posted 05-13-2010 10:39 AM ET (US)            

My 2007 Dauntless 200/175 Verado has a modified deep V hull aft and a fuel capacity of 75 gallons, or 465lbs of fuel when full and a 500 lb motor. That's a lot of weight aft.

With the 3 blade prop I had to use full throttle on transition to plane to avoid a lot of irritating ventilation, something I do frequently in my hobby of photographing sailboat races. I think the squat of the deep V stern was presenting turbulent water to the prop. By the way, the position of the AV plate when up on plane seemed perfect.

With the 4 blade prop, transition to plane can be done at any throttle setting without ventilation, my minimum planing speed has dropped 2 knots by gps, and I have better control at the dock in the gusty crosswinds common at our marina.

Since my WOT RPM with the 3 blade prop was at the top of the recommended range I elected to buy a 4 blade prop with the same pitch as the 3 blade prop, expecting a drop in WOT rpm of about 200. However, this particular 4 blade prop, even with a slightly smaller diameter than the 3 blade, dropped my WOT RPM by 500, placing me at the lower end of the recommended range for my motor (only a 500 RPM range).

I've decided to keep the prop as it accomplished everything I wanted to change about the boat's performance. I'm going into all this detail because of the unexpected difference in WOT RPM between the two props. Blade shape can vary a lot from one prop manufacturer to the next, so you may have to try more than one prop if you decide to change.

posted 05-13-2010 12:00 PM ET (US)            

All advice is welcome. There is no teacher like experience, so I welcome yours...and, of course, it takes a village.

posted 05-13-2010 03:51 PM ET (US)            

Propellers are not generic pieces of hardware; each model of propeller has unique design characteristics that affect how it performs and makes it suitable for some applications and not others.

There are no rules of thumb about four blade propellers vs. three blade propellers except that four blade props will have more stainless steel in them and therefor will cost more and weigh more.

When they need repair they will cost more because there are four blades to check instead of three.

It is not true that any four blade prop will have better "grip" than any three blade prop. It depends.

To me "grip" means the ability of a propeller to resist ventilation during:

- Acceleration to plane.

- Extreme trim.

- During sharp turns.

You have an aluminum prop of unknown brand and model, but I can assure you that any stainless steel propeller you buy that is sized appropriately will offer far better "grip" than what you have now.

Your combination of boat and motor also means there are not a lot of propeller choices so the decision is somewhat easier. A 1973 Outrage 19 is easily driven and accelerates with little bow rise. You do not need a stern lifting prop on a boat like this.

The Johnson 115 four-cycle is a Suzuki DF115 and uses an intermediate gearcase prop. It also has a relatively low gear ratio that will do better turning a slightly larger diameter prop.

My first recommendation would be a 14" x 18" Stiletto Advantage or 14" x 18" Suzuki stainless steel three blade (they are the same prop).

I cannot think of a four blade model that would necessarily be a better fit on this boat/motor combination, but I have no personal experience with Solas or Vortek four blade props in this class of motor. I have never heard of the latter brand.

Mercury four blade props are by far the most common, but in the intermediate size, the only four blade stainless steel model they make is the Trophy Plus and I do not believe it would not be a good fit for this boat/motor.