Duoprop Q

[Tafflad]

Have a new boat with a VP 280-C DPS
Just finished the running-in process ..... and today tried WOT run for the first time.

The average on 3 runs was 5180 rpm
For this motor the WOT range is 5400-5800

This would suggest boat is over propped ...and I should drop pitch by 2"

This is where I am not unsure .... I don't know what pitch is fitted .... the Duoprop set is an FH4 and Volvo do not publish the equivalent pitch for the Duoprop.

Anybody clued up on Dupprops ... and should I look to get this changed.

 

[Scott Danforth]

volvos are simple. if your over piched with the F4's drop to F3's. if your under pitched with F4's, you go up to F5's

their props are in a series, starting with 1 (least aggressive pitch), going to 8 (most aggressive pitch)

for example, my drive uses B or C series props. Im under propped with B6's and over propped with B8's, so I need B7's

 

[alldodge]

volvos are simple. if your over piched with the F4's drop to F3's. if your under pitched with F4's, you go up to F5's

their props are in a series, starting with 1 (least aggressive pitch), going to 8 (most aggressive pitch)

for example, my drive uses B or C series props. Im under propped with B6's and over propped with B8's, so I need B7's

No offense but that is funny.
B, C, F and 1 thru 8, what's more simple then that

Maybe 17 thru 30 pitch, but that's just me

 

[QBhoy]

Is this the same boat and engine you had ran in ages ago at WOT and posted about it ? Haha.
Anyway. Apart from that, if it helps you any, all I’d say having had a 23ft cruiser with a DPA I think... (290 dp from about 89 I think). It had a 4.3 205a gm engine. Rpm range was different from yours of course, she had b5’s and was propped perfectly to 4800 rpm wot and trimmed up...but my point being...if I had the trim tabs down even a little or not trimmed up enough...even lots of fuel on her...she could easily lose 300rpm or sometimes more. Just in case you weren’t thinking about that kind of thing and if it helps. Even at the end of the season she could lose a bit from crap on the hull. Flat calm water could hold her back too from the top of the rpm range.
she managed about 35 mph usually. 23ft U.K. built heavy sealine cruiser. Think she was about 1800/1900 kgs dry.
Is the outdrive new as well as the engine ? Was it set up well on the transom ?
mall the best.

 

[Tafflad]

volvos are simple. if your over piched with the F4's drop to F3's. if your under pitched with F4's, you go up to F5's

their props are in a series, starting with 1 (least aggressive pitch), going to 8 (most aggressive pitch)

for example, my drive uses B or C series props. Im under propped with B6's and over propped with B8's, so I need B7's

My Q though is how much difference in pitch per ‘set number’ .... I don’t have luxury of multiple sets to try.
if I go from F4 to F3. What difference will it make .... 1” change on single prop would be around 200rpm, Is there a defined expected change between each set.

 

[Scott Danforth]

It varies from series to series and is not consistent. But is about 2"

talk to your dealer. They most likely have props you can try

 

[Tafflad]

Boat dealer has no props ... Raised question with Volvo Penta dealer, they deferred to VP UK who are pushing me to go back to FourWinns who in turn tell me it has to dealt with under VP warranty.
Local VP dealer also has no spare props.

I was asked to repeat WOT test ..... so did that yesterday ...

Carried out 3 WOT runs the first 2 upwind, the 3rd downwind.

4 on board, 1/2 tank fuel, trimmed Out as necessary.

5180 rpm at 45 mph 5120 rpm at 44 mph
5100 rpm at 43 mph


RPM band for this motor is 5400-5800

So to me, this confirms that boat is over-propped, currently running H4, and if I follow the above comments I should change to H3 series, is that correct ?

 

[Scott Danforth]

I would drop down to H3 if you are 200-400 RPM under your WOT window

 

[QBhoy]

What engine and boat is this again ? Not sure, but I have it in my head it’s one of the newer VP V6 petrol engines ? What model of four winns is she Taff? Be good to get her sorted out for you.

 

[Tafflad]

Its a 2020 FourWinns H210 fitted with the 4.3L V6 280hp and a DPS drive.
PROPELLER, FH4 #3885840 / MT-20-V6-280C-DP V6-280C-N/DP STDR 280HP 2.14:1

Tested again last night removing wakeboards so no issue with excessive drag .... 3 adults on board, 1/2 tank fuel.
Average of runs was 5,200 rpm and 44.5 mph

 

[Tafflad]

Update after further WOT tests ... VP have agreed to fund one prop and Four Winns the other.
on order so looking FH3 being fitted next week.