I'm finding my 50cm board a bit too big much above 25kts, especially if it's choppy.

I had a go on the Thommen, and it's fine in the strong gusts but at about 50l horrible in the lulls!
I'm getting too old to wallow around up to my waist in water.

So I'm considering making a board with a stepped bottom, somewhere around 42/45 cm on the bottom and 50cm on top, the step about 20/25mm deep.

This will involve a bit more work than a conventional arrangement, so what happens if the board is fairly thick?
Say 130/150mm for 42/45 cm wide, does it make it unstable, increase wind resistance, or make it more likely to do that rail trip thing when the fin lets go?

Why is the Thommen and some other speed boards so thin?

Ian's asymmetric ideas have also got me thinking, but first I need to decide how to get a bit more volume.

Any ideas, thoughts, suggestions all welcome.

Why don't you make Dan an offer for his?

Why not make a 65l version of the thommen. So it will give a the float you want

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Bender said...

Why not make a 65l version of the thommen. So it will give a the float you want

I guess that's exactly my question really, what happens when you make the board thicker?

Hey Dan. If you read this. If you ever want to sell that 'step board' I would like first dibs.

So do I take it Dan's made one and it works OK?????

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decrepit said...

I'm finding my 50cm board a bit too big much above 25kts, especially if it's choppy.

I had a go on the Thommen, and it's fine in the strong gusts but at about 50l horrible in the lulls!
I'm getting too old to wallow around up to my waist in water.

So I'm considering making a board with a stepped bottom, somewhere around 42/45 cm on the bottom and 50cm on top, the step about 20/25mm deep.

This will involve a bit more work than a conventional arrangement, so what happens if the board is fairly thick?
Say 130/150mm for 42/45 cm wide, does it make it unstable, increase wind resistance, or make it more likely to do that rail trip thing when the fin lets go?

Why is the Thommen and some other speed boards so thin?

Ian's asymmetric ideas have also got me thinking, but first I need to decide how to get a bit more volume.

Any ideas, thoughts, suggestions all welcome.

The most 2 most stable, confidence giving boards I have ridden in chop at speed are the iS50 and my custom 48cm polyester board.

The Custom because it is a great shape but also has that little bit of flex that polyester gives that takes away some of the harsh vibration of high speed chop.

The IS50 because it is narrow enough (46.5cm) to cut through pretty well but mainly because it's rockerline and outline combine for a very flat ride with very little fore aft pitching. (This is also it's disadvantage because it is harder to 'fly' the board for minimal contact at anything but top speed.) There is a limit though. Once the waves get to a certain length (what we call a rolling chop) you are going to get fore/aft pitch. That wavelength varies with the board length and design. One has to find a board that fits the type and frequency of chop your local venue gets when it get good.

The other idea that I really like is Dans step board. This design should almost totally eliminate pitching and has the potential to be extremely stable. It also has the advantage of perfect trim, but this is built into the design and might take some trial and error to get right. BTW, Dan also has an offset fin both in position and angle. Its a pity he has not persevered with the design more as I think it has shown enormous potential (44 knots peak in very rough water?)

Oh, you haven't seen it? It has a 'step' under the mast base and rides on that point and a short area at the back as well. Very stable longitudinally. Great concept for a tandem I recon

Thanks Andrew, all food for thought.

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yoyo said...

Why don't you make Dan an offer for his?

Ah now I see, not exactly what I had in mind, but very interesting all the same.

Put an image for you to see.

Rear half is dead straight. Same width and thickness at mid section as at tail. It trucks back upwind with even the smallest fin.

It rode too flat. He has since added another 2.5cm? to the bottom before the step. Of course bringing the step further back would have the same effect.

Dan not sure of fin posie. (Whether it is any better than normal.)



Mind you, I think Dan did close to 44s on all his boards.

Hi Decrep . I have just finished CAD designing a 43 cm speed board . It is similar in concept to Chris's Carbon Art boards , very parrallel , wide in the nose with a fairly flat rocker and quite a bit of V . It differs in that it is a little shorter, I have raised the rocker a bit in front of the mast and added parrallel concaves that run out at 600 OFO . I have also put sharp wingers in the tail rather than the pintail .
Like the Carbon Art I have quite volumous rails but I have heavily scooped the deck out . This aids in getting the volume up a bit yet keeps the center of effort down low . It has come out at 61.5 litres which is fairly high for a board as small as this and good for my 90 kilo's .
If you want a board that has reasonable volume perhaps you could make the rails quite "chunky" through the centre of the board but scoop out the deck alot .
I don't have any images of my board at home , they are on my work computer. I,ll stick them up next week and if you are interested I am happy to send you the file.
I am hoping to get somebody to build it for me later in the year . Any offers?????

Back when I worked at Bombora, we had a board maker by the name of Bruce McKee. He was a top bloke who was one of those guys that constantly questioned and looked at ways of improving anything he was involved in. He pioneered wakeboarding, he was one of the best free skiers around, he ended up desiging the Bombora Capricorn as well as making modifications to many of the existing models on sale at the time. He shaped Surf Skis for John Christenson (world champion) and later on moved to France to shape surf boards for names like Sonny Garcia and Occy. Anyway, while he was at Bombora was the era of Pascal Maka and Bruce caught the speed bug good and proper. Totally by chance I came across his personal website the other day and on it are some great pics of some of the speed board designs he shaped back then (late 80's) which are pretty much the forerunners of what I think Dan has made.
The link to his site is http://www.mckeesurf.com/brucemckee/windsurf.htm
This will take you straight to his Windsurf page and once there check out the stepped board collages he has put up. Some of the designs are amazing like the ones that look like Formula 1 boat hulls. They were a bugger to glass due to all the needle noses and curves etc. We had great fun trying them out in various locations but he was very protective of his designs so they never really got too much public exposure. A shame really because I think with some modifications there was some real potential. Hell I'd love to dig them out again now and see what they could do.
It's a cool site showing some of his hundreds of surfboard designs too as well as his 4 fin system he has recently teamed with FCS to produce.
Decrep I emailed him the other day and am sure you could do the same if you wanted to pick his brain on some ideas. I think considering his track record he knows what he's on about regards shapes.
Cheers

Did he design the Astro Toy?
That was my first short board and i totally loved it and still think to this day that the hull design was great

Was that the one with the clinker built hull? I had one. Great board. People were so impressed with them at the time that one or two carbon/glass fibre copies were built. But I suspect the polypropylene flex was essential to the magic.

Mr Love, yes I'm thinking of keeping the mast track as low as possible, may be scoop it out so that when the mast is at 90deg to the deck, it's just about touching it, but a closed well would probably fill up with water, making the board heavy, it'll need some opening at the back so it can drain.

Nebs & Bender were around this arvo and some ideas have emerged.
I think a step all round the board is going to be much too hard to construct, so now I'm thinking of just the last meter or so.
Think having the feet out a bit enables them to be higher without increasing the rolling moment on the board, just might need a slightly longer fin though.

Your board sounds good, but I can't offer to build it for you, we're going on a European trip later in the year.

Sick_em_rex,

I see what you mean, some interesting stuff there, but not really what I have in mind.

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Ian K said...

Was that the one with the clinker built hull? I had one. Great board. People were so impressed with them at the time that one or two carbon/glass fibre copies were built. But I suspect the polypropylene flex was essential to the magic.

Actually Ian there were quite a few of those built. They were marketed under the moniker of Astro Toy APC which stood for applied polymer construction. From memory Bob McTavish actually vacuum bagged the boards and then they were filled with 2 part polyurethane. I had one for a while then also got a more traditional concave/vee bottom one called an APC slalom which I preferred. I even got myself in Freesail photographed chop hopping one in Long Reef lagoon for a test the mag did Still got the mag too Their problem was the inconsistency of the filling causing some pretty dramatic holes and delams occurring which resulted in a lot of returns.
I'm pretty sure Bruce did design the Astro Toy in conjunction with a lot of input from Mark Paul also. I remember riding the board we used for the mould but it was glassed a lot heavier than normal.

Hi Decrep , I will stick some images up tommorrow for you to have a geek . I have also been thinking about an assymetrical "stepped" board for a while but as yet have done nothing. The one I have modelled is symetrical as has no cutouts or steps , just wingers like the Isonics.
Peter Nitschke is building me a Bump and Jump board at the moment that I designed but is off to Brasil next Saturday for 2 months . I was hoping to get it built for speed week but I guess it will have to wait unless anyone can suggest somebody else who could build it ?

Hi again Decrep ,here are some quick screen dumps of the board . The spooning out of the deck and the concaves aren't as severe as they look on the images , the concaves are only 1.5 mm deep at 1500 . I am going to widen the tail a touch in front of the wingers ,I think it tapers just a bit severly .
You are welcome to the file if you wish .

I have also stuck an image of the Bump and jump board in the gallery ,I designed it and Peter Nitschke should have finished this week .

I have an epoxy version of the Astro Toy hanging in my garage. Its quite heavy and doesnt seem to have any foam in the nose section but ist perfectly sailable.
Its from Bob Mctavish and is called Shock Treatment, no idea why. If anyone wants to check it out give me a call.

It looks like Chris' first CA 50 which had a nose like that before they decided to round them off completely.

Should be good. Whether the tail trimming offers any benefit only trial will tell. It is a better way than cutouts in my book but not sure if necessary on speed guns.

Hi Yoyo , yep ,obviously heavily influenced by Chris' brilliant Carbon Arts , but in reality it is quite different. The rocker is not quite as flat and I have the double parrallel concaves in the front running out to flat V. I thought the Isonic type wingers were a great way to narrow the tail down as well as get that really clean release of the rails. I do think I need to widen the board a touch just in front of the wingers though ,maybe only 2mm,s a side .There is no reason for the arrow like nose shape other than aesthetics , I thought it looks fast!!! The main thing was to have the wide nose to produce the lift to help unstick the board.
I would love to make it , but I don't have the time or skill .Hopefully when Pete Nitschke gets back from Brasil he can build it for me.

another way of lowering planing threshold of the narrow boards is to introduce a single entry concave (scoop).

Just couldn't resist today, there's a poor trapped speed board in that blank trying to get out, and it's calling to me for help.

Think I've found the bottom of it.






Outside rail is 50cm inside 45cm, will probably make it smaller, I just need to sail some high wind boards and see how they go.

Any comments on negative aspects of this idea, please don't hold back. (or positive ones too of course)

And obviously in case you were wondering, the rails and thickness aren't going to stay like that.
At the moment it's about 130 litres, I'm aiming for a bit over 70

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mr love said...

Hi again Decrep ,here are some quick screen dumps of the board . The spooning out of the deck and the concaves aren't as severe as they look on the images , the concaves are only 1.5 mm deep at 1500 . I am going to widen the tail a touch in front of the wingers ,I think it tapers just a bit severly .
You are welcome to the file if you wish .

Yeah, looks great, but no thanks to the file, I wouldn't know what to do with it.
As you can see mine's also inspired by slowboat's boards, in this case 2 at once.

As my board will be thicker than yours, I might make the deck spooning deeper.

And what about Gestalt's idea of a single concave underneath instead of a double???
Any idea what the differences are?

Hey decrepit, not sure if you've built a stepped board or not before. The first time I did one and put it in the bag to suck the top on, the stepped section didnt have dcell on it and the foam compressed realy badly (that one ended up in the bin) I've done a couple since and put a layer of 4oz over the stepped section to give it some strength when it goes in the bag. Hope that makes sense.

Hi Decrepit , I could print sections ect for you but it looks like you are having your own fun. It,s an interesting concept and I will be keen to see how it develops .
Is the idea of the steps just a way to get the volume up on a narrow board or is it also to get you weight out a bit further ?

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decrepit said...

mr love said...

Hi again Decrep ,here are some quick screen dumps of the board . The spooning out of the deck and the concaves aren't as severe as they look on the images , the concaves are only 1.5 mm deep at 1500 . I am going to widen the tail a touch in front of the wingers ,I think it tapers just a bit severly .
You are welcome to the file if you wish .

Yeah, looks great, but no thanks to the file, I wouldn't know what to do with it.
As you can see mine's also inspired by slowboat's boards, in this case 2 at once.

As my board will be thicker than yours, I might make the deck spooning deeper.

And what about Gestalt's idea of a single concave underneath instead of a double???
Any idea what the differences are?

hi decrepit,

i meant a single concave only in the front part of the board at the nose. maybe front fifth of the board.

i'll take some photos of my boards and put them online.

i've had a lot of thick boards. 150mm + etc.

personally i think thinner is better, or certainly far more lively anyways. thick boards to me feel more stable under foot but the downside is they don't react as well to trim. scooping out the deck does help fix this as mr love has said.

one of the areas really over looked with boards is the rail shape towards the front. i'd go soft or tucked if it was me. a 60/40 tuck like on a freestyle board is nice. then go hard at the tail for release.

i've had some situations where i've been following people along a run on a hard railed board and had the board trip up on the wake left behind by the person in front. not much fun.

other thing i would do is install 2 mast tracks. these days they are really short. with proto boards it's handy to have some extra length to play with.

forgot to mention. 230cm would be my ideal length on a board. i've had 220-245 boards.

the 220 are a little on the short side for gybing. 245 the nose can be to big.

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decrepit said...


Any comments on negative aspects of this idea, please don't hold back. (or positive ones too of course)

I think the main negative about the board is that it won't be mine