What is a Volvo Penta Propeller?

John F. Kennedy once said that “we are tied to the ocean. And when we go back to the sea, whether it is to sail or to watch, we are going back from whence we came.” If you happen to ask anyone about their favorite place, the majority of people will answer with the beach.  In fact, for most people, just admiring the serene, vast horizon on the beach is worth making long trips. However, if you want to really appreciate the sea and its majestic prowess, you would be much better off if you embark on a sailing journey. You get to be out there, at the heart of the sea, with nothing around you but blue waters and the ever-colorful marine life –– not to mention some breathtaking sunrises and sunsets. If you want to go sailing though, you might want to learn about the Volvo Penta propellers. 

What is a Volvo Penta propeller?

As the name implies, it is a sailboat propeller, and it is an engineering work of art. It is one of the most sophisticated propellers you could get your hands on, and its performance is quite powerful and efficient. You can buy volvo penta propellers from Getaprop.com, and you will find a wide variety of options to choose from, each with different features that you need to carefully go through to make sure you have the right one for your boat. Generally speaking, the Volvo Penta propellers are designed to work with engines from 5 to 40 HP, and they come in different sizes and pitches. 

What makes them so special?

• Quality materials 

Well, the ingenuity in the design aside, those propellers are made of some very powerful and durable materials, which is very important for your boat. You want to buy something that would last for quite some time, without malfunctioning after every boat ride. This is why these are very popular in the markets, as people always look for the highest quality materials. The Volvo Penta propellers are made of very strong nickel-bronze-aluminum alloy, which is the secret behind their endurance levels. 

• Variety 

One of the most popular reasons why the Volvo Penta propellers are popular is because they can be used with the different propulsion systems out there. Whether you have a powerboat or a sailboat, these ones will work just fine and can give you the best performance possible out of your propulsion systems, because they are specifically designed to be a part of that system, which makes their presence quite efficient. 

• Bonus features

These powerful propellers come with a 12-month warranty, which can even be doubled if you have authorized Volvo Penta dealers do the installation for you. This is a great option in the unlikely case that you find problems with your propellers, but that isn’t likely to happen because they are designed to give you excellent performance for years to come. 

If you are considering getting a boat to go on sailing expeditions, then you should definitely consider getting yourself a Volvo Penta propeller, too. It will definitely help you make the most out of your sailing trips, and it will also ensure that your driveline has been healthy for many years. 

Propellers and Prop Walk

Propellers are something that you don’t always think about while sailing. These little machines play a huge role in how your time on the water will be spent!

This video shows you the ins and outs of propellers and also helps shed some light on the mystery of prop walk.

How Many Propeller Blades for an Electric Motor?

Propellers come with all different numbers of blades. In general, the more blades you have, the more thrust you will be able to generate. For a fuel burning engine, this is the only concern. For an electric motor on a sailboat, there are other factors to consider.

The ideal number of blades is an odd number. On a smaller boat, 3 blades; if the boat can fit it, 5 blades.

The reason an odd number is ideal is because this keeps the same number of blades exposed to the water around the keel the same which makes regeneration of power from the motor a lot more uniform.

When a propeller spins behind the keel, the blades exposed to the water will oscillate as such:

• 2 blades: 2,0,2,0,…

• 3 blades: 2,2,2,2,…

• 4 blades: 4,2,4,2,…

• 5 blades: 4,4,4,4,…

When an even number of blades spin, the propeller will oscillate between all the blades showing and then two of the blades hiding behind the keel.

When an odd number of blades spin, there will always be just one blade hiding behind the keel. This will oscillate between being up or down blade behind the keel, but the number of blades exposed to the water will always be one less, not two, than the number on blades on the propeller.

This means that an even number of blades will oscillate in power while an odd number of blades will remain steady and constant while you sail.

Propeller Nuts

The propeller fits onto the tapered shaft tip and is tightened into place by two nuts that thread onto the end of the propeller shaft. One nut is small, the other nut is big. This brings up the question of which order should the nuts be placed?

You could either place the big one on first, tighten it all the way, and then place and tighten the smaller one. Or you could place the smaller one first and tighten it all the way, and then place and tighten the bigger one. So many options on such a tiny part of the boat that is instantly forgotten the moment the boat goes into the water.

The proper order is the small nut first and the big nut second.

When you tighten the small nut against the propeller, the force of the propeller is then pushed onto the threads of the nut and shaft. When you tighten the big nut, the lateral pressure from the small nut is transferred to the big nut which has more threads and transmits the force more evenly to the threads of the shaft tip.

The reason to have two nuts is simple, when they are tightened against each other, they will apply lateral pressure away from each other and seize to the threads that they are pushing against. When the two nuts are tightened into each other, they will not come loose as the entire assembly spins furiously without any inspection. As a safety precaution, the end of the shaft will have a cotter pin just in case the nuts come loose. A loose propeller is a problem that can quickly be remedied. A lost propeller is an expensive problem that is not easy to fix when out at sea!

Next time you are on the hard, take a look at the nuts at the end of the propeller shaft and make sure that the small one is next to the propeller, followed by the big one. 

Prop Walk Test

Your yacht is floating in her slip, securely tied to the pier and ready to go sailing. You need to reverse you yacht out of the slip, but which way will she walk?

A very simple test to see which way and how severely your yacht will walk is to put the boat in reverse under full throttle and evaluate the prop wash. 

The side with more prop wash will be the side you walk away from. If you see prop wash on your port side, you will walk to starboard. If you see prop wash on your starboard side, you will walk to port.

While most of the factors that compound to create prop walk are beyond your control right before you go sailing, one key factor is: engine speed.

Hello, World!

With the engine off, there is no prop wash and the water around the boat will be still.

With a little bit of throttle, the engine is consuming 32.1 amps and the propeller is spinning at 697 RPM. There is very little prop wash on either side, as there is little thrust being produced. 

Hello, World!

With the engine drawing 61.2 amps, and the propeller spinning at 889 RPM, there is considerably more prop wash and prop walk. You can see from this picture looking at the bow how the docklines are holding the boat steady as well as the difference in the amounts of prop wash on each side of the boat. The port side is very disturbed, while the starboard side is very calm. This illustrates why the boat will walk to starboard.

With the engine drawing 89.4 amps, and the propeller spinning at 1012 RPM, the prop wash is considerably strong on the port side and only beginning to disturb the water on the starboard side.

Hello, World!

With the engine drawing 178 amps, and the propeller spinning at 1255 RPM, we are creating considerable trust and prop wash on the port side.There is a very slight amount of prop wash showing up on the starboard side.

The final test was performed at full throttle, with the electric motor drawing 302 amps, and spinning the propeller 1480 RPM. At this pace, our very small battery bank will only last for 0.4 hours, or 24 minutes, which illustrates why we sail everywhere instead of motoring everywhere. With a larger battery bank and a generator, we could have a significantly longer range under power, but we chose a simpler and less costly installation and opted for a small battery bank with a full suit of sails.

Hello, World!

At full throttle astern, the prop wash on the starboard side is starting to be more evident, but nowhere near the level of disturbed water on the port side. Under full throttle, the boat will walk to starboard as all of the thrust is being directed towards the port side of the hull.

As the RPMs increase so does the bias in the in thrust, leading to an increase in prop walk to one side while moving astern.

Light Throttle

Full Throttle

The prop wash on the side the boat walks towards in reverse is about the same under light and full throttle.

Light Throttle

Full Throttle

On the contrary, the prop wash on the side the boat walks away from in reverse is vastly different. Under light throttle, the prop wash is very light and can be somewhat combated by the opposing sides prop wash. Under full throttle, the prop is very powerful and will push the boat over, causing the phenomenon known as prop walk.

Next time you need to reverse into a slip, try using a light amount of throttle. If you are reversing out of the slip and have significant prop walk, maybe you should consider walking the boat out of the slip by hand and then motoring away once clear of the slip.