Worthless ski pylon?

[scooper77515]

OK, Up front. I KNOW the hollow aluminum ski pylon on our late 90s challengers and speedsters is worthless as far as actually pulling up an adult skier when fully extended.

BUT...how about just pulled up an inch or so above the hatch?

Any engineers out there know dynamics enough to calculate if my 195 lb butt can be pulled up on a wakeboard behind the boat with only 2" sticking up without bending it?

If not, I have access to a machine shop and endless supplies of stainless stock and tubing.

If I put a solid chunk of stainless or thick-walled tubing there and mounted the black knob on top (or lathed in a new knob), would the hull be able to handle my forces without breaking the pylon mount from the fiberglass?

This is a serious question. I can start making decent pylons and sell them to other members if we can determine if the boat can handle it with the way they are mounted.

I am getting really tired of being pulled DOWN by hooking up to the ring by the pee hole.:ack:

 

[jords]

If your going to want to make your own and be cost effcient then you have to figure out the max tensil or load strength of your tube

strength (psi) = yield * (wall thickness / radius)

I would use 5052 Aluminum it has a tensil strength of about 28000 psi

so let's say you had a 2 inch diamtere tube with a wall thickness of .12 " it would have a tensil strength of 110 lbs. So its not how much of the tube is sticking out its how strong the tube is. If you pull the tube up only an inch it may hold but how much force is pulling on the bottom of tube.

With your weight and drag the tensile strength you would need would have to be around 1500 lbs to be ultimate safe. So a 2 inch rod would have a tensil strength of about 1800 - 2000 pounds. Now you have to harness that pulling power, I don't know the breaking point of fiberglass , but how about attaching the pole to where the ski hook is by the pee hole and attaching top of it with a strap to the exisiting pylon?

 

[scooper77515]

but how about attaching the pole to where the ski hook is by the pee hole and attaching top of it with a strap to the exisiting pylon?

THAT is actually my next idea if we determine that the fiberglass won't hold. I was thinking of running straps to the two cleats on the sides at the back to split the load and to give side-to-side support, but didn't think of one up the middle to the existing pylon.

 

[Thunderkat13]

So your Ski Pylon is sucking>? I have a 2000 speedster and not having a tower sucks but we use the factory pylon nonstop till the funds come in for the tower... We often pull the pole to full extension and then tighten down the rub insert by twisting the top to lock it into place...

I weigh 200lbs 6'0 and my buddies weigh anywhere from 185lbs - 225lbs and we have had no issues what so ever with the factory mounted pole. You could look into using a solid stock and either attaching your rope tie or making one on top.. Im not 100% sure where your pole is mounted but in the speedster seadoo actually made a pretty good mounting/support system to help handle the loading and stress...

 

[scooper77515]

Not sure how tuff the 2000 pylon is, but it looks sturdier than what I have. Mine feels like an aluminum can, and extends about 6" when pulled out fully.

These are notorious for bending.

Please ignore how dirty the tops of my seats are. I had a starter seize up on the flywheel, and in the process of yanking it out, cut my hand up on a hose clamp and bled all over that seat. I will clean it up after I get the new starter in. :ack:

 

[Thunderkat13]

oh wow... yea completely different setup... yea.. i have to say fail on the 97 pylon..
Ill take some more detailed pictures of the 2000 setup so maybe you can fabricate something similar...

 

[scooper77515]

That would be great Thunderkat. I might even be able to skip fabrication by just buying one and mounting it to my boat.:cheers:

 

[verk182]

keep us posted, would like to mod mine as well.

 

[scooper77515]

Sorry, man. I don't like to keep friends posted of what I am doing.

I tend to get ideas, then do them, and reap the benefits for myself...

:reddevil: Naw...do a search for scooper77515 on google. See what pops up. I THRIVE on experimenting with what others wont do and reporting the outcome:cheers: Most will pop up in the Maverick forum, but several here and in the Kawasaki Versys forums (fori???) also.

Who needs science when you have forums?

 

[Thunderkat13]

Just took the pictures of the 2000 speedster pylon setup....
Pictures to follow..... Used my pinky to give you a size comparison..

 

[scooper77515]

Thunderkat!!! Thanks for the detailed pics!

Is that long bolt down the middle going all the way down to the bracket on the floor of the hull?

Those pics change the entire direction I was going. Mine is oly attached at the top of the hull where it comes up out of the boat, then bracket basically behind the seats about 12" down. MUCH weaker than having it connect to the floor.

 

[Thunderkat13]

no the threaded bolt inside the tube goes to a rubber stopper at the end of the extension.. A tightening mechanism, you twist the pole and the rubber fattens up to hold nice and sturdy!

Picture to show ya what im talking about

 

[Thunderkat13]

no the threaded bolt inside the tube goes to a rubber stopper at the end of the extension and is tied into the rope cap to keep it onboard the boat lol. It is a tightening mechanism, you twist the pole and the rubber fattens up to hold nice and sturdy inside the other bracing tube.

Picture to show ya what im talking about

 

[swill777]

I have a 98 sportster, I weigh 195-200, and I wakeboard off of the same tow pole thing that you have. It is a pos, and slightly bent (from the last owner), but it has worked fine for the last 20-30 times out.
98 Sportster with the dual 717's.

Def not skinny, using shit pole

THAT is actually my next idea if we determine that the fiberglass won't hold. I was thinking of running straps to the two cleats on the sides at the back to split the load and to give side-to-side support, but didn't think of one up the middle to the existing pylon.

 

[scooper77515]

Hmmm...if it is not stressing the fiberglass, I may just insert a stainless solid or thickerwalled tube into the aluminum one to strengthen it up. That would be the easiest fix.

Hell, I will just replace the aluminum tube with stainless and see how that works.

 

[scooper77515]

OK. Here is what I am going to try first.

Dad (a machinist) is going to stop by in the morning and take the stock pylon. I am going to have him cut me another one just like it out of stainless, but longer and with a second "notch" cut another 6" down, giving me 2 places for the rubber-band loaded catch to catch. This will allow it to stick up at the current height or at another 6" higher. (EDIT--no 6" extra extension...would extend down too close to the exhaust pipe and get in the way when working on engine, also, pushing my luck on stress on the fiberglass.)

Then I will pop off the plastic top with the roll pin in it and snap it onto the new stainless pole.

Now that I have the stock one out, it feels like solid aluminum. Does anyone know if it is solid or hollow?

I will have to keep a close eye on the fiberglass, especially if I use it at the highest setting. If it starts to crack (or breaks outright, which I doubt it will), then I will work on another plan. Either reinforcing the fiberglass or devising a new setup from scratch.

 

[scooper77515]

got my new pylon from dad today. Instead of using the black plastic top, he machined one from a scrap piece of plastic. He asked me by email what color I wanted out of white, red, or green, and I said green, but he had already left for work and made the red one before he got the email. Oh well, this is just experimental.

It is milled down from a solid chunk of 1" stainless rod, and is a bit heavier, but I am sure it will not bend before it takes the back half of the boat off in chunks and pieces :reddevil:

There is room at the bottom for an extra 6" long pipe, but it would get really close to the exhaust tube if you pushed it down. Of course, you could go up 2 extra feet if you wanted, if you pulled it completely out rather than pushing it down when you are done skiing.

But if you went any longer, I would think about running some support lines toward the front and sides of the boat to keep from yanking the mounting brackets out of the hull.

 

[scooper77515]

Bump!!!

Tried out my new stainless pylon today and it works GREAT. No flex in the pole or in the fiberglass where it mounts. I was able to get 2' "airs" and hop from one wake to just past the center of the slop behind the jet. I am working to get from wake-to-wake and skip the slop, eventually.

Using the pylon compared to the hook down on the platform...hops me out of the water faster on takeoff, and triples the air I can get.

So, at this point, I guess I have a stock aluminum straight pylon for sale, if someone needs to replace a bent one. If you don't hurry, I may take the black plastic thingamabob off and put it on my stainless one just so it matches the boat better. But the aluminum shaft would still be for sale...

 

[Aqua-Holic]

sorry...just saw this thread.

Any interest in selling these? If so, how much?

 

[scooper77515]

I don't make them, but my dad might do it if he can make a couple bucks. I need to ask him how much the materials and labor would run...

 

[maxtoro]

PM'd you...

 

[verk182]

I would be interested in one if your dad goes into production on these

 

[scooper77515]

If I get enough WANTS, I might take a day and go make them myself. I guess I would need to get 5 or 8 requests, then I would be motivated to figure out the cost of material and labor and see if it is still worth it.

 

[ryanlberg]

i want one for my speedster 150 let me know if you are going to make them it looks great :hurray::cheers:

 

[scooper77515]

That sounds like 3 wants.

I will look into the cost of materials today.

I need you guys that want one to verify that it is the same size as the ones I am making.

The one on my challenger was 20mm diameter (.783") and 13" long, that is the pole itself, not the plastick knob on top.

I don't want to make several trips to the machine shop, since it is a 2 hour drive each way for me. I may pound out about 10 of these and sell the ones ordered, and keep a couple to the side in case they are needed later.

Being stainless, and a fairly high grade, I have no idea what the cost might be when done. I will call around today for materials and have a better idea.