Prop options for Mariner 125hp

Stevie J · 01 March 2016, 21:38

Hi All,

I have purchased a Delta 5.8m Rib with a 125hp Mariner 2 stroke.

It has a Mercury Marine Lazer II - 48.16990 20P on it at the moment.

The prop is OK but was thinking of getting a 2nd/spare.

Is there a better prop to try for this boat engine?

Cheers Stevie

whiskylee · 02 March 2016, 08:22

We have only ever had good experiences with a High 5 prop, we have had a High 5 for over 20 years and it has been used on outboards & stern drive boats with great results, we also have a Laser 2 prop and others that get little use

Searider · 02 March 2016, 17:24

How is it running with the current prop?

paintman · 02 March 2016, 17:58

Is it within the engine's specified WOT rev range under your normal usage with the current prop?

Stevie J · 02 March 2016, 19:29

Hi all, appreciate the replies

Whiskylee - aren't the High Five props for 135 hp and above? Would they work well on the 124 hp I have? Are the Laser 2 props surplus? PM if they are compatible and available.

Searider/Paintman - had it out as soon as I got home (as you do). WOT it reached 5000 rpm and 45 knots (ish with some more in there if I'd feathered it better). At 3500 rpm it was 26.5 knots and 2000 rpm 8 knots. Tick over at 800 rpm gave 2.5 knots. Does that sound right?

I've no idea what the engine's specified WOT rev range is. Will dig around for that info, unless anyone out there can help with that?

There is a brutal pick up between 2000 and 3500 rpm. I've ordered Hydrifoil fins to see if I can smooth that out a bit, they did well on my previous rib with a 90hp Mariner.

S

whiskylee · 02 March 2016, 19:49

The even no's are for 75 - 115hp (20,22pitch)

I keep all our props, wouldn't want to sell any, they look too good on the garage wall !

paintman · 03 March 2016, 00:04

If your motor is the 125hp here: Mariner 125 - Mercury Marine then the WOT should be 4750-5250.
At 5000 you're right in the middle of the range which suggests with the loading you had that the prop is fine - although you seem to be saying that you could have gone faster so your actual WOT revs might be higher.
Be worth another run with what you would normally have in the boat to see if it stays in the range.
There are various prop calculators on the internet & I'd be inclined to enter your details into a few to see what comes up.
I've just had a play with this one & for 'good all round performance' it comes up with 3 props of 20 or 21 pitch - including what you've got fitted.
https://www.mercurymarine.com/en-gb/...tion#/step-one

ETA you mention 'brutal pick-up'. If that is your engine then the spec listed says that up to 1800 rpm (ish) it only runs on two cylinders so the other two coming in could explain it.

Stevie J · 05 March 2016, 08:12

Cheers guys,

I did not know about the 2 cylinder thing at low revs!

So from this I'm hearing that the Laser II 20P prop is fine for this setup and getting a similar one as a spare would be sensible.

Anyone out there have one to sell?

Any advice on where I should go to get one?

S

whiskylee · 05 March 2016, 10:17

Put a wanted add on here

Internet auction sites etc etc

Stevie J · 05 March 2016, 11:55

Done! Ad in bits and pieces.

Not much on ebay, all from the states.

S

whiskylee · 05 March 2016, 12:01

https://www.ebay.co.uk/ulk/itm/381439832483

They have a few prop options for your motor

whiskylee · 05 March 2016, 12:02

https://www.ebay.co.uk/ulk/itm/381439832483

They have a few prop options for your motor

whiskylee · 05 March 2016, 12:04

https://www.ebay.co.uk/ulk/itm/381439832483

They have a few props for your motor

whiskylee · 05 March 2016, 12:06

Apologies for the duplicate messages working from my phone on 3G signal

whiskylee · 05 March 2016, 12:14

This one is the older style but less money

https://www.ebay.co.uk/ulk/itm/361470460159

Iron Dials · 05 March 2016, 12:49

Just to confuse things. And I'm relatively new to this whole ribbing thing....

As it's your spare prop, would you consider a brand new aluminium prop?

(I can hear the sharp intakes of breath already- a local powerboat racer describe aluminium props as something similar to spacesaver tyres, although only one of us in the conversation had been flung from a boat at over 50 mph and hospitalised, so it's about expectations really)

They don't cost that much.
Brand new condition = no question marks over condition
If you had any leanings toward a different prop size you can try it at minimal risk.
As it's a spare, you can use it as a selling point if you're ever tempted to change boat.

I have 19in aluminium prop on my 115 4 stroke which performs fine for my needs (spare is a slightly dinged High 5).

paintman · 05 March 2016, 19:55

It's a thought. I have an ally prop on mine although I DO toy with the idea of buying a SS.
My spare prop - which was the one on the boat when I bought it & wasn't quite right - is an ally one.
AIUI if you hit something solid with an ally prop you are less likely to damage the gears than with a SS. From personal experience I saw a friend hit the concrete of a lifeboat slip with an ally prop & apart from fairly severe damage to the prop there were no other consequences.

Searider · 05 March 2016, 20:46

Quote:

Originally Posted by whiskylee

This one is the older style but less money

https://www.ebay.co.uk/ulk/itm/361470460159

Nothing wrong with that propeller.
Perfect as a spare at that price.