New power which prop

[Mac525]

Hi guys I have and 1972 Zeta 24 that Im repowering with a mercruiser 2008 350 mpi mag and a bravo 2 leg with 2.0 gearing. 24 feet 24 degree dead rise fully loaded with gear and 55 gallons of fuel ot will be around 5500lbs. I would like to put a stainless prop on and there are not many to be had to try out. I'm looking for the best mpg cruise as the most important goal. There is very little info on boats with the bravo 2 so any help would be great thanks

 

[steelespike]

Re: New power which prop

Welcome,
Unfortunately I have no experience with a B2.
I can tell you that any marine engine needs to rev freely within its rated rpm
range.and should be propped to reach very close to its max rated rpm at wot.
If you read the stickies at the top of the page and the helps on the prop store page it will help you understand prop selection.Your info to this point seems very good and we'll be glad to help with any confusion.
If you have a prop at this point run it and get us the size and results.max rpm and speed.

 

[Mac525]

Re: New power which prop

I do not have a prop because they are few and far between and I cant find one to "try" the recomended wot is 5200 and the rev limiter will be at 5400 which is where I want it to be when empty at wot. The boat will be used for inshore and offshore fishing with some extended cruise times to the fishing spots. A stainless prop is what I will be putting on due to the fact that it is in the water all the time. Its too bad piranha does not make one for the bravo two because I like all the pluses of a comp prop. Please I dont want 16 posts from people telling me how bad comp props are unless you've had one on your boat.Any way I need to be pretty sure of the prop before I order it so if you guys could help me out that would be great Thanks Cam

 

[Robbabob]

Re: New power which prop

Mac,

As you well understand, your uncertainty is the same as ours. Prop selection is usually based on current results and what you want to change. In your case, you've increased HP and do not have any data to really give us.

How about starting with what the boat had for HP and prop pitch before the transformation. As HP goes up, so will prop pitch.

Good luck!

 

[Mac525]

Re: New power which prop

Im really only looking for some data to give me a starting point it is a complete repower leg and motor the old one was a 190 hp omc with a electro shift leg all I ever got out of it was 29 mph gps @ what I think was 4200 but I dont think the tack was working right the prop was a 15p X 16.5 aluminium pin drive omc not in new condition. I'm not new to propping A boat when I have some data to start with. Is there a calculator online that could give me a good idea, I've tried the mercruiser site and there is no bravo two options surpiseing since they make it. Any way thanks for the time too look at this PS if any one has some used bravo two props here on vancouver island that I could use to get a base line it would be a huge help

 

[Robbabob]

Re: New power which prop

bump

Mac, thought I'd bump this to the top today. Hoping someone with this experience will see it to chime in.

Good luck!

 

[Mac525]

Re: New power which prop

Thanks Rob I'm hoping to do the sea trials this weekend in Vancouver and then run it across to schooner cove I have a maybe on a loaner prop but I would like to start close to what I need Plus I dont want to make the hour long crossing with to much pitch

 

[Mac525]

Re: New power which prop

Well looks like I wont be getting the "Shark Bait" this weekend due to unforseen refit issue lol never fails But on the bright side I think I' ve found a loaner ss 21p 18.5d that from all the prop calcutaters and some comon sense looks like it will be close to where I want it. They will be sea trialing it early next week and it should be tip top on friday ready for me to run it over. One minor issue I'm going to have after all the math is done my speed at 600 rpm will be 5.6 mph or there abouts lol a little more than the 2.2 to 3.2 I Want for trolling guess I will have to put the tabs all the was down, maybe get low enough or put a troll plate on the drive