Derek's first eFoil build — 65161/75200/Gong V2/14S9P DIY from Boise

CaptainDerek · April 12, 2026, 4:17am

Hey everyone,

Long-time lurker, first post. I’ve been reading through build threads here for weeks and finally pulled the trigger on my first eFoil build. Wanted to share my plans and get feedback before I start cutting foam. This community has been an incredible resource — the Danish V2 build, the French BOM build, the board construction tips thread, and dozens of others have shaped every decision below.

About Me & The Project

Rider: 190 lbs / 86 kg
Location: Boise, Idaho — riding at Lucky Peak Reservoir (freshwater)
Budget: ~$2,700 all-in
Experience: Zero foiling experience, decent with hand tools, have a Bambu Lab A1 Combo 3D printer
Other riders: My girlfriend and a couple friends will be riding too, so the safety system is designed with beginners in mind
No CNC, no vacuum bagging — hand tools only for the board build

Components

Propulsion:

Flipsky 65161 120KV (round, threaded shaft — chose threaded for community prop STL compatibility)
Flipsky 75200 Pro V2.0 ESC with built-in power button (aluminum PCB)
Flipsky VX3 Pro remote + wireless receiver module

Foil:

Gong Allvator V2 complete setup, pieced together from Bons Plans:
- Alu Mast V2 85cm
- Top Plate Alu V2
- Mast Fuselage Connector V2
- Pro Alu Fuselage V2 (Regular)
- Front Wing X-Over V2 XL (~1300cm²)
- Stab X-Over V2 48cm
- Complete Screw Kit Alu Foil V2

Battery:

14S9P using BAK N21700CG-50 cells (5000mAh, 15A continuous)
126 cells, 45Ah, ~2,331 Wh
P-group layout: 1×9 rows (9 cells side by side, single nickel strip top and bottom — trivial to weld)
14 P-groups stacked in series, zigzag serpentine pattern
Pack dimensions: ~200mm × 305mm × 90mm (8" × 12" × 3.5")
Connection: 0.2mm × 8mm pure nickel strip spot welded for parallel, nickel strip + 8AWG bus wire for series (redundant path for 80-100A takeoff demands)
JK BMS BD6A20S10P 100A with 0.6A active balance — charge only, bypass on discharge
100A ANL fuse between battery and ESC
XT90H main disconnect
58.8V 5A charger (~9 hour charge time)

Estimated current demands:

Cruising: 15-25A battery current
Takeoff: 50-70A (~10 seconds)
Full throttle: 80-100A
Per cell at takeoff: ~8-11A (well under 15A rating)

Board Design

Dimensions: 1524mm × 650mm × 120mm (60" × 25.5" × 4.7"), ~95 liters

Shape: Blunt rounded nose (R~200mm), nearly parallel sides, squared tail (R~100mm), soft rounded rails. Minimal rocker — just 10-15mm nose kick over the front 300mm, flat from there to tail. Slight deck crown 5-10mm.

Construction: 3-layer XPS foam (Kingspan 2" sheets from Lowe’s), all internal cuts done on flat sheets with hand tools before gluing layers together with Gorilla Glue. Outline cut from a cardboard half-template for symmetry, rails shaped with surform rasp + orbital sander.

Fiberglass: 4-5 layers of 6oz (280 g/m²) each side, wet layup by hand. Extra 2-3 layers on hatch flanges with thickened epoxy corner fillets. All internal cavity surfaces fiberglassed for waterproofing. TotalBoat 5:1 epoxy with slow hardener.

Finishing: Lime green (Rust-Oleum Painter’s Touch 2X Gloss Key Lime) with black/green diamond EVA deck pad covering the full deck.

Internal Layout (all dimensions from tail)

TAIL ←————————————————————————————————→ NOSE

0"    11"      19"       27"            43"         60"
|      |        |         |              |           |
| Tail | Mast   | Service | Battery/ESC  |   Nose    |
|      | Zone   | Cavity  | Cavity       |           |
|solid | plywood| 8" port | 16"x10"x3.7"| solid     |
|      | deck   | Cnlinko | birch ply    | foam      |
|      | to     | power   | hatch lid    |           |
|      | hull   | charger | EPDM seal    |           |
|      | solid  | button  | M6 bolts     |           |

Mast Hardpoint

This is the area I’ve thought about the most, based on the excellent advice in the “board construction tips and learning from failures” thread.

1/4" birch plywood recessed into bottom of Layer 1, flush with hull surface
~8" × 12" footprint, larger than Gong V2 top plate
M6 stainless steel flanged threaded inserts (E-Z LOK) epoxied into plywood from below
Foam remains solid above plywood — full deck-to-hull structural connection maintained (no cavity above mast zone)
During fiberglass layup: bolts threaded into inserts with wax on heads to prevent epoxy from filling threads
After cure: unscrew bolts, drill through thin fiberglass to expose clean threads

Wire Routing

Gong V2 mast is hollow — rubber plugs pop out for wire access
Drilling a wire pass-through hole in the Gong V2 top plate, aligned with a matching hole in the plywood hardpoint
3/4" split wire loom tubing embedded in foam channels from mast wire exit to service cavity — allows future cable removal/replacement without cutting the board open
Phase wires route: ESC → main cavity → loom → service cavity → Cnlinko LP-20 3-pin disconnect → loom → plywood wire hole → top plate → hollow mast → motor
Enough slack in the service cavity to fold the mast flat against the board for transport (Prius life) without disconnecting cables

Service Hatch (Daily Access — 8" Smartmarine Round Port)

Everything I need for a session is accessed through this single hatch:

Cnlinko LP-20 3-pin: motor phase wire quick disconnect
Cnlinko LP-20 2-pin: charging port
75200 Pro V2 power button
Phase wire slack loop
Water alarm sensor

Pre-ride: Twist open → click phase connector → press power → twist closed → stick magnet to deck → attach leash → ride

Post-ride: Twist open → power off → unplug phase connector → plug in charger → leave open for ventilation

Main Hatch (Rarely Opened — Bolted Plywood/Fiberglass Lid)

The hatch lid uses a rabbet/ledge system across the top two foam layers:

Layer 3 cutout: 18" × 12" (wider), cut only ~0.5" deep as a shallow rabbet
Layer 2 cutout: 16" × 10" (narrower), cut all the way through — creates 1" ledge all around
Lid: 1/4" birch plywood core wrapped in 2 layers fiberglass each side (~8-9mm total)
Lid drops into the Layer 3 rabbet and rests on the Layer 2 ledge, flush with the deck surface
EPDM D-section seal (Frost King) stuck to underside of lid, compresses against the fiberglassed ledge
E-Z LOK M6 brass knife inserts epoxied into fiberglass flange around cavity
M6×20mm stainless countersunk bolts flush with deck
Contains: battery pack (12"×8"), ESC (5.1"×2.7"), BMS, fuse, XT90, all main wiring
Only opened for maintenance or if water alarm triggers

Kill Switch

Reed switch (normally open, 1.8×10mm) embedded in deck foam near rear foot (~20" from tail), fiberglassed over (invisible)
Steel disc (~30-40mm) embedded above reed switch as magnet target, also fiberglassed over
Neodymium disc magnet (20×3mm) on ankle leash sticks to steel disc on deck surface
Fall off → magnet pulls away → reed switch opens → VX3 receiver loses 5V power → ESC signal timeout → motor stops
Chose this method over ADC2/hall effect approach based on the “cutting ESC power under load” thread — avoids VESC stuttering and cruise control restart issues

Water Alarm

XH-M131 module powered from main battery via BMS (always on, ~1-2mA draw — negligible)
Sensor probes mounted at lowest point of main cavity
No separate battery to go dead — always monitoring as long as pack has charge
Buzzes loud enough to hear through the sealed board

ESC Cooling

No water cooling, no aluminum base plate. The 75200 Pro V2 with aluminum PCB runs at ~25°C reported by other builders on this forum — barely above ambient. At 14S pulling 80-100A max (50% of the ESC’s rated capacity), the aluminum substrate handles heat dissipation on its own. ESC mounted with aluminum side facing down toward the hull for passive thermal transfer toward the water.

Propeller

Planning to 3D print V_S 2-blade props on my Bambu Lab A1 Combo:

PETG, 100% infill, 0.12mm layer height
140-155mm diameter, medium pitch, 12mm threaded bore
Post-processing: sand → epoxy coat → wet sand → second epoxy coat → wet sand
Balance by hanging on bolt through center bore
Printing 4-5 copies as spares

Motor Mount

Using the community-designed FS65161 motor mount for Gong V1/V2 masts from the forum. 3D printed PETG. Designed so motor wires don’t need to be removed from mast during assembly.

Budget Breakdown

Component	Cost
Battery Hookup (130 cells + spot welder)	$364
Flipsky (motor + ESC + remote)	$664
Gong V2 foil (7 parts + screws + tariff)	$613
Amazon (fiberglass, epoxy, deck pad, tools, hardware)	$549
AliExpress (BMS, charger, connectors, fuse, leash, electrical misc)	$206
Lowe’s + Home Depot (foam, plywood, paint, tools, workspace)	$340
Total	~$2,736

Expected Performance

Based on the efficiency thread and similar builds:

Comfortable cruising: 12-15 mph at 1,000-1,500W
Fast cruising: 15-19 mph at 2,500-3,500W
Full throttle: 22-25 mph
Estimated ride time: 75-90 minutes at cruising speed
Efficiency target: ~52 Wh/km (per the 95kg rider benchmark)

Parts are all ordered and on the way. Battery Hookup cells should arrive first, then I’ll start the pack build while waiting for everything else. Build updates to follow.

Thanks for all the knowledge this community has shared. Couldn’t have gotten this far without it.

— Derek, Boise ID

HOF · April 12, 2026, 11:49am

Amazing, looking forward to the build.

Kian · April 12, 2026, 1:13pm

I am not sure about this!

DutchFoiler · April 12, 2026, 1:28pm

Cool build. Just make sure you do your own due diligence, as it does read like “chat gpt”.
Also, skip the prop printing. Way too much work.
Just get a fliteboard prop, drill it out with the adapter here on the forum, and be over with it. Got me going around 50kmh with 15S.

S_Roger · April 12, 2026, 1:56pm

I am not sure these connectors will work. The 65161 phase wires are 8awg and so are the esc phase wires. Those connectors say 12-14awg. Also they state 20A, I think a bit low for EFoil. I have my phase wires crimped to the esc wires, that of course is not for disconnecting.

You could try looking at trolling motor connectors, similar design but larger. Or go for Surlok connectors, those are common for efoils. If you buy the genuine Amphenol they are waterproof, but expensive

Kian · April 12, 2026, 2:21pm

The — in his text are the telltale signs.
I do not even know how to get them with my keyboard.

Ps. Do you like the new mast my dad build for you?
He told me that there is a small surprise in it

Foilguy · April 12, 2026, 4:15pm

@Kian

Perhaps you are kidding about not knowing but I think it is ALT 196

Foilguy · April 12, 2026, 4:34pm

@CaptainDerek

A few comments since you asked.

I’m not sure your nose rocker is large enough. I use a Fliteboard (full size 100l) and the rocker (kicker) starts about 400mm from nose and rises about 140mm. Makes no difference when foiling but is a factor in takeoff, landing and touchdowns. Too little and you stuff the nose and the board stops!
The L size of V2 XOver is 1300 not the XL
I agree with @Kian that assuming the VESC doesn’t need cooling might be a mistake that’s hard to rectify.
Printing props and getting good results is harder than you seem to think. Flite prop is an inexpensive, proven, and long lasting option that is worth considering.

CaptainDerek · April 12, 2026, 8:47pm

@HOF thanks man, excited to get started. Will post updates as parts arrive.

@Kian – fair point on the cooling. I’ll be monitoring temps through VESC Bluetooth on my early rides and will report back with real numbers. One builder reported 25C max on the remote with a 75200/65161 setup here: VESC Cutting Flipsky 75200 – though I know that wasn’t a sustained high-current thermal test. Another builder in the “to watercool or not” thread said passive cooling is fine on a 5ft+ board with volume, especially if the ESC is mounted on aluminum in contact with the mast baseplate: To watercool ESC or not? . Your setup with the PCB mounted directly to the aluminum base plate with thermal bridge to the mast is smarter than what I’m doing though. I might look into something similar instead of just sitting the ESC in a foam cavity.

@DutchFoiler – I did use claude to draft up the post and responses, I’m not a very good writer. However the design and component choices have been my failures / successes lol. Really interested in the Fliteboard prop suggestion. 50kmh on 15S is wild. Do you have a link to the adapter thread for fitting it to the 65161 threaded shaft? And what’s your full setup?

@S_Roger – you were absolutely right and I appreciate you catching that. Already cancelled the Cnlinko LP-20 order. 20A rated connectors on 80-100A phase wires is a no-go. Going with XT150 connectors packed with dielectric grease instead. They’re rated 150A peak, handle 8AWG, and the connection lives inside a sealed service cavity behind an O-ring hatch so they never see direct water. Builders on here and Endless Sphere have run XT150s on efoils in salt water for years with just dielectric grease, so freshwater at Lucky Peak should be fine. For charging I’m just using an XT60 inside the same cavity – open hatch, plug in, done.

Cells should arrive this week. Battery build first, then foam. Updates coming.

DutchFoiler · April 12, 2026, 9:41pm

You can find the drill bit here: Flite Prop Drill Guide by Caleb | Download free STL model | Printables.com

Maybe interesting to go with the QS8 plug? It will also do the precharging for you, I don’t think the XT150 does. You’ll need a big iron to solder those btw.

Oh and my setup consists of a fliteboard, 65161 120KV, 75200 Vesc, v2/v3 gong mast, gong curve V2 M, topped out at 50 with 15S. Now I’ve got a 16S with high power cells, so curious how much faster I will go.

CaptainDerek · April 14, 2026, 2:43am

Hey everyone,

Big update on my build. After spending a long night studying Gustav’s Danish V2 build thread and photos in detail, I’ve redesigned the board layout pretty significantly. The core components haven’t changed, but the board internals, hatch design, waterproofing strategy, and BMS have all been reworked. Wanted to share the changes and reasoning in case it helps other first-time builders thinking through the same decisions.

TL;DR: Switched from a two-cavity layout (service hatch + bolted battery hatch) to a single-cavity Gustav-style layout. Everything sits on one shared 1/2" birch plywood base plate that doubles as the mast hardpoint. Battery and ESC each live in their own sealed waterproof PETG enclosures inside the cavity. Single hatch with 4 compression cam latches for quick access. All electrical connections use XT150 connectors inside IP68 waterproof inline junction boxes. BMS upgraded from 100A to 150A with switch function for anti-spark power on/off.

What Changed and Why

Board Layout: Two Cavities → One

The original plan had the mast zone as a solid foam I-beam (deck-to-hull structural connection), with the battery cavity pushed forward ~21" ahead of the mast. A separate 6" Smartmarine screw hatch gave daily access to phase wire connectors and the power button.

Problems I identified before cutting any foam:

CG offset: The ~10.5 kg battery sitting 21" forward of the mast created a significant nose-heavy moment. Manageable but not ideal for a first-time builder/rider.
Structural complexity: Two cavities + foam wall between them + conduit channels through the wall = more cuts, more failure points, more fiberglassing.
Daily access was clunky: Even with the service hatch, I’d be reaching through a 6" hole to plug in connectors and press buttons.

Gustav’s V2 showed a cleaner approach — one big cavity spanning the mast area, with everything mounted on a shared birch plywood base plate. The plywood IS the mast hardpoint AND the electronics floor. Battery and VESC sit on the same plate, directly over or near the mast.

My adaptation of his layout:

Cavity: 26" × 11" (660 × 280mm), full through-cut on all 3 foam layers (same width), spanning from 11" to 37" from tail. Layer 3 has a shallow 1/2" recess in the top face around the opening for the hatch lid to sit flush.
Plywood base plate: 1/2" (12mm) birch, 28" × 13" — extends 1" beyond the cavity opening on all sides, overlapping under the foam of Layer 1 for mechanical bonding. Epoxied into a shallow recess, flush with hull surface.
Mast bolts: Rear section of the same plywood plate. M6 hex bolts from below, nyloc nuts tightened from inside the cavity. No more threaded inserts — simpler, stronger, replaceable.
Battery CG: Now ~22" from tail vs 43" before. Only ~7" forward of the mast center instead of 21".

Hatch: Bolts → Cam Latches

The old design used 14-16 M6 countersunk bolts with E-Z LOK threaded inserts in a fiberglassed ledge. Bombproof seal but terrible for daily access — I’d never want to open it.

New design: 4× QWORK 316 SS flush-mount compression cam latches, one near each corner. Quarter-turn to open, quarter-turn to close. Lid lifts completely off (no hinges). Each cam has adjustable compression range (1-1/4" to 2-3/4").

The lid is 1/2" birch plywood fiberglassed with 3-4 layers 6oz on both faces, plus wooden braces on the underside — matching Gustav’s V2 spec. His V1 hatch leaked because it flexed; the V2 with the stiffer lid hasn’t leaked. Layer 3 has a shallow 1/2" recess carved into the top face around the cavity opening so the lid sits flush with the deck. TORRAMI 1/8" solid neoprene sheet gasket glued to the lid underside, compressed against the recess floor when the cams pull the lid down.

3D-printed PETG strike plates epoxied to the fiberglassed cavity walls give the cam hooks something solid to grab onto. The cams extend down from the lid through the recess and hook the strike plates on the wall, pulling the lid down and compressing the gasket.

Waterproofing: Trust the Hatch → Seal Everything

The old design relied on the hatch seal as the primary water barrier, with the ESC and battery exposed inside the cavity. After reading the thread about the Flipsky 75200 not being waterproof, and thinking through nosedive scenarios where the board goes fully underwater with force, I decided the hatch can’t be the only line of defense.

New strategy — everything is individually waterproofed:

Battery Enclosure: Gustav-style 3D-printed PETG body with aluminum plates top and bottom, M4 threaded inserts, sealed with thickened epoxy interior coating + silicone between plastic and aluminum. Contains the battery pack, JK BMS, 150A ANL inline fuse, balance wires, and NTC temp sensor. Single APIELE 12mm waterproof push button mounted through the enclosure wall, wired to the BMS switch input for power on/off (anti-spark soft start). Two XT150 female connectors on short 8AWG pigtails exit through PG11 cable glands.

ESC Enclosure: Same construction as the battery box — PETG body with 2mm aluminum plates top and bottom, M4 threaded inserts, sealed with thickened epoxy + silicone. Sized for the 75200 Pro V2 with VX3 receiver inside. ESC aluminum PCB face down against the bottom aluminum plate for heat transfer. Cable glands for all wire pass-throughs (2× power in, 3× phase out, reed switch, water alarm). Community reports 25°C max on the 75200 in eFoil use, so heat isn’t a concern even in a sealed box. All 4 aluminum plates (2 per box) cut from a single 12" × 12" sheet of 2mm 6061 aluminum (~$12).

The hatch with cam latches + neoprene gasket keeps out most water, but even if some gets in during a bad wipeout, nothing dies. The water alarm tells me about it, and I dry the cavity after the session.

Connectors: Bare Plugs → IP68 Waterproof Housings

This was a fun one to figure out. XT150 connectors are only rated IP40 — basically zero water protection. Trolling motor connectors are IP67 but expensive and only 50-100A. Cnlinko aviation connectors were my original plan but at $34+ per set they were overkill.

Solution: CESFONJER IP68 M25 inline junction boxes ($5.49 for a 2-pack). These are waterproof barrel housings with cable gland seals on both ends. The XT150 pair mates inside the sealed barrel. Unscrew the barrel to disconnect, screw together for an IP68 sealed connection.

5 housings total: 2 for battery power (positive + negative), 3 for phase wires. All connections are fully waterproof when assembled and fully disconnectable for transport. Foil separates completely from the board — zero wires tethering.

Packed with dielectric grease on the XT150 contacts for extra protection. At $27.50 for all 5 housings (bought 10 total for spares), this is way cheaper than any purpose-built marine connector solution.

BMS: 100A → 150A, Bypass → Inline with Switch

The original plan was a JK BMS BD6A20S10P 100A, discharge bypassed, with the ESC’s built-in power button for on/off.

Problems:

100A overcurrent protection could trip during hard takeoffs (DutchFoiler on this forum confirmed he hits 100A regularly)
Bypassing discharge means no BMS protection for overcurrent, overtemp, or cell undervoltage during riding
The ESC power button can’t handle anti-spark for the main battery connection

Upgraded to JK BMS BD6A20S15P 150A ($62 on AliExpress). Running it inline for both charge and discharge. The BMS switch wire connects to a waterproof push button on the battery enclosure wall. Power sequence:

Plug XT150 connections (BMS is off, no current flowing, no spark)
Press button → BMS soft-starts → ESC powers up
Ride
Press button → BMS off → safe to unplug (no current)

This eliminates the need for a separate anti-spark switch entirely. The BMS handles it.

Also upgraded the fuse from 100A to 150A ANL (BOJACK inline holder, $10.59 on Amazon) to match the BMS rating and avoid nuisance trips during takeoff.

Mast Mounting: Threaded Inserts → Through-Bolts

Eliminated all E-Z LOK threaded inserts. The mast now uses simple M6 hex bolts inserted from below through the hull fiberglass + plywood, with nyloc nuts tightened from inside the cavity. If a thread strips, replace a $0.10 nut instead of trying to extract and re-epoxy a $2 threaded insert from cured fiberglass.

Bolt holes are drilled after all fiberglassing is complete — using the Gong V2 top plate as a template held against the hull. No pre-drilling, no protecting threads during layup. Drill through fiberglass + plywood in one shot from below.

Gong V2 top plate sealed to hull with 3M 4200 marine sealant between the plate and fiberglass surface.

Updated Component List Changes

Removed	Added
Smartmarine 6" inspection hatch	4× QWORK 316 SS cam latches ($56)
E-Z LOK brass inserts (hatch)	CESFONJER IP68 junction boxes ×10 ($50)
E-Z LOK stainless inserts (mast)	BOJACK 150A ANL inline fuse ($11)
Frost King EPDM D-section seal	JK BMS BD6A20S15P 150A ($62)
Alex Tech wire loom tubing	LISTENJIALE 50pc cable glands ($14)
M6 countersunk bolts 50-pack	M6 hex bolts + nyloc nuts (Home Depot, ~$8)
XT90H connectors (charger)	2mm 6061 aluminum sheet 12"×12" (~$12)
1/4" birch plywood	1/2" birch plywood (~$25)

Net cost change: roughly break-even after returns and cancellations. The redesign actually saved about $20.

Budget is sitting at ~$2,880 all-in.

Updated Board Dimensions

Changed from 1524×650×120mm to 1600×600×120mm to match Gustav’s proven dimensions exactly. Slightly longer, slightly narrower. ~100L volume.

What Stayed the Same

Flipsky 65161 120KV + 75200 Pro V2 + VX3 Pro
Gong V2 complete foil setup
14S9P BAK N21700CG-50 battery (45Ah, 2.3 kWh)
3-layer XPS foam construction, hand-shaped
4 layers 6oz fiberglass each side, one layer at a time, no vacuum bag
TotalBoat 5:1 epoxy with slow hardener
Reed switch kill system on ankle leash
jkoljo motor mount for Gong V2 (Thingiverse)
3D printed PETG propellers (MakerWorld STL)
Lime green paint + black/green diamond EVA pad

Current Status

All parts ordered. Most Amazon items delivered or arriving this week. Gong V2 foil arriving Wednesday (faster than expected — UPS Express from France, though tariffs came in at $102 instead of the $89 I estimated). Battery cells + spot welder shipped via FedEx, should arrive Thu/Fri. AliExpress small parts trickling in over the next 2 weeks. BMS 150A is the last piece — estimated late April.

Planning to start cutting foam this week once I grab XPS from Lowe’s. Will post build photos as I go.

Thanks to Gustav especially — your V2 build thread is basically the blueprint for this board. And to DutchFoiler, Foilguy, sat_be, and HOF whose comments in that thread directly influenced the BMS and fuse upgrades.

— Derek, Boise ID

CaptainDerek · April 14, 2026, 7:46am

Hey everyone,

Quick update — spent the afternoon getting the board modeled in Onshape before I start cutting foam this week. Wanted to share the progress and get any feedback before I commit to cutting.

DutchFoiler · April 14, 2026, 9:04am

Hmm, looks extremely bulk, almost like a brick. Try to make it less thick, and maybe you can make the sides more rounded? Get some inspo from the boards alreay out there.

sat_be · April 14, 2026, 9:28am

Sharp edge at the bottom in the back is better for easy takeoff. Round corners cause trouble towards the end of the rails.
I made them round first and corrected it, see here, scroll down:

Works great.

Kian · April 14, 2026, 10:50am

maybe this will give you some inspiration.
It’s for the “flite” mast system box

CaptainDerek · April 15, 2026, 5:17am

Big update — took all of your feedback and reworked the board shape in Onshape. Here’s what changed:

Board shape: Ditched the pill-capsule nose for a swept/tapered profile with 400mm fillets. Much less brick, much more eFoil. Tail stays blunter than the nose. Thanks @DutchFoiler for the reality check and @Kian for the Flite board inspo images — that wedge profile with the angled deck edge and flat sharp bottom is exactly what I was missing.

Rails: 20mm chamfer on the bottom edges (sharp, no rounding), 30mm fillet on the top edges. @sat_be your thread was exactly what I needed — sharp bottom-to-side transition for clean water release, rounded top for comfort. No more uniform rounding all the way around.

Nose bevel: Bottom surface now kicks up starting at 1000mm from tail (600mm from nose) instead of 320mm — way more gradual. Should help with takeoff and touchdowns. @Foilguy yours starts 400mm from nose with 140mm rise — mine is more gradual but starts much earlier, so the total rise should be comparable.

Thickness: Can’t go thinner overall — the battery enclosure just barely fits between the two 1/2" plywood plates with the cavity height I have. But I’m thinking I could build up the nose slightly (extra half inch on top that curves down to the 6" section where the enclosure sits) and/or do chamfers on the sides and tail to slim the visual profile, similar to @Kian’s Flite reference.

Other changes from this session:

Solid tail increased to 300mm (was ~280mm) — more structural foam behind cavity
Mast mount centered at 400mm from tail on a 90×165mm bolt pattern (confirmed standard via the mast/plate database thread)
Battery and ESC enclosure walls upgraded from 4mm to 8mm PETG — cheap insurance for rigidity on 350mm+ spans
Volume confirmed at ~77L via Onshape mass properties

Gong V2 foil arriving tomorrow. Cells should be here Thu/Fri. Will measure the actual top plate and verify bolt spacing before drilling anything.

Thanks again everyone — night and day difference from the first Onshape screenshot.

— Derek

sat_be · April 15, 2026, 6:37am

Looks good. One more thing, the Volume in the tip does not help a lot, if you cut the tip and make it flat, it is much easier to place the board on wing and tip, it will not flip to one side.

S_Roger · April 15, 2026, 11:20am

Looking good @CaptainDerek. Since you’re in the USA, definitely check out SendCutSend for the aluminum plates you’re planning to esc and battery enclosures. I’m always happy when I find something I can order from them (instead of waiting for shipping from China).

For the esc box, you will want to use some thermal paste and work out some way to mechanically fasten the esc down against the alu plate. Glue is also an option but might make replacing the esc harder

CaptainDerek · April 18, 2026, 12:21am

Sharing my enclosure plan before committing to print. Feedback welcome.

Constraints: board cavity 660×280×115mm (+4 mm due to lid compression ), 14S9P BAK cells (~211×339×70mm), JK BD6A20S15P BMS, Flipsky 75200 ESC, Bambu A1 printer.

Architecture: PETG walls + 4mm aluminum top and bottom plates, bonded with 3M 4200 on bottom plate, top plate gets Permatex Ultra Blac .

Walls: 6mm PETG, 104mm tall. Printed as 4 L-shaped corners (A1 bed can’t fit a monolithic box). Seams at wall midpoints with self-mating finger joints.

Shoes / Flanges: 4mm inward × 5mm tall projections at top and bottom of walls. Creates a 10mm sealing surface without eating interior vertical height. Pack can extend full 104mm interior since pack is narrower.

Sealing:

4200 at all permanent joints (wall seams, aluminum-to-shoe bonds)
Permatex Ultra Black as FIPG between top aluminum lid and top shoe (razor-removable for service)

Lid closure: 6× stainless 90° corner toggle latches instead of ~30 perimeter bolts. Inspired by Eduard’s build from Germany. Side-mounted latch body fits in the ~18mm clearance between enclosure and cavity wall. Strike plates protrude ~2mm above the lid, which fits in available vertical space.

No dedicated charge port: charging goes through the same XT150 lines that feed the ESC. Disconnect ESC XT150s post-ride, plug in charger. Fewer penetrations, forces BMS off during connector mating (anti-spark workflow).

ESC enclosure: same architecture, smaller (~176×126×71mm). Aluminum plates provide thermal mass for passive cooling — ESC mounts face-down on bottom plate with thermal paste.

Anything obviously broken?

Latches I plan to use

Everything just barely fits, but I do have some margin to mess around with

The reason I didn’t want bolts is because I didn’t want to to have to make so many holes in the alu top plate and get them directly over the heat set inserts I would make in the plastic walls.