Magnum 27 prop selection

[Staffan Berg]

Hi
I asked you last year about my propeller choice.
Last season I did 57 mph 4900 rpm with Mirage 23
The engine is a single 496 HO

This winter I remounted the engine 2 inches higher.
The engine performs like
56 mph 4900 rpm with Mirage 23 AND the boat is haveing problems to lift from the water.
Any idees what to do. I am also cavatating if I do sharp turns.
Would a 4 blade Bravo (24) solve my problem.
It feels like there is much power in the engine
that just throws water up in the air instead of lifting the boat up and getting that last 5-6 mph.
Any comments are appriciated.
Staffan

[Forrest]

Staffan, how straight is that hull? Any hooks or bumps on the bottom? That has to delt with first before trying different props. Even with a single engine, the Magnum 27 is no lightweight boat. With all that in mind, if you are running a 1.32:1 gear ratio in your Bravo drive then you have a whopping 45% slip (81 mph @ 0% slip). If you have 1.50:1 gear ratio you have 25% slip (71 mph @ 0% slip).

Prop Slip Calculator (http://www.go-fast.com/Prop_Slip_Calculator.htm)

The trick will be getting your prop slip under control. If I were you, I would try a number of different props. Four blade and large diameter props should slip less than three blade props, but try every prop that you can get your hands on. Running that high on the transom, you may even want to try a 15" or 16" diameter 3- or 4-blade cleaver prop for grins. I have a 15x23 3-blade Kiekhaefer cleaver that I could let you borrow if you weren't so far away. Maybe you can borrow a nice Rolla prop from a neighbor for testing. :D

Best of luck

[smoothie]

Some guys on this site have had good numbers with the hydromotive quad IV and the outdrive raised up,heres the web page (http://www.hydromotive.com/int_quad4.html) I just happen to have a 23p left-hand for sale in great shape for $250.00 :D .