understanding volvo prop sizes & pitches????

[jawzzy]

As a new owner of a volvo DP-C outdrive, I'm trying to understand the sizing of props and pitches as I already understand in reference to OMC/Merc sizing (ie: 14x19, that's simple to grasp). Volvo have A4,5,etc, B4,5,etc, etc, etc..... Personally, I have a set of B4 aluminum props on my DP-C outdrive with a 501B engine, and was looking to possibly acquire a set of SS props, but just not sure what I need, or should be looking for. Any guidance improving my knowledge on this matter would be greatly appreciated, thanks

 

[Don S]

Re: understanding volvo prop sizes & pitches????

You are not going to be able to compare the props the way you do with OMC and Merc or even the Volvo single props. The DuoProps are completely different. The front prop is pitched differently from the aft prop. This is done so the props work together, so changing only the front or back prop to a different size is not a good idea, because they won't work well with each other.<br />What is your maximum WOT rpm with the props you now have.

 

[tommays]

Re: understanding volvo prop sizes & pitches????

don<br />how do volvos due with ss props and corrision compared to a bravo 3 in saltwater<br /><br />tommays

 

[jawzzy]

Re: understanding volvo prop sizes & pitches????

Don:<br />I've just purchased the boat, and haven't, and won't get a chance to test it for WOT till spring. During the test run though, it pulled out of the hole like nothing, but it was too rough to test it at high speed. I'm planning on replacing both props, I'm aware of that, but was lookng to understand pitches and diamaters. I've researched enough now to know that B4(aluminum) and C4 (SS) are for low end, out of the hole power, and the higher I go, like B6/B7, I will get higher speed, but very sluggish out of the hole, like moving from a 15 to 19 pitch OMC prop, right? So I guess I'm looking for a set of C4's or C5's if I want to move into SS. <br />Thanks for the help.

 

[Don S]

Re: understanding volvo prop sizes & pitches????

We only see boats here that are used in salt water, and I've not noticed any difference in corrosion between the alum, or ss props on the Volvo duoprop drives.<br />Even the DP-S drives (Volvo SX Style) don't seem to have any difference either.

 

[Don S]

Re: understanding volvo prop sizes & pitches????

jawzzy, You need to get the WOT right on the dp's. The A1 or B1 props have the least amount of pitch and as the number increases (A1, A2, A3, etc.) the more pitch to the props. Good hole shots may mean you are under propped and not getting full potential out of the props plus having too high a WOT rpm can damage your engine.<br />Also a boat that is over propped will overload the engine and will cause excessive engine wear from being overloaded.<br />That is why you need to get props that keep you in the proper WOT range, usually 4400 to 4800 rpm.

 

[jawzzy]

Re: understanding volvo prop sizes & pitches????

being the B4's are original factory equipped, I would presume they were meant to be the proper pitched props, so if I replace them with the same C4's in SS, they should perform within the proper peramaters, right? I may be able to go to C5's but I wouldn't want to go any higher.

 

[Don S]

Re: understanding volvo prop sizes & pitches????

"original factory equipped" doesn't mean anything. All that means is that was the original prop from the boat manufacturer that is usually "Close" to what is needed. Depending on the other equipment and weight of allthe "Stuff" added to boats over the years, what you need to know before changing props is the WOT rpm.

 

[jawzzy]

Re: understanding volvo prop sizes & pitches????

Good point, I guess I'll have to wait and check that out next spring, thanks!