Pacemaker Boat Owners Association

For under the waterline you should barrier coat it. In order to properly do that you should strip off all the old bottom paint (it will usually result in more speed as well). Look for a product called peel-away to strip off all old or have it media blasted

If you go the media blasting route opt for Soda.

The spider web crazing is not unusual for boats of our vintage. My '67 has the same thing. I was told it was due to the factory going way thick with the gel coat.

That, and gel coat is more brittle than the rest of the layup, and the resins continue to cure as time goes on, granted at a much slower rate than when first mixed.

My 72' had the same problem. Some folks said "just slap another coat of bottom paint on it" but when I felt the weight of a gallon of bottom paint I couldn't help but think of how many gallons of bottom paint were still on the hull, doing nothing but adding an awful lot of weight to an already very heavy boat. I ended up having everything removed up to the water line and covering it all with barrier coating and then bottom paint. I have only had to repaint the bottom once in the past 5 years, where before that I was doing it every year because of the constant peeling of old non binding paint.This is probably the best money I have ever put into the boat. I also agree with Ken above where he says to opt for soda media if you decide to go the media route, it's much kinder to the hull and does an excellent job. The sand blast method is really rough on the hull , requires you to do a lot of fairing and patching before the barrier coat is applied, and finally you can do it by hand....I did it that way , definitly something I would never do again, save the energy for something else on the boat, this is one job that is worth spending some money on to have it done professionally, just the applying of the coats of barrier coat and bottom coats will keep you plenty busy. I put one coat of black and two of blue....so when the black starts to show thru the blue I know it's time to recoat the bottom and my chipping and flaking problem has been cured for good.

Peel-a-way is a great product, easy to use and safer (not only for the boat but also for anyone in the vicinity) than any other removal method. However, I suggest you try a small patch before you go "all out", simply because it's expensive for the area you need to treat; and a series of 1 square foot "test patches" will teach you how much of the gel you'll need to apply to get the job done at the lowest cost.

Above the waterline: there's a lot of gel-coat replenishers designed to address the crazing (which is mainly an aesthetic problem, unless left unaddressed.) Any decent marine supplier can show you a variety.

BTW...a common mistake is to paint the driveshafts with bottom paint....DO NOT DO THIS! it can lower or stop the efficiency of your zincs.

rgr

I used Interprotect by Interlux after having my bottom blasted. It is a great product with an easy application process. I would also HIGHLY recommend a product called Propspeed for your running gear. If you are blasting your bottom do the running gear as well. I used it on my tabs, struts, wheels, rudders, and all thru hulls. It kept the gear barnacle free all summer. As long as you run the boat weekly you will not have a growth problem. My friends who didn't have PS had a diver go over monthly to scrape their gear. We also have a fast current flow at the marina which IMHO promotes growth. Well worth the effort.
If you also have ceazing cracks on your topsides remember the cure is worse than the disease. Unless you grind off all the gelcoat the cracks will return. And who wants to strip a boat. Use AWLGRIP primer ams topcoat and you have a good 5 to 7 years before you see them return. And if folks are noticing them they are looking too hard.