Fiberglass mat or cloth

[torpedoseal]

I have just purchased an aftermarket wakeboard tower for my '95 Mirage 19 ft. I have been told to reinforce the hull at the four attachment points of the tower. The company I bought the tower from recomends the hull thickness to be at least 3/8 of an inch not including the gelcoat. I was surprised to drill in to my hull and discover the thickness to be only 1/4 inch. Is that standard? I expected it to be twice as thick. <br />Now I have to reinforce the hull but I wanted to know what you guys thought about the fiberglass cloth vs. mat. I know little about fiberglass but I have heard that the strength is in the glass not the resin. If I use the mat I will only have to use one layer to achieve the proper thickness, with the cloth I'll nedd probably 3-4. I have also heard that a piece of plywood can be used under the fiberglass layer for addded strength. I guess I don't really now enough to make an informed decision. What should I do? Any advice would be a big help.

 

[prockvoan]

Re: Fiberglass mat or cloth

You don't need to fiberglass anything.Add some 3/4" plywood.Cut it to the biggest size that will fit.Find some big ss flatwashers to back up the nuts.Don't forget to put some clear silicone from the top in each hole.

 

[walleyehed]

Re: Fiberglass mat or cloth

Mat is for build-up, cloth is for strength (Directional)

 

[torpedoseal]

Re: Fiberglass mat or cloth

The tower company says unless I do a fiberglass reinforcment there is a greater chance of stress crack to the gelcoat at the attachment points. Do you really think it would be safe to just through a piece of plywood below and call it good?

 

[walleyehed]

Re: Fiberglass mat or cloth

What's your gut feeling telling you?????<br />Follow it....

 

[KCook]

Re: Fiberglass mat or cloth

To be really nuts about this glass in the wood with cloth.<br /><br />Kelly Cook

 

[bvprice]

Re: Fiberglass mat or cloth

Originally posted by KCook:<br /> To be really nuts about this glass in the wood with cloth.<br /><br />Kelly Cook

I agree, Can't go wrong with glass and wood!!!!!

 

[ondarvr]

Re: Fiberglass mat or cloth

Do not use only cloth if you plan on using polyester resin, the bond will be poor, it will work well with epoxy, but not poly. Polyester will work fine, but for a good bond you need to use some mat against the hull and next to the plywood.<br />First sand the hull very well with 36 grit paper, if using wood, round the edges of it so the glass will wrap around them easier.<br />If there is room, using the wood is the best way.

 

[prockvoan]

Re: Fiberglass mat or cloth

You will get stress cracks no matter what you dnly thing that might help stop them is drilling out the holes a bit bigger.When installing the tower,under the base plates where it bolts to the deck,put some 3m 4800.Any excess can be clean up with acetone before it cures.I have a 900lb tower/hard top on my boat with very little stress cracks,just plywood under.

 

[craze1cars]

Re: Fiberglass mat or cloth

If you post this question on the "Boat Restoration and Building" thread of this site, you'll get a lot more knowledgable answers from people who work with fiberglass/mat/cloth/epoxy/poly combos every day.<br /><br />My suggestion would be for you to contact West Systems or Raka, Inc. and explain to them exactly what you're doing. They'll sell you the correct resin and cloth/mat to do the job with maximum strength.

 

[walleyehed]

Re: Fiberglass mat or cloth

Glad I know where I stand on knowledge now....<br />Thanks, craze1cars...<br />I guess my years of composite aircraft structures have taught me nothing...glad to hear it didn't. Now I have no liability.

 

[torpedoseal]

Re: Fiberglass mat or cloth

Hey I real appreciated everyone's help. I'm going to glass and wood the area. The trouble is that 2 of the four spots aren't realy convient to get at, (I'll be working with one arm). I may have to take the combing pad down and cut an access hole in behind. Thanks for the advice.

 

[BillP]

Re: Fiberglass mat or cloth

Glass a round 1/2" ply backing plate with a layer of 1.5 or 3oz mat and one layer of 18 or 24oz woven roven. Sand the surface and wipe down with styrene before glassing. Like already posted, use big azz SS fender washers. The bolts will clamp the backing plate tight even if you don't glass it.