Benefits of a Max-Prop Propeller BENEFITS
VERY LOW DRAG UNDER SAIL Under sail a Max-Prop will increase sailing speed between 10% to 15% compared to a fixed blade propeller, the largest difference being noticed when sailing in light air. The drag under sail varies widely between propellers, number of blades, angle of the shaft as well as location of the propeller on the boat. It is fair to say that a 2 blade Max-Prop propeller located on a horizontal shaft (sail-drive) will have the least drag while a 5 blade Max-Prop on a high angle shaft will have the most drag. However, even a 5 blade Max-Prop on a high angle shaft will have substantially less drag and provide more power when motoring than a fixed 2 blade propeller.
Whether purchasing, refitting, or re-powering, a boat owner is faced with a somewhat confusing choice of propellers: fixed bladed, folding, feathering, brands, material, number of blades. It becomes daunting. So why choose a Max-Prop?
RELIABILITY IN OPERATION Max-Props are "feathering propellers". Unlike folding propellers, Max-Props do not rely on centrifugal force to open. Instead, the Max-Prop relies on the torque from the shaft rotation acting on the "differential" type gear design in the body of the propeller. This in turns ensures an immediate opening in forward and more importantly, in reverse, unlike folding propellers which have a lag time in reverse.
RELIABILITY OVER TIME Through the years, Max-Prop propellers have acquired a flawless reputation for reliability and longevity. It is not uncommon to see a boat built in the 70's or 80's still using its orginally installed Max-Prop. A simple check on the internet would allow you to see the renowned reputation of Max-Prop. While we all wish that we could sail all the time, a propeller is a very important part of any sailboat. Sailboats end up powering a substantial amount of time and sometimes, in an emergency, we have to use our engine. In times like this it is critical to know that your propeller will open and will function as designed. Max-Prop has proven that time and again for decades.
PROPELLER DRAG
10 15 20 25 30 35 40 45
0 5
1
2
3
4 5 6 7 8
Boat speed in knots
Max-Prop 2 Blade Max-Prop 3 Blade Max-Prop 4 Blade
Max-Prop 5 Blade Fixed 3 Blade
EFFICIENT IN FORWARD While not always as efficient as a perfectly sized fixed propeller, the right choice of Max- Prop diameter, pitch and number of blades will usually achieve 96% or better efficiency compared to a fixed blade propeller. This maximum of 4% drop in efficiency is only seen at maximum throttle, which is seldom, if ever, used. The fact that with a Max-Prop, a boat owner or a designer can choose not only the diameter and number of blades of the propeller but can also adjust the pitch easily after sea trials makes the Max-Prop an ideal tool to fine tune a boat’s performance under power.
EFFICIENT IN REVERSE The simple fact that the Max-Prop blades use the same leading edge and pitch in reverse as in forward results in identical power in both directions. A fixed blade propeller loses almost 50% of its power in reverse. Worse yet - a folding propeller which, depending on the brand, can lose up to 80% of its power in reverse. The Max-Prop blades switch from forward to reverse instantaneously. It takes only ¾ of the shaft rotation for the blade switch to occur.
BOLLARD PULL In kg, engine 50 HP, propeller diameter 18"
100 150 200 250 300 350 400
0 0 300 450 600 750 900 1050 1200 50
Shaft RPM
TO ORDER VISIT WWW.PYIINC.COM OR CALL 425-355-3669
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