Need to sand before antifouling?

[andreas.mehlin]

Hauled out now and Will start to put on antifouling soon. Pressure washed. Do i need to sand? If so, how much?

Now, ses hawk soft paint
Then, micron 66 soft

[fstbttms]

Originally Posted by andreas.mehlin

Hauled out now and Will start to put on antifouling soon. Pressure washed. Do i need to sand? If so, how much?

Now, ses hawk soft paint
Then, micron 66 soft

Pre-paint prep is completely dependent upon what product you are painting over. What Seahawk paint is currently on the boat?

[reiner]

I just finished my anti fouling for the year. I use Altex No 5.
I would sand in any case. Sanding will show you any problems with the hull and it makes the new stuff hang on better. On my previous boat I found some, not much, osmosis which I would not have found without sanding. It is a painful job but well worth doing in my books.
Cheers
Reiner

[bobconnie]

I mostly sand before a new coat go's on ! But have used the tide to do the bottom and sure did not sand those times ! and it went on ok, with a soft paint ! but if im doing it on the hard I will always sand cus as said it will show any problems ! Just my 2 cents

[fstbttms]

Any old paint will need to be sanded before new paint goes on. But there is a difference between "sanding" and "removing." What the OP needs to determined before anything else happens is whether or not the old paint is compatible with the new. Most commonly used copper-based anti fouling paints are compatible with one another (whether they be hard or ablative), but if the two paints do happen to be incompatible, the OP's new paint job would likley be ruined, unless the previous paint had been completely removed first.

I suggest the OP go to the Interlux forum and ask the Interlux Technical rep there what the proper preparation for the two products he's dealing with is.

Antifouling - Yachtpaintforum.com - Page 1

[Rocketman]

Whether or not to sand depends greatly on the condition of the curent paint and hull. If the old paint is intact, not peeling, or cracking, then power washing and cleaning with scotchbright pads to remove all residue maybe all that is needed.Remember painting over old paint make the new paint stick as good as the old. If the old paint is flaking, cracking, and generally in poor condition, then new paint over that will not last a year before it will need to be done again. If you have many, many layers of old paint, I would sand off most of the layers if not all of them getting back to the original gel-coat, apply an epoxy coat, then at least a couple of layers of new bottom paint. That should last you around 3 years in most salt water eviroments.

[fstbttms]

Originally Posted by Rocketman

That should last you around 3 years in most salt water eviroments.

Again, completely dependant on product used and maintenance regimen. There are some paints that can last 3+ years with proper maintenance (typically high quality hard paints) and some that will be shot within 12-18 months, regardless of how they are maintained.

[Rocketman]

Originally Posted by fstbttms

Again, completely dependant on product used and maintenance regimen. There are some paints that can last 3+ years with proper maintenance (typically high quality hard paints) and some that will be shot within 12-18 months, regardless of how they are maintained.

Fstbttms, thanks for your expert advise.

I was wondering if you could tell me what you recomend as proper maintenance. I live in an area in the gulf where we get a lot of growth on even the highest quality of paint in a month. I know that cleaning is absolutly needed but what do you use to clean the growth off without removing excess paint?

[fstbttms]

Originally Posted by Rocketman

Fstbttms, thanks for your expert advise.

I was wondering if you could tell me what you recomend as proper maintenance. I live in an area in the gulf where we get a lot of growth on even the highest quality of paint in a month. I know that cleaning is absolutly needed but what do you use to clean the growth off without removing excess paint?

Regardless of where your boat lives, you should clean your hull before it becomes too foul to be cleaned with anything but the softest cleaning media possible. Typically this would be a piece of carpet or a white 3M Doodlebug pad. Just how frequently that works out to be for you is dependant upon the anti fouling paint you use and the fouling conditions where your boat lives.

Relatively frequent, gentle cleanings will dramatically extend the lifespan of your anti fouling paint as opposed to less frequent, more abrasive cleanings.

[Rocketman]

Originally Posted by fstbttms

Regardless of where your boat lives, you should clean your hull before it becomes too foul to be cleaned with anything but the softest cleaning media possible. Typically this would be a piece of carpet or a white 3M Doodlebug pad.

What type of carpet do you use? Are you using the back of the carpet? or maybe indoor outdoor carpet? and where do you buy the 3M Doodlebug pad?

[fstbttms]

Originally Posted by Rocketman

What type of carpet do you use? Are you using the back of the carpet? or maybe indoor outdoor carpet? and where do you buy the 3M Doodlebug pad?

Most hull cleaners that use carpet use a low shag remnant. And you use the "up" side. I do not use carpet, however. I use Doodlebug pads. Available at well-stocked chandleries or janitorial supply houses.

[Rocketman]

Originally Posted by fstbttms

Most hull cleaners that use carpet use a low shag remnant. And you use the "up" side. I do not use carpet, however. I use Doodlebug pads. Available at well-stocked chandleries or janitorial supply houses.

Thanks again for the helpful information. I have been using a green scotch bright pad, and I think it is removing to much paint. I will try the softer Doodlebug pad.