Duo Prop knowledge?!

[New Boater]

Hi all,

Have been getting conflicting advice (even from one dealer to another) so I am throwing this out to the community!

I need new props but which ones? Can’t tell what the old ones were (yes that bad)

Anyway,

The Boat is a Hardy Marine 305 (weight is between 3.5 to 4.0 ton)

Engines are KAD32’s (s/c version)
Drives are DP-E

What would you put on?

I know the KAD32’s with DPE’s went into lots of similar sized boats so any info from actual experience would be valuable!

We are using her on the Sea

 

[Chris_d]

Have look here https://techzon.bg/wp-content/uploads/2020/03/Volvo_Penta_propeller_guide.pdf
Your probably looking for size A5 or A6, however it will be marked on your props somewhere inside the hub and you might have to scrap the crud away a bit to find it..

Bear in mind In that document you won't find any reference to DPE's thats because they are a version of the 290DP.

 

[SC35]

The top speed on similar advertised boats seems to be 28-30kts, which puts it in the range of A5.
I think A6 is too big - my S28 had A6, but that could hit 34kts on a good day with a bit of tide.

 

[ChromeDome]

Make sure you're GW is correct. 3.5 to 4 ton sounds like the empty, dry boat factory figure.

Add the weight of all stuff onboard. Fuel, water, tools, gear, spares, anchor+chain, crew.

And, since weight is critical for planing boats' performance, remove any dead weight.

 

[Andyroonot]

Any VP Dealer should be asking you the right questions and putting the data into the prop calculator tool. If the data going in is correct then it’s pretty accurate for churning out the prop size required, although as suggested above, weight is critical so an actual measured weight would be ideal if known

 

[ChromeDome]

Calculators are good and can be accurate but nothing beats real life testing. Good dealers allow you to buy one set and swap them if needed.

You may end up in a pinch between two prop sets. I'd recommend the set that allows the engines to reach max. recommended rpm (3800). Gives you better acceleration and a reserve when having guests. The max. recommended rpm for cruising is 3600, btw.

 

[Andyroonot]

Which Dealers are doing that??? Do they have a stock of their own props or do they return the 'wrong' ones to Volvo?
I wouldn't be happy buying a new set of props that someone else has already fitted & used

 

[SC35]

Which Dealers are doing that??? Do they have a stock of their own props or do they return the 'wrong' ones to Volvo?
I wouldn't be happy buying a new set of props that someone else has already fitted & used

Sealine had a stock of props of different sizes which were trialled, a size chosen, then customer boats were fitted with new props of the same size.
Not sure how other manufacturers did it.

I wasn't aware that a Volvo dealer would keep a stock of props for test purposes.

 

[Mr Googler]

Maybe cockwells have a folder somewhere and can tell you what was fitted from new?

 

[ChromeDome]

Which Dealers are doing that??? Do they have a stock of their own props or do they return the 'wrong' ones to Volvo?
I wouldn't be happy buying a new set of props that someone else has already fitted & used

As long as props are like new when returned, the next customer wouldn't even know.

I might have bet on a presumption of Volvo Duo props. I have borrowed all sorts of other propellers from dealers - new or used, in connection with purchases. So, my bad apparently.

On that basis I'd suggest you turn to FYB carrying "port wine and smooth talk".

Edit: Would this be something for you?