Hold comes from release = keeping the surface in - on- contected to the water
Not grabbing action
Not grabbing action
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Shortboard thruster rockers 1980 - early 90s.
- Thread starter casa_mugrienta
- Start date
Greg, There is a picture of someone riding your groveller model - is it called hovercraft? Rider is quite tall, board is quite short and he is racing across a small wave, I think there may be some silhouettes of seaweed in the face (not sure about that, my memory unlike your is not great). If you could find that pic from your archives that would be great. That picture just oozes SPEED.
A reason why your boards are fast is because you incorporate a full length hard tucked edge. This has a lifting effect similar in feeling to the shallow concave as the rail gets unweighted - water leaves the hull cleanly instead of wrapping when unweighted. I have built myself a full length tucked edge - I used a sludge of microballoons and epoxy to build up a lightweight resin dam and then sand it - I expect you are cringing at this technique, but I just wanted to achieve the edge in the easiest way with limited skills. I am not going to do this again because the board also was concaved and the result was too skatey - although very fast in an unweighting inside rail situation. I can imagine however that a flat board would complement the full length hard tucked edge nicely without being too skatey.
So if you think the concave restricts release (and your definition of release is a bit different to mine), what do you think deep channels do? Those ruts must be clawing at the water and having a far more restrictive release effect.
I have always said this, but there are a lot of principles we agree with. I also believe that keeping the (hull) surface in (buried) and connected with the water is what provides most of the hold. There was an old theory that we can now debunk about how the hold comes from the water wrapping the rail and providing suction - therefore the theory went rounded chunky rails provided more hold because there is more water wrap.
I have personally disproved this in a couple of ways. Firstly by standing up the front of my shortboard and keeping the hull fairly flat instead of banked deep and having the water wrap the inside rail - the board just slips out from the wave. I have also spoken to two skilled surfers who acquired themselves old school logs with 50-50 egg shaped rails. One is an excellent shortboarder, the other good HP longboarder. They both told me that their logs would slip out unexpectedly from them, and it was quite tricky to keep them holding in - the egg shaped rails encourage wrap because there is no tuck, yet despite this they have less hold not more.
The other way I have proved this is with my skimboard, I am not very good, but can sometimes build enough speed to run into deep water and bank it into a u-turn. The rails of my skimboard are very thin with hull edge taken right to the perimeter of the board - no tuck whatsoever - water does not want to wrap such a sharp corner. My skimboard has no fins. Yet despite this it grips perfectly well when banked provided I been able to submerge the inside rail. The hull is being pushed down from my weight and banked over it presses sideways and the "lift" force has a big sideways component - this is what gives it the hold.
For what its worth, the best shortboard from the 80s and 90s I ever had was heavy V from nose to tail. Still have it. Check out how much V this board has in front of the fins. Its a little different style of surfing than what you get out of todays boards. Much more top to bottom than down the line surfing. If you don't have a good rail game you'd probably struggle on a board like this.
This begs the question of how it may effect the amount of net cant the side fins end up with in relation to the center fin. Is anyone taking this into consideration on both Vee bottom and deeper concave bottom boards?For what its worth, the best shortboard from the 80s and 90s I ever had was heavy V from nose to tail. Still have it. Check out how much V this board has in front of the fins. Its a little different style of surfing than what you get out of todays boards. Much more top to bottom than down the line surfing. If you don't have a good rail game you'd probably struggle on a board like this.
I would have to take some measurements. I would say the fins are very upright in relation to the surface of the V of the board. The overall cant relative to if the bottom were flat would likely be about 9* if I had to guess. Toe in points directly at the nose.....that I know for sure.
Flat straight across creates 100 % effective planing of that width - you plane on top of it
Any rearward angle the rocker creates release upward off that plane to the rear
This is at about 45 degrees , acts like Vee without the drag
The very slight- 1/8" or less " Brewer Tri PLane created in the 70's amplified this effect
Any rearward angle the rocker creates release upward off that plane to the rear
This is at about 45 degrees , acts like Vee without the drag
The very slight- 1/8" or less " Brewer Tri PLane created in the 70's amplified this effect
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Yes, to get the most out of a V'd board, need to go top to bottom. I borrowed a McCoy nugget and it would go fast was in big top to bottom pumps on clean down the line waves. It was incredibly unresponsive to smaller rail to rail input which is the reason why I only consider the concave board. I know the best surfing is top to bottom, but I do a lot of surfing in junk where I need to quickly bank off the hidden corners and pockets to keep my speed up. All boards go top to bottom, but the V bottom encourages/forces it. edit--> McCoy nugget is very deep rolled V to deep panel V in the tail.
In between top to bottom the world's best are doing little wiggles to maximise the lifting effect of the concave.
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Yes, it is normally taken into consideration e.g. FCS II boxes come in 5 and 9 degree cant. 9 degree is the more popular one for HPSBs because it is designed to take into account concave in the tail tilting them inwards.
That's a great explanation on how you holistically balance flat with extra tail rocker. The old shaping style of putting increasing V in the tail to put more curve in the rail line means that there will be a line of low pressure on the downstream side of the ridge where the stringer forms the V. The line of low pressure is good for stability in heavy waves, but bad for speed.
I think most here know I use lower tail rockers compared to HPSB concave bottoms
They plane instantly and higher than a sunken surface = concave
They plane instantly and higher than a sunken surface = concave
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That's the pic I was talking about! That's the type of speed I was talking about - unweighting the inside rail down the line. I like to call that "easy speed".
See how the board sits high on the water as the inside rail releases water off the tucked full length edge. Hovercraft is an apt name. By reducing the rail wrap suction the effect is overall more lift - less form drag (not so much pushing water).
Water doesn't like to turn tight corners, so when it is directed along the flat bottom and meets the edge it leaves cleanly instead of wrapping when the rail is unweighted. Concave has a similar effect the water directed slightly downwards also has to turn a tighter corner to wrap, so when unweighted it too releases.