Bottom paint question

[briggs]

Hi all,
The anti-fouling paint that was on the boath when purchased has almost completely worn off leaving behind a black paint that does not appear to be anti-fouling, but has chipped on the bottom near the transom. I'm thinking of repainting but am being told that the black paint must be anti-fouling because there has never been a black barrier bottom paint.

My question is....Was a black barrier paint an option from MacGregor that the PO may have purchased? or am I doomed to remove all the black in order to paint the bottom/

Any advice would be much appreciated, so much of what's out there is sooo confusing.
Thanks
Briggs

[yukonbob]

why not re-anti-foul paint?

[briggs]

The black paint has not faded, it appears to be good except where hit seems to have chipped on the bottom, was hoping to just touch-up the bad spots. I'm just not sure what it is. After that's figured out new anti-foul would be in order.

[Ormonddude]

It sounds like they put Ablative over hard anti fouling paint Ablative is made to wear off and make repainting easy So basically you most likely could just repaint it now how to test for a barrier paint in this situation is beyond me and hopefully someone with more experience will chime in. Basically you want a water proofing barrier coat then you want the anti fouling and it sounds like you had Hard anti fouling then a coat of Ablative anti fouling is the barrier coat under the Hard anti fouling is your main consideration.

[seahouse]

Brigger--
There might be exceptions that I'm unaware of, but anti-foul hull coating is normally offered as an add-on option by the selling dealer of the Macgregor, or as a DIY, and does not come from the factory. It's especially unlikely at this price point.

So the black layer doesn't appear to have a layer below it (take a close look where the fibreglass shows through at the transom where the wear is at an oblique angle to the surface)?

Rub the black layer with a damp rag on your finger, if it doesn't continue to come off, then it's likely non- ablative, and the PO likely put that underneath the now-worn off ablative layer.

So assuming you can't locate the PO, or he doesn't know, and the black layer is intact and not peeling elsewhere, you can touch up, then take your chances and sand and apply a product from the West Marine chart below.

I put a barrier coat, then black ablative, then blue ablative (Micron CSC) so I could tell when I need to renew the blue layer by the appearance of the black layer. Then only light scuff-sanding is needed to give tooth to the new paint. No heavy sanding, scraping, chipping, peeling etc to cause an uneven surface down the road.

BTW- put ablative paint on thick (epoxy). Its lifespan is a function of the paint thickness, so more coats (up to manufacturer's recommendation) means a longer time will pass before you have to do it all again. Why not do it while you're already at it?

Choose, then stick exclusively with that manufacturer's product line and you will avoid compatibility questions in the future. Record it and keep receipts for you and for future owners – it will increase your resalability to a knowledgeable buyer.
http://content.westmarine.com/documents ... 12.xls.pdf

Good luck! -Brian.

[seahouse]

Of course, that is assuming that you don't want to go the incompatibility-risk-free but costly route and remove it all down to the gelcoat (fibreglass) and start over from scratch with a barrier and anti-foul coats.

-B.

[kurz]

concerning "barrier coat":

A dealer that sells antifouling (and also barrier coats) givs the advice to me, not to put any barrier coats, becouse it is just for nothing and will just coas money.
The reasen was that the water moleculs are so small that they can easily penetrat all chemical coats. And also can penetrate epoxy. So it would be normal that epoxy gets somewhat "wet", nothing possible to do against.

All the chemiclas would just be money maker for the sellers.

He could be right... But I cannot say what is true... Wo my boat is now for 3 years in the water (lake) and I will put an antifouling soon. BUT also a Barrier coat????

[Catigale]

Please look at the bottom of your hull, Herr Kurz, when you pull your boat put. If you have no blistering then I would skip barrier coat after three seasons in fresh water.

There are many unions about this and lots of bad science of "acid in polymers" which is very complex chemistry beyond most people's understanding. Europe seems to be ahead of us recognizing that there are a lot of scare tactics used to sell barrier coats.

[briggs]

Seahouse, I'm really hoping to avoid both the work and cost of that
Brian, I think I'll try the touch-up and put new anti-foul over the black. Have to assume(we all know what that does) that the black is hard anti-fouling, will prep and touch that up before putting a different color anti-foul over that.

Thanks for all the help and suggestions guys, see you on the water!

Briggs

[seahouse]

Oops, sorry, duplicate post removed.

[seahouse]

Hmm Catigale… blistering… au contraire mon frère - my position differs.

While undoubtedly geographical differences are one of the many factors influencing blistering, I doubt that the global distribution of gullibility or any special understanding of chemistry is one of them!

As I recall, an active and very credible participant (and a member of the most highly-educated population on the planet, I might point out to eliminate that variable) on this forum was "suppressed" after presenting his experience on this issue. He had blistering on his purchased-new by him boat, with no barrier coat applied. And he is far from being the only person to have had such an experience, his experience is not somehow "isolated" - a simple survey of current literature will back up this position, not common , but not uncommon either.

Gel coat is well known among even the most casual of observers for its porous (="bad") qualities, almost any finish you care to apply will be less porous (="good") than it is. So far from being a "scare tactic", blistering is very real, very costly to repair properly, and largely preventable, by those who choose. Or you can take your chances, which can make perfect sense in some circumstances, such as the situation Briggs finds himself in. Of course, it can also represent a substantial portion of the cost of ownership, progressing to an ever-increasing portion as the boat ages.

No product is perfect, and expecting it to be is unreasonable and asking for disappointment. A barrier coat can be looked at more for what it is, a barrier for the purpose of slowing, not completely halting, the osmotic-driven migration of water which leads to blistering. I do not recall seeing a claim that a barrier coat is completely water-impermeable. One product that I am familiar with is composed of micro plates, which act as a physical/mechanical impediment to the progress of water by creating a longer path, not an impermeable block, for water. Water passing through the matrix must take a longer route and move laterally around the more impermeable overlapping plates to enter the substrate material, essentially producing a "compressed" version of what otherwise would have to be a thicker barrier.

If so inclined, sceptics can demonstrate this to themselves by immersing "chunks" of the finished product, and other control material of their choice, gelcoat, etc, in water and weighing it after a given time period to determine water uptake. Most of the material water-absorption properties data is already available, but it is not illogical to believe that a product that is designed to hinder the passage of water through its thickness does so better than a product that is not designed to do so.

As the expression goes, the proof is in the puddin'.

A barrier coat also functions to isolate the gelcoat from other materials (such as anti-foul) applied to the hull. Stripping old layers from a hull carries certain risk of damaging the porous, sensitive, and soft gelcoat. Stripping down to a more durable and visible barrier layer reduces that risk.

Briggs - that's what I'd be doing if I were you, too. (BTW - visited Cleveland for the first time 2 weeks ago (by car) - loved the city! - Beautiful waterfront! Cleveland rocks!)

-Brian.

[briggs]

Thanks Brian,

Next time you're going to be in C-town,let me know ,can show you around. And thanks for the advise.

Briggs