Sean H

one method puts more tab in the water than the other, all depends on what your hull needs...

32 caliber

I have hydro props that lift the stern well, but on lake michigan well the swells are deep the front end seems to want to bounce up and down to much. When I put the tabs all the way down it does help alot...it seems if I had a bit more tab down force that the boat would be more stable in the rough. My tabs are long enough, I just think they would work better if the downforce was in line with the surface of the water.

mmwalters

Jim Be sure and post your results. There is nothing like real world testing to answer questions

tcelano

My understanding is that mounting the tabs flat was a solution to a chinewalking problem. As far as lifting performance goes, I think it is a wash either way. With the tabs parallel to the running surface, the tab is in the optimal contact to the water to make lift, but that lift vector is not directed straight up. With the tabs set level, they are not meeting the flow straight on, and will actually funnel water back toward the boat centerline, and that momentum reaction will cause an outward force in addition to an upward force. The relative quantaties of all of these can be computed on a by-boat basis, but in the end, realize that the tabs are only needed for transom lift through getting on plane and maintaining longitudinal/vertical stability from porpoising through the midrange. If you need anything in the top end, it's only going to be the tip of the tab anyway, and it's efficiency as a pure lifting surface is not nearly as big of a concern as how much lift the incredibly small angles of attack can produce at high speeds, and how the boat will react to it.

skaterboy

What about the effect on turning if you were to mount them flat ???? Too much drag on the boat I would think.

32 caliber

Skater, take a look at the pics above...did you ever see a fountain have a turning issue? I would think that theres less drag in a turn...just my 0.02

32 caliber

I checked the flow of the water on mine with the tabs angled. Right now the water flow is being funneled back toward the centerline. It almost appears like it actually causing alot of turbulance toward the props. I still would like to know why on the 2005 fountains they are mounted straight accross the stern.

32 caliber

I posted a thread in the fountain owners area, here was a responce..

According to Fountain, "to get more leverage while reducing wetted surface drag". I guess they have been doing it on the racing boats and it makes a big difference in tab effectiveness.

It is good to see that racing technology works itself down to the production level.

Sounds like I'm on the right track with my thinking....

32 caliber

ok the tabs came off last night, tonight they go back on straight. Thursday night will get the test, I'll post the results...

fund razor

Try drilling some holes in one of the tabs like you did on the Chris Craft.