Wakeboard tower- hull thickness

dremmick85

Cadet
Joined
Jul 10, 2011
Messages
11
I installed a aerial tower on my 91 ski supreme and worried my hull is not thick enough it looks to be 3/8" thich but is layered fiberglass, blue (styrofoam?), fiberglass, foam and fiberglass again. Will this be thick enough? im thinking about building up the fiberglass on the back side or marine wood and pl premium adhesive. Any ideas
 

craze1cars

Lieutenant Commander
Joined
Dec 26, 2004
Messages
1,822
Re: Wakeboard tower- hull thickness

Just fully epoxy a block of 1/2"-ish plywood on the backside of each leg...as big as will fit. That will distribute force and strenghten the mount points.
 

brick75

Petty Officer 1st Class
Joined
Apr 21, 2010
Messages
289
Re: Wakeboard tower- hull thickness

Yeah, the hull thickness where I mounted the rear legs seemed a little thin to me too. But it seems to be holding up just fine after installing some plywood blocks with marine epoxy on the inside.
 

dremmick

Cadet
Joined
Jul 7, 2010
Messages
13
Re: Wakeboard tower- hull thickness

What type of epoxy? 5200, liquid nails, pl premium
 

brick75

Petty Officer 1st Class
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Apr 21, 2010
Messages
289
Re: Wakeboard tower- hull thickness

Not sure what type of epoxy off the top of my head. Bought it at a marine supply store though, so it is intended for this type of use. It came in two separate containers that I had to mix together prior to using.

I was thinking of using liquid nails as well since it was a bit cheaper, but after reading the label on liquid nails, I decided it would probably be worth spending a few extra dollars for the real deal.
 

sickwilly

Lieutenant Junior Grade
Joined
Jul 9, 2007
Messages
1,089
Re: Wakeboard tower- hull thickness

I used pl premium construction adhesive based on a thread here. I think the argument was that it woudl flex with the fiberglass a little more than 5200, and is still water proof, strong as concrete, etc. It seemed easy enough to work with and dried hard as rocks. It was also very reasonable from Home Depot.
 

Hansolo99

Petty Officer 1st Class
Joined
Jun 27, 2009
Messages
302
Re: Wakeboard tower- hull thickness

I used 3/8 plywood and liquid nails. I have always used this to install towers and have never had a problem. Basically you want to make sure they is something between the wood and the hull (something that will dry) and take shape of the holl from the inside. Here is mine and has been on for years with NO cracks, sqeaks etc.

DSCF0028-2.jpg
 

pat8839

Petty Officer 1st Class
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Apr 18, 2008
Messages
270
Re: Wakeboard tower- hull thickness

Do you guys make your backing plates out of marine grade plywood? How about Starboard? Or does starboard compress too much?
 

sickwilly

Lieutenant Junior Grade
Joined
Jul 9, 2007
Messages
1,089
Re: Wakeboard tower- hull thickness

I purchased a sheet of marine plywood online when I could not find it locally. I got it from an aviation store. I have no clue about starboard. I know where I mounted the tower the backing plates should never get wet, but I still wanted to use marine just in case.
 

Hansolo99

Petty Officer 1st Class
Joined
Jun 27, 2009
Messages
302
Re: Wakeboard tower- hull thickness

Do you guys make your backing plates out of marine grade plywood? How about Starboard? Or does starboard compress too much?

I always use regular plywood, but some guys will tell you only use marine. I have done it this way for 20 years and NEVER had a problem as it never gets wet, but if you want to be safe use marine grade. The most IMPORTANT part is what is between the hull and the wood remember that...................
 

pat8839

Petty Officer 1st Class
Joined
Apr 18, 2008
Messages
270
Re: Wakeboard tower- hull thickness

Hansolo-I know there are multuple types of liquid nails-which type do you use? Also, do you fill the holes where the bolts go through?
 

Hansolo99

Petty Officer 1st Class
Joined
Jun 27, 2009
Messages
302
Re: Wakeboard tower- hull thickness

Hansolo-I know there are multuple types of liquid nails-which type do you use? Also, do you fill the holes where the bolts go through?

I just use the good old regular liquid nails, I looked in the garage to see if I had an old one, but I dont. I think it is gold and white in color. NO do not put it in the holes. First get everything drilled and ready to bolt then use a liberal amout of liquid nails to the plywood (around the holes) and put it in place and cranks down the bolt just enough to where the glue starts to squeeze out then stop and wait till the following day to tighten it all up. When you crank it down the first time with the liquid nails still soft crank it enough to spread it out and then stop this way it will form to the contour of the hull.....
 

oops!

Supreme Mariner
Joined
Oct 18, 2007
Messages
12,932
Re: Wakeboard tower- hull thickness

hi guys......the proper way to install a backing plate is to use a fiberglassed piece of ply..

marine or exterior grade plywood ....it does not matter.

when i make backing plates.....i glass both sides and gellcoat the outer side. (the side that will not contact the hull)

i pre drill the holes for the 4 bolts. both thru the hull and thru the backing plate.

then scuff the area inside the hull and clean with acetone.....then re glass the innerside of the plate and stick it to the hull.......put the bolts thru, tighten and let that cure.

remove bolts and install as pre regular.

if the tower foot goes on a curved part of the hull......you need to sand the backing plate so it fits the curve of the inner hull.

you can just pl it in place.....but if you glass it.....it becomes part of the hull. and you will not have to worry about crazing
 
Joined
Jun 9, 2009
Messages
7
Re: Wakeboard tower- hull thickness

Do you have any pictures of the tower and the mounting points? I am getting ready to install a tower on a friends tournament series and would like to take the right precautions before hand.
 

Litigator

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Joined
Apr 24, 2012
Messages
17
Re: Wakeboard tower- hull thickness

Has anybody ever used MDF over plywood? I would think MDF would hold up better since it is much denser then plywood. Of course cover it in resin and mold it to the tower bases on the under side of the fiberglass.
 

davras

Recruit
Joined
Apr 4, 2010
Messages
5
Re: Wakeboard tower- hull thickness

Has anybody ever used MDF over plywood? I would think MDF would hold up better since it is much denser then plywood. Of course cover it in resin and mold it to the tower bases on the under side of the fiberglass.

MDF is denser, but tends to crumble under repeated flexing. Plywood, with it's longer grains, can stay intact under repeated flexing. A person jumping the wake will exert up to 300 lbs of force on the very top of the tower, which is the long end of the lever. At the hull attachment, it will multiply the force based on distance between the forward and aft mounting points of the tower, and the height of the tower. Repeated compression of MDF in the thousand pound range will make it crumble, while appearing to be intact under the epoxy.
 

itcowboy

Cadet
Joined
Apr 8, 2007
Messages
17
Re: Wakeboard tower- hull thickness

I'm about to install a tower and like suggested will use a backing plate. My question is when snugging the bolts up to spread the adhesive out what keeps the bolts from getting frozen up too?
 
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