which prop?

humper · 13 May 2008, 19:53

Hi, I have recently launched my new boat. Vipermax 7.5 with 250 etec. I wanted a 23" prop as I had this set up on my 7m Vipermax/250etec.and it proved to be a great all rounder. It was good out of the hole but could sometimes slip a bit.Top speed was good at 59mph.Ecomony was very good as we regularly saw around 1mile/litre when crusing. The trouble is the new etec has come with a 21" viper prop and 23" vipers are very hard to come by.
My engine supplier is being very helpful and has offered me various alternatives. A 23" 4 blade, a 22" viper or a 24". The 24" has to be rejected because of the potential slip problem.so it comes down to the 4 blade 23 or a 3 blade 22. I have got no experience of 4 bladed props so am struggling to reach an informed decision.The trouble is that I can`t try the 23/4blade as this will then become a used prop if I don`t like it and the dealer will lose out.I am tempted to go for the 22. Has anyone got an opinion on my choices?
Thanks

Mollers · 13 May 2008, 20:09

Oh 'eck. I was just about to mail Ian to enquire as to when my 23" might turn up.

Mine also came with a 21", I asked Ian to keep it as there was no point in dragging it to Cornwall to send it back. Which 23" did you have on your previous boat?

humper · 13 May 2008, 20:27

I had a 23" viper. It came recommended by Kris at Bruggemarine and he was adamant that it was the right prop. I was always happy with it although I did have the odd slip but I could`nt fault the overall usefulness of it,I spoke to Roger Swettenham(Ribster Rache)last week as he had both 21" and 23" props for his 7m vipermax/250etec. He reckons the 21 for extreme seas(in Roger speak extreme means effing ridiculous seas to the rest of us) and 23" for everything else in fact he now only uses the 23.
I know someone else who has a 7.5/250 etec who runs a 23 and is really happy with it. So anything else will not be as good. Given that 23 vipers are near impossible to get it`s going to come down to the 22 or 23/4blade i think.
Oh eck! indeed

Mollers · 13 May 2008, 20:36

How come the Viper 23's are so hard to get hold of?

humper · 13 May 2008, 20:58

Ian says they`ve stopped making them. Roger got his 2 years ago and it cost him 750quid and a lot of ringing around. I spoke to Kris today and he reckoned the 22 was the best option. But like everyone else he did`nt know much about the 23/4blade. He did`nt offer a 23" viper so I guess he can`t get them either.

codprawn · 13 May 2008, 21:08

4 blade props are great - you may lose a slight bit of top speed but you will get better grip.

There are plenty of other props on the market and a lot cheaper than those. Trouble is prop selection is such a black art I can understand why you want to stick with something you know works!!!

Mollers · 13 May 2008, 21:15

I've just mailed Steel Dev for an exact match with a Viper 23"

humper · 13 May 2008, 21:39

Quote:

Originally Posted by codprawn

4 blade props are great - you may lose a slight bit of top speed but you will get better grip.

There are plenty of other props on the market and a lot cheaper than those. Trouble is prop selection is such a black art I can understand why you want to stick with something you know works!!!

Thanks for your opinion, do you know if there is a ratio difference ie 23/4blade = 22/3blade or could you have a 23/4 in place of a 23/3?
I once had a hi-five on a 150 opti it was dreadfull!

Mollers · 13 May 2008, 21:48

Quote:

Originally Posted by humper

Thanks for your opinion, do you know if there is a ratio difference ie 23/4blade = 22/3blade or could you have a 23/4 in place of a 23/3?
I once had a hi-five on a 150 opti it was dreadfull!

No, 23 is 23 regardless of no. of blades. Four/five blades ( which I consider a little gimmiky) will give differing performance characteristics.

The gauge is, if the prop were passing through solid matter it would travel 23" in one rotation.

Chris · 14 May 2008, 23:41

Why don't you look at the Evinrude Rebel Prop they do a 23" in that style.

Cookee · 27 May 2008, 15:39

Quote:

Originally Posted by Mollers

I've just mailed Steel Dev for an exact match with a Viper 23"

I think the best ideas is sell the 21 and buy something else - as Mollers has done ~Steel Developments are great at providing solutions for just this sort of issue.

humper · 28 May 2008, 11:37

Hi Mollers have you tried the 4 blade yet?

Mollers · 28 May 2008, 11:55

Quote:

Originally Posted by humper

Hi Mollers have you tried the 4 blade yet?

Yep, chucked some Moet over it last night. See PM.

Tarbh · 18 June 2009, 08:39

I realise this is an old post....

Which props did you guys go with in the end then?...

I have an Etec 200 with a Viper 21, at WOT and fully trimmed up...the RPM can touch 6000, (the handbook states 5800 as max RPM).
Should i be looking to change up to a 22 or 23 pitch?...

Mollers · 18 June 2009, 08:56

Quote:

Originally Posted by Tarbh

I realise this is an old post....

Which props did you guys go with in the end then?...

I have an Etec 200 with a Viper 21, at WOT and fully trimmed up...the RPM can touch 6000, (the handbook states 5800 as max RPM).
Should i be looking to change up to a 22 or 23 pitch?...

I went for the 23"P 4 blade. Awesome grip and pull out, losing a bit to top end though and only pulling 5100rpm.

Chris · 18 June 2009, 08:59

Quote:

Originally Posted by Tarbh

I realise this is an old post....

Which props did you guys go with in the end then?...

I have an Etec 200 with a Viper 21, at WOT and fully trimmed up...the RPM can touch 6000, (the handbook states 5800 as max RPM).
Should i be looking to change up to a 22 or 23 pitch?...

Which 200 do you have? The big block or the small block ?

Tarbh · 18 June 2009, 09:02

It's a 2005 Big block...

Chris · 18 June 2009, 09:19

Quote:

Originally Posted by Tarbh

It's a 2005 Big block...

BRP quote the ideal RPMs for this engine are between 5500 and 5600 this should be your target RPM when trimmed out and a nornal load.

I would say you can try a 23 pitch Viper.

What speed are you currently seeing?

Tarbh · 18 June 2009, 09:33

Around about 45Kts...

2 People, 3/4 fuel...RIB is a 7m Humber Ocean Pro

From what i've read the 23" Viper is very hard to find?...

Tarbh · 19 June 2009, 08:25

I've just checked and my prop is actually a 19 Viper!

Based on that, would a 21 Viper be my best option?...

If that is the case, has anyone got a 14 3/4 x 21 Viper prop they no longer use and would like to sell on?...