[Skippern]

Hello

Is there anyone on the forum with a Mariah SC23 with 5.0 MPI engine and Bravo 1 outdrive?

I'm only getting 4300 - 4500 RPM (engine shoud have 4600 - 5000) and the boat accelerates slower than i should I think.

What propeller do you have? I have a Stainless Steel Turbo 14 1/4 X 21.

Top speed is about 46 MPH measured on GPS.

[mikeyt]

hi there. First off i'm going to suggest that you read the STICKYS located at the top of the Prop Talk Forum. They will educate you on how to fix these issues and with props, a little self-education is always a good thing.

As a short answer, you need to drop your prop pitch by up to 2" (ie 14.25 x 19 or 14.25 x 20). That will increase your rpms by about 200 per inch and greatly improve your hole shot. You might also want to consider going to a 4 blade prop. If you go this route i would suggest a 20" - 4 blade. All is explained in those STICKYS.

btw... 46 mph isn't terrible for a 23ft boat with a 5.0 pushing it but with the change in props as suggested you can improve your hole shot and your mid-range acceleration which to my way of thinking is far more useful for everyday use than a higher top speed.

[Skippern]

Thank you!

I have no problems with the top speed. I will read the stickys and buy me a new prop. Hopefully It will make the boat going faster into plane and still have the top speed.

[dcalhoun]

I have an sc23 and my prop is a 14.25x21 3 blade aluminum black max. I only get about 4300 rpm at 41 mph on gps....consider this as terrible and estimate slip at about 27%.. This gave a fair hole shot and was with 2 people one cooler a full tank of fuel. I then went out with with 5 people with 2 full large coolers and one small cooler with a full tank of fuel and no water in the freshwater (12 gallon) tank. It ran 4000 rpm and about 39-40 mph gps. Again I considered this pretty bad and the rpm is too low. It also had a terrible hole shot with full trim tabs down. I orderd an 18 pitch 14.25 diameter 4 blade stainless Stiletto bay pro 2 and am hoping for improved holes shot, better speed and way less prop slip. The boat has an alpha one drive and a 5.0 mercruiser. I am curious if my best guess for a better prop and estimate at size and pitch will be close to desired 4400 rpm fully loaded and hope for about 46 mph. I may be dreaming and never had to try and prop a boat that had this poor of performance. I do love the boat and am an avid boater, owning 3 boats and one back to 1987. I am considering trying a 17 pitch revolution 4 but have concerns that I may be shooting for too low of a pitch. I have never tried going from 3-4 blades and have no idea if I am going to come even close to what I am after. I have read so much about props and what folks did with the rev 4 that I'm cross eyed. From what I can tell the Mercury tool is pointing to a 17 rev 4. I'm considering buying one, as they seldom go up for sale for less than 350 used in premium shape and I found one. I also found one for 350 in a 19 pitch but fear it will not give me desired results as the blades are 14.6 vs the 14.25 that was on the boat. I fear the 19 pitch Revolution 4 will not give me the proper rpm range for the motor (fear it will be too low). To sum it up I have a 14.25x21 3 blade aluminum stock prop and am hoping to gain about 300 rpm with a 18 pitch stainless 4 blade that is 14.25x18. It has a moderate rake and cup vs the aluminum one and I read the bay pro 2 has a good bite on the water. I'm considering buying a 14.6x17 and 14.6x19 revolution 4 for trials, as I found a couple for good price. There are not any big shops near me that will lend props and even if they did they would expect a premiums price for whatever I got. Any comment or input is appreciated. The hull is in premium shape having only 88 one owner hours on a 2007 model. In fact the boat nearly looks new. I thought I would find the hub kit had been slipping but it is not the case. I have fast become a Mariah lover. Look forward to replies! Yes I also read Stickys post.