Glassing over Thru Hull

[John R]

I have a couple 1" round thru hulls on the bottom of the boat that I am contemplating to get rid of and relocate. What is the best way (or best easy way [img]/images/graemlins/grin.gif[/img] ) to glass over them??

Thanks

[Ed]

Hi John-

I did a bunch of these on a 31 Chris-Craft.

After you have removed thru-hull, clean & dewax the entire area you want to grind. Next, take a grinder and grind back about 5-6 inches around the thru-hull on the outside and the inside. As you move outward from the original hole, gradually taper the depth of your grinding.

Next, vacuum up all the dust and wipe down the area with acetone.

Then, take some 1.5 oz mat and cut it in circles with varying diameters 4 inches, 6 inches, 8 inches, etc. Do the same with a couple of pieces of roving.

Then mix up your resin, and put the smallest piece of mat on the inside first and push slightly down into hole then roll out excess resin and air bubbles. Next, take the next larger size of roven or biaxial and repeat the process. The idea is that since each layer is larger than the last, it forms its own bond with the hull.

You'll probably own be able to do 2-3 layers at a time. Once you have about 5, maybe 6 layers, on the inside stop.

Now go to the underside of the hull,and then repeat the process on the outside with a few layers. After it all cures, grind down the excess glass so that is flush with the hull and then cover with bilge and bottom paint.

I dont think I left out anything...but if I did I am sure someone will correct me.

[other tom]

what ed said....although I have had great success by simply doing it in one step from the inside....tape a piece of mylar or 'mica (waxed) on the outside of the hull (after the grinding/cleaning steps) and start with a thickened mix of WEST and high density/chopped fibers. Then lay in your wetted-out disks of cloth/roving. Key is to expose as much of the laminate as possible on the hole edge and the inside of the tapered laminate. Filled at least 12 holes on a 3/4" thick Bertram hull this way, including main raw water intakes that were 6" in diameter. still floating (this morning)....