Trying to stick some LED's and velcro to various spots under the gunnel to unfinished fiberglass. Anything out there that will stick and hold under boating condtions? The generic stuff I got and the 3M on the velcro wont hold very well or at all, even after cleaning with alcohol.

their may be wax in the fiberglass,you will need to wipe with acitone to remove the wax,alcohol is not strong enough yo remove the wax from the fiberglass. you can also try silicone sealer on the ends or apply the sealer to the back side of the light then tape them in place until the sealer drys but you will still need to wipe the fiberglass with the acitone..

Sand the glass first so that you have a smooth, flat surface that is free from wax's, oils, etc. Use like 180 grit.

I just added Led's in my bilge as well. I ended up using the little plastic mounting pads for ty-raps. I attached them to the fiberglass with 3M 4200. It was the best thing I could come up with.

Is it feasible to glass in a block of wood and screw the light to that ? Maybe 4200 or 5200 the block of wood.If not I would suggest roughing the surface a bit wipe with acetone and use the silicone or 3m 4200 should to the trick.

They are flex strip lights, very thin and flexible, will be a bear to use 4200 without having it everywhere or over the led's

Dont use velcro, use 3M dual lock and clean the area with acetone or alcohol. I have a lot of stuff mounyed with dual lock. You can buy it at Target by the tape in hardware.

3m emblem adhesive 2 faced tape. Make sure surface is clean . If still having problems, adhesion promoter can work magic. You can get the tape at walmart and the adhesion promoter at napa.

Just clean the surface and apply some 3M adhesive promoter to the boat surface then stick away. Make sure its lined up because there will be no moving or changing your mind!!

Here in the Texas heat were it regularly hits 100+ in the summer any type of tape will melt right off the fiberglass regardless how well you clean it or sand it.Its resin or 5200 if you want it to last.