Retrofitting a G3 Tower to older boat

The Swap

In this project I replaced the stock Illusion (first generation) wakeboard tower from my 2007 247 boat with a G3.2 that was made for a 2016 Malibu VLX.   Both beams are 102” but the top of the gunwales have a different shape and the project took a lot of modification.

I liked the Illusion tower and think it’s one of the best looking ones out there with it’s curved arches.  But I love the height and strength of the G3, I’ve been a big fan since it first appeared in 2010.  For me it combined the good looks of the forward swoop "Illusion" tower with the rigidness of the Titan towers.  

G3s are less accessible and very expensive.  I bit the bullet when my dealer had an “extra” tower after someone did not want one on their boat.  This particular tower was from a 2016 Malibu VLX, and the tower was the 3.2 version with the all black upgrade and grey anodized Malibu combo racks.

Swapping towers was not as easy as I thought!

Removing Illusion

Removing the Illusion tower started with simply removing the bimini and wakeboard racks first, to take weight off the tower.   The speakers were then removed one at a time, and required cutting wires or un-splicing them.  The wires were labeled prior to removal as well, so the next owner of the Illusion tower could make an easier transition.

Once the tower was stripped of accessories, the next step was to remove the Illusion’s hardware underneath the gunwale.  Access to the hardware and mounting bolts was limited without removing the interior panels on each side.   There were nine or small bolts running through from the interior panel into the gunwale, each with a brass locking nut that had to be removed.  This part sucked because it was hard to reach them all with a 7/16 ratchet wrench.  There’s usually an easier way, but I’m not one for patience and I seem to get bloody knuckles on all my projects anyway.  At this point I could peel the interior panel down far enough, although I later removed three more lag bolts on the bottom to completely remove the panels (and cup holders, speakers, etc that were attached).

The Illusion uses a small cable that attaches on one end to a large spring that’s clipped to the mounting bracket beneath the gunwale.  The cable runs around a pulley and up through the base of the tower to an eyelet on the tower itself.   This allows the Illusion to fold down with weight assistance of the spring (adjustable with a tensioner). This cable needed to be removed first, carefully, in a position the that provides the least amount of tension possible.

Once the cable/spring was removed from the bottom rear point of the tower, I was able to remove the allen bolt holding the front pivot point of the Illusion tower to the tower base.   You will need assistance because once you remove both sides the tower top is free and you don’t want to scratch up the boat.

Now the easy part, there were three 1/2” bolts that attached the tower legs to the gunwale.  The bolts came right out.  Once you remove the legs you’ll see two more allen head tapered bolts on the gunwale that basically hold the bottom bracket up.  I removed the allen bolts and the bottom mounting bracket came right out smoothly.

Measuring for the G3

Now that the Illusion tower was off, I hoped the bolts of the new tower would line up, but they were not even close.   The G3.2 mounts also have three holes, but they are spaced more evenly with each other, front, middle, rear.   Instead of bolt heads, the new tower has 1/2” stainless studs, that screw into the base from the bottom via an allen head.   Then you secure it with a brass locking nut and washer, with the an included aluminum bracket between the nut and hull. I added lock tight prior to final installation.

First step was to tape off the gunwale with masking tape so that we could mark the holes and to prevent scratching it when lining it up.  It’s good to measure multiple times to ensure the tower folds down where you want it to, typically, behind the windshield to create a lower profile in the stowed position.   I ended up mounting the new tower approximately 5” back from where the Illusion mounted in order to clear the window from.  The G3 is taller and the pivot point different.

I then temporarily mounted the G3 with just the center stud bolt with one new hole drilled, to make sure it fit and folded prior to drilling the others.   

From there I marked the two additional holes based on the bracket with the predrilled holes.  You can see in the picture how the holes were totally different in alignment.   The tower was moved further than the bracket in picture.

Once the holes were drilled, they were chamfered to prevent gel coat cracking later under stress.  The bit I had was a little too small for 1/2" hole, but I made it work.

Gelcoat Repair

Once the tower fit, I was ready to fix the hull before final installation.  Since the tower was moved back 5” and the mounting points were different, drilling new holes next to the previous made swiss cheese of the gunwale.  Additionally the front two holes were now exposed and would not be hidden by the G3 mount.

First step was to fill the holes in to strengthen the gunwale again.   I used chopped fiberglass with epoxy resin to fill in the holes (because I had some),  and then used 3M patch filler and sanded the top deck in preparation for gelcoat.   For the gel, I used Spectrum’s color matched gelcoat from iBoats.com.  I’m no gelcoat expert but I’ve done the basics many times before.  My preference was to keep the filled-in holes just slightly lower than the surface, rather than make it perfectly flat and add on top with gel coat. I think this is against what I’ve read.  If the gel is too thick you run the risk of cracking, but I think a little on the hole top makes it blend better and is more forgiving with sanding.  I mixed up the gelcoat according to instructions.  I then diluted with styrene at 10%.  Taped off the gunwale and sprayed using the cheap little preval sprayer.   I did two coats, the first just on the holes, then sanded, and then a second over the section that was taped off.   I probably went thicker than I needed to, but that just meant more sanding and it was a little area.

You’ll use lots of masking/painters tape for both the sanding and the spraying.   The key is to create the hot zone where you will sand and spray, and then as you wet sand it move the tape out in small increments to make the zone a little bigger each time.   I started with 400, then made the zone 1/2 bigger, then went to 600, made it bigger again, etc.  This way you’ve feathered it all the way to 2000.   I used a sanding block for every step.

Next step was to polish it to a shiny finish.   I used Maguire’s 105 to start it off, and then switched to 3M’s Finesse it, with a rotary polisher and a wool cut pad.    I waxed it and it looked as good as new.   It almost has to be shiny before you can tell if there are any indentations.

I did make a mistake on one side that requires another pass.    I sanded a little too deep and a dark spot appeared from the red gel coat that is layered under the white.   I was pretty pissed at myself because it was a careless mistake from rushing the job.   So I will have to go back and fix it.  Oops! 

Before mounting the tower, you’ll also want to chamfer the new holes as best you can.  My chamfer bit was on the small side for 1/2” holes, so I ended up using a much larger bit and spun it in reverse to get the same effect.  Chamfering helps minimize gelcoat cracking, which is especially important with tight fitting bolts.
 

Installing the G3 tower

The correct way to lift and lower the G3 tower would be using a hoist in a shop. That being said, I used my teenagers to hold up each leg and we walked it forward.   My ten year old helped line up the holes before lowering the tower.   Not the best way, but it worked without a scratch.  The other option is to screw the studs up from underneath the gunwale into the tower, then put the bottom bracket and then the lock nuts.  

I found that even though I measured many times, I still ended up needing to drill slightly larger holes to ensure a fit that wasn’t forced.   Once again, having those interior panels removed all the way will make installation much easier.

Done! 

Overall I am stoked to have it finished.  It took me over a week of on-off work.   I’m sure others would be faster but it was worth the investment to me once it finally “fit”.   We also purchased the 2016 bimini with surf straps and that was a breeze to install.  Took over a month for Malibu to build and send it but the bimini matched perfectly.

The new tower lined up, not 100% perfectly but nothing on a fiberglass boat is ever absolutely perfect, no matter how much it costs!  I’m stoked about the project, and think the boat looks like it came with it. 

The only downside so far is that it pushed me to spend more money on a windshield tint, which I think tied the all-black G3 in even better with my color scheme. I didn't use to be a fan of tinting, until I test drove a boat that had it, and loved the clarity inside).  I also picked up some used Rev10s that came from another G3, because I sold all the speakers from the Illusion.   Was going to wait until winter (because all of this was expensive for me), but I just couldn’t pass up the Revs.

Here's my recipe list:

1/2” drill bit and drill
Masking tape
Spectrum Gelcoat
Preval sprayer
3M Vinylester Patch putty
Fiberglass resin
Wetsand paper (400, 600, 800, 1000, 1500, 2000)
Rotary buffer and cutting pad
3/4” Wrench
Allen Wrench
Locktite
Accessory wire
Patience!!!