Does width on SUP surfing boards equal drag

IMO:
Over a certain point I think it would... but outline curve has a greater effect. A more parallel outline aids speed
The right rocker helps.

eg; Smik Hipster Twin. Quite a curvy wide shape, wide nose, flat-ish rocker, hip in the outline, twin fins. It is a really fast board...

As we all know everything is a compromise. Getting the right balance of compromises is the hard part which can make a good board great.

width adds drag, but:
width also increases the lift force while planing. (this lift does not comes from nowhere, thus it adds drag)

So, if a board is just around the lower range of planing speeds (i.e. surfing in slow waves), more width can make the difference between slogging in displacement mode (longboard glide) and zipping in planing mode (fish accelerations).

In a nutshell, narrow boards are generally faster, except when you are feeling the waves are so slow that you find your board tends to bog down. Then either using wider boards (for lifting it more out of the water) and/or shorter ones (for lowering the range of their planing speeds) can make you surf faster. This is why short small wave boards are generally wider.

Nice feed in Tardy...,the tease continues.

CheersTardy, hope you are healing well,we are all enjoying the ghostly journey,however personally,I don't think I will fit in the chosen numbers.I also had the same result from the placid,incredibly stable but could not surf it .

Nice hook up to Brenno fast tuna ,its seems longboard are your thing dude ,but yes the glide is totally awesome on longer boards I often take my 9'11 insane out at 29 1/2 ,it has factors I like but then the nose swing for me it just gets in the way for lip bashing surfing ,but it is my fastest board and awesome on huge waves ,so I'm going the opposite ,next GR board 8'7 x 31 x 133 ,I have just gained all this relaxed muscle lately ,so the new stick has some beef ,getting made as we speak ,in saying that the 12 search @ 30 wide is a little wave crazy fun board to ride ,you need to be able to walk up and down ,so took some getting use not being a longboard background I usually hang at da rear kick pad ,
9,4 sound good for you ,can't wait to see your plan .heres mine ,its gonna be a machine. from the SUNOVA factory ,going my block emblem again ,(please note mine ) no copying, ha ,ha , Sunova can do anything for you ,I really like Creeks Ghost look with the black in the grain looks so nice ,

Looks good Tardy. I was just checking out the SPX and the various sizes. I'd be interested to hear how it compares to the 8'8 SP25.

Hey mate,

Take a look at the OAM sup deckpad here : www.oamsurf.com.au/products/on-a-mission-blur-stand-up-paddle-board-grip-black

Not cheap, but hey, you're this deep into it already ;)

They make the pads for Infinity Sups...

Great job of making an awesome board even better. Your design looks awesome!

I will bite on your width question with a few different perspectives.
For SUP, the slowest board I have ever ridden was an 8'3" x 32" Naish. A friend offered to give me the board for free and after a few waves, I turned him down because the board was pathetically slow. When I was learning, I briefly owned an 8'8" X 32" Starboard. It was thin and light and turned kind of okay but if you dropped down off the lip with the board flat, the width in the front slowed the board to nearly a stop when it hit the transition at the bottom of the wave. The fastest board I have ridden was my Speeed at 29.5". Like you, I have settled at right around 31" as being my perfect width.

You mentioned 14s. We do some downwinding here on Maui when the winds are 27 to 30 mph. My wife and I used to have SIC 16' x 27.5" boards that were fast in a straight line downwind but we did not like the way they surfed the bumps so we ordered a couple of custom 14s; hers is 28.5" and mine is 29.5". My wider board is definitely slower in displacement mode but it planes up faster when catching a bump or a swell. Once planing downwind, neither board will maintain speed as well as the 16' x 27.5, but they catch bumps easier and are way more fun to surf because of the width and outline curve.

Lastly, I have three wavesailing boards that are 75 liters, 82 liters, and 92 liters that range from 7.25 to 7.5 feet and from 22" to 23" wide. My flat water board for pure speed is 8'5" x 21' @ 87 liters making it longer and narrower than any of the wave boards. It is way faster than the shorter and wider waveboards, planes just as quick, carries speed through the jibes, but is not going to crank any tight vertical turns on a wave.

Balancing length versus width is always an interesting topic.

Some great feed back guys and can tell its from personal experiences in riding different board ,Thank you .
I also felt the Naish x 32 's where slow John ,I put that down to the high rocker ,but very loose boards .
I am also thinking a constant speed in boards is also as important as just being fast in the pocket and in transitions ,
I remember my 8'7 flow at 120 was fast but as I approached the bottom hand turn area of the wave my weight would sink the board
to no return ,I had many times where i just kept going too deep into the water and either nose dived or sunk ,note I was 100-110 kgs suited up ,
also it would need extra pumping to stay moving or flowing on the wave
But once I went a bit wider it was easier to achieve my constant speed ,thus making it easier to surf ,
Maybe a more in-depth question would of been appropriate as to say which size wave ,and your weight ,and steepness of wave
our wave is a very vertical hard breaking wave ,after 1 year of riding the new 8,8 flow I could not ride the 8'7 anymore ,it was just to
difficult ,but did have fantastic speed at 30,25 wide ,but required more power in the wave ,so now it felt slow again ,I sold it not long after ,so maybe ,width + wave size + your weight is a equation to be considered rather than picking on width ,I am thinking the correct volume for your weight is also just as important ,which is why I have considered the GR boards .higher volume .
.does it create more speed ??? or is it just for catching waves in competitions,I am also guessing riding the wave till it is nothing will score extra points thus the extra Volume .anyway I am very keen to try the new SPX with a higher volume I would not normally ride .
The GR 8'8 wedge has 141 litres x 30.25 wide and is designed for small and bigger waves .

just when I thought I knew everything about boards I am still learning after 10 years ,

Tardy, your thoughts on the ratio of weight to rail thickness being a big component of speed made me think of an experience I had a couple of weeks ago. I realize that this is not a windsurfing forum but I think this experience is relevant to SUP rail thickness.
On that day. the waves were small, waist to shoulder high. The wind was light so I needed to take out my largest sail. Though it was a mismatch, I wanted to take out my smaller board for more maneuverability on the small waves. The combination didn't work because the extra weight of the larger sail was burying the rails too deep during the bottom turn and bogging down. I moved the large sail onto my larger board which has much thicker rails and the board carried great speed through the turns. Later when the wind got stronger, I needed to put on a smaller sail but decided to stay on the larger board. Again, the mismatch did not work because the lighter sail did not have enough weight to set the rail and I could not get any grip on the bottom turn. With the lighter sail, I needed to move to my smaller board with thinner rails. The width and volume of the boards definitely played the major role in getting planing and control with the different size sails and boards, but on the wave it was all about matching the rail thickness to the size and weight of the sails.

Great conversation. Here are some connections that might be relevant since you can relate to translating windsurfing board variables to SUP.
I have two Quatro windsurf boards that are both 92-liter dedicated light-wind wave boards for 12 to 18 mph winds with a 5.9 sail. The custom from about 10 years ago is 8'4" long and very narrow with very thin rails and tons of rocker. The newer one is about 7'6, 1.5 inches wider with very thick rails, much less rocker, and the rear footstrap is much further back right on the tail. The older board is a dog to get planing, instantly loses speed when jibing, and needs to be pumped to generate speed on the wave, but it has incredible control in bigger surf (10'- 20') which is what I ordered it for. The newer one planes instantly in the slightest breeze, carries speed through jibes and on average waves, and turns on a dime. However, it is scary as hell on waves much over 10 feet because it generates so much speed on the drops that it is hard to set the wide/thick rails in the bottom turn because the board is in the air half the time on the drop if there is any chop.
Even with much less rocker, the new board turns much tighter because the rear foot is right on the tail so there is no resistance behind the rear foot, kind of like infinite tail rocker. The old board with the rear foot further forward will not hook the turns nearly as tight but carves a secure high-speed arc on larger waves using its nose-to-tail rocker.
As you said, there are lots of variables contributing to speed; width, rail profile, and rocker all have pluses and minuses depending on the conditions.

Now a SUP analogy. Everyone knows that narrower boards are faster for racing and downwinding so those boards tend to range from 23.5" to 27.5". However, Robert Stehlik of Blue Planet Surf fame made a video titled "Wider boards can sometimes be faster." His example was on a downwinder on Oahu where the wind is lighter and the bumps smaller than on Maui. In that video on a day with mellower winds and smaller bumps, a 30" wide board was beating the 27.5" boards because it was easier to catch the smaller bumps. I designed my custom SIC downwind board for the South shore of Maui where the wind swells are much smaller and tighter than on the famous North shore. I wanted something that would plane up quicker to catch the smaller bumps and was not concerned about the top speed because I am not interested in racing. I went with 29.5" and it does just what I wanted. My previous 27.5" board had a higher top and speed but was harder to initially catch bumps because it was harder to get planing.

By the way, thanks for sending the nice south swell we had here this morning coming from your area.