Oh boy....I thought I had it figured out!

[mvn]

Here's the deal,

Our boat below (19' bowrider with 4.3L Volvo SX) is equipped with the stock 14.25" x 19" 4-blade aluminum prop. I put a set of Smart Tabs on shortly after getting the boat to improve slow speed performance (slower planing for tubing, eliminate porpoising). I have adjusted the 60 lb actuators to the lightest pressure possible and am still experiencing a loss of top end speed and increased WOT rpm 4,800 (not the 4200-4600 recommended) but still have excellent low/mid range performance & handling. John at Nauticus says that 60's are the actuator of choice and that 40's will be too light but he has arranged for 40's to be sent to me any way.

Here's what I've been thinking so far. Let's assume I get the boat fine tuned with the 40's. Once that is done, get a 4-blade stainless prop (Turbo II 2+2 TH for example) in a 14.25 x 18 to eliminate the horrible ventilation (blow-out)I am experiencing in tight turns. I don't know if the ventilation issue was there before I put on the tabs or not.

After talking to the local Nauticus distributor regarding the replacement actuators and mentioning the ventilation issue I was having, he said I should be going to a 3-blade because I may be getting too much stern lift from the stock 4-blade. He highly recommended the Turning Point Hustler aluminum 3-blade.

I thought 4-blade props had better grip in the corners? Now I'm confused!!

 

[steelespike]

Re: Oh boy....I thought I had it figured out!

Go to fiberglassics.com there is a prop section explaining prop design/performance, an informative easy read.

 

[SPUNWHEELS]

Re: Oh boy....I thought I had it figured out!

I'm also running the SMART TABS and I think they are the best money I have spent. I mounted them high and wide on the transom, at a slightly cocked angle, (so as to funnel more water to the prop). I run the gas shocks in the stiffest position at just slightly more than half way down at about a 45 degree angle.
I run just under 75 mph on the gps @ 6,000 rpm, with 24 gallons of gas with me and my fat, oops, pleasingly plump wife. The deal with the way they are mounted is when I'm on the pad, they are fully down and clear the water. They only function fully when I have the hull completely wetted, like in a hole shot or cruising at barely on step speeds.

The rig is a stock 1980 Black Max V150 hp on 1984 Hydrostream Vector. 6" setback jack plate all the way up, Bob's Machine low water pick up nose cone and a 5 blade Merc Maximus 26" prop, soon to be 28 pitch, because there is still more in there with further tuning. I never burnt any pistons using Royal Purple motor oil. Hence the 28 year old engine has never been overhauled.