I'm trying to separate the marketing hype from fact when it comes to the tail sections of unlimited downwind boards. Clearly there's a stability trade off but is the narrow tail to help with tracking or to reduce volume to allow the tail to 'sink' into a wave or swell?

Can a similar result be achieved with a wider, thinner tail that similarly 'sinks' into a wave but provides greater stability?

Your thoughts please?

very good question

The SIC Bullet 17'4" though 'narrow' at the tail still has quite a lot of volume there.
I think it's more a question of tail shape and then The resulting volume rather than volume alone.
I find the tail of the Bullet difficult to sink sometimes as I'm under 80kgs and I don't have a wide stance.
My new 17' V3 shape custom will have even less volume back there due to being very thinned out compared to the production Bullet.
I find the narrow, lower volume tails work better as you don't get 'tipped' forward so much when catching a bump.

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magillamelb said..
I'm trying to separate the marketing hype from fact when it comes to the tail sections of unlimited downwind boards. Clearly there's a stability trade off but is the narrow tail to help with tracking or to reduce volume to allow the tail to 'sink' into a wave or swell?

Can a similar result be achieved with a wider, thinner tail that similarly 'sinks' into a wave but provides greater stability?

Your thoughts please?

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Kieranr said..
The SIC Bullet 17'4" though 'narrow' at the tail still has quite a lot of volume there.
I think it's more a question of tail shape and then The resulting volume rather than volume alone.
I find the tail of the Bullet difficult to sink sometimes as I'm under 80kgs and I don't have a wide stance.
My new 17' V3 shape custom will have even less volume back there due to being very thinned out compared to the production Bullet.
I find the narrow, lower volume tails work better as you don't get 'tipped' forward so much when catching a bump.

With Unlimited Boards a NARROW TAIL is the way to go. My original Bullet has a narrow tail, my new Custom V3 Bullet 2016 model will have a PIN TAIL, The tail on LOW PRESSURE has a narrow Tail. Best to have a razor sharp edge at least 2 1/2 feet from the tail all the way to the tail so the Unlimited board will bit when you're surfing the ocean swells, just like a surfboard does surfing a wave.

The Beauty about a NARROW TAIL is it makes the board very easy to surf the ocean swell. the fatter the tail the harder an Unlimited board is to surf. Sure a FAT TAIL will go fast in a straight line but makes it very imposable to surf the ocean swells.

I paddled Dave Kalama's 19ft Unlimited board great board (Magic) but the tail was to wide the board was super fast going straight but you could not turn (SURF) the f###en thing, Dave Kalama agreed with my quote on his 19fter. Tail.

Check out the tail in the photo

IMO.. squaring off the tail is a way of shortening a board (fitting a 15' board into a 14' class) with slightly added stability being a benifit.. But that bit of extra board behind your rear foot can cushion things when the nose is bouncing up and down when standing on the tail and you're planing down the face of a big choppy wave.. There is also a slight rocking motion when paddling that a narrow tail allowes the board to move up and down in the tail more than a big wide square tail would.. This is why there is a lot of volume there (high rails) so when the tail moves up and down you reduce any water flowing over the tail (which slows you down).. Better tracking and controle at speed are other benifits of a long piny tail.. I find all this pretty interesting and I'm sure there's a lot more going on.. I'm guessing a pin tail will allow you to use a smaller fin and smaller fins can mean more speed.. Also that rail curve in the outline towards the tail will help with turning because big square tails have very little curve in the rail back there.. I have to laugh sometimes when I hear people say that a big thick square tail get a push from the wave behind when catching runners..

Thanks for your thoughts!

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Al Hunter said..
very good question

we want more than that Al Hunter, we would love to hear you're thoughts on this question from a true board designer point a view

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AndyR said..

Al Hunter said..
very good question

we want more than that Al Hunter, we would love to hear you're thoughts on this question from a true board designer point a view

Tail on the new 17'10 DC might give to a clue to his thinking...

Can't tell you why, but I can show you a bit of what.
From my measurements of unlimited boards, I overlaid the tails with the noses lined up.
These vary from squared off pin, rounded pin, cut off pin, etc.
These are straight lines at 300mm intervals, no curves fitted.
Iron Phil's 17' F16 looks a lot like a 17'4 Bullet plan shape with the last 4" chopped off.



I was doing some measuring on the Bullet and Iron Phil's board, and I noticed the rudders were the same distance from the back.
So since we're looking at the tails of the boards, I lined the tails up.
Variations on a similar profile.
But there's a lot more to it than plan shape - rail shape and volume distribution vary even from the same manufacturer.







17 Naish javelin LE-17
Narrow pin and hard rails tucked in from the widest point.

Not much volume above the rails









2012 17' Glide
Still hard rails, but the rail is nearly at the widest part of the board.






And a lot more volume than the LE




Iron Phil's 17 Custom F16
As well as the square cut off, rails are only tucked in about 10mm
Massive volume







17'4" Bullet.
Much more rounded in the sides, and strange how the deck pad comes much further back.
I think this is to disguise the volume visually - the deck cross section is not dramatically smaller than Phil's board.








Phil's 17' F16 and 17'4" Bullet.
The F16 is almost straight on the sides, the rails less than 10mm narrower than the widest point. The Bullet has much rounder sides, the rails tucked in about 25mm from the widest point each side.
Makes it look a much smaller board.
Paddling Phil's board in flat / choppy water upwind, I am now standing on the front of the steering to use the tail rocker to lift the back and give a cleaner release from the water. The board feels much better doing this, but I've never felt the need to do it on the Bullet. But I will give it a try.







Not a downwind board, but JM 17'6" has similarities to Phil's 17' F16.
Still a narrow tail, similar section profile.







Helmy's Hollow Maui F16 - pin tail, very hard rails




I don't have the board with me, but the rails appear to be almost the widest point of the board, similar to the back of Phil's board.
But much finer, much lower volume.





Not sure what the conclusion is Magilla, and I've probably asked more questions than I've answered.
But then these boards are probably just variations on a narrow tail.


Especially compared to 2010 C4 waterman. (photos from advertisement - I haven't got it)

Interesting that when you line those boards all up that their width at that point (I'm assuming) 1' from the transom their width is quite similar.

What I had designed is more like the 17' F16 and the JM, with the slab sides and hardish rails, but with a little less thickness.

Given Dave Kalama is a pretty sizeable unit, his Imagine looks like it's got some 17' F16 pedigree also. I would only think that volume & stability are the reasons DK did what he did with his Imagine board...

Excellent Homework Nozza

17'4 Bullet with a little extra foam trimmed off the sides

the production v2 foam core f16 I think has same rail more or less as the bullet but with the tucked hard edge running nearly all the way up.

also the classic double concave.

I noticed phils board he went the double

The more I paddle / look / learn, the more I like what I think are classic longboard shapes.
The Bullet single concave and hard rails, the F16 double concave and hard rails.
The hard rails give you stability, and steerability.
Coming from a yacht background, I can understand the single concave and hard rails give you a catamaran stability effect.
Keel line and double concave you have a trimaran.
Both give you a stable board for it's width, that tracks nicely but steers easily.
Maui F16 and Thailand Bullet 17'4"


Note the Bullet gets a double concave right at the back, for when Area10 has his foot back there steering it.
Maui F16 has the most pronounced keel all the way forward, huge concaves,
You will pry it from the fingers of Helmy's rotting corpse when the time comes.



Iron Phil's F16 has the double, possibly not as pronounced, particularly forward.




Not an unlimited, but surprise for me was the 14' V1.
I was underwhelmed by the V2 I bought from Lacey.
Nice enough, single concave, somehow, if it's possible to be emotional about boards, it emotionally failed to click.
Maybe the black, maybe just because I bought it in Melbourne winter.
But The V1! Love at first sight.
Should have been called an F14, almost identical to the F16 double concave.







Lovely board.
I'm sure Mac has posted pictures of his McToshish or whatever longboards with almost identical shapes.
The Jimmy Lewis M14 wasn't that far removed either.

Thanks for all the pics with all this talk of unlimiteds I think I may have to do a little 16'er for myself to play with for when out summer dw season kicks in.
Area10 and myself did a back to back the other day with the bullet14 v1 and I was presently surprised to see how well mine measured up against it so I think im going to just go a little longer a little narrower and tweak the rocker a tinny bit. The frustrating bit is Im not going to be able to start it till I get back from holiday.

Yeah, I can confirm that my speeds on Charlie's board was at least as fast as on my Bullet 14v1, and I felt more in control on his board, and less likely to fall. If I had had to pick one of them for a third run I'd have chosen his board over my Bullet. The remarkable thing about this is that Charlie's board is 26" wide compared with the Bullet's 27.25". And I'm a wobbly old git. So I expected to feel more unstable on the borrowed board. But in fact it was the narrower board that felt easier for me. I think one of the issues I have with the boards tuned for eg. Maui conditions is that they might be on occasion unnecessarily thick for our very short period, peaky, choppy, confused, blown-out high-wind conditions. The big thick rails just catch everything in cross-wind and cross-chop, and you are standing so high that you feel like a cork bouncing around. Also, the bigger tail volume makes it harder to surf the board on bumps and to sink the tail to get yourself out of a critical potential pearling situation. Charlie's board was quite a bit more svelte and thinned-out than the Bullet and it seemed to work well in those particular conditions. Maybe in more lined-up, longer period stuff high volume is king.

I'm guessing that in time we as a community will work out what design features in a DW board work best in which conditions (and perhaps where), but at the moment I suspect we are all just feeling around, seeing what works.

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Area10 said..
Yeah, I can confirm that my speeds on Charlie's board was at least as fast as on my Bullet 14v1, and I felt more in control on his board, and less likely to fall. If I had had to pick one of them for a third run I'd have chosen his board over my Bullet. The remarkable thing about this is that Charlie's board is 26" wide compared with the Bullet's 27.25". And I'm a wobbly old git. So I expected to feel more unstable on the borrowed board. But in fact it was the narrower board that felt easier for me. I think one of the issues I have with the boards tuned for eg. Maui conditions is that they might be on occasion unnecessarily thick for our very short period, peaky, choppy, confused, blown-out high-wind conditions. The big thick rails just catch everything in cross-wind and cross-chop, and you are standing so high that you feel like a cork bouncing around. Also, the bigger tail volume makes it harder to surf the board on bumps and to sink the tail to get yourself out of a critical potential pearling situation. Charlie's board was quite a bit more svelte and thinned-out than the Bullet and it seemed to work well in those particular conditions. Maybe in more lined-up, longer period stuff high volume is king.

I'm guessing that in time we as a community will work out what design features in a DW board work best in which conditions (and perhaps where), but at the moment I suspect we are all just feeling around, seeing what works.

I think you guys are so specialized in where and what you dw you would almost the to be locally designed and made.

I just cant see major brands being interested in producing really radical suited dw boards

You might be right, Lacey. But as downwinding spreads across the globe, I wonder if we will find that it is Maui conditions that are the most unusual, and the majority of other places across the globe might be different from Maui, but more similar to each other. I saw some footage of the Gorge a while back and that looked more like our conditions (albeit much better lined up) than it did Maliko. Is it possible that we might in time start to talk about eg. "Gorge-spec" designs and "Maliko-spec" designs. There are certainly different surfboard designs that work at different breaks around the world - so why not downwind boards too? But for sure, the big brands will only likely turn out designs oriented towards the biggest markets. That's OK, it's nice to have a local market for local shapers.

Here in Melbourne it seems 17' boards are just that bit too long. Just as you run down a wave, you're headbutting the one in front. Helmy's F16 is nearly perfect for Melbourne.

Big, long boards are ideal for big long swells and tradewinds that start for hundreds of miles away. In Melbourne, we have a short, choppy wave on a very small, short pitched swell - almost a polar opposite from the Hawaiian boards.

Why wouldn't you optimise a board for the conditions you play in most?

Hate to doubt you Stu, but I think you're doing that on assumption rather than evidence.
Spent 30 years odd on the Bay sailing 14' Skiffs against 19' (?) Sharpies.
Downwind, I don't think they were ever thinking "I wish we were shorter"
Nosedived a 14 so hard I left my wetsuit boots in the footloops, landed forward of the boat and first thought was "why are my feet cold?"
Came up under spinnaker, stuck to the water, had to dive down 3 times to try and clear the sails before I came up.
Got on the 'plate and wondered "Where is Helmy?'
He had fallen off early in the exercise and was way behind.
We did not consider wave period, length, or height, but a longer boat would have been better.
There has been too little downwinding of 16' or 17' boards on the Bay to draw any conclusions, and the waves I have seen out there won't differentiate by a foot.
Fully support what you are doing, but no evidence 14', 16' or 17' is any different.
Apart from as far as I have got, the bigger, and longer the board is, the more stable it is.
Rocker will also be more determinate than length if you are trying to fit in waves.
But the ongoing discussion is vital!

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magillamelb said..
Here in Melbourne it seems 17' boards are just that bit too long. Just as you run down a wave, you're headbutting the one in front. Helmy's F16 is nearly perfect for Melbourne.

Big, long boards are ideal for big long swells and tradewinds that start for hundreds of miles away. In Melbourne, we have a short, choppy wave on a very small, short pitched swell - almost a polar opposite from the Hawaiian boards.

Why wouldn't you optimise a board for the conditions you play in most?

G'day megillameld sorry mate I'd have to disagree with your statement your most probably a very intelligent man but your quote sounds like a beginner novice with no idea on Downwind paddling (nothing wrong with that megaillamelb we all have to learn somehow time on the water will tell - your just no an Unlimited fan - all good.) "In Melbourne we have a short, choppy waves on a very small, short pitched swell"

Have a look at this video that supsurfers shot in the Gold Coast Broadwater last week NO OCEAN SWELLS here just short, choppy waves on a very small pitched swells watch the unlimited board fly in these conditions. I'll post you another video of a unlimited SUP in s###er conditions than this and you watch it Glide.

Have to agree with Downwinder. Unlimiteds are underrated in inshore dwers. The other day I did an 6km offshore dw on the F17 and went straight to a 10km lake run afterwards with another group.
Normally I would do the lake run with my Falcon 14 which is awesome for short interval dwing.
But with no time to change boards I thought wtf could be fun.
Little did I know how much fun it could be. The big girl carried constant speed better, and its sheer length meant it didn't tilt far enough to warrant dancing back as much as the 14.
The wind was 20kt+ and I am 100kg if that helps.
The wonderfull nose contoured well on the back of the preceding swell and pearling was intentional and easy to control without loss of momentum.
The glide was much better than the 14, and as each swell died the sprints to the swell in front were less frantic and sooo much smoother with a much higher succes rate.
There are times where you can feel the rudder come free of the water like ocean skis sometimes do but with positive rail control she behaved beautifully.
It's definitely opened my eyes to the unlimited's versatility.
In a nutshell I'd sell the Falcon before the Bullet.
Rather keep both for the time being tho.

I'm going to third Downwinder and CrazyBula. Longer is better... And especially in short period conditions. Easier to stick the nose onto the back of the wave you're catching up to... Which then sucks you up for another glide..and so on and so on.. Clickety clickety.. Railroading the bumps..
Wonder why you don't see 14' surf skis,or outrigger canoes.. It's pretty obvious that longer is best... Unlimiteds are win win.

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SUPerD said..
I'm going to third Downwinder and CrazyBula. Longer is better... And especially in short period conditions. Easier to stick the nose onto the back of the wave you're catching up to... Which then sucks you up for another glide..and so on and so on.. Clickety clickety.. Railroading the bumps..
Wonder why you don't see 14' surf skis,or outrigger canoes.. It's pretty obvious that longer is best... Unlimiteds are win win.

EXCELLENT Quote SUPerD

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crazybula said..
Have to agree with Downwinder. Unlimiteds are underrated in inshore dwers. The other day I did an 6km offshore dw on the F17 and went straight to a 10km lake run afterwards with another group.
Normally I would do the lake run with my Falcon 14 which is awesome for short interval dwing.
But with no time to change boards I thought wtf could be fun.
Little did I know how much fun it could be. The big girl carried constant speed better, and its sheer length meant it didn't tilt far enough to warrant dancing back as much as the 14.
The wind was 20kt+ and I am 100kg if that helps.
The wonderfull nose contoured well on the back of the preceding swell and pearling was intentional and easy to control without loss of momentum.
The glide was much better than the 14, and as each swell died the sprints to the swell in front were less frantic and sooo much smoother with a much higher succes rate.
There are times where you can feel the rudder come free of the water like ocean skis sometimes do but with positive rail control she behaved beautifully.
It's definitely opened my eyes to the unlimited's versatility.
In a nutshell I'd sell the Falcon before the Bullet.
Rather keep both for the time being tho.

Well Said crazybula

I'm not so sure that longer is that much better for our bay conditions because 14's work so well here..

Better than 14's do in the open ocean compared to unlimited boards where longer is most certanly better..

I find using my 17' Jav a little tricky at times in the close bumps but there are also times that it's noticably better..

I know what you mean about the naish 17 being a little tricky. As a former owner of one I relate to how they are sometimes prone to nose-steering more than the Bullets. This is more prevalent as they transition from full waterline running to planing and in winds below 20kts. I'm not talking about the nose tip, but rather the rails 3-4 feet down. They simply are not as forgiving as the Bullet and that comes down to the differences in the nose shape - however, they are still a great board and haul in the right conditions.

Also I've found the Bullet develops more lift in the forward part of the board at earlier speeds making trough navigation much easier.

This isn't a dig at the Naish by any stretch as I enjoyed having one as my first unlimited - but they are simply different beasts.

If anyone is contemplating an unlimited do not be put off by the Naish though as they are still a great board and do so many things well, and a cheap and rewarding way to get into unlimited dwing.

But I digress, getting back to the original topic - narrow tails are better for Dwing - period.

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Nozza said..
Hate to doubt you Stu, but I think you're doing that on assumption rather than evidence.
Spent 30 years odd on the Bay sailing 14' Skiffs against 19' (?) Sharpies.
Downwind, I don't think they were ever thinking "I wish we were shorter"
Nosedived a 14 so hard I left my wetsuit boots in the footloops, landed forward of the boat and first thought was "why are my feet cold?"
Came up under spinnaker, stuck to the water, had to dive down 3 times to try and clear the sails before I came up.
Got on the 'plate and wondered "Where is Helmy?'
He had fallen off early in the exercise and was way behind.
We did not consider wave period, length, or height, but a longer boat would have been better.
There has been too little downwinding of 16' or 17' boards on the Bay to draw any conclusions, and the waves I have seen out there won't differentiate by a foot.
Fully support what you are doing, but no evidence 14', 16' or 17' is any different.
Apart from as far as I have got, the bigger, and longer the board is, the more stable it is.
Rocker will also be more determinate than length if you are trying to fit in waves.
But the ongoing discussion is vital!

Nozza

Nice to hear Helmy left you to your own devices just before the **** hit the fan! I bet it was more than once too...

There is some evidence my theory is based on.

A couple of DJ's video's show people on 17'+ boards (of different brands) doing just what I've said. They get on a bump and almost straight away, they're headbutting the next one. DJ's video of PT on this Ace GT is a case in point. Check them out and see what you think?

I think DJ has echoed a similar view...

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Downwinder said..

magillamelb said..
Here in Melbourne it seems 17' boards are just that bit too long. Just as you run down a wave, you're headbutting the one in front. Helmy's F16 is nearly perfect for Melbourne.

Big, long boards are ideal for big long swells and tradewinds that start for hundreds of miles away. In Melbourne, we have a short, choppy wave on a very small, short pitched swell - almost a polar opposite from the Hawaiian boards.

Why wouldn't you optimise a board for the conditions you play in most?

G'day megillameld sorry mate I'd have to disagree with your statement your most probably a very intelligent man but your quote sounds like a beginner novice with no idea on Downwind paddling (nothing wrong with that megaillamelb we all have to learn somehow time on the water will tell - your just no an Unlimited fan - all good.) "In Melbourne we have a short, choppy waves on a very small, short pitched swell"

Have a look at this video that supsurfers shot in the Gold Coast Broadwater last week NO OCEAN SWELLS here just short, choppy waves on a very small pitched swells watch the unlimited board fly in these conditions. I'll post you another video of a unlimited SUP in s###er conditions than this and you watch it Glide.

I'm not sure how you think I'm not an unlimited fan. I'm actually planning to build a DW and flatwater unlimited. (16'8" & 19' respectively) Regrettably, I'm not the most experienced, but certainly in that short pitched chop the unlimited board worked really well, hence why I'm building a couple...

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magillamelb said..

Nozza said..

Nozza

Nice to hear Helmy left you to your own devices just before the **** hit the fan! I bet it was more than once too...

There is some evidence my theory is based on.

A couple of DJ's video's show people on 17'+ boards (of different brands) doing just what I've said. They get on a bump and almost straight away, they're headbutting the next one. DJ's video of PT on this Ace GT is a case in point. Check them out and see what you think?

I think DJ has echoed a similar view...

I noticed that in PT video of the Ace GT.
I have tried to delicately word something else and failed, so will leave it at that.

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magillamelb said...

Nozza said..
Hate to doubt you Stu, but I think you're doing that on assumption rather than evidence.
Spent 30 years odd on the Bay sailing 14' Skiffs against 19' (?) Sharpies.
Downwind, I don't think they were ever thinking "I wish we were shorter"
Nosedived a 14 so hard I left my wetsuit boots in the footloops, landed forward of the boat and first thought was "why are my feet cold?"
Came up under spinnaker, stuck to the water, had to dive down 3 times to try and clear the sails before I came up.
Got on the 'plate and wondered "Where is Helmy?'
He had fallen off early in the exercise and was way behind.
We did not consider wave period, length, or height, but a longer boat would have been better.
There has been too little downwinding of 16' or 17' boards on the Bay to draw any conclusions, and the waves I have seen out there won't differentiate by a foot.
Fully support what you are doing, but no evidence 14', 16' or 17' is any different.
Apart from as far as I have got, the bigger, and longer the board is, the more stable it is.
Rocker will also be more determinate than length if you are trying to fit in waves.
But the ongoing discussion is vital!

Nozza

Nice to hear Helmy left you to your own devices just before the **** hit the fan! I bet it was more than once too...

There is some evidence my theory is based on.

A couple of DJ's video's show people on 17'+ boards (of different brands) doing just what I've said. They get on a bump and almost straight away, they're headbutting the next one. DJ's video of PT on this Ace GT is a case in point. Check them out and see what you think?

I think DJ has echoed a similar view...

To avoid headbutting the bump in front and slowing down isn't it the idea to be getting that nose running up over it or to the side buy getting back enough on the board to lift, and the length and volume of the unlimited should be giving you enough speed to easily rider over it at speed and drop down onto the next bump in short bay stuff.
Also shouldn't be going straight down once picked up on the bump should be turning and aiming that nose/board on an angle that is going to keep you on that bump or group of bumps for longer aiming for the V in front.
I could be wrong but thats what i am doing on the 14 so the 17 should be the same theory and it works for me.