Whats the point of this high performance part

**killerpirate** · 09-23-2021, 03:29 AM

Hello,

I was wondering, what does this thing specifically do? I can think of 2 things:
Its the same as a hydrofoil but smaller and cooler (i doubt this since most of the high prf. guys run LWP's and the plate is above the water
2: it keeps water from going up, above the plate, directing this water to the propellor, and thus giving the prop more water/ slip?

Othrr then its just cool looking, when should one consider installing this, and is there a notable difference? So yes, what is the difference.

Thanks!

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**bullet20vee** · 09-23-2021, 05:29 AM

It will help your hole shot and it will also let you plane at a lower speed.

**killerpirate** · 09-23-2021, 09:59 AM

Why does it do that? What the theory behind it? Does it trap more water beneath the cavitation plate?

**Stoker boy** · 09-23-2021, 10:43 AM

When the boat launches it puts pressure in the rear causing the bow to lower.

**David** · 09-23-2021, 12:49 PM

I had a Hydrostream Virage (mod tunnel) that was hard to plane with an over hub prop. I put on a Bob’s true tracker. It was a huge improvement. Instead of revving to 5000 and waiting, the boat just planed

**Forkin' Crazy** · 09-23-2021, 01:56 PM

Originally Posted by killerpirate

Why does it do that? What the theory behind it? Does it trap more water beneath the cavitation plate?

Yes. Think hydrofoil and how it creates lift, same principle. On my application, it would keep stern up and bow down getting on and off plane. My Allison XB used to take on water over the stern if you didn't ease off the throttle. Now you can drop it and hardly a drop will come in. After the boat gets on plane it is out of the water, so no drag to speak of.

**bullet123** · 09-23-2021, 03:23 PM

Helped my bullet to run at lower speeds without porpoising

**Merc Speed** · 09-23-2021, 06:07 PM

Agree my Hydrostream Vasseret was porpoising up to 30 MPH with the bobs tracker now can run 18 MPH on plane.

**phillnjack** · 10-03-2021, 06:27 AM

Great for holeshot. but once on plane should NOT be touching water....this " Allison type" is the coolest looking foil around.

**Merc Speed** · 10-03-2021, 04:45 PM

I leave mine all the way down for a slow smooth cruise on plane then lift it up for faster speeds.

**Jay Smith** · 10-05-2021, 01:28 PM

Always helped my race boat “set” quicker …

Jay @ JSRE

**25two.stroke** · 10-11-2021, 11:15 AM

Originally Posted by Stoker boy

When the boat launches it puts pressure in the rear causing the bow to lower.

Now that I have my mirage together it does take like 20 seconds to plane. Bow goes way up and it blows out to 5000 rpm then hooks up and drops back down. I know you are running a completely different mid and setback, and so is Kevin here, but do you know if theres an easy way to correct that? It does it pretty much the same no matter what style prop I run.

And what is the performance difference between a hydrofoil like the one pictured in this thread and a blow-out plate bolted to the transom in front of the motor? As I understand they do the same thing, but is there a preference or different function?

**David** · 10-11-2021, 07:57 PM

[QUOTE=25two.stroke;3311976]Now that I have my mirage together it does take like 20 seconds to plane. Bow goes way up and it blows out to 5000 rpm then hooks up and drops back down. I know you are running a completely different mid and setback, and so is Kevin here, but do you know if theres an easy way to correct that? It does it pretty much the same no matter what style prop I run.

That was my experience with my old Hydrostram Virage, and a Bob’s True Tracker completely cured it. I would like to know the relative benefits of the Allison skid planer and their foil. I have an Allison foil on my SS2000 now

**Forkin' Crazy** · 10-12-2021, 07:30 PM

That depends. Mine would dig sometimes and water would run up the jack plate and slap the motor. The wing or cap on the back of the jack plates helps sometimes. The Allison style wing is pretty easy to make. I used 3/16" if I remember right.

Where does your exhaust exit? Around the prop?

**25two.stroke** · 10-13-2021, 04:10 PM

Originally Posted by Forkin' Crazy

That depends. Mine would dig sometimes and water would run up the jack plate and slap the motor. The wing or cap on the back of the jack plates helps sometimes. The Allison style wing is pretty easy to make. I used 3/16" if I remember right.

Where does your exhaust exit? Around the prop?

Don't know if that last question was for me or not, but I'm running a chopper and a factory 15" can, so some exhaust goes around the prop and some out the can. When you are jumping up most of it flows over the prop.