Here is the latest build:
Results: 8' 8" x 19" x 6" @ 128.6 liters just 10 lbs 11 oz or 4.9 kg. HL factor = 8.3 lbs / 100 liters.
If your board weighs more than this you have to ask - Why?
- Because I wanted it to be beautiful
- Because it was affordable
- I am planning for 10,000 dings
- Because I want the workout
- Because I want it to last 10 years
- Because I plan to use a foil drive
- There is No F-ing way I am going to build a board
- Other . . . . ?
This ended up among the lightest design structure in the world for any foil board as measured by pounds per 100 liters.
When Elon Musk built the first commercial rocket company in history he observed:
"If you're not adding things back in at least 10% of the time, you're clearly not deleting enough. . . the bias will be to add things 'in case', "but you can make 'in case' arguments for so many things."
Design was as follows:
- XPS Core closed cell waterproof - Density 1.45 lbs / cubic foot
- Center of Buoyancy measured with Naked Blank
- Estimated CG ended up 1.5" behind Center of Buoyancy aka balance point with tracks
- 10" Box centered 9.3" behind estimated CG (Note CG did not move after lamination)
- Box centered 10.8" behind Center of Buoyancy
- Reinforced with 11 Vertical Carbon Arrow shafts deck to deck
- 2 ?" x 8.9 oz Full length Unidirectional Carbon Stringer Top and Bottom
- 3 x 5.8 oz Carbon Deck - Triaxial layup 30 / 60 / 90 degree bias
- 1 layer 3.7 oz S-Glass Bottom
- 1 layer 2.2 oz Kevlar nose and tail -
- 1 x 1.5" x 3.7 oz S-Glass Strip on Front Rails for paddle protection
First Principles: This is the concept that you break everything down to the basic laws of physics and think for yourself. When I built my first board I wanted to know how light it could be.
I saw a post here on Seabreeze about a guy with a downwind Kalama board that he claimed weighed 6 lbs. I went berserk trying to figure out how that was possible aka use EPS foam, single layer 4 oz glass, light deck . . . I pinged the guy and then he said "Oh no that board was more like 10 lbs." But I had calculated how to make a super light board.
On a liter per liter basis production boards come out 30% to 50% heavier than my 'garage built' board. The weight of a board is the last thing ever discussed IF it is even fair to ask. Its as if there is some political correctness and its unfair to ask.
After 4 builds here is what I have concluded:
- Gold Standard is 10 lbs per 100 liters (4.5 kg / HL)
- Platinum Standard is 9 lbs per 100 liters (4.1 kg / HL)
- Ethereal Standard is 8 lbs per 100 liters (3.6 kg / HL)
Heavier than Gold standard means that builders are adding unnecessary weight because of
1) Cost
2) Good Looks
3) Lack of Build Experience
4) Time to build (cost again)
5) Ding resistance for garages, cars, trucks and rocks
6) Durability ? (to last 30 years)
One builder (off the record) said "I have to make them heavy because customers are kooks." Not very nice but . . . . . ask more from your builder.
Having held some of your creations I am super impressed - and I think your perspective mirrors that of the Lotus Elise designers .... "Simplify, then add lightness."To achieve this level of board though, it does seem like you have to adjust in a couple areas ... careful to not puncture the skin with an elbow, or paddle strike - you have to know exactly where you will stand with that pad austerity, and you might have to skip the "everyone's boards in the back of the uhaul" shuttle situation.That being said, would love for a craft like this for the 'redpoint attempts' as we call them in sport climbing, where you put away the workhorse 11mm rope, and pull out the 9mm for that extra edge. Nice work. 
I love the boards you are building and pushing the envelope!
That said, I think you need to at least acknowledge that a durable board has serious benefit for some people and the way they use their equipment.
After a week of daily downwinding with a crew in Hawaii, I learned a few things that might be of interest. My board was piled into pickup truck bed, roof racks, inside minivan with 4 other boards floor to ceiliing, on the side of a jetski, and awkwardly on and off of a small boat. It would have been impossible to be constantly babying my board and still have fun. I was incredibly glad to have my 12lb PVC sandwich construction @ 20% heavier but 10x more durable.
Select to expand quotejondrums said..
I love the boards you are building and pushing the envelope!
That said, I think you need to at least acknowledge that a durable board has serious benefit for some people and the way they use their equipment.
After a week of daily downwinding with a crew in Hawaii, I learned a few things that might be of interest. My board was piled into pickup truck bed, roof racks, inside minivan with 4 other boards floor to ceiliing, on the side of a jetski, and awkwardly on and off of a small boat. It would have been impossible to be constantly babying my board and still have fun. I was incredibly glad to have my 12lb PVC sandwich construction @ 20% heavier but 10x more durable.
After coming from a lightweight construction that has let me down, my new board was only going to be full PVC wrapped. More than happy for the slight weight penalty but have the confidence that it is durable and therefore last.
As a backyard builder I enjoy the discussion on board building. I would like to attempt something like the orange crush but the XPS here is pink Home Depot stuff that is rarely available over 2" thick. I once thought of gluing several 2" strips together after chambering them to save some weight. Not sure if any weight savings would overcome the added weight of the glue. My last DW board 7'7" X. 19" eps was 6.2kg. However it has gained a bit due to some dings from the occasional paddle strikes/ remounts. I'm not nearly technical enough to breakdown the glassing as beasho does but I'm enjoying the ride. Keep up the innovative ideas. Some of us are taking notes.??
Well done and great video , I know you were saving weight on the deck grip but I think a one or two piece grip is deserved on this build
The single greatest benefit in weight reduction was the XPS foam. Because it is waterproof it needs NO lamination, no skin structure, no gloss coat.
Jeff Clark built the first XPS board that I saw. He SUP foiled and winged the board for 2 years. It wasn't necessarily light. BUT he had areas that had no lamination at all. He just painted over the exposed foam.
After 2 years the board was still intact. There were impacts to the bare foam and some places the foam had flecked away or where he had laminated the fiber had ripped away and been repaired. I realized that XPS was 100% waterproof over time and pretty durable but it could be dinged easily with a finger nail.
So treat the XPS board like a foamie and give it a light 'glass' lamination layer to prevent the foam from flecking away. Reinforce the 'cassette' area where you stand provide compressive structure for the boxes but keep it light in the ends.
Anything over 1 ounce, or 30 grams, was considered potentially unnecessary.
People complain about XPS delaminating but NO ONE leaves their fiber lamination porous. Everyone thinks they need a waterproof lamination layer. With XPS the pinholes are your friends. IF there is ever any de-gassing from the foam (and this is totally debatable, may be false . . . ) the lamination layer will never delaminate because there is no way for the pressure to build up. No need to gloss coat, no need for multiple lamination layers just vacuum bag a single layer of fiber and you're done.
With regards to footpads I mapped out where the dents were on my prior foil boards. The impacts were 100% consistent on multiple SUP foil boards. The greatest impacts were 1) from knees when getting on to the board 2) heels from standing position and 3) from heels in foiling position. The knees were actually the greatest point loads compared to heels which are pretty soft in comparison. I built a paper template and reinforcement and padding were isolated to the most impacted areas. No need for additional1/2 lbs or more from more padding.
I reorganized my Structural components and added the following commentary. The board could be lightened another 3/4 lbs using a Tuttle box and diluting the resin with Micro balloons.
Note: Total lamination weight was 22 oz. On a traditional board this would be somewhere between 4 to 8 lbs (+2 kg - 3.5 kg) because there are typically 2 layers with added gloss coat and painted resin.
Impressive!
For the pads, the lightest ones are hexatraction, but if you want some cushion feel and better grip, the lightest I have found are the FCS T3, and also the Firewire bloom, a tiny bit heavier but with grip better than anything I tried.
I remember a French shaper (Barland) had designed his own lightweight inserts, footstraps and footmasts for his sailboards as he was sick to see the amount of effort (and cost) involved to shed a pound on a board, for them to have riders bolt heavy foostraps and mastfoots on them, negating all the gains.
I really like the RSPro cork hex pads. super light, just a little cushion, and lots of grip. Pretty expensive though.
I tried purchasing cork in a few thicknesses and applying it with 3M adhesive, but it didn't hold up. Still looking for a low cost cork deck option, but for now RSPro wins for me on weight and overall performance.
