Fiberglassing Help

[Airfooter]

Hello All,

I am in the process of adding a tower to my 1992 Nautique Excel with a closed bow. The tower manufacturer recommends that the glass be at least 3/8" thick. The only place I ran into a problem was on the passenger side front tower leg. It needs to go in a spot that it not very thick or reinforced well (next to the cleat). I have ditched the factory provided 3-1/2" X 4" backing plate and cut/fit a 3/4" thick oak board and a 1/4" thich steel plate to use in place of it. The oak board is roughly 6"x 9" and the steel plate is 4" x 7". I still feel that I should add a couple layers of fiberglass just to be safe. I purchased a fiberglass kit from Napa that included the cloth, resin, hardner, etc. After removing the foam and cleaning up the surface underneath the bow I cut 2 pcs of cloth to fit and mixed the resin and hardner. I laid the cloth flat on a couple sheets of waxpaper and spead out a nice layer of resin. I soon realized there was no way I was going to be able to handle the size of cloth with resin that I working with. I was on my back attempting to lay it in place overhead and it didn't work. I discarded it and quickly cut a smaller piece approximately 8" x 12" and repeated the process. This time I had no problem getting the piece in place but it would not stick/hold. I thought for sure the resin would hold the cloth to the undeside of the bow but I was wrong. I called it a night after this.

Can anyone offer any advice? I've spent the last 2 hours searching for information online and the only thing I can see trying is applying the resin to the underside of the bow first and then laying the cloth up there and adding additional resin if needed.

I won't see the boat for a couple of weeks now so I want to make sure that I am prepared to finished my tower install the next time I am at the lake.

Thanks in advance!

Adam

[TRBenj]

I would consider oak and steel to be less than ideal choices for a replacement backer... for rot/corrosion issues alone. Personally, Id be adding more glass and keeping the aluminum.

What type of resin and cloth are you working with? Polyester may not adhere to the hull at all- it really only sticks well to polyester. Correct Craft hulls are built with an epoxy/vinylester blend. Epoxy resin would be the correct choice, as it will stick to all 3 types of fiberglass (poly, vinyl, epoxy). Its also the easiest to work with, and yields the strongest bond.

And yes, wetting out the surface in question prior to glassing will help it to stick. Make sure its been properly prepped as well- it should be sanded smooth and cleaned (with acetone).

A few more notes...

1. You'll want to be adding a whole heck of a lot more glass than 1 layer if you want to add any appreciable amount of thickness and strength. 5 layers of alternating mat and cloth should yield ~1/8" or so.

2. You'll want to be adding glass to an area greater than the size of your tower foot... Id say 3-6" further in every direction, if possible.

[mcbridek]

When I added a new dimension tower, the process added a layer of fiberglass/resin to the underside of the plate (between plate and underside), which both provides a perfect seal between the plate and underside of the gunnel but also adds support. The product they supplied was a quart of Fibreglass Evercoat 868 Kitty Hair™. This has the long strand glass hair mixed into the resin. This might be a consideration. They supplied the quart - but this is the stuff
http://www.sjdiscounttools.com/fib868.html

[Airfooter]

TRBenj - Thanks for your input. I found out this morning that the resin included in the Napa kit is polyester which means I'll be purchasing an epoxy resin. Is there a specific weight of cloth and mat that you'd recommend?

The area that I'm attempting to glass will be much larger than the tower foot. I'm only able to go approximately 6" behind the foot and about 3" to the side towards the rub rail (i'll be glassing under the cleat too as it's very close to the tower foot) but I will be able to go out approximately 16" in front of the foot.

[Airfooter]

When I added a new dimension tower, the process added a layer of fiberglass/resin to the underside of the plate (between plate and underside), which both provides a perfect seal between the plate and underside of the gunnel but also adds support. The product they supplied was a quart of Fibreglass Evercoat 868 Kitty Hair™. This has the long strand glass hair mixed into the resin. This might be a consideration. They supplied the quart - but this is the stuff
http://www.sjdiscounttools.com/fib868.html

This is good to know. Did you only use the resin then? Or did you still use cloth with it as well?

[TRBenj]

I would recommend purchasing all of your fiberglass supplies from someplace like US Composites. Cloth in the 8-10oz range would build thickness more quickly than the 4-6oz variety. Definitely pick up some mat (1.5oz) as well, this is significantly thicker than the cloth. Their epoxy resin is very reasonably priced.

Bedding the backing plates in thickened resin isnt a bad idea. You'll save a lot of money if you thicken your own resin rather than buy it pre-thickened. A high strength filler like milled fiber or aerosil-cabosil would be ideal. Thicken the resin to a peanut butter like consistency.

FYI, the strength of the fiberglass comes mainly from the cloth (wet out at the proper ratio). The resin itself does not have a lot of strength.

[Airfooter]

I am making a list and will order from US Composites. Thanks for the recommendation.

I originally planned on using 3M 5200 between the backing plate and fiberglass. I'll order some milled fiber and/or chopped strand since I'll have extra resin. I would assume that bedding the backing plate in the resin is being done at the same time that the tower foot is being mounted? If so, I would guess that the threads on the bolts would need to be taped up to keep the resin off when the bolts are pushed through the mounting plate?

[TRBenj]

Theres a few different ways you could go about doing the backing plates. I might be inclined to bed it up there first, let the thickened resin cure, and then match drill your holes afterwards. That way youre covered if the angle of the backing plate isnt perfectly parallel to your tower foot.

[mcbridek]

Backing plates and installing tower-
1. Duck tape top side to protect, put tower on, mark holes, remove tower, drill holes - see picture
2. Put tower on, put bolts through, Install backing plates (with long strand filler on plate - see picture). Bolts will keep alignment perfect
3. Remove bolts (clean off bolts), remove tower, let fiberglass cure
4. Re-drill holes to clear out any fiberglass around plate - good clean holes through hull, added glass, plate....,
5. Remove duck tape, install tower, bolts, add nuts and washers and tighten down
6. Time for a beer !

[Airfooter]

Backing plates and installing tower-
1. Duck tape top side to protect, put tower on, mark holes, remove tower, drill holes - see picture
2. Put tower on, put bolts through, Install backing plates (with long strand filler on plate - see picture). Bolts will keep alignment perfect
3. Remove bolts (clean off bolts), remove tower, let fiberglass cure
4. Re-drill holes to clear out any fiberglass around plate - good clean holes through hull, added glass, plate....,
5. Remove duck tape, install tower, bolts, add nuts and washers and tighten down
6. Time for a beer !

I'm definitely looking forward to step 5 and even more so to step 6! I thank you and TRBenj for all of the information and help. My supplies will be here next week. I can't wait to get the tower mounted and take my first ride!

[lucky7t]

I work with fiberglass everyday. You can use tiger hair and will work great. Once you spread it on you may have to hold it on for a few minutes. Make sure that the area you apply it to has been sanded lightly fir good adhesion