# Jet Ski Sponsons on a Jon Boat



## titus_89 (Jul 10, 2018)

Has anyone tried mounting the small sponsons that come on most jet skis on to a jon boat? Even more than just a pair? I have an old tippy 12 foot jon. Saw these fin looking things on a jet ski and my mind started wondering. Possibly add stability? Looks to be for stability and handling on the jet ski. Thought this could widen the foot print of the boat and help out with stability a little bit. If not, then I will go back to accepting that I have an unstable boat.


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## surfman (Jul 10, 2018)

On a jet ski I think they are more for handling than stability. I don't think they will improve stability on a jon.


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## titus_89 (Jul 11, 2018)

Alright. Wasn't sure if it would help push against the water for side to side stability. May help some of the jet jons out there with cornering.


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## thedude (Jul 11, 2018)

They are for tipping the jet ski back upright if it overturns. You reach over the bottom of the ski and it gives you something to grab and start the roll to get it upright. At least that is the purpose they have served me!


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## Bateman (Jul 12, 2018)

Haha they are actually for handling and they grab the water as the hull rolls port or starboard. A flat bottom boat turns flat though so they will serve zero purpose other than reducing spray depending on where you mount them.


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## turbotodd (Jul 13, 2018)

They have multiple purposes on the ski's. They give a little bit of lift to the hull at lower speeds. They aid in handling. A side benefit is giving a swimmer (former operator) a place to grab hold and roll it back over. Usually on top of them.

They weren't real common until the early 90's. Yamaha had built the wave raider 700 and at the time, the Kawasaki 750 SS was the bad boy that everyone wanted. That wave raider had longer sponsons, and they ran slightly deeper while on slow plane. I can tell you this much. I sold the pee out of the raiders (hundreds of them) and I was commonly asked what the sponsons were for. I told most folks that they'd find out one of two ways. (1)-read up on it and (2) go to the lake, get it up to about 60mph, let off the throttle completely, turn, and then get back on the throttle quickly.....if you can stay on the ski, you're a better rider than I am. And that is the honest truth. They were hard to hold onto in a turn, they'd turn on a dime-literally. No spinout like everyone wanted. Actually I have bent handlebars on the Raider 1100's trying to hold onto them while doing a high speed turn. Sit on teh side of the seat, grab the throttle and hold on as tight as I could and still couldn't stay on the hull, found myself commonly holding onto the bars while the ski was still trying to turn, thrown to the side like a ragdoll. They were bad dudes in that department. Thank goodness I don't have to mess with them anymore!! The 2 best things about jet ski's are (1) they got rid of 2 strokes and (2) I no longer work on them, with #2 being my favorite!

I've often wondered if the duck hunters out here would benefit from the sponsons, seeing that they're many times maneuvering into/out of flooded timber, and a lot of the boat manufacturers tout their handling in such hunting waters. But then that begs the question, would a tiller operator be able to stay in the boat being that he's normally sitting atop? I know I'm certainly afraid to spin my war eagle at speed, I've never blatantly tried to turn it like that but I've come close a couple times and it don't spin out....that I know of. Can't imagine "cornering" any harder than it already does, or more specifically I can't imagine needing it to and what would happen if it did. Not my cup of tea so to speak.

But...if sponsons do indeed aid in lifting the back of the hull at low speed plane, makes me wonder if there's anyone who's tried them, just as the OP mentioned?

On the ski's, they're completely out of the water once up on plane going straight, no drag. Don't know if a typical Jon boat would be able to do that or not.

Question. I wonder if a jet outboard would benefit from sponsons more than, say, a prop outboard? 

I'd be willing to try them but I ain't cutting any holes in my hull. It works fine just like it is, for what I need it for.


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## richg99 (Jul 14, 2018)

Consider Smart Tabs. They will add some stability and lots of other benefits.


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## mbweimar (Jul 18, 2018)

I second Rich. I put Bennett SLT's on my rig, and it made a noticeable difference in stability while under way. However, while while anchored or drifting these won't heloat all. For stability while stationary, float pods would be most effective. There are also several cases where people fabricated outriggers, or some sort of PVC pods to mount on the gunnels, but they add unnecessary weight, and slow you down considerably.

Sorry, for getting a little off topic.


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## richg99 (Jul 18, 2018)

Re Bennet SLT. Is the force applied by Springs or by Gas Actuators?


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## onthewater102 (Jul 18, 2018)

PVC outriggers would help stabilize when not in motion, but only if they're big enough. A 6" pvc pipe that's 5' long would displace ~1 cubic foot of water (62lbs), so it would add buoyancy equal to 62lbs less the weight of the assembly. Put two on a jon in such a way that they're held below the water line and it'll be more stable, but you'll look ridiculous and it will be a PITA when under power. Either you'll need to add some sort of lifting contraption (adding weight and defeating the effectiveness of the setup) or you'll have to drag those big tubes in the water and get sprayed for it.

Not worth it, better off selling your rig and buying a bigger one IMHO.


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## richg99 (Jul 18, 2018)

I don't have any "tippiness' issues with either my 1652 or my 1756. 

After I add my (fourth!) set of Smart Tabs onto the 1652 in the Fall, I have considered adding a "topper" of foam on the top surface of the tabs. Since the tabs are small, the added "lift" and stabilizing effect would also be small. 

We shall see.
rich


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## surfman (Jul 19, 2018)

richg99 said:


> Re Bennet SLT. Is the force applied by Springs or by Gas Actuators?



Bennetts are hydraulic but, I believe they have electric ones now, electric would be a screw actuator.

By 4th set? is that because of failure? I had them on another boat and they did not really hold up that well in salt water, otherwise they worked great.


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## richg99 (Jul 19, 2018)

Fourth set fail?.....NO...

Fourth set on my fourth boat. All of mine have held up well in both salt and fresh. I put my first set on a 16 foot Carolina Skiff about 15/20 years ago.

Re the Bennett's SLT query. 

Smart Tabs have always been driven by gas shocks, similar to the device that holds up the hood on a truck/car. 

Bennett's hydraulic systems are well regarded, but expensive and take up a lot of space in the boat.

Bennett apparently saw the benefits of the Smart Tab system and copied it. SLT version.

I wondered if the SLT system used gas shocks or springs. From the little I've read, it sounds like they used springs. I prefer gas shocks.
rich


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## surfman (Jul 19, 2018)

Ok, I did not look up the SLT, I just A.S.S.U.M.E.d they were what they usually are. My smart tabs have had the gas struts corrode several times causing them to either lock up or just break. They last a few years though and are fairly inexpensive to replace the struts. And yes hydraulic is a hassle but they are pretty bullet proof, overkill for a jon for sure.


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## mbweimar (Jul 19, 2018)

Rich, I'm going to assume they're gas. When moving up and down by hand, it's very smooth and quiet. No springy sounds or feeling. They've held up well iver the last year, and even look like real trim tabs.


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## Partradams (Mar 9, 2022)

Hi. I understand that sponsons help with turns and U-turns so that the stern doesn't drift, right? The standard ones look just like a wing, and the tuning ones are L-shaped to better cling to the water when turning, for example, around a buoy. And the question is, but can they help to turn over on their side at a decent speed, or not? I learned this information from my coach and an article about driving a jet ski, so I would like to know if what I'm saying is accurate? I don't deny that I could have messed up something, but I hope not. If you have any advice, I will be glad to read it.


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## Pappy (Mar 9, 2022)

Sponsons provide lift. Once on plane the reduced running surface usually allows additional performance. In the case of adding them to a Jon boat there would be no additional benefit since the running surface is probably equal to or even greater than the original hull. They will not turn like a vee hull can. Watch a hydro and you will see them slide during a turn.
Interesting project though but to do it right I think two hulls would be necessary to get the running surfaces you would need. 
By the way....welcome to the forum!!


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## cmgw (Mar 10, 2022)

My boat has "outriggers" on it, they have the ability to be aired up even. 

https://flic.kr/p/2n4EX5i


Album
https://flic.kr/s/aHBqjzD5iN


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