Ultralight Board II – SUP Foil Bumblebee

[Beasho]

My desire was to replace one or both of my 6’ x 30” x 115 liter Jeff Clark board and my 7’ 4” x 31” x 125 liter L41.  And to make one of the lightest SUP foil boards in the world.

And this is the Bumblebee 6’ 9” x 26” x 5” x 115 liters @ 11 lbs (5.0 kg). 

The construction was from 1.5 lbs/cu. foot XPS waterproof foam.  2 x 2” Layers from Home Depot.  The top layer was 1.8 lbs/cu. foot 1” thick.
The ‘Cassette’ standing area was reinforced with 2 layers of 5.8 oz carbon in a T-orientation 38” long and 24” wide by the base.  The top of the Cassette, the dance floor, is 3 layers of 5.8 oz carbon oriented in a 30-, 60- and 90-degree bias to add significant stiffness to the deck patch.

The nose and tail, ~ 18” each end, were covered in 2.2 oz Kevlar.  The objective was to keep the board as light as possible in the ends.  The Kevlar on XPS is very puncture resistant.

The side walls were 44” x 7” of 3.7 oz S-Glass and I added 48” x 2” @ 3.7oz S-Glass rail guards for paddle protection.  The top rails were also overlapped by ~1.5” with 2 layers of the Kevlar.  One layer from the bottom and one layer from the top. 

The final build came out to 11 lbs with pads and Strap making for an HL (Hectoliter) Factor of 9.6 lbs / 100 Liter. 

HL Factor = 9.6

   

[Beasho]

Layup of the Tri-Axial deck top patch.

[Beasho]

This is the second ultralight board that I have built. 

I can now say from experience that when you map out the build for the board you should be able to estimate and then achieve within a few percentage points the lamination weight from both fiber and resin. 

I originally wanted this board to be just 10 lbs.  But my first build would have benefitted from a slightly more robust deck area.  The solution here was to use 3 nearly full deck coverings that were in a Tri-Axial bias.  This was an idea procured from here on the Zone and STRETCH where he discussed the stiffness benefits of Bi-Axial layups.  And if Bi was Good Tri should be better.

There was no final gloss coat on this board.  I did paint over the pink rails with Yellow spray paint for some more aesthetic appeal.  The lack of gloss coat means that the board breathes through the multiple pinholes mostly in the Kevlar layers.  This has become a feature more than a flaw and the board will sweat if left in the sun. 

What better way to stay cool 

[Beasho]

Transcends the Barracuda

[Hdip]

The board will sweat? Meaning it's taking in water and then spitting it back out when it heats up?

[Beasho]

The board will sweat? Meaning it's taking in water and then spitting it back out when it heats up?

I can't tell how much emotion there is in these phrases.  But Yes!  It will take in water and then breathe it out like a living organism. 

No hard candy shell.  No additional weight. 

It is incredibly hard to make a board waterproof with one layer of fiber and resin.  Pinholes abound.  Builders have traditionally added 2 - 6 lbs of weight to fill pinholes and give a gloss finish to the board. 

I ask: "Do you want pretty, or do you want high performance?" 

The sweating doesn't happen everywhere.  Typically at the boundary between the XPS layers on the forward rocker.  A few drips in, a few drips out. 

[Hdip]

Ah OK. No emotion. Just wanted to make sure I was understanding what you were saying. I've taken to not repairing a few cracks on my wing board for the same reason. I tape it up when I ride. Then take the tape off and let it drain between sessions.

[jondrums]

never seen anyone laminate a board in khakis and a white button down.  very nice work!
I love that it doesn't look like much finish work of coating/sanding, etc. 

[Califoilia]

never seen anyone laminate a board in khakis and a white button down.  very nice work!
I love that it doesn't look like much finish work of coating/sanding, etc.

Hahaha... and sandals!  That's exactly the first thing that caught my attention, and I immediately thought, "That's one confident, and experienced laminator right there."

I'm happy when I don't epoxy my shoes to the floor when I'm just doing ding repair. I'd probably wind up being an epoxy covered statue by the end of a full on lamination session.

[SUPeter]

Quick question. Why Kevlar? It's a hydrophilic cloth meaning the cloth itself will absorb water. It is also has a higher density than Innegra. Innegra is hydrophobic as well as being lower in density. I cant be sure, but you could possibly shave a few ounces off with different materials as well as avoid possible water intrusion into the fibers.  It's only a guess of course, but id be curious to find out.

[Beasho]

Quick question. Why Kevlar? It's a hydrophilic cloth meaning the cloth itself will absorb water. It is also has a higher density than Innegra. Innegra is hydrophobic as well as being lower in density. I cant be sure, but you could possibly shave a few ounces off with different materials as well as avoid possible water intrusion into the fibers.  It's only a guess of course, but id be curious to find out.

The primary objective was to be "light in the ends."  Similar to America's Cup boats that were illegally fast because they had reduced swing weight back in the 1980's. 

The secondary objective was to be ding proof.  On my first board I used 1.4 ounce/Yard fiberglass.  The lightweight glass was intended to keep the XPS from flaking off over time.  However it does ding, or puncture, with sharper impact.  Even my big toe.  The Kevlar, on test samples, proved to be very ding proof against acute impact and was only 2.2 ounce/Yard.  Semi affordable @ $32 per yard from Fiberglass supply.  I would use Innegra if available, or affordable (??). 

The hydrophilic/hydrophobic didn't necessarily apply because I am not making my XPS boards waterproof.  To do that takes too much time, material, weight and quality control.  Ironically I have found that the moisture, if any in the fiber, serves as a natural evaporative coolant to keep the XPS from baking in the sun.  Although I have kept the boards out of direct sunlight when not in use. 

Between the 2 boards I have > 120 sessions combined and they are both holding up with no random XPS delamination that people seemed wary of. 

Now when I look at a board with full Carbon layers tip to tail I just see unnecessary dead weight.  The nose and tails of SUP foil boards serve no purpose but for flotation on takeoff.  They only need to be strong enough to not to randomly snap off.  The America's Cup'ers were pushing the limits of this idea 37 years ago, and I remember some boats did break.  We will only know we've gone too light, too far when things start to break off.   

IMO most production boards are way too heavy focusing on aesthetics and given the amount of box failures NOT investing in Track strength.  I went the other way and Invested heavily on deck structure and in the track support with carbon rods and XPS infrastructure but still less than a Full Divinycell high density stringer design.  I Divested of strength in the ends, waterproofing and showroom finish.  This board ended up 2 to 5 lbs lighter than comparable 115 liter boards. 

In a world where people are talking about 1% improvements in foil efficiency its crazy to me that board weight, meaning advantages of 15% to 50% are largely ignored.

https://www.latimes.com/archives/la-xpm-1986-12-23-sp-122-story.html

"The fiberglass boat was found not illegally light in the ends, unfairly enhancing its speed, and was not in violation of the rule prohibiting a more beneficial weight distribution than an aluminium yacht."

[Beasho]

It floats like a Butterfly . . . .

The biggest day of the summer!  A Sunday, so it was SUPER crowded, slightly overhead on sets.  I would just sit wide, out paddle the long boarders and stay wide of the mayhem.

Ultralight is high performance.  Axis 1201 with 300P tail and 75 cm High Modulus mast.  This was the 65th Session on this board.   

[Admin]

Looks fantastic!  Great drone footage and an amazing day as well.

[Dwight (DW)]

……. out paddle the long boarders ……

That’s all I want from my board. I don’t need to flat water pop up.

When I return from the Gorge, it will be my next board project.

I’m going to do 1 lb foam ends and 1.5 lb foam middle.

[surfcowboy]

That’s all I want from my board..

Same here. I want to slip into nothing bumps outside on high tide when there's no wind and no surfers. I'm starting to borrow and try boards and find a design. Dwight, expect some DM's. I am thinking that we don't need a 12" wide slipper of a board to do this.