Stress Cracks From Tower

(bond) · (bond) **Join Date: Nov 2002** 02-27-2003, 10:21 AM

Just wondering who all is having issues with stress cracks in there gel coat around where your tower is mounted to boat.

leggester 02-27-2003, 10:44 AM

Nope

(phaeton) · (phaeton) **Join Date: Feb 2002** 02-27-2003, 10:48 AM

Nope

Travis Farber
Wake Me Products
www.Wake-Me.com

(bond) · (bond) **Join Date: Nov 2002** 02-27-2003, 10:53 AM

Thats a good thing me niether but I have a friend that has a AIR WARRIOR big time stress cracks.

(malibudude) · (malibudude) **Join Date: Feb 2001** 02-27-2003, 11:34 AM

None here

leggester 02-27-2003, 12:46 PM

Who mounted the tower? I'd be willing to bet it's a bad mount job.

(fogey) · (fogey) **Join Date: Mar 2002** 02-27-2003, 1:27 PM

None here.

(colorider) · (colorider) **Join Date: Jun 2001** 02-27-2003, 2:11 PM

I had them on a factory mounted tower on my x-5. Warranty covered the repair.

(bond) · (bond) **Join Date: Nov 2002** 02-27-2003, 2:44 PM

..His is in for repair as we speak, dealer installed tower, they are fixen everything for him he said.

buttskimmer 02-27-2003, 3:03 PM

Not I

(hillbilly) · (hillbilly) **Join Date: Aug 2002** 02-27-2003, 3:51 PM

Do heim joints make a difference in no stress cracks??Looking at towers for an old nauti and want to make sure I dont ruin the hull

(bob) · (bob) **Join Date: Feb 2001** 02-27-2003, 5:55 PM

better add some meat to the glass around the area where you plan to mount the legs and add large surface area back plates.
Ive got a question from those who DONT have stress cracks forming: What are the conditions you run in, we often cross the bay with 2-3' swells and larger when large boats pass? With boards and speakers up that is alot of weight shaking around up there. During the summer we have to go in search of water that is worth getting in to board, so many boats and the wind causes waves from 10-4 at least in the main areas.

turtle 02-27-2003, 6:17 PM

I was told this, the holes that go into the hull need to be countersunk. (Into the gelcoat)

turtle 02-27-2003, 6:23 PM

http://www.13thfloortowers.com/Installation%20Manuals/Tower%20Installation%20Manual.pdf

(monstertower) · (monstertower) **Join Date: Mar 2003** 03-19-2003, 9:58 PM

I've been trying to figure this out the best I can and so far I think:

1) The older towers that are 1-1/2" diameter tube or smaller with welded on base plates caused a lot of problems but all the newer designs with larger tubing and flexible bases have not been a problem.

2) People jumping off of towers, doing gymnastics or riding on towers is really bad for your gelcoat.

3) The really low end boats (chopped glass layup) have a lot more problems than all the ski boats and higher end boats (SeaRay, Chapparel, etc) becuase they are a lot thinner.

4) Pulling the newer galactic 4-8 person tube vessels should not be done from a tower.

The maximum stress a wakeboarder was able to put on a tower from testing we did was about 350lb. This cound not be much of a problem for any boat if the tower base can flex with the movement of the tower.

Bill
www.MonsterTower.com

(monstertower) · (monstertower) **Join Date: Mar 2003** 03-19-2003, 10:06 PM

Jeff,

"Heim Joints" are a cool name for rod end bearings and they do help becuase then the base that mounts to the boat can only PUSH or PULL against the base and can not TWIST it. Titan was the company we felt had done the best job in this area but many are moving to in with their 2003 designs.

Turtle,

Countersinking (actually Chamfering) the hole is a real good idea. Can't hurt and can only help and it's easy. If the hole into the boat is 3/8", just run a 1/2 or larger bit to open it up with an angle (email me if you want me to send pics)

It's also a very good idea to put silicone sealant down to make sure water does not go under the base and into the fiberglass. It's not very likely to happen, but it would cause the gelcoat to dimple.

Bill
www.MonsterTower.com

(timmy) · (timmy) **Join Date: Jul 2001** 03-19-2003, 10:24 PM

i would like to challenge the 350 lb force (stress is measured in psi or Pa by the way)

I am 280 lb and I am certain I could load a tower with more than 350 lb especially on a fall where i hang on too long or what not.

by the way no stress cracks on my ride either.

(wakeside1) · (wakeside1) **Join Date: Nov 2002** 03-19-2003, 11:33 PM

The key is that the tower needs to have Heim Joints. The Heim joints can move in any direction and that takes the stress off of the hull. Boss, Skylon, Titan, and Wake Designs all use heim joints for that reason.

Mike Hellweg
Wakeside.com

(bob) · (bob) **Join Date: Feb 2001** 03-20-2003, 4:55 PM

why dont large fishing boats that run in open seas have heim joints(rod ends) on their fishing towers??

(wakeside1) · (wakeside1) **Join Date: Nov 2002** 03-20-2003, 5:30 PM

I can't really answer that question, but I think that a wakeboarder can put a tremendous short-term stress on the tower that pulls from side to side. The Heim Joints allow the tower to move slightly from side to side so that the hull doesn't take stress.

There is a reason that Boss, Skylon, Titan, and Wake Designs have all gone to the heim joint. It works!

(riothepimp) · (riothepimp) **Join Date: Mar 2003** 03-22-2003, 7:51 AM

Ahh, stress cracks. Hey guys it is all in the mounting system, first of all the installers should chamfer the hole after drilling them this will prevent spyder cracks around the hole, and after that you are relying on the mounting system to take up some of the flex. Remeber all boats flex and twist in the water, you may not see it but they do some more tan others. THE MOUNTING SYSTEM.

(monstertower) · (monstertower) **Join Date: Mar 2003** 03-22-2003, 7:49 PM

Sorry about the error of using stress when it should have been force (It was late, no . . .I was tired, no . . . I forgot, no . . )

Check out http://www.inboardtalk.com/tower/tower.html and see the stress analysis link at the bottom. In summary with a load cell being used to measure the exact force, and advanced skier was pulled through a slalom course and the force on the rope never got over 600 lbs, certainly pulls a boat around much more than a wakeboarder and would not expect a wakeboarder force to be this high.

This resulted in a 300 lb downward and 50 lb rear force at the rear legs (with a 2" x 3" base plate the sress on the deck is 50 psi). The front legs are less of a concern since the force is UP but it is the place where reinforcing the underside of the boat is most important.

If your building a tower for a fishing boat they have mounts both on the floor and side of the boat/console so the issue of side stresses are well covered. It would be the same as mounting the tower to the floor of the boat and then having additional mounts on the inside at the top of the gunwale.

I agree with the use of Heim Joint which is why we chose to use them on the Monster Tower. This is even more important on a universal tower often going on boats that were made with chopped glass and not hand laid like higher end boats.

Heim joints make sure the force can not torque or twist the mount, and most of the tower builders have gone to them, especially for universal towers.

Thats my opinion but I could be wrong.

Bill
www.MonsterTower.com

blackhawk 03-22-2003, 8:33 PM

I plan on building a tower per "Wakeboardin"'s drawings. Where can I get heim joints. I will probably use 2" stainless steel tubing. also, what wall thickness should I use? Thanks.

(monstertower) · (monstertower) **Join Date: Mar 2003** 03-23-2003, 9:52 AM

Nato,

The Heim joints are really just Rod End Bearings that have been around longer than any of us. The Heim joint moniker is only used in this market, I guess to make them sound expensive!

Below is a link to National Rod Ends, check out http://www.nationalrodends.com/prodmedia/msm.pdf for a PDF of the commonly used ones. You can probably buy them at Grainger.com or McMaster.com for like $10 - $30 each depending on what type (zinc coated vs stainless vs Teflon lined, etc).

Good luck and post a link to the drawings you found, I have'nt see those.

Please post up some pic's of your tower when your done. There have been some awesome towers people built posted up here in the past.

Good luck and shoot me an e-mail if I can be of help.

Bill
www.MonsterTower.com