Prop Boffins

Mollers · 10 October 2005, 18:27

OK all you prop boffins, I need a little help. I'm currently running a Quicksilver Vengeance 19"P on my 150 Opti. The pull-out is superb and the top speed is just over 40knts at 5400rpm. I know that Opti's rev out to 5750, but mine wont. This is prob due to throttle adjustment not propping. I want to buy a stainless 21"P to use for extended cruising to give a higher cruise speed. I've been offered a Laser 2 which is 21"P, It's the rest of the part numbers that I'm not sure about. They are:- 48 16546 A40 21P. Does anyone have access to a Merc/mariner comp. or parts book to let me know whether this is the prop for me? Thanks.

Kernow Buoy · 10 October 2005, 18:42

[QUOTE=Mollulnan] They are:- 48 16546 A40 21P.

Yep, that's a Mercury part

Mollers · 10 October 2005, 18:48

[QUOTE=Kernow]

Quote:

Originally Posted by Mollulnan

They are:- 48 16546 A40 21P.

Yep, that's a Mercury part

So can I slam this baby straight on there and go flying up and down the Roads at Warp Factor 3?!!

Pete7 · 10 October 2005, 19:11

Quote:

Originally Posted by Mollulnan

So can I slam this baby straight on there and go flying up and down the Roads at Warp Factor 3?!!

No. If your only pulling 5400 with the 19" then you will have alot less revs with 21" It will be slow use more petrol and put unessary strain on the motor. Sort the revs out first so that it can pull full revs or even higher if you want to turn a bigger prop. 1" equals about 200 revs btw.

For comparison, Stu's ex Scorpion and my ex Tohatsu (both 6.5m) and both light boats with Opti 150s, ran best with a 19" laser II props. Think Duncan has 19" on his 6.5m Scorpion.

Pete

Searider · 10 October 2005, 19:43

5400rpm 150hp opti 6.5m scorpion for about 41/42 knots.

Mollers · 10 October 2005, 19:57

Quote:

Originally Posted by Pete7

No. If your only pulling 5400 with the 19" then you will have alot less revs with 21" It will be slow use more petrol and put unessary strain on the motor. Sort the revs out first so that it can pull full revs or even higher if you want to turn a bigger prop. 1" equals about 200 revs btw.

For comparison, Stu's ex Scorpion and my ex Tohatsu (both 6.5m) and both light boats with Opti 150s, ran best with a 19" laser II props. Think Duncan has 19" on his 6.5m Scorpion.

Pete

It depends what you mean by "Best"? I'm keeping the 19" and will run both. I don't need it to scream out at 5750 as I don't intend to run the thing flat out! What I'm looking for is another 2 or 3 knts at 3800-4000 rpm which is my prefered cruising rpm. I'll run the 19" for general use, wakeboarding etc.

nugent · 10 October 2005, 20:13

why do i think i have droped a clanger here,,,
bought a 21" wid my new 150 opti on my 6.5 osprey can see that getting changed pretty soon allthough get it in the water first .

Mollers · 10 October 2005, 20:31

Not sure that you have Nuge. I'm running A 19" on the same rig and I'm not 100% with it. So we'll compare notes eh?

nugent · 10 October 2005, 20:37

all going well she will be in the water saturday

Mollers · 10 October 2005, 21:40

Put mine to bed today

Gave her a nice soapy wash and dry. Flushed with anti-freeze, nice spray up with GT85. In the Father in laws barn covered up with 1000 bales one side, two tractors and a skid steer the other. Nick that ya' b'tards!!!

Daniel · 10 October 2005, 22:18

Never really decided if i like the 19" or 21" best on my rig either. 19" rev's higher but does not go any faster.

Kernow Buoy · 10 October 2005, 22:29

1000 bales in a barn , nothing for you to worry about then

Mollers · 10 October 2005, 23:00

Quote:

Originally Posted by Kernow

1000 bales in a barn , nothing for you to worry about then

Actually, the rats having a gnaw are more of a worry!

jwalker · 10 October 2005, 23:07

Shit, I'll need to get that big bag of sodium chlorate moved, pronto.

Pete7 · 10 October 2005, 23:26

Quote:

Originally Posted by Mollulnan

It depends what you mean by "Best"? I'm keeping the 19" and will run both. I don't need it to scream out at 5750 as I don't intend to run the thing flat out! What I'm looking for is another 2 or 3 knts at 3800-4000 rpm which is my prefered cruising rpm. I'll run the 19" for general use, wakeboarding etc.

It might be enough just to change the prop from a vengence to laser II keeping the 19" pitch. See if you can borrow one.

Quote:

Originally Posted by nugent

why do i think i have droped a clanger here,,,
bought a 21" wid my new 150 opti on my 6.5 osprey can see that getting changed pretty soon allthough get it in the water first .

Run it in first and see what its like. Both sizes are very popular so lots about on the second hand market.

Pete

Mollers · 11 October 2005, 09:54

What about the prop part number? Can anyone shine a little more light?

Daniel · 11 October 2005, 09:56

Is it important? A mercury agent will be able to look it up and tell you the diamater and hub type i suppose.

Mollers · 11 October 2005, 10:12

Quote:

Originally Posted by Daniel

Is it important? A mercury agent will be able to look it up and tell you the diamater and hub type i suppose.

Too right it's important! I like to get the numbers spot on. There's a hell of a difference between 6 and 8. Ask the missus!

Don't worry John, mine's a mathmatition. Honest.

Daniel · 11 October 2005, 10:37

I'm obviously missing something. This is a 21" Mercury Laser II prop that will fit a v6 gear case. They've been making them for years. What else is important?

Nick Hearne · 11 October 2005, 10:42

As I have said B4 I have a 5.75 Viper with a 150 Opti & running a 19" Lazier II, as recommended by many people on hear

I have not had the chance to do too much testing as 40+ knots dose not go down well with the family! But so far 46 Knots at 4500 approx, but trying to look at the gages at this speed is not so easy