and another

last one... then maybe this thread should go bye bye.

Looks good. Glad you like it. It's really hard to take pictures that do it justice. In person it's much more impressive.

Have a great weekend.
Greg

Busy week,
But I do have some comments.
Greg your boat looks good. I have a friend that purchased a older faded yellow H14 and I plan on getting him to try it. Good tip Jake. I have seen this stuff at boat shows but I am skeptical of these kind of products and am tired of wasting my money on the latest quick fix that doesn't work. Fact is it's still just a band aid but the best I've seen so far.

I preface my comments with some of my experience just so you know. In the late 70's early 80's I worked for KIWI BOATS. We built custom one-off racing yachts. IMP,LOVE MACHINE, EVERGREEN, KIALOA IV. Just to name a very few. We were on the cutting edge building composite,balsa cored boats. Back then we built them on a male mold. As you might guess the outside of the boat is raw glass and has to be finished by hand. So how do you fair a 81 ft. hull to perfection? Sandpaper, fart rock, putty,epoxy primer, paint and a lot of work day and night. We also built the KIWI 40 and MINI TONNER in female molds. Those had gel coat exteriors. For the last 22 years I've worked in my own business touching up cars. The last 5 for high end dealers only. I have had Cats since 1982.
I don't claim to know everything but I do have a good working knowledge of finishes painted and gel coated.

One other thing Greg, none of us really explained why your hulls look good for a short time after you buffed and waxed and then go bad so fast. Picture a cross section of the surface. A new surface is smooth. A degraded surface looks like a mountian range with peaks, valleys and slopes. When you buff you polish only the peaks. Not the slopes which depending on how bad the surface is has much more surface area than the
peaks. You have done nothing to polish or remove the oxidation from the slopes and valleys. Wax leaves, right back where you started.

If the gel coat is not that badly degraded it can be sanded and polished. We have first hand experience not coming from me but MBOUNDS. He lays out a good schedule of sanding. The only thing I would add is a guide coat so you don't over sand or under sand. A guide coat is simply a can of flat black spray paint. Dust it very lightly on before you start sanding. Sand until the paint is gone. This will also show the highs and lows which may be too much info for some. Sanding should be done by hand with a board file and there is a right way to sand. I could go on and on about this and if anyone wants to know more PM with your PH# and I'll gladly call you and discuss it.

Fact is there is only few ways to fix bad gel coat. Polish,sand and polish,re-gel coat or paint.



Daniel,
This comment,are you speaking of yourself? Let me straighten you out on a some of things. My comment about polishing my painted hulls meant after four years they looked as good as the day they were painted. Like Greg's hulls do now. I don't use wax,I was simply trying show the guy who bought my boat how nice it could look. It's all I had at the time. I have argued against waxing for racing on this forum before. The paint has lasted longer than any gel coated surface I have seen.

You say don't sand and buff, but you say it's ok to use a rag and compound. Talk about paddling upstream. The gel coated surface of a cat is the best surface you could ever get to buff for an amateur. It's not that hard to learn.

I've given you examples of painted boats. No comment?

I did go buy some 303. 16 oz bottle. Now it may help keep a new boat looking new. The bottle says 100% Prevention of UV caused slow-fade with regular use. SPF 40 for your stuff. Like your comment about Vertglas I doubt it. I can tell you that on the places I tried it there was no difference in color or sheen. I used a third of the bottle just on my decks in front of the main beam. It does not make an old boat that needs restoration look better. I have friends whose boats have aluminum strips on the bottom of their boats to help protect the hulls from beaching. Trust me the aluminum wears. This stuff will not prevent any wear from the beach.

Referencing your comment above. A lot of people visit this site to get info. Some are people that have never had a boat before. Make sure you don't cause them to paddle upstream.

As much as I do like the vertglass- I agree.. nothing will protect the boat from being dragged on the sand- in fact.. when I was using the oxidation remover you could tell there was less oxidation under the boat from the "polishing" of draggin it across the sand occassionally (although, admittedly, the bottom of the hulls get less UV rad).

Steveh,
He may not have the credentials your looking for but Jack Sammons wrote on this subject in his book Welcome to A-Fleet. I think he's in the sailing hall of fame on this site. He discusses the various drag layers and does not recommend wax for racing. Though the book is written for the Hobie 16 it has a lot of good info and is well worth reading. It's also fun to read. Problem is I don't know if it's still in print. Someone has to have a copy.

Rick, did you use regular RainX or the concentrate that you add to the water in the washer fluid tank?

Jake, I'm thinking if you push the water away you go deeper.

Assume a glass-smooth finish. The problem as I see it is that, according to boundary layer theory, that very first layer of water next to the hull is going at hull speed no matter what the surface is. So unless that magic coating can allow that first layer of water slip by in violation of the theory, what's to improve on?

Steve,

The navy has been working on this for years. They discovered years ago that dolphins and whales as well as many fish exhibit far less drag than theory says they should given their shapes. They think they have it down to some substance exuded by their skin. Every now and then you hear a little blurb about it but I have not seen anything published recently. Not suprising with the Russians revealing their FULLY OPERATIONAL super-cavitating torpedoes. Can you say ketchup?

Jimbo

Maybe it's not as complicated as we think it is.

We have been through this before. Catamarans are in the laminar flow regime. That means the water touching the hulls does not move. For all practical purposes, as long as the surface roughness is the same, it does not matter what is on the surface.

Because wax makes the surface smoother a hard wax surface, should make you a little faster. Hydracoat, hydracote, etc. are supposed to work by adding something to the water to reduce boundary layer friction. The only data I have ever seen says you need a lot (about 1 beer bottle per day) A few drops wiped on before a race is not going to do anything, for very long.

I do not know how this, "do not wax" idea got started. "Welcome To A Fleet" has helped it and some other odd ideas keep going. I do know that knowledgeable people have told annoying novices silly things like "don't wax your hull and 2000 grit wet sand it with the grooves all going in the same direction" or "wipe the rudders with raw fish oil" and armor all the tramp to help you get across faster".

If you really want your boat to go faster, wash it really good at the regatta site.

I will not argue this point anymore, go look it up for yourselves.




As for vertglass and such, I used it on a monohull I was trying to sell. I think it is thinned water based polyurethane. Think of it as a delicate decorative finish. It is sensitive to UV and do not ever use harsh cleaners. It will look like old varnish. Opps or ammonia will take it off if it starts to look bad. I have never used it on catamarans.

It is slippery but that can be fixed. I use my leftovers to make non-skid. I add Interlux grit to it and roll it where I want it.

Carl

" I likes to rub me and me boat down with day old Squid before I race"! Ow, me head hurts ...3m wax makes her slide right up on the beach and straight thru umbrella and beach chairs just ask mr. Chip from Delray. The day he slapped a tourist sunglasses off with rudder was pretty impressive too,as his 6.0 was skidding sideways sailing up the beach, the bottoms of these boats are all in great shape still.

I've been using Starbright marine polish with teflon for quite a few years. I don't know if it's a wax or not.



This stuff is to protect a good finish not for restoration. I put two coats on about twice a year and it seems to keep my new boats looking new. It also makes the hulls slicker so that they wash easier. I would not go near my hulls with sandpaper until they were in bad shape with lots of oxidation. I would also not ever paint a cat. The paint looks great until it starts getting dinged up then the old color shows through and the boat starts looking bad.

Mike Hill
www.stlouiscats.com

I disagree that cats are in the laminar flow regime. They may be traveling at a speed where one would expect laminar flow under ideal conditions, but there is nothing laminar about the the flow near the air-water interface. Too much entrained air and eddies from the wave action. And those eddies will be deep enough to affect a portion of the dagger and rudder, so I'd skip prepping for laminar flow on those, too. Another problem with laminar flow is that it separates more easily than turbulent flow and separation is the big drag producer.

Once you accept that laminar flow is, at best, a fantasy and, at worst, undesirable, then you can move on to the smooth vs "rough" argument. Personally, from the journal articles that I've read, I see turbulence as sort of a microscopic version of separation. With separation, there is an adverse pressure gradient that builds up near the surface due to viscosity, and when this pressure reaches a certain value, the flow separates from the surface forming a coherent eddy structure behind the object. The way to prevent this from happening is to induce randomized, turbulent flow which brings energy down closer to the surface. Well, a similar thing occurs in the boundary layer of fluid. A coherent vortex structure builds up with vortices forming and bursting in periodic fashion and the thinking is that a randomized "rough" surface prevents this coherent vortex structure from forming.

But, there's arguments both ways, some more supported by experimentation and theory than others.

Not that I'm worried about a bit of this on my cat.

So which produces the "lesser of two evils", the rough or the smooth?

Rough. Though rough is on the order of hundredths of a millimeter. Plus, there's the possibility that the same disturbances that prevent laminar flow could prevent the coherent vortex structure from forming so the point could well be moot. Extrapolating results from one situation to the next doesn't always work.

Good to know, although I'm going to keep my hulls shiny until someone can prove to me that the shiny hulls are slowing me down more than a blown tack or getting rolled at a starting line...

Smooth vs. Rough or Textured? Remember the 12 meter Stars & Stripes down in Australia. Riblets. They won that one. Fun topic.

RIBLETS-You do not know what a riblet is? It is not an animal. Airlines in the United States are saving $300,000 a year because of riblets. Here is the story behind them:

Scientists at NASA tried to figure out how certain water creatures could swim so rapidly. They studied porpoises and sharks for months. The friction of the porpoise's body as it moves through the water ought to be great enough to slow it quite a bit. Yet the amount of drag that should be present-simply was not there! Given the drag of the water and the amount of flipper motion, something was enabling the porpoise to swim much faster through the water than it ought to be able to swim.

Then the experts figured it out: riblets. These are small triangular-shaped groves on the outer surface of the porpoise's skin. They are also found on fast-swimming sharks, but never on the slow ones. These grooves run from front to back. As the water touches the body, it is carried along in those riblets, and this reduces the amount of frictional drag as the large creature swims rapidly through the water.

NASA's Langley Research Center developed the riblets and tested them in wind tunnels. They then asked 3M Company to manufacture riblets in large, flat vinyl sheets. When these sheets were placed on the outside of large airplanes, the resulting savings were immense. It now costs airline companies a lot less in fuel to fly a jet liner a given distance.


Just when you think you got it all figured out.

Kind of like the dimples in a golf ball. Should we all be orange peeling our gelcoats? Maybe next time you mess up a paint job you can tell them "Those aren't fisheyes, those are speed riblets."

-Rob V.
Nacra 5.2
Panama City

More on riblets.

http://oea.larc.nasa.gov/PAIS/Riblets.html

http://www.google.com/search?hl=en&ie=ISO-8859-1&q=3m+riblets&btnG=Google+Search