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 Post subject: Propeller info
PostPosted: Sun Dec 18, 2011 5:59 pm 
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Joined: Sun Oct 19, 2008 11:33 pm
Posts: 9006
Not All Props Are The Same!

Size — Props size is are described by referring to diameter and pitch. Diameter is twice the distance from the center of the hub to the tip of any blade. Generally smaller diameter props correspond with smaller engines and boats, while larger diameter props correspond with larger boats. Pitch is the forward movement of a propeller through one complete revolution measured in inches. Lowering prop pitch will increase acceleration and pulling power. A higher pitch prop will make a boat go faster as long as the engine has enough power to keep the rpms in the optimum range. If the engine doesn't produce enough power to run a higher pitch prop all performance suffers and engine damage can result. So - select the prop size that lets your engine operate at WOT within its correct rpm range.

Number of Blades —When the number of blades are changed, diameter and pitch may require a minimal adjustment to keep the RPMs in the proper range. For most purposes, 3 and 4-blade props can be used interchangeably on outboards and sterndrives without much of a change in performance

Material —We offer propellers made of composite, aluminum, and stainless steel. Composite props offer good performance, are durable, and inexpensive. They also offer some protection for your lower unit during a prop strike. Aluminum props are the most common and are suitable for the widest range of applications since there are so many models and styles available. Stainless steel props offer the highest performance and best durability.

Weight Flex Repair Cost
Composite Least Little Not Possible Least
Aluminum Medium Little Easy Medium
Stainless Steel Greatest Least Difficult Greatest

Cupped Propellers —Special curved trailing edges enable the prop to maintain performance at higher trim levels and in tight corners. Cupped props allow most boats to achieve a higher top-end speed or at least the same speed at a lower engine RPM. They also promote more efficient fuel consumption.

Wide Open Throttle (WOT) rpm Range —When selecting a prop, the goal is to choose one that allows the engine to reach its optimal WOT. This is generally between 5000 and 5500 rpm for outboards, 4400 to 4800 for sterndrives, depending on engine type. This information is included in the owner's manual of a new boat or engine.

Replacement Considerations
If your current prop's performance is acceptable (WOT is within manufacturer's guidelines) -- Choose a replacement prop that is very similar to the diameter and pitch of your current prop. You might consider upgrading to a different material such as stainless steel or trying a 4-blade prop instead of a 3 blade.

If your current prop is unsatisfactory —What if your engine operates at the wrong rpm at WOT? Pitch and rpm have an inverse relationship. Increasing pitch reduces rpm and reducing pitch increases rpm. A 1" change in pitch will usually result in a 200 RPM change in engine speed. Therefore, if your engine operates below the optimum proper rpm, you should consider a propeller with less pitch. If your engine over-revs, consider increasing the pitch.

Example: Your sterndrive tach limit (red line or rpm limit) is 4800. Your motor at WOT with full trim only turns 4300 rpm. Buy a prop with 2 less pitch to bring it up within 100 rpm of your tach limit. Your acceleration will improve and your top end will stay the same or improve because your engine puts out more power closer to its rev limit.
You might also consider changing the propeller size to affect a specific performance attribute. A lower-pitch power prop makes it easier to pop skiers out of the water. Tournament bass boats may need more top end speed and should use a prop with a higher pitch. Houseboats and cruisers care more about efficiency at displacement speeds, therefore they require a lower pitch to achieve low-end power and the largest diameter their lower unit can handle.

What's New With Propellers? Modular propellers are becoming increasingly popular. In fact many engine manufacturers are now selling modular props as original equipment. Our current offering of modular props includes Michigan Wheel XHS Propellers in both Vortex Aluminum and Apollo Stainless Steel.

also you can change the hubs to save cost.
you can have mercury hub pressed into a Michigan wheel for cheaper money than buying a mercury prop. and so on etc.

 Post subject:
PostPosted: Sun Dec 18, 2011 6:10 pm 
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Joined: Sun Oct 19, 2008 11:33 pm
Posts: 9006
It is a good idea to carry a spare prop.
with you at all times you never know
when you may loose a rubber in a hub
or roll or break some blades off a prop.
also extra shear pins on troll motor and
small engine props.

your not safe with stainless props either
once on lake livingston i hit something in
the water running at high speed and it rolled
all the blades on a stainless prop right next
to the hub it looked like a cork screw.
thankfully i had a brass prop for a spare.
i was miles from the launch site.

but you can get a good composite prop
for the least amount or a good repaired
one for a spare.

 Post subject:
PostPosted: Sun Dec 18, 2011 7:47 pm 
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Joined: Thu Mar 04, 2010 10:18 pm
Posts: 260
Location: LaPorte,Tx
Sticko are you posting all this info in the classifieds because you are selling a prop?

Just remember you work to live not live to work. Enjoy this life

 Post subject:
PostPosted: Sun Dec 18, 2011 10:36 pm 
Site Admin
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Joined: Sun Oct 19, 2008 11:33 pm
Posts: 9006
no jim just put it in Miscellaneous.

if i can find something i think may
help a newbe to the boating or fishing
world i post it

in case anyone was having problems with the prop not getting them out of the hole

or pulling a skier up ,

or top end speed

or need a spare prop.

thought it would be helpful information

for them.

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