I dunno if smooth is faster. Carbon Art boards come with a smooth teflon polished finish and they go pretty quick.

Used to see Mal Wright at sandy point polishing his boards. I think the community is divided about if this makes a difference or not. Dont quote me on it but i think he used car polish

pacman76 said...

Used to see Mal Wright at sandy point polishing his boards. I think the community is divided about if this makes a difference or not. Dont quote me on it but i think he used car polish

I haven't yet seen Mal polish the bottom of any of his boards, but I have seen him polished a few fins, and yep, we used car polish (cutting polish).

I remove my post of info as some geezer was upset about the facts![}:)]

Slightly off topic, when I used to race Lasers at the British Nationals, the really good guys that got a new hull every year always sanded the shine off the bottom. They did tell my why but this was 12 years ago!

There's always been 2 schools of thought on this one, probably always will be.

Theory says the layer of water closest to the hull is stuck to the hull, and that the ridges left from 600/1200 grit sandpaper don't stick up through the stationary layer and therefore don't affect performance.

Frank Bethwaite, famous author of "High performance sailing" made many experiments of fins and hulls with various finishes. Many experiments where he towed fins and hulls through water carefully measuring the drag. He is well up on the theory but had to conclude the higher the polish the better.

He also noted polished surfaces don't collect grime as easily.

Here's a video of a highly polished bowl rotating. Water passing under a hull is probably equivalent to about 3 turns of the bowl.

best way to get a slippery board is to rub the underside of the board with a cake of soap!

Ian K said...

There's always been 2 schools of thought on this one, probably always will be.

Theory says the layer of water closest to the hull is stuck to the hull, and that the ridges left from 600/1200 grit sandpaper don't stick up through the stationary layer and therefore don't affect performance.

Frank Bethwaite, famous author of "High performance sailing" made many experiments of fins and hulls with various finishes. Many experiments where he towed fins and hulls through water carefully measuring the drag. He is well up on the theory but had to conclude the higher the polish the better.

He also noted polished surfaces don't collect grime as easily.

Here's a video of a highly polished bowl rotating. Water passing under a hull is probably equivalent to about 3 turns of the bowl.

yes this is true the smoother the finish the better but the initial shinny gloss you get on a brand new gel coat is much slower than a boat sanded with wet and dry 1000< this initial layer wears quickly though and is almost gone after a couple of months but for the top sailors that get brand new boats all the time they need to get rid of this finish faster

desta said...

choco said...

best way to get a slippery board is to rub the underside of the board with a cake of soap!

im so trying this one

use tuna oil. on the return run you go faster for 3 reasons:
1. water is flatter.
2. board is slicker
3. the big grey fish chasing you.

Bonominator said...

scarrgo said...

Ian K said...

There's always been 2 schools of thought on this one, probably always will be.

Theory says the layer of water closest to the hull is stuck to the hull, and that the ridges left from 600/1200 grit sandpaper don't stick up through the stationary layer and therefore don't affect performance.

Frank Bethwaite, famous author of "High performance sailing" made many experiments of fins and hulls with various finishes. Many experiments where he towed fins and hulls through water carefully measuring the drag. He is well up on the theory but had to conclude the higher the polish the better.

He also noted polished surfaces don't collect grime as easily.

Here's a video of a highly polished bowl rotating. Water passing under a hull is probably equivalent to about 3 turns of the bowl.

yes this is true the smoother the finish the better but the initial shinny gloss you get on a brand new gel coat is much slower than a boat sanded with wet and dry 1000< this initial layer wears quickly though and is almost gone after a couple of months but for the top sailors that get brand new boats all the time they need to get rid of this finish faster

I understand the CA boards use a DuPont Teflon compound coat that doesn't wear off that easily. My pro model has the same shiny bum as the day it arrived and it's 18 months old. We'll see. Wet and dry finishes need constant upkeep to keep the scum out of the grooves, but the speed advantage is well, debatable.

yep fair enough there probably isn't a significant difference when talking about polished or wet and dry surfaces on windsurfing boards besides that the polished one tends to collect less grime but i was answering a question about why the top guys in fiberglass gel coat hull boats wet and dry their boats, trust me on this gel coat wet and dry is way faster than a shinny new gel coat

scarrgo said...

Bonominator said...

scarrgo said...

Ian K said...

There's always been 2 schools of thought on this one, probably always will be.

Theory says the layer of water closest to the hull is stuck to the hull, and that the ridges left from 600/1200 grit sandpaper don't stick up through the stationary layer and therefore don't affect performance.

Frank Bethwaite, famous author of "High performance sailing" made many experiments of fins and hulls with various finishes. Many experiments where he towed fins and hulls through water carefully measuring the drag. He is well up on the theory but had to conclude the higher the polish the better.

He also noted polished surfaces don't collect grime as easily.

Here's a video of a highly polished bowl rotating. Water passing under a hull is probably equivalent to about 3 turns of the bowl.

yes this is true the smoother the finish the better but the initial shinny gloss you get on a brand new gel coat is much slower than a boat sanded with wet and dry 1000< this initial layer wears quickly though and is almost gone after a couple of months but for the top sailors that get brand new boats all the time they need to get rid of this finish faster

I understand the CA boards use a DuPont Teflon compound coat that doesn't wear off that easily. My pro model has the same shiny bum as the day it arrived and it's 18 months old. We'll see. Wet and dry finishes need constant upkeep to keep the scum out of the grooves, but the speed advantage is well, debatable.

yep fair enough there probably isn't a significant difference when talking about polished or wet and dry surfaces on windsurfing boards besides that the polished one tends to collect less grime but i was answering a question about why the top guys in fiberglass gel coat hull boats wet and dry their boats, trust me on this gel coat wet and dry is way faster than a shinny new gel coat

Yeh I know. Depends on the quality of the gel coat no doubt. If it's got something slightly hydrophobic in it then it's going to outperform dirty wet n dry any day.

i think polishing the underside of your board will make very little difference, in fact if you could somehow recreate the same speed run twice with all the other variables exactly the same i think the difference would be points of a knot so put it into a practicle sense would make absolutely no difference. also i dont think yacht theory can be crossed over into windsurfer theory(in this topic) because as a yacht displaces over the water, a thin film of water sticks to the hull which creates a water on water sliding action which reduces drag dramaticaly this is why yachties dont want a smooth hull and its the same reason swimmers use the suits with the rough shark skin stuff on them to encourage the film of water to stick however when windsurfers move through the water they are planing which means its always air, water, air ,water as the board passes over chop so any film of water that is created is destroyed by the air passing over the board so the fastest finish in my oppinion would be the most polished one but it doesn't really matter really because it wont make much difference anyway. factors that make the most difference are your technique,the conditions ,your tuning(sail,fin,harness lines etc)

just my thoughts, might not be completely correct

[quote
Your bang on. Technique, fitness and correct equipment selection are much greater factors in overall speed. We're really just talking about that last 5% of potential speed that you'll only achieve if you keep your gear in top shape. You know, polish your fins and board, tune your sail, play with mast, boom and harness position etc until everything just hums. Being a gorilla also helps when it's windy!

Where do you get a Gorilla from

Why not paint the bottom of your board with egg whites and let it dry in the sun. Then whola, you have a self polishing copolymer. All the yachties in the 70's used this one before the rule was brought in that no sacrifical coatings were to be used.

The only problem with the egg white is it use to were off by half way through the first race any way.

I'm still going to have a go at it one day at a speed bank.

i think i'd be a bit buggered if i ever went speedsailing because im just 63kls and yet i'm 188cm tall, i think thats why i do waves mostly