Maybe its a simple answer, I don’t know
What would be the difference’s in how the board rides between belly/disp. hull entry vs. say a single to double concave
Interesting timing. My longboard has a nose concave, and this morning in strong offshores i had trouble getting into the waves, i could feel the lift, lifting me up and out of the wave. And every time i turned up toward the lip, i couldn't get back down again haha. Very windy though, and i was desperate. I'd be very keen to try a longboard with belly in the nose. I dont really like the concave, though im new to longboards so i might just need to get used to it. Never surfed a board with belly. You should get some interesting replies, i'm keen to know myself.
convex shapes feel like you are in the wave. kinda "boaty" like feeling. rolls onto rail and feels smooth. concave produces lift and feels like you are skimming ontop of the wave surface. thats my take. you should understand that bottom contours go hand in hand with outline and rail and stringer rocker, don't just slap them on a design to achive your desired feel
The spoon and faucet experiment can explain alot about these two contours. As for applying this to surfboards, astevens nails it. Hold a spoon by the end of the handle loosely between your thumb and index finger. Run a faucet at a mild rate. Slowly bring the spoon in contact with the stream. The convex approach will show the spoon to be pulled into the stream. The convex approach will show the spoon pushing away from the stream. I love thinking about this in relation to surfboards and their contours. Now try to scrape the spoon against some butter with the two different sides. The convex side will yield less butter than the concave side. Now, a board with belly when on rail will push less water than a board with concave on rail for the same amount of area under water. Water that is pushed pushes back. That is drive. When the board is flat on the water surface this can create lift/planing. Also, with a convex bottom or belly, think of a ball and socket with the belly being the ball. Think of this versus a flat surface and the socket. The ball will rock back and forth far more readily. So belly or convex can be tipped more easily rail to rail. This idea can also be used to think about rocker in relation wave size, shape and turning radii. Have fun.
I’ll have stab at this…
i rode a ’ performance ’ style displacement single of a mates in perfect right hand points waist/shoulder high, i think it was around 6’2
neil purchase jnr shape
the ‘feeling’ from jumping from a single to double ( my shape 5’8) to his board is** like **riding a bar of soap, quite fast and ‘free’
i get why these guys have them in their quiver , good/top surfers who are bored with the predictability of concave and thrusters etc
on another note: - my second shape i rounded out the first 12" of the bottom from the nose and had full round rails( belly style up front) into a deep single and hard edge
the feeling was a little numb up front when wanting to pump for speed , kind of no feedback from the rails up front but gee it would glide thru the most critical sections with ease , as in finsihing turns and floaters
have since made a few more similiar template , mucked around with thickness /foil/ tail block /fin layout and recently made one with hard bottom edge over pretty much the entire length of board - the hard edge is responsive and drivey and super cool in the barrel
I’ve made the “same” board 4 times. 2 with flat into spiral vee, 2 with concave into spiral vee. If it’s windy/bumpy, then the flat bottoms are the go because they don’t bounce in chop the way the concaves do. If it’s smooth then the concave boards are the go because they have faster acceleration. I think top end is about the same (but the flats may have the edge). The flat bottoms are better tube riders where the concaves need more controlling - they have to be pointed downhill more because they tend to get pulled up the face.The flats paddle/drop in easier - everything seems a split later on the concaves.
The way rolled bottoms were described to me was, “Consider a log and how it wallows.” I’ve had some vee bottomed boards (through the middle) and they just never seemed to get up and go, but you could ride them with 1’ cross chop and they were unfazed.
Concave is just double belly.
[quote="$1"]
I'll have stab at this...
i rode a ' performance ' style displacement single of a mates in perfect right hand points waist/shoulder high, i think it was around 6'2
neil purchase jnr shape
the 'feeling' from jumping from a single to double ( my shape 5'8) to his board is like riding a bar of soap, quite fast and 'free'
i get why these guys have them in their quiver , good/top surfers who are bored with the predictability of concave and thrusters etc
on another note: - my second shape i rounded out the first 12" of the bottom from the nose and had full round rails( belly style up front) into a deep single and hard edge
the feeling was a little numb up front when wanting to pump for speed , kind of no feedback from the rails up front but gee it would glide thru the most critical sections with ease , as in finsihing turns and floaters
have since made a few more similiar template , mucked around with thickness /foil/ tail block /fin layout and recently made one with hard bottom edge over pretty much the entire length of board - the hard edge is responsive and drivey and super cool in the barrel
[/quote]
What sort of shape was it? I have a 6'6'' egg shape, which is almost ready to have the rails shaped ( when i get my new shed/bay this week ) and i think it would go well with a bit of belly up the front. From your description i would really like the way belly'd boards surf.
Nice username ;)
If the waves you surf have size, power and down the line speed, then I think you would be pleasantly suprised by a belly bottomed short board - at least that's been my experience. As mentioned above though they don't have much "get up and go".
They seem to help smooth out your surfing and also feel good in strong offshore or choppy conditions as they tend to "sit down and run" in the water nicely.
**What sort of shape was it? **
- **( **It was a 5'8" x 19 1/2 x 2 1/2 ish , wide nose into wideish diamond tail **, **thruster** )**
- **(** the purcho i rode was a full displacement hull throughout - s deck , truly a different feel to anything ive stood on** ) **
Nice username 
- **(** cheers , i enjoy a homebrew on tap maybe we can swap notes ...**) **
**Surfing for me is mostly two turns and a wipeout**
- **( **i know this is your sig , but if you want to try some softness/ dish up front be prepared for two turns and a floater over closeout section**! :)**
i have some scrappy/crappy footage -have posted b4- of riding the board before i sold it , probably should have kept it but when the waves were good she rode a little high in the water for me , was number 2 and can't keep em all ! heres the link
Went pretty well for such small waves, looks like you had no drama's surfing it!. Pretty sure i'll give it a go on the egg.
Got 3 kegs, and a temp controlled fermenting fridge as well as the keg fridge!. Got a bitter ready to gas up, and a porter that'll end up around 7.5% going now. I'll bottle that one though, it'll need a few months conditioning haha.