Can someone give me the low down on what vents do on props? I know the newer ones come with the vent system with a selection of plugs. Do vents only work with thru hub exhaust?

I have thru hull exhaust so would vents benifit me? What I am trying to do is with a 4 people in the boat it takes awhile to get on plane because my motor doesn't start making torque till around 3000 rpm. So I am thinking with the vents in a prop that it will allow the prop to cavaitate and bring my rpms up so my torque is usable to get me on plane faster without having to go WOT and smoke my alpha.. I know our hydromotive came with instructions on how to drill vents in the prop... So i think I can do it to any prop i choose to run..

any opinions?

Thanks

Travis they are mostly for outboards from what I know. They allow the motor to spin up to get more into their power band. Not sure that it will help you.

Jon

sure.. for outboards LOL! damn eggbeaters Its exactly what i need to get into the powerband.. or maybe just your 400 lbs girl freind on my bow

Audio is right in that they allow the prop to spin up, but I think they'll work on any appication that has through prop exhaust.

Sounds like a dead end for that idea.. I guess my boat just became a 2 person boat LOL! me and my little lady for evening adventures

The vent holes allow the prop to cavitate and spin up to higher rpms faster. I think you can get them on a lot of Merc props. The REV4 I tested last year had them and I have also seen them on newer Mirage Pluses.

The holes allow engine exhaust to ventilate the prop so it can spin up more easily, allowing the boat to plane faster. When the boat attains planing speed the water moving across the prop "seals" the vent holes. Mercury offers different size plugs.

I tried using the vent plugs on my Mercury Offshore prop. The prop ventilated so much I could not get the boat on plane!

P. S. The ventilation system is ineffective on boats running thru-hull exhaust. You need exhaust gas through the outdrive for the vents to work.

Traviss,
I had vents on the prop on my last boat. The prop was a Laser II, the boat was a 350 Mag with an alpha. I tried them every different way it found it was best with the vents plugged. I also had thru hull. Boat was still pretty slow out of the hole no matter what plug i put in, just ran a tad better top end with them plugged.

Scott

Traviss,

The newer Mirage Plus props have vent holes in them between each blade. Merc has a part number for plugs with various size holes in them. They do have a significant effect even with through hull exhaust. On the 25 MP if you remove them completely the boat will not even come on plane. I experimented with them some and found that the smaller holes did allow the prop to spin up before really hooking up but decided that I did not really need them.

You could probably drill a non Merc prop to the same size hole and use their plug kit. If you decide to go that route let me know, I can find the P.N. for you.

Tim T.

I have through hull exhaust and tried removing one plug at a time, when I took out the third plug, the boat would not even get on plane.. I now have two of the three plugs removed and it does make a difference, allowing the prop to cavitate ever so slightly to get into the meat of the power band quiker..