| OUTBOARD PROPELLERS FOR GENERAL BOATING | | | | 4. On a twin motor installation you could run two |
| USE | | | | different propeller pitches but there would be a |
| The majority of you readers who are currently | | | | distinct performance disadvantage and it is highly |
| reading this probably have absolutely none to very | | | | recommendable to get two propellers that are of the |
| little knowledge about outboard propellers and their | | | | same pitch otherwise trying to balance equal thrust |
| functions. | | | | becomes almost impossible to do so. |
| Common questions that you might have would be | | | | 5. Propeller pitch is the angle of the blades of the |
| like; | | | | propeller to the hub of the propeller. Propeller pitch |
| 1. What propeller is best for my boat? | | | | can also be described as the theoretical distance a |
| 2. What's the difference between 3 and 4 blade | | | | propeller will move through the water for each |
| propellers? | | | | revolution (i.e. a 21 pitch propeller should move a boat |
| 3. Are there specific propellers for different outboard | | | | forward 21 inches for each revolution, assuming there |
| motors? | | | | is no slippage). |
| 4. Can I run two different propeller pitches on my | | | | 6. A counter rotation (or left hand rotation) propeller |
| motors? | | | | is a propeller that has its blades fixed in the opposite |
| 5. What's propeller pitch? | | | | direction to that of an ordinary right hand rotation |
| 6. What are people talking about when they mention | | | | propeller. These two propellers are used in unison for |
| counter - rotation propellers? | | | | larger boat setups with two high horsepower |
| 7. What's the difference between stainless - steel | | | | (normally above a 60HP motor) motors because due |
| propellers and aluminum propellers? | | | | to the two propellers rotating in an inwards direction, |
| 8. Would a stainless steel propeller work with my | | | | it cancels out the torque affect that would normally |
| boat and motor? | | | | be caused by the bigger motors. If counter rotation |
| 9. If my propeller is broken, can I get it repaired? | | | | propellers are not used on bigger setups, the torque |
| 10. And, what on earth is an outboard propeller? | | | | affect would make the boat very difficult to steer. |
| Well, I can assure you that by the time you have | | | | 7. Aluminum propellers are a lot cheaper than stainless |
| finished reading this article, you WILL have a firm | | | | steel and normally come standard with outboard |
| understanding what an outboard propeller is and what | | | | motors. Aluminum propellers flex when they are |
| its functions are. You will have a good understanding | | | | operated at higher speeds thus causing a general loss |
| as to what the best propeller for your boat setup | | | | in performance. The outboard motor must also be at |
| would be and you will be able to make decisions | | | | a fairly low setting on the boat transom as too little |
| based upon your own knowledge and not some sales | | | | prop in the water with an aluminum would cause |
| consultant that is only intent upon selling you any old | | | | cavitation (when the prop slips in the water because |
| propeller regardless whether it is correct or not. | | | | of air bubbles in the water around the prop) |
| So, let's get to answering those questions that I'm | | | | problems. A stainless steel propeller remains rigid in |
| sure you have... | | | | the water thus eliminating flex thus giving much |
| 1. It is always difficult to establish which propeller | | | | better performance. A stainless steel propeller also |
| would be best for a boat setup as everyone has | | | | delivers outstanding acceleration and bow lift and |
| different setups. There are certain guidelines for | | | | delivers a much better handling performance. The |
| establishing the correct propeller application. 1. We | | | | stainless steel also lasts a lot longer in salt or polluted |
| look at what the RPM of the motor at Wide Open | | | | water than an aluminum propeller. The downsides of |
| Throttle (WOT), this rpm should be between 5200 - | | | | a stainless steel propeller are its cost. |
| 5500 for a 2stroke motor and between 5200 - 6000 | | | | 8. Yes, a stainless steel will work with any boat |
| for a 4stroke motor. If the rpm is higher than 5500 | | | | setup; a standard aluminum setup is when the |
| then you have a too lower pitch prop on and if it is | | | | cavitation plate (that fin thing that is just above the |
| below 5200 then you have a too higher pitch prop | | | | propeller) is in line with the bottom of the boat. A |
| on. 2. We look at the amount of people that are | | | | stainless steel setup is when you raise that cavitation |
| normally on the boat. More weight means you would | | | | plate about 4 cm above the bottom of the boat |
| need a lower pitched propeller. 3. We look at the size | | | | (you normally raise the motor by about 2 holes on |
| of the boat and the size of the motor on the boat. | | | | the transom but on certain setups it can vary). The |
| In general, a bigger boat would result in a lower | | | | reason that a stainless steel propeller can be higher |
| pitched prop and a bigger motor with more Horse | | | | out the water is because of its non - flex ability in |
| Power (HP) would result in a higher pitched prop. 4. | | | | the water. On smaller motors (less than 50HP) a |
| Most importantly, you have to see the characteristics | | | | stainless steel propeller doesn't provide as bigger |
| of the boat on the water. If the boat battles to get | | | | performance gain as on a bigger motor. THIS |
| on the plane then you would need a lower pitched | | | | excludes racing where a stainless steel prop is |
| prop and if the boat revs very high and doesn't have | | | | definitely a better option. |
| much speed, then you would need a higher pitched | | | | 9. Yes, providing the damage isn't too serious, you |
| prop. | | | | can get the propeller professionally repaired at certain |
| 2. The difference between a 3 and 4 blade propeller | | | | places. |
| is; a 4 blade propeller gives you much better out the | | | | 10. A propeller is the funny looking thing that spins in |
| hole performance, a better more comfortable cruising | | | | the water when you move the throttle leaver |
| speed, better handling characteristics from the boat | | | | backwards and forwards. It is not advisable to put |
| and a better fuel efficiency as you can have the | | | | your hand near it when it's spinning! |
| boat at a lower cruising speed. The 3 blade is a bit | | | | Well, that's it. I hope you found this article interesting |
| better in top end speed though. | | | | and that you come away with a much better |
| 3. Some aftermarket propellers come with a multi-fit | | | | understanding of outboard propellers than when you |
| kit thus enabling the propeller to fit on most makes | | | | started reading. |
| of outboard motors. | | | | |