What is Boat Fiberglass Tabbing? This is where bulkheads and supports in your Powerboat or Sailboat are fiber glassed in. This gives your outer hull support and beefiness as you pound through the water and waves. Some Boats and Yachts have that solid feel as they cut through waves, and even when they fall off a wave pounding into the water below. Boat fiberglass tabbing makes the difference of a boat or yacht shuttering as it hits the waves…it stops some of the “Boat Oil Canning” also.
Boat oil canning is a term that is used to describe a boat that twists as it goes through the water. If you take an empty soda can and hold both ends and twist them in different directions (slightly), you’ll see the twisting effect…yet the can keeps it’s form. Well that is what the water does to your boat. Imagine when your stern area is still in the water and the forward portion is out off the wave hanging in mid air….What keeps your boat’s form? It is the fiberglass tabbing of all structures in your boat or yacht that make it keep its hull shape/form. If your hull thickness was massive, you would not need as much tabbing. But in today’s world, the hulls are not too thick. Fiberglass is strong, but it needs a good skeleton or structure fiber glassed in. That’s the trick… Well actually the trick is getting to all the areas to tab in.
Some vessels have a lot of tabbing, but after awhile the tabbing breaks away after the years of pounding and cutting through the waves. Some of the tabbing is not reinforced by having multiple layers and failure is a sure thing. You should go forward to the “V” and have someone cut through some waves. You will be amazed at the movement or flex of the hull. You will wonder why you don’t have more Gelcoat cracks and crazing. BTW, that is why you get those cracks… usually no support or fiberglass tabbing.
There are several ways boats and yachts are made…one is the hull is popped out of a mold and the interior is built within piece by piece. They do all the tabbing to hold everything in place as the interior gets tied together. Another way is the interior is made on an interior pan (a whole inner hull) that gets inserted into the hull. In this way, the interior can be done and finished, ready when the hull pops out of the mold. Which way is better is up to you.
Now let’s talk about doing the fiberglass tabbing. You will need Fiberglass Resin and hardener and of course Fiberglass cloth. Get two types…fiberglass mat, which is chopped fiberglass strands put together in a roll or squares and the other is fiberglass woven cloth. The chopped fiberglass mat forms easily to any surface contours and then putting the woven mat on top gives it plenty of strength. You can put a layer of the chopped fiberglass followed by the woven fiberglass and then do a final chopped again wider than the area you have done….that’s real beefy. There are so many ways to do this, and you will get opinions from everyone…some who have never done this, but to do is better to not do. You will also learn and see the intricacies of the inner parts of your hull.
To do the fiberglass tabbing you first want to clean the area and rough it up with 60 or 80 grit sand paper really well. Then clean up the area again, and this time have a rag moisten with acetone to then wipe the area down….(of course do not use any solvent in a closed area, read all instructions on anything you use). Now let’s say it is a bulkhead running from the bilge area upward. You want to tab along where the bulkhead runs (both sides if you can get to it) and about 2 1/2 to 3 1/2 inches or more (depending what you can get at). So clean the area up, sand, clean again and wipe with moistened rag with acetone on it.
Cut out a piece of chopped fiberglass mat that covers what we just spoke of before. Mix the fiberglass resin with hardener and apply the resin to the areas with a brush, read instructions.. Any drips clean be wiped clean with that acetone rag. Now that the area has the resin on it, take the chopped fiberglass mat that you cut out and apply/stick it to the area. Use the brush to push it into the area you want it to cover and of course into the corners. They have mini fiberglass steel rollers to get out the bubbles if you have the room to use them, but push the matting firmly down from the center outwards to get the, if any bubbles out. Now add more resin and push in the woven fiberglass cloth and work the same way…Apply another chopped mat to cover a little more area as a final…That’s it! Start from the bow aft or from the stern forward. You will find areas easy to get out and others that your whole arm needs to stretch into. Get as much as you can in as many areas as you can. In areas that show, you may want to tint your resin with a color on the last coat over the top of all the mats.
This does not have to be done in one day. Do a section at a time and let cure for at least a day (I’d give it more to make sure the resin cures) and check that it did cure…again read all instructions on all cans, especially the cautions.
You will find that you have turned your boat into a strong solid feeling boat or yacht that you always wanted. It’s amazing!…. You’ll even want to get to those harder areas…. and Why Knot?