Prop problems

[scottym]

Hi all

After loosing the prop on my boat I rang up a shop that specialises in props and on their recomendation purchased a 12 pitch prop to replace it.

The proplem is that the new prop does not perform nearly as well as the old one. At 4500rpm the new prop does about 20 to 21 knots and has a top speed of around 25 knots. The old prop at 4500 rpm would do 24 knots and had a top speed of about 28 to 29 knots. Both are alloy 3 blade props.

I bought the boat second hand and am asuming that the prop it had on it was the original yamaha prop which I was told is a 12 pitch. My question is, could the old prop have been a 13 pitch and hence explain the difference in performance between the two? I dont know a whole lot about props so I would be greatful if anyone could shed some light on my problem. The boat is a quintrex hornet trophey with a 60hp yamaha 4 stroke. I would also be interested to hear what size/type prop other guys use on similair size boats and how they perform.

Thanks alot

Scotty

[Zooter]

m8 your old prop should have its size/pitch inscribed inside it :)

I would give Stevo a call at solas props
http://www.solas.com.au/?gclid=CLKliZuk7ZoCFRMUagodDhUxBQ

He is the guru of props, they have a data base to help get the right prop for each set up, they will also exchange a prop you bought from them if you are not happy with it to a different one until you are happy with performance,
As long as you dont dint or damage it while testing!

Let us know how you go :)

[megafish71]

Good advice there zooter, solas is good to deal with. You could always use a prop slip calculator to try and figure out what prop you were running. Try this link http://www.rbbi.com/folders/prop/propcalc.htm

Cheers Ron

[scottym]

The problem is that the mechanic that serviced the outboard forgot to replace the split pin and my prop came off while at sea. The replacement prop that I purchased was from solas but when I asked about changing the pitch they didnt sound too keen. That left me wondering where the difference in performance came from. Thanks for the replies fellas.

[finga]

I hope the mechanic is paying for the new prop.

[Rockrash]

Both my F60's came with 13's standard. Going to a 12 on an F60 will make a big difference in a number of areas.
Not sure about speed figures. I am running a 12" equipped F60 on a 4.8mt 4mm alloy deep vee hull and GPS higher (just) top end kn figures than those you are quoting for the 13. Mine is all but on the limiter with the 12 with light loads at WOT. 11" Solas puts the engine on the limiter even with 2 up and the factory 13 only produces an extra kn or so but bogs it out of the hole. My GPS could well be inaccurate aswell I guess.