Fiberglass Sea Kayak Repair: How to Repair Gelcoat

To repair gelcoat damage to a fiberglass kayak, get down to work first with a rubber sanding block and some fairly heavy grit sandpaper - in most cases, 80 grit.

Look carefully at Brian's index finger and at the section forward of the keel, to the right. Note the sanding dust. Brian will keep sanding with the 80 grit, perhaps moving up to 120, until he has transformed the rugged, textured damage into a smooth hollow.

This step is important. You want to sand extensively and aggressively, so that none of the gelcoat around the damage chips or flakes off when you knock the damage area with your hand or pick at it with your fingernail. If any gelcoat chips off, sand it down.

There's a note here worth mentioning also: sanding dust. It's toxic. Not suffocate-you-today toxic, but toxic nonetheless. So although you might be tempted to sand without a mask, think twice. At the least work in a well-ventilated area.

As for masks, there are two sorts made for consumers: dust masks, which look rather like a surgeon's mask, and VOC respirators, which use multiple filters to protect you from dust particles and the fumes you will encounter come time to apply fresh gelcoat.

Your better bet is the VOC respirator. It provides superior protection.

VOC respirator is nowhere near as esoteric as it may sound. You can buy one at places like Home Depot for under $40/U.S. Once you've bought one you have it for good and simply replace its filters according to the packaged specs.

Below, the damage after Brian went at it with his rubber sanding block. He knocked down all of the damage - the rough, burred, and chipped spots - and has left in the hull a simple hollow:

Here's the damage before. Note how much longer the sanded area is than the damage area. That's because Brian sanded off not only the obvious damage but the radiated damage:

To repair the gelocat damage shown in the previous post, Brian gets down to work with a rubber sanding block and some fairly heavy grit sandpaper - in this case probably 80 grit.

Look carefully at Brian's index finger and at the section forward of the keel, to the right. Note the sanding dust. Brian will keep sanding with the 80 grit, perhaps moving up to 120, until he has transformed the rugged, textured damage into a smooth hollow.

This step is important. You want to sand extensively and aggressively, so that none of the gelcoat around the damage chips or flakes off when you knock the damage area with your hand or pick at it with your fingernail. If any gelcoat chips off, sand it down.

There's a note here worth mentioning also: sanding dust. It's toxic. Not suffocate-you-today toxic, but toxic nonetheless. So although you might be tempted to sand without a mask, think twice. At the least work in a well-ventilated area.

As for masks, there are two sorts made for consumers: dust masks, which look rather like a surgeon's mask, and VOC respirators, which use multiple filters to protect you from dust particles and the fumes you will encounter come time to apply fresh gelcoat.

Your better bet is the VOC respirator. It provides superior protection.

VOC respirator is nowhere near as esoteric as it may sound. You can buy one at places like Home Depot for under $40/U.S. Once you've bought one you have it for good and simply replace its filters according to the packaged specs.

Below, the damage after one kayaker went at chipped gelcoat with a rubber sanding block. The kayak owner knocked down all of the damage - the rough, burred, and chipped spots - and has left in the hull a simple hollow:

Here's the damage before. Note how much longer the sanded area is than the damage area. That's because Brian sanded off not only the obvious damage but the radiated damage: