Need serious help with Duo Props!

[doral270]

I need some serious advice from anyone out there that really knows props and in particular the mercruiser duo props. Here's my dilema....

I have a 2001 Doral Monticello 270 with 7.4 MPI and Bravo three drive with 22p duo props.

I can barely get out of the hole with only a couple of people on board with fuel water and a moderate load. With four people, I can't get on plane at all. The manufactures recommended RPM range for that engine is 4200-4600. I can only reach 3600 at full speed and slightly trimmed up. From what I understand, for every pitch you drop, you increase your RPMs by 200 and increase your low end power out of the hole.

So here is the other problem, apparently the lowest pitch duo props made are 22p. Not to mention, I am only getting a top end speed of 32 mph when I finally do get on plane.

Does anyone have any suggestions on what I should do?

Thanks

 

[tommays]

Re: Need serious help with Duo Props!

A quick look online shows they do make a 20" pich set

Has this boat ever worked well OR is it new to you ?

Does the boat also have trim tabs ?


What happpens as you trim up more ? If you trim limit switch is working correctly you will not hurt anything going higher than a littel bit

At some point when your trim to high the props will just start to slip and you have to just trim down again


Tommays

 

[doral270]

Re: Need serious help with Duo Props!

Thanks for the reply.


The boat is new to us. We do have trim tabs and I have tried multiple locations with them for help. The boat litteraly just plows water for 3-4 mins before finally getting on plane no matter where the tabs are. I still believe that more than anything it has to be a prop problem because we are not even coming close to the recommended RPM range for the engine at full speed.

You say you saw 20 pitch duo props online somewhere. Can you give me an idea of where you looked. I was under the impression that only quicksilver makes the duo props for mercruiser and they only have listed 22p-28p.

Thanks for the advice.

Tim

 

[tommays]

Re: Need serious help with Duo Props!

Everything said assumes that your engine is in good condition


I think you need to get the Trim Tabs UP and see what happens when you trim the drive UP

If you are only useing a littel bit of trim with the drive it will still be pushing the bow down into the water creating huge drag and it will never get on plane correctly


If you google bravo 3 props many places come up that sell them

Tommays