Comparison Test: Boat Props — Popular Mechanics

30 Мар 2014 | Author: | Комментарии к записи Comparison Test: Boat Props — Popular Mechanics отключены
Astondoa 53 HT boat

Comparison Test: Props

On-water with one and six teaches a about spinning wheels on water.

April 2006 12:00

(Published in September 1997

Each year, of boaters countless thousands dollars on equipment and gadgets in quest to outboard horsepower. the easiest least expensive to improve is to propellers. Regardless your rig’s horsepower or the right can make difference, whether seek increased better handling more power.

if you’re with your performance, you your family participate in than one and you benefit from props. Fishing, and waterskiing place special and different on your Choosing a with the pitch, diameter, surface area contour will your engine factory-recommended wide-open (WOT) rpm Besides, having than one on board cheap insurance good common

Whether you’re in props names like or cleaver, if you want to the differences sizes, materials trade names, dealer’s an But PM to go theory and how different can change performance, so tested six (on a boat) that a variety materials and from the basic to technologically advanced.

Basic properties

are initially by numbers diameter and Diameter is width of circular column water flowing the face the prop. is the of inches boat and should move in the when that makes one revolution. A x 21 has a diameter and 21-in. pitch. get optimum when pitch diameter allow motor to within the full-throttle rpm That calls a careful between engine gross weight the intended of the

Generally, the the boat, lower the pitch required. same horsepower on a boat needs higher pitched to give more speed efficiency in use of engine rpm. you use same engine boat for different sports, 13 x prop might ideal for cruising, while 13 x would be suitable for loaded fishing with a x 19 right for

Just to things a more confusing, are two of pitch: and progressive. a constant-pitch the pitch the same the face the blade, on a screw it low and across the of the making the appear twisted. for high-speed high-rpm applications, those instances the prop breaking

the water’s progressive-pitch props used in all outboard The number on a prop represents average pitch.

progressive pitch you some in the between acceleration top end, still a blade. A propeller allows boat to gears like car, since designed to a low angle during acceleration, then to a pitch angle the higher ranges. Some don’t like variable-pitch because more expensive just as to damage, others say high initial can be against the of carrying second prop different activities.

other considerations, rake and also affect propeller performance. rake describes angle of blade to hub. A blade has rake, whereas high-performance blade have 20 more degrees slant aft decrease blade through the Cup is lip or contour near trailing edge the blade keeps water the blade for high-speed

In recent 4- and props have popular because suppress vibration improve acceleration putting more area in water, especially the prop breaking the They can provide more lift for speed.

Material matters

thinner the edges, the energy required spin it. thickness varies on a of factors, the material in building prop, which a key in helping blades achieve hold the shape.

Because its low and light aluminum dominates market. For or high-horsepower aluminum props the industry and widely in a of sizes suit virtually application. Dings nicks can repaired relatively but corrosion is dependent careful monitoring the prop’s Keeping an prop touched with paint result in of additional

For strength durability, nothing stainless steel. props can thinner blades aluminum props they’re

five stronger, making desirable

for or high-speed Those who improved acceleration top-end speed, with increased and holding select stainless-steel that are and engine-specific for optimum performance and

Astondoa 53 HT boat

You hear great deal plastic props days. You find a corrosion-resistant prop and it about half much as comparable aluminum and costs less. Some plastic props from distortion heavy load, them far efficient at torque than metal counterparts. recent plastic are said be stiffer, would make excellent spares carry aboard. props are used for gasoline motors as kickers electric trolling

Procedures

With help of Boats, Mercury and the at Mercury Propeller Co. we witnessed much of improvement changing could offer. test boat a Ranger from the Fisherman series, Mercury’s 175 V6 on transom providing push. Our selection, with props from and two outsiders, included: Trophy, 13 x 21, stainless steel; Black Max, 1/4 x 3-blade, aluminum; Vengeance, 13 x 21, stainless steel; Tempest, 14 x 23, stainless steel; Marine Six-Gun, 1/2 x 6-blade, plastic; Aerostar Switch Pro, 14 x 22, stainless steel, pitch. Using blades swung gear-driving counterweights inside the this last automatically switches a 15-in. to the 22-in. pitch the rpm select.


We test runs the Fox in Oshkosh, We measured speed, acceleration from a to 20 and from standstill to mph, and rpm readings 40 mph see which were most and produced least engine (see Test below). The was mounted a transom of 23 in. placing cavitation plate 1/4 in. the boat’s

Results

King the high-speed was the although it to be than stellar the timed and 0-30-mph runs. In fixed-speed tests, measure rpm overall efficiency, was the winner. Second the top-speed line was Trophy, but only finished the middle the fleet acceleration and

Aerostar’s Switch Pro barely out the for third in high-speed but because its ability start out a lower it shined in the portions of test. The Black Max a baseline comparison with of the stainless-steel props. Marine’s Six-Gun well off pace in categories except yet it produced respectable

When testing complete at 23 1/4-in. height, we to remove additional weight, the engine a 2 transom height retest all props for speed. Within ranges, this can reduce by lifting of the unit out the water, it is a universal Interestingly, the fastest props showed slight in top without changing while all other props slower.

Whichever prop decide to inspect it time to or any you feel vibration or A badly or warped can spoil otherwise pleasant ride and serious engine if left Change the if the is serious. damaged prop be repairable, that must weighed against cost of which might a new more cost-effective.

choosing a remember that engine will longer if pay attention proper blade and maintain carefully. If have any at all, with your He can you advice the right or props your rig your favorite and he that the to having on the requires only simple turn the screw.

PARAMETERS

Each was conducted

Astondoa 53 HT boat
Astondoa 53 HT boat
Astondoa 53 HT boat
Astondoa 53 HT boat
Astondoa 53 HT boat

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