does anyone run a fin?

« **on:** August 28, 2012, 10:29:12 PM »

obviously my boat will never be a 100mph float. one of the things that I dont like about it is in a turn it feels like its sliding rather than turning. not sure if thats just the jet pushing the ass end out. does anyone run a fin under their boat and how much does it affect turning?

« **Reply #1 on:** August 29, 2012, 02:29:53 AM »

I have no rudder on mine. Feels like the more I throttle, the better it turns and tracks.

Only bitch I have on mine is how easily it wants to swap ends when idling or moving slowly through any no-wake with no rudder.

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« **Reply #2 on:** August 29, 2012, 03:19:30 AM »

I used to run a rudder with drop but have taken it off this season, use to think it made a big difference and couldn't go with out but it was all in my head I can't even tell it gone!!

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« **Reply #3 on:** August 29, 2012, 06:44:15 AM »

i have a turn fin in my liberty and it turns very good, no rudder

« **Reply #4 on:** August 29, 2012, 07:44:47 AM »

I also have a turn fin and it helps some. Once I added the straight snoot even more. I also have a place without a rudder.

« **Reply #5 on:** August 30, 2012, 10:59:58 AM »

yeh i think ill grab one from rexmar and give it a try. those pix bring up an interesting point that i might be snagging my trailer with it when i take it on/off the trailer... hrmm.

so does it just mount on the outside, drill holes thru the bottom of the hull and then a backing plate?

i googled around and some people say that the fins cause some type of disturbance with the way the intake gets water, almost diverting it away from the intake as you go thru the water. but then again im sure a lot of circle jets must fun scag fins so they can bury it in a turn without spinning out...

« **Reply #6 on:** August 30, 2012, 11:54:00 AM »

I think the regulations require a fin, or maybe they just require a rudder. I don't remember. Clearance is deffinately something to think about. Have you talked to anyone from gs marine about it? They are in norco I believe. They do alot of race boat stuff so they should know.

« **Reply #7 on:** August 30, 2012, 12:47:33 PM »

I installed a fin on our '77 Hondo. Dramatic difference in turning. Granted my fin is about 10"s deep, and 14"s long, it's the largest single fin I've seen (same pattern as the hurry round Hondo). With nothing hanging down, the boat would spin out constantly or cavitate. Then I added a rudder and a spin fin on the ride plate, helped alot. Took that stuff off and put the fin in, now I can make 40mph high G turns pretty confidently, and if it does cavitate it doesn't spin, just let off the gas and it hooks back up. I found the center of gravity first, then dropped the fin right there. Drilled through the hull, laid some sea goin epoxy down, and bolted it with stainless bolts and nylocks. It is about a 1/4" from a trailer support, but once it's in the water it floats high enough to clear all the supports.

« **Reply #8 on:** August 30, 2012, 01:24:35 PM »

I cut about 1" off to fix a small break and bend floating down river a few years back(floated onto a rock). The fin has two bolt thru and epoxy. Mine doesn't have a backing plate as the bottom of most boats is usually the thickest part but wouldn't hurt.

« **Reply #9 on:** August 30, 2012, 01:39:03 PM »

anyone have any advice as far as fin placement? im thinking a profile pic while at cruise (3k to 4k) should show me where the water is breaking on the hull and go from there?

« **Reply #10 on:** August 30, 2012, 01:52:04 PM »

I drive a youngblood, doesn't need a fin in the slightest, I have to try and pitch it sideways to make it go (it's actually kind of fun

)

« **Reply #11 on:** August 30, 2012, 11:01:30 PM »

Quote from: ka0tyk on August 30, 2012, 01:39:03 PM

anyone have any advice as far as fin placement? im thinking a profile pic while at cruise (3k to 4k) should show me where the water is breaking on the hull and go from there?

I have never heard of this having anything to do with fin placement.

-beerjet-

« **Reply #12 on:** August 30, 2012, 11:31:28 PM »

Alrite, had a few drinks so gonna talk shit. The most of us cruise the boat around with others and occasional throttle blast for shits and grins, whatya tryin to get out of it?

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« **Reply #13 on:** August 31, 2012, 04:55:59 AM »

Quote from: BIG JOHNSON on August 30, 2012, 11:31:28 PM

Alrite, had a few drinks so gonna talk shit. The most of us cruise the boat around with others and occasional throttle blast for shits and grins, whatya tryin to get out of it?

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Big J that's not talking shit that's just telling it how it is lol!!

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« **Reply #14 on:** August 31, 2012, 07:31:45 AM »

Eh, was just thinkin aloud.

Honestly I thought a fin was the same as a rudder on a nozzle

Don't all pumps have a fin on both sides of the intake?

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« **Reply #15 on:** August 31, 2012, 07:46:50 AM »

Quote from: BIG JOHNSON on August 31, 2012, 07:31:45 AM

Eh, was just thinkin aloud.

Don't all pumps have a fin on both sides of the intake?

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Gonna pull my intake, it has a leak near the front- under the pan, and machine/mill off the fins, as they are cracked halfway or better (been is some skinny water

)...and it handles fine
I know I'm not the first to do this

100's of seadoo's and jet skis and the twin powered pwc "boats" never had intake fins...why? less drag?

Daniel

« **Reply #16 on:** August 31, 2012, 11:15:28 AM »

Quote from: beerjet on August 30, 2012, 11:01:30 PM

I have never heard of this having anything to do with fin placement.

-beerjet-

i just figured it wouldnt do any good if it was out of the water all the time?

« **Reply #17 on:** August 31, 2012, 12:53:30 PM »

Yeah but....generally you're not trying to make a tight turn at speeds where you're flying the boat....at least not if you wanna stay dry

« **Reply #18 on:** August 31, 2012, 08:27:31 PM »

no fins!!!!

« **Reply #19 on:** August 31, 2012, 09:56:56 PM »

Quote from: ka0tyk on August 31, 2012, 11:15:28 AM

i just figured it wouldnt do any good if it was out of the water all the time?

Your right, it doesn't do any good out of the water but its a "turn" fin and has nothing to do with your boat cruising at 3k-4k rpm.

I did mine on the trailer.

-beerjet-

« **Reply #20 on:** August 31, 2012, 10:10:36 PM »

Quote from: beerjet on August 31, 2012, 09:56:56 PM

Your right, it doesn't do any good out of the water but its a "turn" fin and has nothing to do with your boat cruising at 3k-4k rpm.

I did mine on the trailer.

-beerjet-

so you just guessed where it should go?

« **Reply #21 on:** September 02, 2012, 10:02:14 AM »

There is a thread on it in the tech section....
I think.

-beerjet-

« **Reply #22 on:** September 10, 2012, 03:50:19 PM »

fin arrived today. now where the hell do i put it... hrmm.

« **Reply #23 on:** September 10, 2012, 04:58:49 PM »

I put mine right where the center of gravity is on my boat. There was a long, detailed thread from circle racers about it on here, and that's what I took away from the subject. I will try to find it. There's several members on here that have tried different placements in their boats, maybe they'll chime in as well.

« **Reply #24 on:** September 10, 2012, 05:10:21 PM »

Can't find a picture of the fin installed unfortunately, just a pre-install picture. I first found the COG with a 2x4 and a jack, with the boat under full weight with me sitting in it, marked it on the boat and also wrote it down for future reference. Then out came the motor, pump, and everything else (I was resetting the intake) and we added a brace and cut the boat where it would sit, followed by 12 countersunk bolts from the bottom, and nylocks atop the fin mounting plate. Also had sea-goin epoxied the fin in from the top like an intake, and filled the bottom gaps with epoxy, again for added strength and no leaks. That turn fin looks around a 1/3rd of the surface area as mine is, and I'm betting your boat has a thicker bottom, I wouldn't imagine strength being as large of an issue to you.

Mine was installed right behind this brace.

ka0tyk

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