What is a "Spun Prop" or "Spun-Hub"?
In years past, props were a one piece design, using a shear pin, placed through the prop hub and drive shaft, as a means of both driving the prop and acting as a safety device. When the prop struck an object under water, the shear pin was designed to 'shear' or break, allowing the drive shaft to continue to spin, avoiding major damage to drive train. The shear pins were unreliable because they were not always consistent in their tensile strength or they became 'work hardened' and would sometimes shear too easily or not shear at all.
With the introduction of higher horsepower engines, finding pins large enough to handle the torque became impractical, so this along with the earlier problems experienced with shear pins, prompted prop manufacturers to design the modern day outboard and outdrive marine propeller. Today's props consist of some variation of the following components (see illustration below): A) Inner Splined Metal Bushing, B) Shock Absorbing Rubber Sleeve, C) Inner Hub of Prop Assembly, D) Propeller Blade, E) 'Ribs' or 'Webs', and F) Through Hub Exhaust Port.
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The A) inner splined metal bushing is pressed or molded into the B) shock absorbing rubber sleeve and this assembly is pressed into the C) inner hub of the prop assembly. When a piece of rope or aquatic weed becomes entangled in the prop, or when the prop hits an under water obstruction, and the prop is prevented from spinning, the rubber sleeve absorbs the shock and then breaks loose allowing the inner splined bushing, drive shaft and other critical components in the engine to continue to 'spin' - avoiding major damage to the drive train and engine components.
After a prop or hub has spun, it is difficult or sometimes impossible to resume power and bring the craft back to shore. This is because the outer surface of the shock absorbing rubber sleeve has been torn or broken loose from the inside of the prop assembly and cannot adequately transmit torque from the lower unit drive shaft to the outer prop assembly. Because of this inability to transmit torque when under power, the engine will rev, but little or no forward speed will be realized by boater.
The only solution up to this point has been to carry and install a spare prop. If the boater does not have a spare prop or cannot remove the old prop, the boater is either left stranded having to float aimlessly for hours, forced to call for an expensive tow or has to inconvenience other boaters in the area to spend their recreational time towing the disabled boater in. There is now an inexpensive and quick solution to this problem - Hank Parker's Prop-Aid!
Hank Parker's Prop-Aid is designed to fit over the end of the exposed drive shaft and into the through hub exhaust ports of the prop (see illustration below), allowing the splined drive shaft to drive Hank Parker's Prop-Aid, which in turn drives the outer prop assembly with the fingers of Hank Parker's Prop-Aid pressed against the webs or ribs that connect the inner hub to the outer hub. This bypasses the disabled rubber sleeve assembly which is no longer able to transmit torque to the outer prop assembly. Simply remove your nut and washer, then insert Hank Parker's Prop-Aid, replace the nut and return to shore! It's that easy!
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If I have I have a spare prop do I need Hank Parker's Prop-Aid?
Yes, there are situations when you would need to install Hank Parker's Prop-Aid instead of a spare prop. First, if you strike an object hard enough, the teeth of the inner splined bushing, which is usually made of brass, will deform or become jammed against the teeth of the hardened steel drive shaft. When this happens, it becomes difficult if not impossible to remove the old prop.
We have also heard from boaters that have maintained their drive shaft with grease or never-seize, but because of electrolysis or the harsh salt water environment in our bays and gulfs, the inner splined metal bushing had become corroded or fused to the drive shaft, again making it very difficult to remove their prop. Others have talked about removing and then dropping their props in rolling seas! The beauty of Hank Parker's Prop-Aid is that you don't have to remove your old prop to install Hank Parker's Prop-Aid- why take the chance!
Remember, even if you buy an inexpensive composite prop - if you cannot remove the old prop - having a spare prop, even a free one, is useless!
If I buy Hank Parker's Prop-Aid do I need a spare prop?
You won't need a spare prop for most situations if you carry a Hank Parker's Prop-Aid, but if you break a blade on your prop, even Hank Parker's Prop-Aid cannot overcome this problem. That is why we recommend carrying both a spare prop and Hank Parker's Prop-Aid, just as most drivers carry a spare tire and a can of Fix-A-Flat in the trunk. There are situations when one is better to use than the other. Of course, if you cannot afford a spare prop, at least carry a Hank Parker's Prop-Aid with you, so that you can go boating with some piece of mind!
How fast can I go with Hank Parker's Prop-Aid installed?
Because the fingers of Hank Parker's Prop-Aid are inserted into the through hub exhaust ports, these ports are somewhat restricted. As long as the engine does not exceed 2500 rpm, the exhaust will pass properly through these ports. Even though coming in at 2500 rpm's is not enough to plane most boats, this is still far preferable to being towed in at a little over trolling speed or worse yet stranded for hours!
How do I install Hank Parker's Prop-Aid?
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