mareks360 forum posts in last 60 days

joe87879 said..
Great info thanks Marek.

With my + fuse, I am very close to the mast cutout if I maintain a 71mm space between the saddles. (Roughly 0mm between the mast cutout and the new saddle cutout)

Do I risk that either (1) the aluminium sides are strong enough at the mast cutout or (2) do I cheat and shrink the distance between the wings say from 125mm to 95mm (would give me about 30mm between the mast cutout and the new saddle cutout)

It looks like Marek has ~ 50mm between the mast cutout and the new saddle cutout.

Edit: AI says 30mm is the minimum I could go

Joe,
My thinking is very similar to yours. "The chain is as strong as the weakest link". The thickness of the fuse at this point is 35mm, width 25mm, making a saddle narrows fuse to about 22mm . Major forces are the upward fuse pressure on front of the mast but the torque from the riding dynamics in particular during cranking upwind (railing, hilling) can not be ignored.
BTW: This is also why I wanted the foil fit very snug in the fuse (like it is in the original port).
Also, the mast socket is at an angle therefore if you leave 30mm (on top), as you plan, it will be about 35mm space between foil port and start of foil mast cavity.
To me, there is no reason how this could create the weakest link.
Also, your plan is like my plan: If I expect wind to be consistent over 11mph (9.5kt), lulls not dropping below 7mph (6kt), I would remove 800 and put dummy plug.
My personal preference is to play with changing foil wings rather than a rig. Faster. Simpler.
Since I created "dragonfly (M1000+800)" back in February this year, I rode about 300miles on it with max board/GPS speed at 16.7mph (14.5kt) .
BTW2: You already have in the post my total weight (gear + me) ands sail size to evaluate loads I am creating.
So far the setup works exactly as expected. No interference between wings.
I am really happy with the setup therefore I am happy to share what can help others too.

Yesterday Session 7/13/26 (July 13th) on “dragonfly (SB M1000 +800) platypus” is a perfect example of what I stated earlier:
“5) If someone guarantees me wind speed between 7-11mph, I would be the fastest on SB mod mareks360 dragonfly”

Let’s examine some details:

Forecast:







Actual Wind for 7h 11min complete session duration: total 48.7 miles:
In red is a specific (best period) part for analysis 1h 40 min, 15 miles (for deeper dive):





Table of parts saved individually:









Best Wind Best Part (Board GPS Speed):












Conclusion:
With “dragonfly (SB M1000+800) platypus”, there is no way to sustain flight if “Lull” drops below 4mph (3.5kt) at total weight of 297LB = 135kg (more details shared in response to “Formula” User above).
Some flights in gusts possible as you can see from sub session average GPS board speed (and max speed).
When the “Lull” is at 4mph (3.5kt) and above, you can sustain continuous flights.

3 years ago I did an elaborate deep dive post:
“Ultralight wind (~5mph or ~4kt) windfoiling BAF for older "Heavy Dudes" 90kg+ and no pumping”
www.seabreeze.com.au/forums/Windsurfing/Foiling/Ultralight-wind--5mph-or--4kt--windfoiling-BAF-for-older--Heavy-Dudes--90kg--and-no-pumping?page=1

Now people ask me directly about my new “mareks360 dragonfly” config therefore It is better to share the Concept, Design and its actual Performance in my “platypus” configuration.
Why “platypus” ? You got to read the old post above.
Lets get back to where we left 3 years ago Graph:





Basic conclusion is that the bigger the foil, the earlier take off, BUT the narrowest range where the foil outperforms all the other.
Therefore we have to find different solution to reduce overall drag in wider range.
Science of Aerial drones come to help and rather than explaining complex equations, dominant vs contributing vs none-dominant factors: “picture tells the 1000 words”:





Source: “ Improvement of Micro UAV Performance using Tandem-Wing Design “
Figure7 The comparison of Drag force between the two models

Lets examine now new graph and conclusions:
1) Despite my mareks360 dragonfly config (SB M1000+800) at 1800cm2 comparable to Slingshot Quantum 100 at 1724cm2, the efficiency of twin config reduces the drag (both induced and parasitic) to the extent of faster slogging, earlier take off and faster fly when wind increases.
2) If someone guarantees me wind speed between 4-5mph, I would be the fastest on SS i99 + i84 biplane (see other post for details)
3) If someone guarantees me wind speed between 5-6mph, I would be the fastest on SS i84+i76 (my past tested config)
4) If someone guarantees me wind speed between 6-7mph, I would be the fastest on SS i99
5) If someone guarantees me wind speed between 7-11mph, I would be the fastest on SB mod mareks 360 dragonfly
6) If someone guarantees me wind above 11mph, I would be the fastest on the original SB Millenium 1000 – please note this is only up to 20 MPH wind analysis





Recommended by me Resources for your personal “deep dive and study”:
1. “ Improvement of Micro UAV Performance using Tandem-Wing Design “
2. “Twin-Wing Design Options Used for Unmanned Aerial Vehicles to Achieve High Altitudes at Low Speeds”
3. “Hydrofoil Design, Build Fly” by Ray Vellinga – Outstanding book to understand how hydrofoil works !
4. “What wing spacing is best for a tandem wing configuration?”
5. “Exploring the Different Wing Configurations Used in Airplanes”

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Here is Q & A:
From people asking directly:
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Please note that I am using 115++ in this case. There is more space between the wing and the mast to add 2nd foil.
I also have 115+ unmodified I use with SB Race 100 board single M1000 wing.

Questions:

Q: - What distance is the second wing from the first? How far back
A: Now we have to distinguish distance between the wings (which is still variable) vs distance from end of front saddle to beginning of second saddle.
Keep in mind that Starboard made wings that are not centric to the saddle therefore it will be different distance between wings (for interference sake) if I swap 800 to the front and M1000 to the back or if I use other wings I have e.g. FR1100 or 500
Distance between end of front saddle and beginning of second saddle is 71mm while distance from Trailing edge of M1000 to front edge of 800 is 127mm.

Q: - What stabilizer goes best w/dual wings?
A: Before adding second wing, I foiled this setup for 1000s of miles in M1000/115++/255(-2ver) +0.5 shim with Starboard Go 180 board. You can see my older post for pictures that I references from 3 years ago.
So I added just 800 wing and the setup is still balanced therefore I did not feel to change anything.

Q: - Any structural reinforcements when the second wing is installed?
A: Nothing, There is no need. SB 115 fuselages are solid alumunum

Q: - How did you machine the profile?
A: This was a “labor of love” with simple tools with “measure twice cut once” approach.
First I drilled the fuse horizontally with many holes. Fuse in a vise, hand drill [Upd: I meant electrical handheld drill]. Used reciprocal saw [Upd: I meant electrical] to cut out the aluminum out. Then used hand files to get to profile marked with permanent marker on the sides. Then I drilled the smaller holes and used threading tool.

I will share some Conventional and Unconventional Wisdom for gusty conditions.

Conditions:
The most challenging wind direction at my location is SW direction where wind gets really shifty and gusty because of topography (hills and high rise buildings).
It can drop to 0mph any moment and can gust to 25-30mph in a next (back and forth).
I still use one sail (usually around 11m) for gusts up to 25mph but I am heavy. 200LB (90kg) net, often over 220LB in full gear.

I have a tendency to dive really deep, I will first do the highlights then I can elaborate on any specific item in case there is an interest.
I can also provide some videos that support what I wrote below.

So let’s start:


Sail:

Highly Cambered:
My preference for gusty conditions is to use race sails (highly cambered) and stable in wide wind range. They luff does not collapse in heavy gust, additional “bear wrestling” avoided.

RAF (no cams):
Counterintuitive: For 10.8m Loft Oxygen sail, I use adjustable outhaul to minimum tension in heavy gusts and longer boom setting. Therefore if no gust then boom tension downwards (seat harness) keeps the leach close but when gust hits the upper sail twists, opens and depowers.


Board:
There are several effects that are your enemies in heavy gusts:
1. Wetted area = drag (no matter wide or narrow)
2. Narrow board = board sinks in the chop in lulls instead of staying on top (vs Formula boards, wide boards stay on top and plane the earliest)
3. Fin vs hydrofoil – adding well balanced for speed (slippery) race hydrofoil can enhance early planing while avoiding excessive lift and induced drag
4. Weight of the overall gear: more inertia = less immediate acceleration


The Technique:
Being heavy back footed, and using seat harness with generating MBP (mast base pressure) gives you opportunity to react to the gust and shift weight forward.
I had many “wise guys” who are heavy front footed who tried to convince me that it is a better way, but they like “face planting” or they have never been in conditions where you have 0mph one moment then next 20mph.

It took me 7 years of light wind windfoiling (including 46 years of windsurfing) to do pretty much impossible into possible.
I went from building biplane configurations (with 3600cm2 foils SS i84 +SS i76) to SB Millennium 1000 (1000cm2) for light winds. Using boards from Slingshot Flyer 280 to Starboard Race 100 (experimented with 7 different boards).
Please note I am currently at about 200LB - 90kg but I started windfoiling at 220LB or 100kg.
To answer your question:
I can take off, without pumping, with board speed between 4 and 5mph in wind of 8 mph. I am driving the MBP (mast base pressure) for the board to plane first to build speed then pop up to full foiling.
Gear:
Foil: My own innovation: Starboard 115++ fuse customized to 2 foils M1000 + 800 (SB race foils) in my "mareks360 dragon fly" - this concept comes from high efficiency aerial drones for high aspect double wings efficiency with appropriate wing spacing.





Board: I am using SB Go 180- 180 L, 100cm wide.- the board that planes earliest from all other 7 (wind-foil able) boards I have - without pumping.

Sail: I mostly use ~11m variety of race sails in winds from 5mph to 20mph. Still able to survive some gusts to 25mph for the same config.
In this case it is old KA-7 Phil McGain's Gaastra Nitro 4K Pro 11.0m sail.






Here is a session example where wind (even gust) never exceed 16mph (sensor is on the dock on the water) while average wind speed for my session is between 6 and 10 mph.
My average speed from Garmin Smart Watch is 8.2kt (9.4mph) max speed 14.3kt (16.5mph).
I did ~52 miles in ~5h30min.









Ultralight windfoiling was posted and discussed by me in 2023 posting (3 years ago) :
You will find more graphs for different foils I tested wind to board speed as well.

www.seabreeze.com.au/forums/Windsurfing/Foiling/Ultralight-wind--5mph-or--4kt--windfoiling-BAF-for-older--Heavy-Dudes--90kg--and-no-pumping