# Let's talk Cavitation Plates....



## Tsip (May 21, 2004)

We have a 21ft Flats Cat that we are having trouble finding the right prop for a decent hole shot. We've been thru 4 props already and still can't get the boat up in less than 16-18" on hard sand. It should do better, lot's better. Our El Pescador was better. We are getting closer with each tweak, though. With the amount of water coming up and off the lower unit during takeoff, we think a cav plate will help the situation even though the builder says this boat doesn't need one.

If there are any FC owners out ther running a cav plate, let me know which one and where to find one on the net, if available. Also let me know if/how much it improved your performance after installation.

For other boat owners that have cav plates, what are your thoughts on Shallowblaster, Nedski, etc..., whatever you run. I think we are hoping to find one that is bolt on and no drilling needed, which would be the Shallowblaster over the Nedski unless I am mistaken.

Thoughts? Suggestions?

Thanks,

Tsip


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## Speckwrangler (May 27, 2004)

*Cav Plate*

I am partial to the one made by Boatright marine it is a bolt on and is virtually indestructible. The shallowblaster is fiberglass and breaks pretty easily from what I hear. It helped with hole shot, planing at slower speeds, and top end.
I run a 17' shoalwater tunnel v with a 90 Johnson...

Hope this helps some

SW


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## Spots and Dots (May 23, 2004)

Why not talk to the builder of Flats Cat and ask him what prop he recommends?


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## Tsip (May 21, 2004)

Bill at Flats Cat has his props made by Phil in Victoria. Phil only works with manufacturers, no longer the public. So, in effect, we are working thru FC.

Tsip


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## InfamousJ (May 21, 2004)

Did you buy from Bill? You need to keep on him till it's right. Can't believe they dont know with all the shallow advertisement they do on that boat.


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## kenny (May 21, 2004)

Tsip,
IMHO, "getting up shallow" is way over rated. What's the hurry to leave? Why not throttle up slower rather than going WOT from a dead stop?

What size and kind of engine on your 22' FC? Sounds like you may be under powered.
My little 17' FC with Yamaha 60 jumps up shallow very well with a 4 blade prop.
Are you trimmed all the way down when you get up? If I'm really shallow I'll throttle up trimmed down and be trimming up as I come up, or idle to deeper water.


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## Back Country (Oct 14, 2004)

What engine do you run?


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## panamajack99 (Jul 8, 2004)

I have a 24' pesky and I have no problem getting up in 12" of water. No cav. plate required. With a 150 opti. and a great 4 blade powertec prop. You really need someone that know props and your boat . No complaints here.


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## fishnlab (Jul 10, 2004)

Tsip,
That is ****. Bill should help you out until it is right. Take him out on your boat. You bought that boat to run shallow. You don't want to "idle" to deeper water, you don't want to drag *** through the mud, and you shouldn't want to tear up the ground or grass you are fishing over. I would be sure to express your frustration to them until it is fixed.
As far as a cavitation plate is concerned, I think they make a huge difference. They push the back end of your boat up, when trimmed under, and help keep water on the prop. I run a full fiberglass cavitation plate on my Shoalwater, and it truly helps. Drilling and mounting is pretty easy with a buddy's help.
Call the sponsored guides from Flats Cats website, and ask what prop and plate they are rigged with.
*Captain Tom Kruft* *361-729-2981* (Rockport, Texas)

*Captain Jay Bunch* *504-340-1510* (New Orleans, Louisiana)

*John Fox's Trophy Guide Service 800 643-2665 *(Ocklawaha, Florida)

*Captian Chris LaCross* *956-739-2142* (South Padre Island, Texas)

Good luck.


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## Back Country (Oct 14, 2004)

Tsip, was the pescador getting old or you just wanted to try the FC? I have heard FC run shallow but never really heard any discussion on wether or not they get up shallow. You would think so.


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## grinderman (Jun 22, 2004)

I put a Nedski on a 1990 22ft Redfin (ok, wet fin - LOL) with a 175 and it made a tremendous difference in that boats shallow water and low-speed performance. The drilling in the cav plate wasn't an issue at the time since the motor was 10 years old at the time. BUT, the only complaint I ever had with that plate was that when it came time to change the water pump, you had to undo all the bolts for the cav. plate. Other than that, it performed as advertised. I thought about one for my current rig (Mowdy w/ TRP), but really can't imagine a cav plate could help, well, except maybe slightly on turns with the engine jacked up.


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## cfred (Jun 13, 2004)

I want to go back to Speckwrangler's comment, helped with top end? Never heard of a cav plate helping with top end, always heard the opposite, that has always been my concern with getting one. Can you elaborate?


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## Tsip (May 21, 2004)

Comments on everything so far....

Let me start by putting to rest the fact that Bill at FC is working with us. We have a brand new boat, one of the first with a larger back deck, and running a Suzi 4-stroke 140. This is going to change some of the weight distribution over previous rigs and we just need to keep working to dial in the prop just right. He is working with us on this and both of us are being patient with the process.

The engine has plenty of power to run a light boat like this, so I don't think that is an issue. These boats don't have a 'put the hammer down' holeshot, you ease it up onto plane with the full length 'tunnel' the cat hull creates. We've tried trimmed up, trimmed down, in between and changing as we power up, jack plate on many different settings, etc. The best we can get right now is take-off in somewhere in between 15 and 18 inches. I can get up on 18, but not 15, which is where we were taking more precise measurements.

Kenny, we run this boat in the backcountry, stuff that's not hardly on the map. I don't always have the option of idling out to deeper water when the whole lake we just put down in is only 12" deep. See what I'm saying? We already idle into the hole shot to fill the tunnel with water before takeoff. Bill has told us this rig should be able to get up in 8 over sand, and we are trying to get to 10 or under on sand. Over the softer mud in most back lakes this will suffice.

When powering up there is a lot of water that shoots up and off the lower unit and our current thought is that a good cav plate would keep that water down and on the prop longer, providing better bite. Bill says the boat doesn't need a cav plate. Kruft doesn't run one, and also cannot tell us what prop he runs. John Fox in Florida doesn't run as shallow as we do and wasn't able to give us the info we were looking for, and also runs a different motor, so prop info was out. LaCrosse in south Texas wants to move to the same motor we have and is waiting to hear how we do with the setup. I can't remember if he runs a plate, but I don't think that he does. Haven't talked with the guy from LA that I can remember, I'll have to go back and check our notes.

Thanks for the thoughts on cav plates so far guys. Keep'em coming if there are any more. I'm thinking we will try at least one more prop tweak before deciding about a plate back there.


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## WillieP (Jul 2, 2004)

I have a 22ft Pathfinder with a 150 yamaha. I added 2 wedges to each side of the motor (between motor and jackplate) so it would push up with the motor trimmed in and had Baumann Propellers build me a 3 bladed prop. 4 blades use too much gas on long runs. I have the hole shot and still have the speed. Wedges came from www.jimtrix.com.


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## Stuart (May 21, 2004)

Crank, we tried a Shallow Blaster on our 18ft FC once. When coming up on plane water would pour over the transom. To be honest we didn't really try all different trim and height levels. Maybe we could have found a spot where it didn't do this. The Shallow Blaster was bolt on bolt off so no foul there. You are in quite a spot with the cav plates where you drill holes in your lower unit, not as easy to try before you buy. Have you talked to Tran? Not exactly the same hull, but similar and I think he has his own line of cav plates.


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## Redfishr (Jul 26, 2004)

I think if you put trim tabs on,(electric or hydraulic) you will solve your problem.
They push the transom of your booat up with take off .They solved my problem.
20ft Transport. 
I know my boat wont get up were yours will, but It gets up in about 6 inches less than it would before the trim tabs.
I had a 19 shoalwater before this boat and they helped it as well.
R.R.....


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## Back Country (Oct 14, 2004)

Ditto on trim tabs....


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## TooShallow (May 21, 2004)

I prefer the ShawWing plates. They have a side panel that will help hold the water around the prop. If you have not done so yet, try a heavy cupped (custom) three blade prop with a 15" pitch.That should be about right for that rig. I have never seen a four blade prop that will get-up where a three blade will. 8" over sand is a pipe dream for that rig. Very, very, very, few rigs can do that and a Flats Cat aint one of them.


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## Dieselpowerman (Oct 29, 2004)

t-sip,
I have a 21 ft Flats Cat with a 175 Johnson (boat was re-rated by the Coast Guard). I can get up in about 12" with a hard bottom. Last weekend in Mansfield we were drifting a flat that was about 9" deep. The combination of not having a cavitation plate or trim tabs, having a full load of fuel and 3 people on board, and the weight of the motor kept us from getting up. Once we found those extra 3-4" of water, we popped right out...
I am running a 4 blade prop, 17 pitch. It is dinged up very badly and cavitates its tail off. A rebuild is coming soon, so let me know who you use to do your prop work.
You are on the right track, a cav plate is what is needed. I could see the prop blowing alot of water up over the lower unit, instead of down and back. When the prop is out of the water, the cav plate will force water back instead of slinging it everywhere.
I have to have my jackplate all the way down in order to take off. The prop blows out if it is raised up more than about .5"


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## Dieselpowerman (Oct 29, 2004)

*ttt*

t-sip,
Any updates on your prop/cav plate selection?


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## Capt. Lowtide (Jun 30, 2004)

Wedges would definately help you with negative trim. this will put your prop closer to the tunnel and the jackplate will be run up a little also. Lenco trim tabs would give you additional lift at the transom, but you have to get about 1/2 the boat length in forward motion to get the lift. Bolt on Step-N-Trim tabs work similiar, but are not adjustable like electrics.
Some smaller boats can even get up better with the engine tilted up approximately 45 degrees with electric trim tabs down 3/4.
You can also try engine position trimmed negatively while pushing water the length of the hull and easing off back to almost neutral and then go 3/4 throttle once the wave from behind hits your transom. In most instances this will give you 6" of lift or so.

Propping a boat for hole shot and top end speed sometimes gives me a headache.


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## Tsip (May 21, 2004)

It will be a couple of weeks before we have a new prop and a free weekend to run some testing. Check back with me in about 3 weeks. I'm planning on using the boat over the 11-14th of this month, but not sure if we'll have a new wheel by then.

Tsip


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## Huntmastr1 (Oct 8, 2004)

Boatright Marine has a "Compression" Plate that clamps to your cavitation plate so no need drill holes in your lower unit.

I recently installed one on my 19' Hydro-Sport Tunnel. I realize my skiff is very different from your cat.
I did see an increase in top speed by a solid 3 MPH. I attribute this to the plate catching and hold the water stream on the prop. Before I could see the water blow vertically past the stock cavitation plate even with the jack plate up all the way. I don't think you would see an accurate comparison on different hull designs with different tunnels.
I am very pleased with my holeshot and wide open performance.

Jeff


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## Catn' Around (May 21, 2004)

I have the boat right on my flats cat. One tip that I learned was when getting on plain have the motor jacked up atleast 3/4 if not all of the way. get the boat moving straight, start easing on the throttle and at about 1/3 to 1/2 throttle give it hell. If it starts to bog jerk the motor to the right and then back to the left. If you can get it moving you can generally get it up on plain. When I first got my boat I couldn't get it up in much under 18" but before I blew my motor I could get it up in about 8-9 inches of mud. It will be intresting to see what the four stroke yamaha I'm putting on it will be like


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## Reel Bender (Sep 30, 2004)

\quote {but before I blew my motor I could get it up in about 8-9 inches of mud}

Now thats something to ponder. LOL


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## Catn' Around (May 21, 2004)

my motor blew because of a blocked carb and two of the cylinders running lean. THe only time I ever used this trick was to prove it to my self it would do it, to get out of a back lake of poc, and to get off of the south flats in mansfield which on that hard sand it took more like 12"-13" to get up. Other wise I could motor up normally in 14 + inches of water. So I doubt that those three times had any thing to do with my motor blowing all though it did take a while for me to get it through my head that 8-9 inches of mansfield sand wasn't the same as 8-9 inches of poc mud.


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## richg99 (Aug 21, 2004)

I've got two hydrofoil anti-cavitation plates that anyone can have for ten bucks each plus shipping..or pick-up. I'm in North Houston... 

I took them off because I put Smart Tabs on both of my 16 ft boats. One is an EL Pescador and the other a Carolina Skiff. I think tabs ( any tabs ) are a great addition for getting up in shallow water. That isn't to say that, in some cases, the right hydrofoil won't help with blow out. We run different, and shallower, water here in TX than much of the country. When I talk on forums with guys in other states, they just don't understand real shallow.

Anyhow, I no longer use anti-cav plates, since the Smart Tabs do the job..for $150.00 for my little boats..I think they are great. RichG TX


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## Hop (May 21, 2004)

Rich what motor are they off of?
--Hop


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## Reel Bender (Sep 30, 2004)

Catn' Around:

Thanks for the clarification. It just sounded funny, after I read the sentence. Good luck with your new motor.


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## richg99 (Aug 21, 2004)

Both came off of Yamahas....the "Bob's Machine Stabilizer plate" off of my 50 hp and the "The Angler - Pro series" came off of a 40 hp Yamaha. RichG TX


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