGHT INLINE DIRECTION. INSTALLATION OF 13" & 14" MUST NOT EXCEED 20MPH AT THIS TIME.

2. Clamp the guard to the cavitation plate using C-clamps or Grip clamps. Insert bolts, washers and Nyloc nuts through bottom of pre-drilled holes at bottom of rings and loosely tighten.

3. Make certain that the guard is square with the cavitation plate, propeller and lower skeg. PROPELLER MUST BE SURROUNDED BY THE PROP GUARD®. MAY NEED TO SLIDE PROP GUARD FORWARD (PG) FORWARD OR AFT FOR PROPER PROP CLEARANCE.

4. Drill 2, 3 or 4 holes (see chart above) through the cavitation plate and guard on each side. Insert bolts, washers and Nyloc nuts as illustrated and loosely tighten.

5. Drill 1 to 2 holes (see chart above) through lower skeg, per illustration. Insert bolt, washer and Nyloc nut, tighten securely. Now tighten cavitation bolts. REMOVE CLAMPS !!!


Please be aware that all products have a production or warehouse lead time. This is the number of business days (typically not including the day the product was ordered) that must pass before the item begins the shipping process. Please see the "Ships: In" information located within the main product description to the right of the product image and below the ADD TO CART button for that particular product's "Ships: In" timeframe.

IMPORTANT: Please note that these timeframes are estimates only based on the latest information provided to us by the manufacturer/supplier. Delays in both material, production and shipping timeframes by manufacturers can vary without advanced notice and while we do our best to keep "Ships: In" timeframes up to date we may not always be able to do so due to a variety of factors.

If a product is needed by a specific date we strongly recommend you reach out to our Sales team (1-800-869-1686) to verify shipping timeframes.

Canadian orders please add an additional 14 business days for processing and shipping. Alaska and Hawaii orders please add 1 additional warehouse processing day.

Click here to see our Standard Shipping Policy

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