NotWal said...

AUS4 said...

wet and dry sand paper 1000 - 1200 grit is the go, polishing will cause the water to stick to the bottom of the board. And that is a proven fact.

Isn't it the other way around? A high polish makes water bead and run off. A sanded finish makes water spread over the surface and wet it.

Thats what beading is....water sticking to the surface causing the water to roll accross the surface like a rolling wave. Not flowing evenly as when sanded.
But be my guest and polish, its your regatta !

NotWal said...

AUS4 said...

NotWal said...

AUS4 said...

wet and dry sand paper 1000 - 1200 grit is the go, polishing will cause the water to stick to the bottom of the board. And that is a proven fact.

Isn't it the other way around? A high polish makes water bead and run off. A sanded finish makes water spread over the surface and wet it.

Thats what beading is....water sticking to the surface causing the water to roll accross the surface like a rolling wave. Not flowing evenly as when sanded.
But be my guest and polish, its your regatta !

No beading is caused by water NOT sticking. Its free to follow its weak molecular bonds and form into droplets. If its wetting the surface its constrained by the surface i.e. sticking to it.

I tried to help you NotWal, like I said it is a proven fact, now go to boat book store and read about it.

Leo I will show you all about it next time I see you.

AND, NotWal and I have almost 8000 posts between us to your 210, that must make us much more knowledgeable, almost experts in fact

isn't debating water beading or not basically a waste of time... i'd would have thought you guys would be more interested in talking about dynamic flow.

interestingly, stuff like lasers and such are generally going a lot slower then a windsurfer, and water over the hull could possibly be laminar, whereas windsurfers are usually going a fair crack faster where flow would definately be turbulent... so saying what applies to boats also applies to windsurfers is kinda silly.

it doesn't surprise that some literature suggest polishing vs some that says sanding. I'd say undoubtedly at low boat speeds where laminar flow is maintained a polished finish would be better, but once you start going faster things get trickier.

Interestingly BOR90, the trimaran that took the americas cup and also does almost 30kts in 10kts of wind uses a "skin-friction reduction riblet film" made by 3m. Thats much closer to the speeds that a windsurfer does so maybe you should be getting some of that if you are really serious about the whole surface finish thing.

valenciasailing.blogspot.com/2010/03/bmw-oracles-skin-friction-reduction.html

I am a bit low on posts, therefore no expert, but the advice from Board Lady is not for a glossy surface.
boardlady.com/fast.htm

I never really bothered much with my sailboards, cos speed was not my goal, but I do know that whenever I polished the bottom of my surfboards, they always went heaps better.
I always favoured a polished finish, rather than the lazy wet/dry they do now.

Hey slowy, where'e me flippin' fin, and where have you hidden the bloody KA crew ?
No-one's answering their e-mail. Not even Gestalt.
Was there an apocalypse ? Will there be zombies ??
Should I do some extra cardio this morning ??

has anyone tryed the 3m foam pads (fine ) they are amazeing you can use them wet or dry even dry they dont scratch, just add a bit of shampoo to the water

swoosh said...

I don't do anything to the bottom of my board cause I don't wanna ruin how purty it looks

swoosh if your board is any older than 12 months, i could almost bet that if you sanded it with a long flat sanding block there would be some high's and low's that weren't there when you brought it, especliy in front of the fin box

decrepit said...

AUS4 said...

NotWal said...

AUS4 said...

NotWal said...

AUS4 said...

wet and dry sand paper 1000 - 1200 grit is the go, polishing will cause the water to stick to the bottom of the board. And that is a proven fact.

Isn't it the other way around? A high polish makes water bead and run off. A sanded finish makes water spread over the surface and wet it.

Thats what beading is....water sticking to the surface causing the water to roll accross the surface like a rolling wave. Not flowing evenly as when sanded.
But be my guest and polish, its your regatta !

No beading is caused by water NOT sticking. Its free to follow its weak molecular bonds and form into droplets. If its wetting the surface its constrained by the surface i.e. sticking to it.

I tried to help you NotWal, like I said it is a proven fact, now go to boat book store and read about it.

Leo I will show you all about it next time I see you.

I'm afraid I have to agree with NotWal here, polished surfaces reject water, wet and drying them allows them to be "wet". Same with "wetting agents" we put in our horrible WA sand gardens. Without wetting agent the water fprms drops on the surface, with wetting agent, the water can flow out and soak into the soil.

Maybe you should read that book again, cause I think you've got something back to front.

Just have to add my two cents here. I wish I had the time to test all this on a windsurfer. Anyway, there are plenty of examples in nature of hydrophobic surfaces, such as penguin's feathers, grasses or lotus leaves that have driven us to develop hydrophobic compounds. These compounds can make the angle of incidence of the water to the polished & coated surface approach 180degrees so that the water is practically not touching the surface.

en.wikipedia.org/wiki/Hydrophobe

The water molecules are almost totally repelled by the surface. The liquid forms a 'bubble' and therefore slides off the surface as though on a cushion of air. Teflon compounds do have some hydrophobic qualities but there are other far more advanced nanotechnologies being developed to reduce surface drag on water craft. How a sanded surface could be faster than this is beyond me, but I guess it's cheaper, readily available and more familiar than new technology. Basically, if we can make the board ride as if on air, rather than dragging water along, it has to be faster than wet and dry, which relies on the principle of water sliding over water. My guess is that it wouldn't be so good on fins, due to the high speed and increased likelihood of cavitation. Perhaps continue to polish like mad here.

Bonominator said...

decrepit said...

AUS4 said...

NotWal said...

AUS4 said...

NotWal said...

AUS4 said...

wet and dry sand paper 1000 - 1200 grit is the go, polishing will cause the water to stick to the bottom of the board. And that is a proven fact.

Isn't it the other way around? A high polish makes water bead and run off. A sanded finish makes water spread over the surface and wet it.

Thats what beading is....water sticking to the surface causing the water to roll accross the surface like a rolling wave. Not flowing evenly as when sanded.
But be my guest and polish, its your regatta !

No beading is caused by water NOT sticking. Its free to follow its weak molecular bonds and form into droplets. If its wetting the surface its constrained by the surface i.e. sticking to it.

I tried to help you NotWal, like I said it is a proven fact, now go to boat book store and read about it.

Leo I will show you all about it next time I see you.

I'm afraid I have to agree with NotWal here, polished surfaces reject water, wet and drying them allows them to be "wet". Same with "wetting agents" we put in our horrible WA sand gardens. Without wetting agent the water fprms drops on the surface, with wetting agent, the water can flow out and soak into the soil.

Maybe you should read that book again, cause I think you've got something back to front.

Just have to add my two cents here. I wish I had the time to test all this on a windsurfer. Anyway, there are plenty of examples in nature of hydrophobic surfaces, such as penguin's feathers, grasses or lotus leaves that have driven us to develop hydrophobic compounds. These compounds can make the angle of incidence of the water to the polished & coated surface approach 180degrees so that the water is practically not touching the surface.

en.wikipedia.org/wiki/Hydrophobe

The water molecules are almost totally repelled by the surface. The liquid forms a 'bubble' and therefore slides off the surface as though on a cushion of air. Teflon compounds do have some hydrophobic qualities but there are other far more advanced nanotechnologies being developed to reduce surface drag on water craft. How a sanded surface could be faster than this is beyond me, but I guess it's cheaper, readily available and more familiar than new technology. Basically, if we can make the board ride as if on air, rather than dragging water along, it has to be faster than wet and dry, which relies on the principle of water sliding over water. My guess is that it wouldn't be so good on fins, due to the high speed and increased likelihood of cavitation. Perhaps continue to polish like mad here.

Adrian, I think you maybe polishing the wrong thing. Try giving your girlfriend a go instead.

kato said...

Wood Duck said...

Adrian, I think you maybe polishing the wrong thing. Try giving your girlfriend a go instead.

Yep I'm happy to provide free entertainment for all sorts. I'm just that kinda guy. If you had a laugh Wood Duck, I'm laughing too!

Still not sure but this happened gpsteamchallenge.com.au/sailor_session/show?date=2010-09-16&team=16

mine wasnt polished

slowboat said...

mine wasnt polished

He,He


Little snippet of me deleted post ~
allowable roughness for turbulent flow is dependent on Re number (thickness of boundary layer). the longer the courser.....

If you're also into polishing and waxing your car then maybe you should read this:

www.madsci.org/posts/archives/mar97/858179474.Eg.r.html