Venting the prop

[Chickenlips]

Has anyone every heard of this. I was told, to give the prop some air you drill the plate above the prop and extend a tube or pipe to pull air down to the prop. I'm have problems getting the boat to plan, if I steer the boat back and forth it will get up ok. The X dem. is too low and the drive wants to lug the motor (HP500) down. The boat came with a Bravo-3 and I want to use a XZ drive. I sent the prop back to Hydromotive (5- blade 25 pitch) and they drilled four holes around the hub, I haven't tryed it yet.

[Daytona100]

Has anyone every heard of this. I was told, to give the prop some air you drill the plate above the prop and extend a tube or pipe to pull air down to the prop. I'm have problems getting the boat to plan, if I steer the boat back and forth it will get up ok. The X dem. is too low and the drive wants to lug the motor (HP500) down. The boat came with a Bravo-3 and I want to use a XZ drive. I sent the prop back to Hydromotive (5- blade 25 pitch) and they drilled four holes around the hub, I haven't tryed it yet.
Should work. The holes will help aereate {sp} the water around the prop. I have a 4 blade that came with 4 holes drilled around the hub with different size plugs for the holes so you can adjust the amount of slippage you get around the prop.:idea:

[2dasand]

Do you guys have any pics? I have seen one prop where they drilled the hub with like 4 1/8" holes. It was for an outboard, and they claimed it made the holeshot a ton better. I have never seen this anywhere else. I would like to see if this is what you guys are doing.
Thanks!

[ToMorrow44]

The props that have the vent holes drilled in them are like the Mercury PVS (http://sites.mercurymarine.com/porta..._schema=PORTAL). According to that site, the vent holes work by drawing exhaust through the holes to vent the prop so I don't know if they really have any effect on thru-hull exhaust boats. As far as venting the prop, I think you might have to have something custom made with the vent hose and everything. This is very common on the #6 drive boats but very rare on bravo boats. Have you considered putting a 2" shorter lower on your boat? It might pick up speed all throughout the rpm range...Just my .02
-Tom

[riverbound]

The props that have the vent holes drilled in them are like the Mercury PVS (http://sites.mercurymarine.com/porta..._schema=PORTAL). According to that site, the vent holes work by drawing exhaust through the holes to vent the prop so I don't know if they really have any effect on thru-hull exhaust boats. As far as venting the prop, I think you might have to have something custom made with the vent hose and everything. This is very common on the #6 drive boats but very rare on bravo boats. Have you considered putting a 2" shorter lower on your boat? It might pick up speed all throughout the rpm range...Just my .02
-Tom
It does work on boats eith thru transom exhausts too. I let Badblown borrow my prop (3/4 vents) and it worked great on his boat with a 500 hp.

[Chickenlips]

The props that have the vent holes drilled in them are like the Mercury PVS (http://sites.mercurymarine.com/porta..._schema=PORTAL). According to that site, the vent holes work by drawing exhaust through the holes to vent the prop so I don't know if they really have any effect on thru-hull exhaust boats. As far as venting the prop, I think you might have to have something custom made with the vent hose and everything. This is very common on the #6 drive boats but very rare on bravo boats. Have you considered putting a 2" shorter lower on your boat? It might pick up speed all throughout the rpm range...Just my .02
-Tom
Do you know of a site where I can see a #6 drive with the vents. My next chose will be a 2" shorty, I was trying to save some $$$. I'm sure the holes in the prop will help. Thanks. Jim

[Tom Brown]

Perhaps this 1978-1979 Mercury service bulletin will be of interest. Personally, I'd go way bigger (1/2 -> 3/4" and a little further from the blade) but the idea is here.
http://www.carlsonspeed.com/componen...com%2F%2Fcompo nents%2Fcom_jd-wiki%2Fimages%2Fprop%2Fprop-drill.jpg

[Rexone]

Vent holes are actually pretty common and have been used for many many years.

[ToMorrow44]

Do you know of a site where I can see a #6 drive with the vents. My next chose will be a 2" shorty, I was trying to save some $$$. I'm sure the holes in the prop will help. Thanks. Jim
With all the hundreds of boats I've seen with this set-up I had a hard time finding pics but heres a few:
http://www.***boat.com/image_center/...dcb-drives.jpg
http://www.***boat.com/image_center/data/500/tcm2.jpg
http://www.***boat.com/image_center/data/500/tcm11.jpg
Above is the kit Teague sells that you set-up and trim according to the prop. I believe you set it up so that the aerator is about 1/4-1/8" from the leading edge of the prop. Again I've only seen one of these done with a bravo and I don't know if I can find a picture of that.
-Tom

[Chickenlips]

With all the hundreds of boats I've seen with this set-up I had a hard time finding pics but heres a few:
http://www.***boat.com/image_center/...dcb-drives.jpg
http://www.***boat.com/image_center/data/500/tcm2.jpg
http://www.***boat.com/image_center/data/500/tcm11.jpg
Above is the kit Teague sells that you set-up and trim according to the prop. I believe you set it up so that the aerator is about 1/4-1/8" from the leading edge of the prop. Again I've only seen one of these done with a bravo and I don't know if I can find a picture of that.
-Tom
I'll check this out. The part going through the plate is facing to the rear which would keep the water from spraying back up the tube. I'm not sure that the ZX plate is big enough to handle that large tube. Thanks again Jim