What is a vented prop??

[HAS]

I have a 1972 ORLANDO FISHERMAN 16 with a 1985 MERCURY 50hp. 4cyl. and a new
10.1/4 x12 prop.The boat will do 28mph. @ 53 or 5400 rpm with 4 people . I dont know
the weight of the boat, I think performance is fine, what I would like to know is, what is a vented prop. and how does it work? I'm new on this forum but I've been on the boat
repair and MERCURY engine forum almost a year.
THANKS TO ALL HAS

 

[hungupthespikes]

Re: What is a vented prop??

This will get you going. Lots more out there.

http://continuouswave.com/ubb/Forum4/HTML/003353.html

 

[rallyart]

Re: What is a vented prop??

Short answer is that the vent puts some exhaust gas up near the blades at slower speed but not once the boat is travelling. You adjust the size of the vent to put more or less gas up there. Usually that's with plastic plugs.
The idea is that at slow speeds the prop slips some but not at high speeds. That means your engine gets to a power RPM faster and you can accelerate faster, without losing upper end performance.
It made a significant difference on my 18' Grew with a 170 Merc. Finding the right vent size was easy. I ran with the holes pluged, then unplugged, then started drilling a hole in the plug. I upped the size of the hole until there was no improvement in hole shot.

 

[HAS]

Re: What is a vented prop??

Thanks Guys but I'm still in the dark, where are the vents? what do the vents and plugs look
like? Are these the props. with small holes in the blades? Anyone out there have any pictures?
THANKS AGAIN HAS

 

[Pas Bon]

Re: What is a vented prop??

The holes are at the base of the prop on the backside of each blade. You can google vented prop images and find some pics

I just got my prop back from my local prop guy and he vented mine to help remedy it's sluggish holeshot. He also added a bit of cup and rolled the blade a little. I'll test it out tomorrow.

 

[hungupthespikes]

Re: What is a vented prop??

here you go. Now you can buy plugs, with or without holes in them to tune the prop to your boat. Getting the right prop to max out your performance takes a ton of homework, and could cost a ton of money, so take your time before you buy.
Just a lot of variables, 2,3,4, or more blades, vented/or not, pitch, cupping, rake, and more to check out. Finding the right prop is a "black art" IMHO, but when the magic happens you won't believe the difference the right prop makes.

 

[Pas Bon]

Re: What is a vented prop??

Well the vent job I just had done worked very well. RPM's ran up and very little bow rise (might be due to other prop mods) but non the less for sluggish holeshots I'd have to say the prop venting works well!!