Propeller sizing and pitch on a Volvo Penta IPS system is critical and having the wrong props can cause costly repairs. Propping the engines correctly ensures the vessel performs as it should and the engine doesn't prematurely wear. This article will address some of the common questions we get regarding IPS propellers.
What size do I have?
This isn't always the easiest question to answer. IPS propellers are usually marked on the side of the hub, between the blades, or inside the rear of the hub. It's not usually something a diver can see underwater, and often requires some light abrading of the propspeed to be able to accurately read the markings, so it is usually best to have a propeller removed for inspection. Markings are usually the Volvo part number, along with the size. Volvo part numbers will be 6-8 numbers. Size will be indicated by 1-2 letters followed by a number, like F4, or TS6. The use of two letters (example TS) indicates a semi-planing hull. 
If the vessel was properly commissioned when it was new there should be documentation in Volvo Central Systems that any dealer can retrieve, showing what propeller size was on the vessel at commissioning.
What size should I have?
Your vessel should be equipped with the size propellers that allow your engines to reach rated speed with the vessel fully loaded. The rated speed for the engine can be found on a data tag on top of the engine, it is the speed at which the engine reaches maximum horsepower. This means if you travel with a jet-ski or tender on the swim platform, it needs to be there. Full fuel tanks, full water tanks, ice, fishing equipment, your wife's luggage... all of it.
If the engine is not able to reach rated speed then there is an issue with the engine or the propeller selection is too aggressive and you should consult a reputable propeller shop or consider purchasing a different size. The general, but not absolute, rule of thumb is going down one size (T4 to T3) should give you approximately 200 more rpms.
Can Propellers be repaired?
This is a controversial subject. To the best of my knowledge Volvo does not release the specifications of their IPS propellers. The only way to know the exact specifications is to buy a brand new set and have them scanned. What most prop shops do is balance the propellers, but that doesn't necessarily mean they were returned to their original specifications of pitch or their exact shape. 
Should I keep Spares?
If you don't like down time , then owning spare propellers for your Volvo IPS boat can be a great idea. Volvo often has supply chain issues with their props and it can often take weeks for new ones to be available. Contact us today and lets talk about our propeller storage options. You can buy spares, we will coat them so they are ready to go, store them free-of-charge for you in our warehouse, and ship them to you anywhere in the world when you need them. Just remember, chances are that if you need the change your props, you need to haul-out and check your shafts to make sure they're still within spec for straightness!
