Another Prop question!

[Whitey72]

Hello all from Australia,
I have recently bought a 2006 Q4 SF with a standard 4.3 mercruiser and a 13.25 x 19 stainless 3 blade prop fitted. The boat will be used for fishing (of course) as well as slalom skiing. With the current prop I get 47mph flat out at 5000rpm limiting. I haven't tried to ski behind her yet but I'm seriously considering buying another prop.
I was thinking of a 4 blade Solas stainless 14 x 20 pitch to help with the hole shot but also keep the revs low when pulling 32 mph. Any advice would be greatly appreciated as to what others have tried. Silly thing is, even with $140 usd for postage from the us to aus and the purchase price, the prop is still half the price as to what they are to buy here.
Cheers Whitey

 

[Lyle29464]

Re: Another Prop question!

Sounds like you have your ski prop. Going up an inch an inch in pitch + 3/4 in dia and adding a blade is a "BIG change". Hard to use numbers when you really do not know what the top end is. Think I would try to borrow a test prop or stay with what you have. Maybe the dealer has other rigs out there?

 

[Hashi]

Re: Another Prop question!

As Lyle said, "Try to borrow a test prop". My local dealer offers test/loaner props before I buy. You should look into this in your area. You may have to put a security deposit down on the prop.

 

[Whitey72]

Re: Another Prop question!

Thanks for the reply Gents trouble is a lot of dealerships aren't that happy letting you try different props down under. I bought my boat from a company that imports them from the states and not a dealership so I can't try that. When we went for the test drive there was an aluminium prop fitted (14" diameter but unknown pitch) which was probably the standard original but it had 2 bent blades. The boat seemed to perform a lot better with hole shot and speed but had terrible vibration due to the bent blades. He changed it to the stainless now fitted (13.25 x 19) but it seems to rev its head off but not get anywhere, hence the questions re a replacement. Another thing is the porpoising is now out of control and extremely hard to trim out where before it was easy to control with the trim. I've crunched the numbers on the mercury marine prop selector site and they are saying with a 4 blade vensura: holeshot - 14x19 and overall performance 14x21. That's why I was thinking of the 14x20 but I'm really new to the sterndrive thing and appreciate any advice.
Cheers and Merry Christmas to all. Whitey

 

[Lyle29464]

Re: Another Prop question!

Search engine height. post a picture of the bottom of the boat showing the engine. Sounds like it could be too high. Do you trim all the way in when starting out? ( drive unit)

 

[Whitey72]

Re: Another Prop question!

Lyle,
Yeah mate she is trimmed all the way down for the start. If she is even a little way up she struggles to get on the plane, 1/4 way up and she just won't plane even at full throttle. I believe it is a standard fit out for a tahoe 2006 q4 with 4.3l carby motor with an Alpha 1, Gen 2 (1.81 ratio) leg, with very low hours (approx 50). Sorry I can't post a picture as the boat is currently stored at a friends while I'm doing a renovation. I might be over exaggerating a bit regarding the getting nowhere and revving with the different prop (seeing she still does 47mph) but I believe there is a noticeable difference between the two props and I'm not happy with the current 13.25 x 19 3 blade stainless as I'll be pulling a single skier from deep water start regularly. Cheers Geoff