Propeller size

[Roger K Sterling]

I own a 2000 240DA with a 5.0 mercruiser engine and bravo 2 outdrive. Do I have to use the oem propeller which is 17.75 Diam. with 21 pitch.

 

[ClarkGriswold]

No. I had the same and I believe I changed pitch a couple of times. I can check what I had on there when I get home tonight.

 

[Steve S]

My first Sea Ray was a 21' Monaco with the 5.7 merc / Alpha drive. I used both a 21P and 17P prop. The 21P was more of a cruise prop while the 17P was for the "hole shot" while towing tubers or skiers...

 

[89P270]

There are numerous Prop options for your boat. Some things to consider - Manufactures may or may not exchange new props if you purchase one and dont like the performance. In this case, best to get information on forums with others having your same boat and different props. Others, like hill Marine and their Big Cow Bravo II props will 1) provide you and idea of best diameter and pitch for your current set up and 2) exchange for a different diameter and pitch if you dont get what your seeking on the first try. So, dig in to the options on line, discuss in forums like this, and make an informed decision to supplement that 21P OEM prop you have. I kinda think 21P might be a bit long for your 5L but I have no experience with that engine/Bravo II set up.

 

[NorCal Boater]

Roger,
The first question to be asked is, what's wrong with the prop you have? What is it you would like to accomplish with a different prop?

I'm going to go out on a limb and assume you are looking for better performance. If that's the case, I have bad news for you. There is no prop in the world that will give you the performance you would like with that boat and engine package. You have a boat that is listed at 5500 lbs. dry weight. It has a 70-gallon fuel tank so let's assume you go out with the tank 3/4 full. Thats about 52 gallons @ just over 6 lbs./gallon that's a bit over 320 lbs. The water tank is 20 gallons so let's figure half full and water weighs just over 8 lbs./gallon so let's add 80 lbs. We're now at 5900 lbs. Now let's add cooler full of beverages, clothes, food, boat stuff (fenders, lines, tools, spare prop? etc.) so let's say another 75 lbs. That's about 6075 lbs. Lastly, lets add people. I'll assume it's you and a sweetie and another couple. Assume the guys weigh in at 175 and the ladies a buck and a quarter. that's an additional 600 lbs. and we are now at 6600 lbs!

Your boat was already under powered at 5500 lbs. and we just added another 1000-1100 lbs. Your engine is only 240HP. That is just not enough power to get that weight on plane and maintain it without running nearly wide-open throttle (WOT) all the time which is horrible for fuel economy.

You can change props and maybe get on plane a little bit faster, but it will hurt you with a lower top speed. If your goal is to go faster at WOT that will hurt you getting on plane. All boat engines have a maximum recommended RPM range at WOT. For your motor that range is 4400-4800. That means that with a boat with about half full of fuel and 2 people on board, your engine should turn in that recommended range at WOT. If it is not you need to ask some questions. Is the motor running at maximum efficiency? (Tuneup?) Is the bottom clean? Is the boat over weight?

So the first thing to do before changing props is to find out what RPMs you're getting at WOT. Once that is answered we can advise going forward. BTW IF you knew all of the above I am sorry....I was not trying to be a showoff. But someone else reading this may not and it might help them.
Shawn

 

[ClarkGriswold]

I will agree that if you are looking for 40+ mph, you are in the wrong boat and engine combo.

That said, I ran a 19x17 and a 19x21 with the same engine/out drive combo on a 2000 240da with great success. Both planed easily for me and held a perfect cruise around 3200-3400rpm with passengers, water and fuel. It certainly can be done. I never ran at WOT as it’s just not my bag.

ymmv

 

[Roger K Sterling]

My first Sea Ray was a 21' Monaco with the 5.7 merc / Alpha drive. I used both a 21P and 17P prop. The 21P was more of a cruise prop while the 17P was for the "hole shot" while towing tubers or skiers...

what diameter(s) did you use

 

[Roger K Sterling]

thanks all This is my first boat and the prop was in need of replacing when I bought it. As a newbie I want to cruise at a moderate speed and have some fun tubing. I'll get the RPM stats for the engine and share

 

[Steve S]

what diameter(s) did you use

That was like 12 years ago and they came with the boat. The previous owner told me how he used the 21p for cruising and the 17p for towing. Not sure what the diameters were.