More Prop Advice

[Pez9001]

Hi and sorry if this has been asked before.

I'm looking for a new stainless steel prop for a Mercury 75 ELPTO.

Any suggestions? I'm not sure if I want speed or economy or a bit of both so any ideas either way would be appreciated.

Thanks

Pez

[Last Tango]

You'll need to give a bit more info. eg exact boat, loading, the speed that you expect?
I had a Seapro 520 with a Merc 75ELPTO. I ran that with a 18" Vengence prop that gave exactly 40 mph with four adults and around 50 litres of fuel and would pull two light skiers with two adults in the boat. It could have been pushed to 20" for "one-up" absolute top end, but the Seapro is quite a light boat and I'm guessing, unless it's something very similar, 17"/18" is probably what you'll need.

[Pez9001]

Thanks and sorry for the lack of info. Bit new here.

Boat's a 5m Narwhal, typically with 2 adults and 50 litres of fuel. No skiers. Hoping to get up to 40 mph. Would you recommend any particular brand of prop other than a Mercury prop?

[Last Tango]

Afraid I've only ever used Merc Vengence and Laser II (the Laser II is better, hangs on for longer when you're trimmed way out.) I've never bought a new one either, there's always plenty of good ones going second hand for less than half the price of a new one.

I don't think your 40 mph is unrealistic but you'll need 18" pitch to get that.

[Pez9001]

Thanks Last Tango. Very much appreciated.

[Searider]

You'll need the small hub propeller s for a 75hp.

I had a 20" laserII on the 90 on my 5.4m searider and got almost 40 knots (46mph)

What size prop do you have now and what RPM are you getting?

[Pez9001]

The boats a bit of a "project" and the rev counter doesn't (currently) work. Engine is rated to 5250 rpm.

Prop was an aluminium 13.25x17 3 bladed prop, though now 2 bladed after one sheared off at the weekend.