Slippery bottom shape for 14'

[SUPflorida]

With all the different bottom designs floating around out there..from flat to single to double, to triple concaves, the Starboard tunnels, V bottoms, convex bottoms and all the varieties which combine these...what bottom shape have you personally found to be both stable and slippery in a 26" X 14' race type board.

The board that made you say out loud....Wow! This thing feels like a hot knife through butter. That goes well in chop upwind, wind on the beam, downwind. What did you attributes do you feel made it paddle so well?

Parameters:
1) Not a "Rat on Acid" pace that the top 2% perform at getting their board to practically plane...
2) Relativly flat water (Intacoastal) with chop, and East Coast of Florida (not Hawaiian) open ocean swells.
3) In the neighborhood of 26" wide.
4) Paddles well into the wind (realitively speaking)

Looking for specifics, not general statements like "nice rockerline"...how much rocker? Was it near flat for 75% of the board with 1" nose kick and 4" of tail kick? If so where was the break? Have sharp rails, soft rails what was the radius?  Etc.

I developed some very effective rocker lines for windsurf boards in the past, tried most of the options available, even phasers, but SUP is a completely different animal.

My last 14 build, while it works well, didn't give me as great a boost in speed over  my 12'-6" as I anticipated. Maybe my expectations were too high. I am a bit faster over all, but I don 't have the ability to dig in and really get the 14 moving in a sprint like my 12-6". My 12-6 really rewards the  effort and takes off. The bottom shape is along the same shape single concave to V on both boards.

I was anticipating noticeably less resistance from a board 1-1/2' longer, 3-1/4"narrower with a much finer entry. The way the nose parts the water is glorious, yet there is a feeling of drag to me that shouldn't be. The board is under finned (7" Fins Unlimited longboard classic shape) and I am sure a slightly larger/better foiled fin would help...how much I'm not certain. I have a new foam core fin under construction. The design is halfway in-between a VMG 37 and VMG TT.

This is more for fitness than anything... but I'm getting board looking at the same 9 miles down and 9 miles back...over and over again...want to cover more ground in the same amount of time...and the less resistance I'm fighting against, the better.

Things  on the forefront to change...
   More tail rocker (1-1/2"-2") in the last 42" (marginal at the moment on the 14') to get better tail release so I can move back on the board and still have a good clean minimum wake. Take 1" of nose rocker out of the first 18" so I can engage the wave piercing nose sooner, and from father back on the board.
   Fill out the hips in the out line slightly.
   Pull in the square tail width 1"-1-1/2".
   Take 1"-1-1/4" thickness/volume out of the board throughout. Way more volume than I need at 150-160 lbs.  Should help in weathercocking in wind on the beam.
   A little more rail tuck but still keep a hard edge for clean release. Lowering the center of gravity should help compensate for increasing tuck in rails (effectively compensate for loss of stability due to reduced bottom width).
    If I stay with single concave, deeper concaves closer to the nose to introduce more  air under the bottom when standing forward (going up wind), as it transitions from V/double concave the first 2 feet to single concave.
   I am more inclined to go with a double concave from nose to tail to help with straight tracking and reduce strokes per side (single concave seems to work against this).
   

If it were not for the enhanced tracking aspect of the double concave, I would be tempted to go with a simple flat bottom with a slight V in the tail...it sure worked great for windsurfing. Less is sometimes more.
After trying a dozen or more bottom configurations with my windsurf boards, the fastest ones inevitably ended up having dead flat bottoms with slight V in the tail.

Please share your experiences. What was The magic board for you? What made it so? Always looking to take it to the next level. Always more to learn. The more detail the better. Thanks to all that participate....

[Dwight (DW)]

After trying a dozen or more bottom configurations with my windsurf boards, the fastest ones inevitably ended up having dead flat bottoms with slight V in the tail.

Yep. You got it.

[PonoBill]

It's horses for courses. Dead flat bottom will give you the minimum form drag for the profile of the board you build. But it won't track very well and you might waste energy and effort keeping it on line and switching the paddle excessively. You'll also probably wind up with a lot of fin.

Any shape that directs the water a bit will track better, that's why concave bottoms are attractive, and tunnel hulls with chines can almost do away with a fin. But they're draggy. You also don't want water rolling up over the rails.

That said I haven't found a magic hull, but I've found some really slow ones.

[Pierre]

definitely, partly rounded bottoms. sorry for translation,look here:
http://paddlespot.net/download/les_carenes_de_SUP_race.pdf
 but also some pics here: http://www.forumdesup.com/t11154p30-pierrotboards-4-et-5#115117
andin that facebook page:
https://m.facebook.com/Hi.fun.hydroworks/?ref=bookmarks
the board shaped by Dave for Jean_Marie here
https://m.facebook.com/photo.php?fbid=10202428602252046&id=1103446562&set=t.701692111&source=42
best glide performance on flat and light DW donditions.

[SUPflorida]

Pierre ... Is that available in English?

[TN_SUP]

No shape details, but I've owned/paddled double concave (original JL Blade), single concave ( SB Sprint), and convex (SIC X-14 ProLite) and prefer convex based on these off the shelf examples.

[blueplanetsurf]

I agree, for flatwater a rounded bottom is the fastest as long as you can handle the roll. 
At planing speeds, a flat bottom with V in the tail works great, but on flatwater you will be at sub-planing speeds and a rounded bottom with rounded rails is the most slippery in my experience.

http://blueplanetsurf.com/blogs/news/48809349-the-fastest-race-sup-displacement-vs-planing-hulls-board-weights

[Pierre]

Pierre ... Is that available in English?

Sorry, not yet, I work on it at times...but still need to translate 100 page, I will prepare an english short version

[Pierre]

I agree, for flatwater a rounded bottom is the fastest as long as you can handle the roll. 
At planing speeds, a flat bottom with V in the tail works great, but on flatwater you will be at sub-planing speeds and a rounded bottom with rounded rails is the most slippery in my experience.

http://blueplanetsurf.com/blogs/news/48809349-the-fastest-race-sup-displacement-vs-planing-hulls-board-weights

....sure, because a planing hull is useless on a UL in flat or light DW condition as we never reach those speeds, and anyway works perfect in semi_planing conditions where it slowly accelerates but does not "stick" on water, means keeps better inertia.,however, I succeded fantastic glides including boat wake riding on mines. drive is just a bit special.

[PaddleSpot]

The board that made you say out loud....Wow! This thing feels like a hot knife through butter. That goes well in chop upwind, wind on the beam, downwind. What did you attributes do you feel made it paddle so well?

Hi guys

We all know that surfskis (rounded bottoms) a really fast, so SUPs with partly rounded bottoms should be the answer, if you find the good compromise between speed and roll. This compromise depends a lot on the paddler's height, weight, and of course skill. Pierre is really good at finding this compromise.

I already built three 14' boards, based on Pierre's designs.

The 1st one (and my home made board), 14' x 29", august 2014, was just a draft. Too wide, quickly built, too heavy, but really impressive. Maybe not the fastest board ever, but definitely slippery and effortless at speeds around 7 km/h (4.5 mph)



(here on the left, compared with a 2012 Naish Glide 12'6)

And really stable

[PaddleSpot]

February 2015 : The 2nd one, 14' x 26". Flatwater version of #1. Really fast, but a terrible roller, my favorite on lakes and rivers but I won't go out to sea with this one.







#1 and #2 (above)



More than 60 km (39 miles) in 8:32, I was not really tired, I could have paddled a few hours more.


Testing #1 and #2, debriefing with Pierre

[PaddleSpot]

#3, just lauched. The qualities of #2, with just the little more stability I needed

[peterwSUPr]

If you have minimal tail rocker on the first 14 then I think that is your major thing to change.  On my first 14 I was very careful to figure out volume and displacement so that the tail would be releasing exactly at the surface for my weight.  But that was all based on standing still and just floating.  In reality, with the dynamic lift from the water, the board pitches up and sinks the tail in a bit more.  I added more tail rocker in board #2 so the tail sits out a bit when stopped, and it feels faster.  It's tough to know what rocker you need, because the volume below the water depends on the rocker curvature, as well as how wide your board is throughout, and not just the maximum width. 

I think rocker is going to be much more important than changing from a flat bottom to a subtle concave type shape.  Also, while rounded bottom is theoretically faster, the balance thing is a draw-back, and can slow you or require more overall width.  I think there are mostly-flat and rounded bottom boards out there that are both fast.  Are there any fast flatwater type boards with minimal tail rocker?  I doubt it, so that has to be the big improvement, I would think.

Peter

[Dwight (DW)]

I haven't done 14 footers in at least 5 years, so I'm not up to date, but here are the few bits I learned shaping them.

- The narrowest board was the fastest. I kept adding tail width to allow me to stand on narrower boards. My last board was darn near parallel in template and my fastest board.
- I tested progressive rocker versus constant curve. Progressive paddled faster, but felt speed limited compared to constant curve. I was building boards for down winding, so mine did plane up. For something that will never plane up, I'd go progressive curve.
- Even though everyone knows displacement is the fastest paddling hull, I never considered it due to stability issues. Flat was as close to displacement as I wanted to go.
- Deep fins are slowest, so I'd follow Larry Allison's development path and go short multi-fin. Larry is doing a mid ship fin. It might be what a flat bottom needs to fly straight.

[Luc Benac]

Flat was as close to displacement as I wanted to go.
- Deep fins are slowest, so I'd follow Larry Allison's development path and go short multi-fin. Larry is doing a mid ship fin. It might be what a flat bottom needs to fly straight.

Good info. I am planning on modifying a board to add multi-fins.

Cheers,

Luc