Bottom Paint for Racing

[rshowarth]

My O'Day Mariner has a "dip" in the bottom near the transom. I understand that is from O'Day popping the hulls out of the molds too soon. I am told the dip drastically slows the boat and want to improve the boat speed. (ok, I know Mariners are not Lightnings, J-22s, etc., but it is one design racing, so it is all relative).

I spent a fair amount of time stripping all the bottom paint and wet sanding two years ago when I first got the boat. Now I am considering fairing the gelcoat hull and painting the bottom.

I spoje to Interlux and they recommend 2 coats of VC Performance Epoxy, then fair with Watertite Epoxy Filler and recoat a number of times with VC Performance Epoxy, being sure to sand after each coat and sand relatively soon after coating. If you let it go too long it will harden to a very hard surface, very difficult to sand.

However, after reading all the warnings against an epoxy barrier coat, I am concerned. My hull is free of any blisters. I dry sail the boat.

Any recommendations on whether or not VC Performance is the way to go? Any other suggestions?


Thank you.

[Case]

I recall in the past in my readings about the Rhodes 19 - which has the same hull as the Mariner... Apparently, the "dip" doesn't have much impact on the speed of the boat. Rhodes 19s with the "dip" and without have traded positions in OD racing.

Information may have changed recently (or I am plain wrong) but I'm inclined to say, leave things as is. Barrier coating isn't worth it unless you actually have problems in my opinion.

- Case

[Rachel]

Reading this made me curious, so I looked up VC Performance Epoxy to see what it was. Here's what Interlux has to say about it:

Product Description

VC Performance Epoxy is a two-part Teflon® bearing epoxy that has a hard, slick finish ideal for use on the underwater surfaces of high performance powerboats and racing sailboats. Teflon® adds lubricity and eases wet sanding and burnishing.

VC Performance Epoxy's hard, stain-resistant finish is also ideal for rack-stored and trailered boats or boats that are kept in the water not requiring antifouling protection. VC Performance Epoxy has no antifouling or foul release properties.

So it looks to me like they're recommending it as a way to get a super-hard, slick, fair finish -- and not as a type of barrier coat.

Based on you saying you want to paint the bottom -- does that mean you want anti-fouling because you're going to keep it in the water? This looks like it's for dry-sailing, and that if you put anti-fouling over it, you'd miss the point of the product (it would then be just a fairing compound, of which there is a large selection).

Or maybe you're thinking about fairing out "the dip"?

R.

[rshowarth]

Hi Rachel-

I want to fair the hull, including fairing out the "dip". (Imagine a large depression about two feet wide and upward into the hull shape from about 2-3 feet from the transom to the transom. I know pictures would be better.)

After I fair the hull I would paint the hull. I dry-sail the boat from a trailer. We put the boats in from a hoist each time we sail them.

I am not looking for antifouling properties. A hard slick surface.

This is why I was interested in the comments some time ago of "He who shall not be named" who had posted some comments about using a product from Hawkeye Industries that allowed the spraying of Gelcoat, called Duratec. http://www.duratec1.com/ProductList.html#painting
Is Duratec a better alternative, to avoid the possible bad side effects of effectively barrier coating with an epoxy based VC Performance?

The boat was looked at by Jonathan Udell of Custom Offshore, who re-fairs a number of competitive J boats, even straight from the factory, and he was the person that suggested that the dip significantly affects speed.

Unfortunately it would not be affordable to hire someone to do this.

I do not know that I will be able to spray. I will probably be rolling and tipping.

[PGplastic]

My plan is to us VC Performance on my com-pac 16 (speed demon that she is). Really, she'll be stored on the trailer. I am curious if she'll accelerate more quickly. Had blisters and followed the West System instructions to a "T" with success. Of course, I faired the hull prior to the barrier coat. The VC is simply applied over the prepared barrier coat. (I bet you're thinking, "Why are you using a barrier coat if it's going to be stored on a trailer?" Just wanted the experience. Not really a big deal to apply this considering the big picture.)

In your case, I don't see any need in using watertight unless you fair the "dip." Just follow the directions on the can for bare fiberglass.

Paul

[rshowarth]

Paul-

I do intend to fair the "dip". So one of my questions is: Do I use Watertite as the fairing medium, as suggested by Interlux, or use West System or something else?

Thanks for the response.

[Rachel]

Read,

I think Watertite is a fine underwater fairing compound. Thickened epoxy would also work, although if you're using something like microballoons you'd have to coat with neat epoxy afterward. Supposedly Watertite has an "easy" sanding window of x number of hours. I used it extensively when I was repairing blisters (years ago) on a trailerable, but as I only had weekends to work, I was never able to take advantage of that window, and can't comment on that facet of it.

My question would be how "deep" is the dip. In other words, how thick will your filler be? Even if you put it on in layers, to avoid heat build-up, you can still only make un-reinforced filler so thick before it'll crack and fall off. I'm not sure what that thickness is though. Not saying you shouldn't fair out the dip, but just a consideration for technique.

If your boat is dry now, I wouldn't worry about any "barrier coat" side effect causing damage. If VC Performance is the product that will work for what you want, I'd say use it. After all, even with "real" barrier coat (e.g. Interlux 2000E), you have to achieve a certain millage thickness to have it work. I'd say a minimum of five coats. You probably won't be putting that much on in any case. 2000E, for example, can also be used as a sticky primer on metal, or as a "tie coat" before bottom painting, but then you only use two coats.

Edited to add: Even though you've already been wet-sanding your gelcoat, I'd still be sure to start with a round of 202 solvent wash - or the like - to remove any residual mold release wax. The stuff seems to stay around for eons unless/until you remove it.

Rachel

[rshowarth]

Rachel-

Thank you.

I will post some pictures of the "dip" before soliciting any more advice. If I put a level or straightedge against the hull and take a picture all will have a better idea of what I am asking about. I really should have been prepared with this before posting and I apologize for not posting it with my first inquiry.

Regards,

[Rachel]

But sometimes you just have to "post it out of your system" even before you have all the facts at hand, don't you :) Sometimes posting and getting feedback helps to organize your thoughts when they're scattered.

I'll be curious to see how that dip looks. Photographing how a straight edge sits on there will be a good visual.

R.

[rshowarth]

Here is a picture of the "dip":

[Rachel]

Could you possibly post that a little larger (or link to a full-sized photo)? I can't quite make it out.

Thanks,

Rachel

[rshowarth]

How about a link to an album?

http://picasaweb.google.com/alchemy2645/Mariner2645Dip

I would say it will be 3/8ths of an inch at its thickest, maybe a bit more?