Home made Ski/Wake Pole Opinions Please

[NZjohnson90]

I'll try n keep chat to a minimum this time....

I have made this from bits n pieces I picked up here n there so has cost basically nothing much. The base and the mounts for the struts are all I had to buy which cost $40NZ or thereabouts.

1st question - which way do you think would be the strongest to mount the struts to the pole? I originally wanted the struts at the stern side, but then on second thoughts it might be stronger from a sideways pull to have them bow side - see pics

http://i497.photobucket.com/albums/rr333/kiwigt/IMG_1677.jpg
http://i497.photobucket.com/albums/rr333/kiwigt/IMG_1680.jpg

2nd you can see the 10mm ply that would be bolted through the fibreglass seat to another piece the same on the other side to strengthen the whole thing up, then It would all be covered in foam/material to make the whole thing look tidy. This saves me from cutting a hole in the seat, drilling holes in the floor, having to buy a much longer piece of stainless, and I was thinking that shorter = stronger and less force being put on the pole it's self. Do you think this would be sufficient??

http://i497.photobucket.com/albums/rr333/kiwigt/IMG_1681.jpg

3rd All the hardware, from base, to strut mounts to all nuts and bolts are stainless and the struts will have a decent size stainless or 5mm marine alloy plate (depending what I can find in the garage) on both top and bottom of the glass. The glass is also reinforced with ply glassed in underneath but do you think they would be strong enough?

http://i497.photobucket.com/albums/rr333/kiwigt/IMG_1682.jpg

I know in an ideal world I would tow to boat to the welders and have them weld up all the feet etc, but firstly I priced that up and simply cannot afford it, secondly I want the pole to be removable.

Any opinions appreciated

 

[5150abf]

Re: Home made Ski/Wake Pole Opinions Please

This is a system, you can have a pole that will support the world but will the hull of the boat support the load?

You are going to be dealing with ALOT of force, and not a steady force, it is is a jerking load which is the worst, so be sure the hull of the boat has been reinforced to deal with it.

Also be preppared for failure, don't assume it is going to work the first time out, have whoever is on the end of the rope be really heads up.

 

[Bob_VT]

Re: Home made Ski/Wake Pole Opinions Please

First..... your pictures should be re-sized to 640 x 480 because they are too large for the forum.

Now for the ski pole

Reverse the angle braces. You need the braces facing forward and away from the transom.

The design you have will put more stress on the transom and the primary design is to get a pull point forward of the transom.

As far as the attachment ......... you could eliminate that band clamp and drill through the center of the pole and use one long bolt.

 

[The_Kid]

Re: Home made Ski/Wake Pole Opinions Please

The ski pole on my Procraft fish N ski has the support arms going towards the stern. I drew them in since they weren't installed when I took the picture.

 

[45Auto]

Re: Home made Ski/Wake Pole Opinions Please

Leave your support struts towards the stern. I've never seen a ski pylon with the supports going forward. Wouldn't make senseto put them in front, to get a narrow enough "V" to provide any meaningful support you would take up all the room in the back of your boat. All your doing is building your own version of these typical ski pylons, as sold by Iboats, Overtons, etc. They all mount the supports to the rear:

http://www.iboats.com/Water-Ski-Pylons/dm/view_id.217689

Your design looks good. Only other thing you need to do is fiberglass some of the 10mm ply (maybe 25cm x 25cm) as a reinforcement on the underside of the rear deck where you will be attaching the support struts.

You can see the ski tripod on the back of my old Bayliner in the pic below. Every runabout down here has one like this on it. We pulled up to 3 skiers, wakeboarders, or tubers at once for over 7 years with this one.

 

[NZjohnson90]

Re: Home made Ski/Wake Pole Opinions Please

Thanks for that guys, In terms of reinforcement, the back where the struts will be mounted is already factory reinforced - has 10mm play glassed into the structure of the boat - in addition to this I will put the stainless or alloy plates on top and bellow to be double sure.

The seat where the pole base will be situated is not currently reinforced at all, my question here was do you thing that 2 10mm ply sheets the width and length of the seat (1 on top and 1 below) bolted through with 8 stainless 8mm bolts will be enough reinforcement????

Also I think everyone misunderstood my first question. I will determinately have the struts facing the transom, not the bow. But the question was about where to fasten it to the pole. Do I have it at the stern side of the pole - pic1 or the bow side of the pole, pic 3.

 

[Willyclay]

Re: Home made Ski/Wake Pole Opinions Please

Hard to tell from the pictures but the support tube attachments on the aft deck remind me of folding top attachments. If that IS what you are using, then I question their strength given the loads you will apply to them while towing. Looks good!

 

[NZjohnson90]

Re: Home made Ski/Wake Pole Opinions Please

Hard to tell from the pictures but the support tube attachments on the aft deck remind me of folding top attachments. If that IS what you are using, then I question their strength given the loads you will apply to them while towing. Looks good!

Yes they are folding top attachments (i think)? I agree with you, and I am a little dubious about them myself, and I am questioning if I should just go get some feet welded on instead once the rest of it is set up. Although this will probably cost double what the whole rest of the job cost put together.

They are solid stainless, not cheap chromed Brass, the guy from the stainless fastner shop where I got them seemed to think they would be strong enough. In his words "I you will rip off the back off your boat before these give way". Hmmm i'm not so sure but I'll see how solid the whole thing feels once finished...

You think the rest of the setup looks ok though?

 

[Bigprairie1]

Re: Home made Ski/Wake Pole Opinions Please

As Bob said, move your upper mount join point to the center of the main vertical pipe...and bolt through all of them.
I would try to move the vertical pole further forward towards the bow to increase the angle on the back struts. This puts the towing stress into a more linear line of action and less into a 'buckling' situation.
The (2) lower strut mount brackets however are not going to cut it in my opinion.
This are going to fail quickly based on what I see. You will shear that cross pin or break the clevis style mount. That bracket is not forged or welded...it is cast and should not be used for this type of application.
Instead I would take the strut end and compress it to produce a horizontal flange flush with the back surface of the boat. Then I would put a vertical pin mount down through the back, typical both sides. (Its a little hard to see, but in 45auto's pic you can see a more similar mount to which I am referring). As well I would reinforce these mounts from below with an additional piece of plywood or metal to distribute the stress that those struts will see.
My two bits, let us know how you make out.
BP

 

[Willyclay]

Re: Home made Ski/Wake Pole Opinions Please

They are solid stainless, not cheap chromed Brass, the guy from the stainless fastner shop where I got them seemed to think they would be strong enough. In his words "I you will rip off the back off your boat before these give way". Hmmm i'm not so sure but I'll see how solid the whole thing feels once finished...

You think the rest of the setup looks ok though?

Bigprairie1 makes a good point about these brackets being "cast" and not forged or welded. However, your local supplier may be right and all our opinions are just that but you are the one who is hands-on with the decisions to make. You have received good input from forum members who are trying to help you. At some point, you need to adopt the suggestions you believe let you reasonably produce a safe, strong ski/wake pole and then test it. Good luck and let us know what you do!

 

[NZjohnson90]

Re: Home made Ski/Wake Pole Opinions Please

OK, finished, what do you think? Just the test to go, maybe I'll try n get out at the weekend. Think I'll try it with the doughnut before I try pulling me on wakeboard or ski.

In the end I took it to a engineers that specialize in stainless and asked their opinion. They insisted the strut brackets were strong enough but said they did not have enough base area or big enough bolt holes. The welded the brackets to a bigger plate for me, hopefully that should do the trick.

They are bolted though fibreglass with 10mm ply glassed into it and a 150mm by 150mm plate under that just to make sure.

The base goes through fibreglass roughly 6 or 7 mm but with 10mm ply bolted (not glassed) with stainless bolts on the top AND bottom of the seat, so that is bolted through 20mm ply + 6mm Glass. The ply runs the full length and width of the seat. The base also has 150 by 150mm plate under the ply as well just for peace of mind. ( unfortunately I have not got the pin to hold the pole to the base yet hence the screwdriver...)

I have done the swing off a rope as hard as I can in the driveway thing and it seems to be solid but I guess the real test will be in the water.....

Build cost all up including welding, all the ply and hardware to reinforce the seat (which needed doing anyway), foam, vinyl etc $120NZ

 

[Willyclay]

Re: Home made Ski/Wake Pole Opinions Please

Very nice! Hope all goes well. Let us know.

 

[wa_ssv197]

Re: Home made Ski/Wake Pole Opinions Please

I use this on my boat.

 

[NZjohnson90]

Re: Home made Ski/Wake Pole Opinions Please

On the braces, where they attach to the boat, that screw looks awful small and will work loose if not secured. If it were me I would drill it out and use a hardened pin with a retaining clip.

That is a good idea, maybe I will do that.

 

[NZjohnson90]

Re: Home made Ski/Wake Pole Opinions Please

OK I know it's been a while but I now have a working usable ski pole....

Had to do a few modifications though, guess I was kinda optimistic to think that it would work 1st try.

Took the boat for a spin with the pole mounted as you saw before, pulled my gf up on the doughnut now probs, but when I tried we got lots of disturbing creaking noises and saw the deck at back where the struts were mounted flexing quite considerably, decided it was probably unwise to push it any further.

Went to the scrap man and got a sheet of 5mm marine Alloy for the huge sum of $20. Cut to shape, bolted in place and job done, new plates distribute the weight quite considerably more than the little round feet I had before.

Gave it a test at the weekend and it pops all 105kg of me out of the water on a wakeboard without a whisper. Hopefully thats job done. All up including reinforcing seat, materials, stainless hardware etc. $140Nz or about $95Us

The finished pole

Then Looking up inside the Hull at under where the struts fasten.

And lastly under the seat where the pole base is bolted through and plated (i may put a longer stiffer plate under there but dont know if it's really necessary.

 

[Willyclay]

Re: Home made Ski/Wake Pole Opinions Please

Great news on the ski/wake pole! Your transom plate looks quite hefty also. You do good work.

 

[Tacklewasher]

Re: Home made Ski/Wake Pole Opinions Please

Very nice looking setup, but I do have a question.

For the center pole, would it add strength to have the pole go all the way to the floor?

What I am thinking for my boat is to have a reinforced hole where you pole ends and secure the pole to the floor.

Not sure if this would work or if it is overkill.

 

[salty87]

Re: Home made Ski/Wake Pole Opinions Please

Very nice looking setup, but I do have a question.

For the center pole, would it add strength to have the pole go all the way to the floor?

What I am thinking for my boat is to have a reinforced hole where you pole ends and secure the pole to the floor.

Not sure if this would work or if it is overkill.

there's a thread in the wakeboarding section where someone has pics of their homemade board racks. he did just what you're describing...thru the gunnel and mounted to the deck. http://forums.iboats.com/showthread.php?t=360853

 

[NZjohnson90]

Re: Home made Ski/Wake Pole Opinions Please

Very nice looking setup, but I do have a question.

For the center pole, would it add strength to have the pole go all the way to the floor?

What I am thinking for my boat is to have a reinforced hole where you pole ends and secure the pole to the floor.

Not sure if this would work or if it is overkill.

Yes I think you are right, it would add strength to put the pole through the seat and into the floor. If I were you, or have more expertise, cash and knowhow that's what I would do too. I didn't do that for the following reasons...

1. I salvaged the SS tube from scrap and that's the longest piece I could scavenge at the time (although I'm sure with a bit of effort/cash I could have found a longer bit if I really tried).

2. I didn't want to block access to valuable stowage space - she's only a little boat and I need all I can get, my fluel tank was behind the pole at the time too - i moved it up front now anyway though.

3. I don't know where the stringers or structural areas are in the floor and dont know how to locate them without pulling up the floor. I thought putting it in the wrong place could be just as weak as putting it in the seat.

4. The seat is basically just fiberglass, and the ply I used to reinforce it is easy to bolt on/bolt off so there is nothing structural to rot after I drill holes in it. If the ply rots in a year or two its a half hour job to replace it, however If i cause the floor to rot over time by drilling holes then it's a much bigger job.

I don't know if these reasons are sound ideas or not, I'm kinda new to this boat stuff, but at the time that was my thoughts. If you can find ways around these things then definitely go through to the floor I'm sure it would be stronger.

Lastly If you wanna do this cheap, then I would not be buying materials directly from the suppliers and shops, it would have cost me double if I did that. Local boat builders, engineering companies, and the scrap metal man are excellent sources of scrap marine alloy, stainless parts and fiberglass cloth and resin. I got almost all my materials by just going in and asking, If you are nice they will generally just give you some for free or very cheap, it's only scrap wastage to them.

Cheers

 

[dachyk22]

Re: Home made Ski/Wake Pole Opinions Please

i made one for my mfg tri hull ill get a pic up tonight but it uses two of the motor mounting holes on the transom and then bolts through the floor it was made out of entirely scrap parts and works great