Tower mount reinforcement?

LFADAM · Posted: Aug 06, 2011 7:47 am Post subject: Tower mount reinforcement?

Our wakeboard club has a 1990 Supra Sunsport that we want to add a tower to. We will probably go with a monster based on their fantastic reputation and price, although I am open to suggestions.

Does anyone with experience with this boat know if it is necessary to reinforce the fiberglass where the tower mounts will be? I have heard sometimes it is necessary and sometimes it is not. Im really hoping it isnt because I dont really know what that entails, but the fiberglass doesnt seem as thick as a newer boat.

Thanks, attached is a picture

intotheflats · Posted: Aug 06, 2011 8:42 am Post subject:

LFADAM, I would always reinforce the areas where the tower is mounted. It's a case of better to be safe than sorry. And of the whole process of installing a tower, putting a few extra layers of fiberglass on the underside of the hull/deck is not that hard. Just messy.

Brit Rider · Posted: Aug 06, 2011 10:00 am Post subject:

LFADAM, Difficult to say whether you'll need to reinforce or not. You'll only really know once you drill the hole, and the thickness will vary from mount to mount. That era of boat was hand built without much more than the guys judgement when laying the glass.

I'd not go as far as reinforcing with fiberglass on that style of boat as it isn't necessary. But it will be worth having some marine ply on hand to work with. If you drill and find less than 3/8ths glass thickness then you will want to make a plate and bond it to the inside of the deck with either 3m 5200 marine adhesive (or 4200 if you can't find 5200). That will be sufficient.

Hope that helps

Mike
(Monster Tower UK)

Okie Boarder · Ladies Man Joined: 03 Mar 2008 Posts: 10056 City: Edmond

Agreed on the marine ply. That's what I did on my '89 Sunsport. I made a 4" x 9" piece and centered in where the mounting foot of the tower goes through. I attached it with basic construction adhesive.

LFADAM · Posted: Aug 08, 2011 1:58 pm Post subject:

marine ply as in marine plywood, just glue a chunk of wood behind it? or is this some kind of fiberglass ply?

thanks

Okie Boarder · Ladies Man Joined: 03 Mar 2008 Posts: 10056 City: Edmond

Yes, marine plywood. Or you can use standard plywood and coat it with something like CPES or a thinned down epoxy to help make it more water resistant. You just want a little beefier surface under there covering a larger area to help better distribute the stress.

Wheeler · Criminal Joined: 04 Sep 2010 Posts: 74 City: Decatur, AL

My thinking on the tower I installed was the since the front supports are under tension, the reinforcemnt need to be under the fiberglass, while the rears, being under compression, the supports needed to be on top. I used some plate aluminum with some stiff rubber sheet sandwiched in between.

Suprahunter · Soul Rider Joined: 28 Apr 2008 Posts: 486 City: Lowell

I agree with okie. You cant have too much support. My 89 has a New Dimensions tower. I did 3/4'' plywood blocks covered with fiberglass then epoxied to the underside of the deck. Then I upgraded the aluminum plates with larger thicker ones. also make sure you bevel the mounting holes to avoid gel cracks. 4 seasons no problems no cracks.