SKIF · Weight and storage
Weight, power, water and storage
Only what is decided so far is weighed against the 6,000 lb towing limit: the carrier, the body, its shielding, the windows and door, the furniture and the appliances. The battery, tanks, wiring and storage are not counted until they are chosen; what is left under the limit is their budget. Nothing has been weighed on a scale: these are design estimates.
Where the 6,000 lb goes
What is decided so far
- Carrier, rails and legs ≈1,490 lb
- Frame, skin, floor, door and windows ≈1,770 lb
- Metal hull and shielding ≈760 lb
- Furniture, appliances and heat pump ≈920 lb
- Left for what is not decided yet ≈1,060 lb
- Only decided items count. The carrier trailer, the body's structure and skin, the metal hull and shielding, the windows and door, the furniture, the appliances and the heat pump: about 5,550 lb ± 110 as drawn.
- In the lighter build, the hull wall is 0.3 mm, the tiles' backing 0.05 mm and the iron 0.1 mm, the south-cap gores are closed in hull, the cabin panels are silk, the lath is cedar strip, the floor is metal-faced balsa and the leg wells are thin metal tubes. That is about 4,940 lb. That leaves about 1,060 lb for everything not yet decided.
- Not yet decided, so not counted: Spare wheel and tire; battery and its size; inverter/charger, wiring and distribution; roof solar; water tanks, water heater, pump and pipe; overhead bins, lockers and other storage; monitoring electronics; extra lifting receivers; food, clothing, tools and loose gear.
Every decided item, as drawn and in the lighter build
| Item | As drawn, lb | Proposed, lb |
|---|---|---|
| Carrier and supports | ||
| Carrier trailerAluma 7814TA-EL-R-RTD, 14 ft tandem aluminum deck, 7,000 lb GVWR: 1,125 lb listed empty | 1,125 | same |
| Main wood rails and leg-station framesTwo rails of paired 2×8s, 153 in long, 123 lb bare, plus the frames that carry them to the legs and ends, and bolts. The floor frames are in the floor line | 180–210 | same |
| Four electric legs, wells and feetRieco-Titan 56212 kit: 23 lb per leg listed, 92 lb for four. Added by the design: four sealed 13 × 13 × 56 in plywood wells the legs retract into, 12 in feet, brackets and transport locksProposed: Wells as 0.3 mm electroformed nickel-iron tubes sized to the leg, widening to 13 in only at the bottom for the foot | 180–220 | 150–185 |
| Frame and skin | ||
| Seven 2×4 ribs404 in perimeter each at 1.17 lb/ft | 260–290 | same |
| End-cap gore frames24 curved studs and two 42 in rings | 100–150 | same |
| Gussets, bronze bolts and fixings84 rib corners plus the cap joints | 130–170 | same |
| Curved lathAbout 690 ft² of skin at 0.25–0.35 lb/ft²Proposed: Western red cedar strips, as in a strip-built canoe, at about 23 lb/ft³ | 175–240 | 125–180 |
| Crescent spacers and wool fillAngled faces of every rib | 70–100 | same |
| Canvas covering with rosin and linseedAbout 690 ft² at 0.15–0.22 lb/ft² | 105–150 | same |
| Wool insulation3½ in batts over about 610 ft² | 145–215 | same |
| Cabin lining panelsUpholstered ply panels, about 560 ft² at 0.35–0.5 lb/ft²Proposed: Silvered-silk panels on light frames, as in the shell stack, at about 0.2–0.3 lb/ft² | 195–280 | 110–160 |
| Metal shielding and hull | ||
| Hull wall, nickel-iron0.5 mm over about 51 m²: the 64 m² skin less 13 m² of window openings, at 8.25–8.7 g/cm³Proposed: 0.3 mm, the handling minimum for a sealed, slightly pressurized hull, now also over the closed south-cap gores | 465–495 | 300–320 |
| Copper and tin outer face25 µm copper, 5 µm tin: the Faraday enclosureProposed: Over the closed south-cap gores too | 28–35 | 30–37 |
| Outer tiles, copper over nickel-phosphorus0.10 mm Ni-P backing with tile fixingsProposed: 0.05 mm Ni-P backing | 130–160 | 90–115 |
| Wool felt and cork under the hull1.2 mm felt over ⅛ in corkProposed: Over the closed south-cap gores too | 90–120 | 95–128 |
| Hull seams, hardpoints, opening frames, ground strapRiveted laps | 50–90 | same |
| Soft-iron cabin layer0.2 mm plates over about 45 m² of cabin-side surfaceProposed: 0.1 mm plates | 150–165 | 80–90 |
| Door gasket, honeycomb vents, filtered penetrations | 20–40 | same |
| Window mesh and its bonding framesMetal mesh over about 140 ft² of windows, bonded to the hull at every edgeProposed: South-cap gores closed | 20–35 | 15–25 |
| Floor, doors and windows | ||
| Floor deck, floor frames and lift-out panels¾ in fir plywood over about 90 ft², a plywood frame at every ribProposed: ¾ in panels of 0.25 mm electroformed nickel-iron faces on end-grain balsa, about 1.5–1.7 lb/ft², on the same frames | 220–280 | 190–240 |
| GlazingAbout 140 ft² of double-glazed acrylic: 24 gore and 10 side windowsProposed: South-cap gores closed in metal hull: about 98 ft². They sit behind the washer, toilet and shower | 195–230 | 135–160 |
| Window frames and sealsAbout 290 ft of frameProposed: About 200 ft | 100–150 | 70–105 |
| Main door and fold-down steps32 in door with an EMI gasket | 70–110 | same |
| Interior | ||
| Couchbed with full-size mattressFrame, pull-out and foam mattress | 120–170 | same |
| Executive office chair26 in five-star base | 45–65 | same |
| Desk, workbench and their mounts | 40–60 | same |
| Bath partition, folding door, shower pan and fittings | 80–125 | same |
| TV and mounts32 in | 12–20 | same |
| Appliances | ||
| Fotile sink-dishwasher and tap49.8 lb listed (one retailer lists 75 lb) | 55–85 | same |
| Folding cooktop/ovenCombo oven in its folding box | 50–70 | same |
| Fridge and freezer boxes with compressor kitBD35F class compressor, 4.3 kg | 55–80 | same |
| Splendide washer/dryer on its 22 in base148 lb listed | 163–175 | same |
| VacuFlush toilet and vacuum generatorDometic: 27 lb toilet, about 15 lb VG4 | 42–44 | same |
| Climate | ||
| Monoblock heat pump, ERV, fans and ductsInnova 2.0 MINI class at 38 kg | 125–160 | same |
| Everything decided so farMidpoint, ± the combined spread | 5,550 ± 110 | 4,940 ± 100 |
| Left under 6,000 lb for everything not yet decided | about 450 | about 1,060 |
Ranges are estimates from areas, lengths and listed product weights. The combined spread assumes the item errors are independent; summing every high end instead gives 6,114 lb as drawn. Metal masses use the skin area less about 13 m² of window openings.
Further cuts to decided items
| Further cut | Saves, lb | What it costs |
|---|---|---|
| Shorten the body by one rib bay, 25½ in: the front room goes from 78 to about 52 in | 290–350 | Length; removes a rib, a side-window pair and about 72 ft² of every skin and metal layer |
| Lighter laundry: twin-tub washer and spin dryer in place of the Splendide | 110–135 | Manual loads and line drying |
| Defer the outer copper/Ni-P tiles; the hull's copper face stays the Faraday enclosure | 90–115 | Loses the outer optical skin and the second metal layer outside the hull |
| Spruce-pine-fir 2×4s and 2×8s in place of Douglas fir for the ribs, cap frames and rails | 75–95 | Same sizes and a common lumber grade, about 26 lb/ft³ against 32; roughly 15% less stiff |
| Light muslin under the hull in place of canvas, with a thinner rosin coat | 60–90 | The hull is the weather skin, so the cloth only has to be a smooth face for the cork; a sample panel must show the hull does not print the lath |
| Glued ¼ in okoume gussets with two bronze bolts per corner, in place of ⅜ in gussets with four | 50–75 | The glue becomes the main joint; needs test joints |
| Hull wall at 0.25 mm | 50–55 | Below the handling minimum; needs a sample panel to prove it |
| Task chair in place of the executive chair | 15–30 | Less comfort for long desk work |
| All of them | 740–945 |
Battery, for when it is sized
Not counted above. For reference: lithium iron phosphate cells at 48 V, in packs of sixteen 314 Ah prismatic cells, are 16 kWh and about 240 lb per pack, cells and pack hardware. Each pack's cells take about 1½ ft³.
Two people use about 6.6 kWh a day without air conditioning: base loads about 2½, cooking 1, a dishwasher cycle 1, two showers 1¼ and laundry every other day about 1. Roof solar of about 900 W makes about 2.7 kWh on a good day. Air conditioning adds about 4 kWh a day in mild heat and 10 or more in hot, humid weather.
| Battery | Mass, lb | Cells, ft³ | Days, sun | Days, sun and mild AC | Days, no sun |
|---|---|---|---|---|---|
| 16 kWh1 × 16 cells, 48 V | 230–250 | 1.5 | 3.4 | 1.7 | 2.0 |
| 32 kWh2 × 16 cells, 48 V | 460–500 | 2.9 | 6.8 | 3.4 | 4.0 |
Days count 90% usable depth and 92% inverter efficiency, with solar at 900 W × 4 full-sun hours × 75%.
Water and waste
Fresh, gray and black tanks travel empty, so their size costs only the empty tanks' weight. Under the floor there is room for 78 gal fresh, 78 gal gray and 15 gal black. The black tank is small because the VacuFlush uses less than a pint per flush.
Two people use about 21 gal a day with laundry and 15 without, so the fresh water lasts 3½–5 days, close to the battery. Gray fills at about the same rate.
A smaller fresh tank saves only its plastic, because the tanks travel empty: 52 gal fresh and gray instead of 78 saves about 25–35 lb and a day of water. Full, the water weighs about 650 lb. That is fine parked, on the legs. Towing with it is not: every 10 gal carried is 83 lb, about the weight of 5½ kWh of battery. The tank-level sensors should drive a "ready to tow" check that shows red until fresh, gray and black are drained.
| Tank | Gallons | Two people, gal/day | Days to empty or full |
|---|---|---|---|
| Fresh | 78 | 21.3 | 3.7; 5.1 without laundry |
| Gray | 78 | 19.2 | 4.1 |
| Black | 15 | 1.4 | 11 |
Under the floor
The service floor has 12½ in of clear depth, 44 in wide at the bottom and 69 in under the deck: about 70 ft³ in all. A floor frame at each rib divides it into six full-width compartments in the straight body, plus shallower ones in the caps where the bottom curves up. Tall items go where a raised fixture above adds height: the washer/dryer's 22 in base gives a well about 35 in deep for the water heater, pump and the toilet's vacuum generator.
- Utility well Water heater, pump/filter/UV module and the toilet's vacuum generator; rises into the washer's 22 in base
- Black tank 15 gal, under the toilet
- Gray tank A 52 gal, under the shower, washer and sink drains
- Gray tank B 26 gal, under the couch
- Freezer 45 L chest with a flush floor hatch by the sink, compressor beside it
- Battery and inverter 16 or 32 kWh LFP at 48 V with the 3 kVA inverter/charger, at the middle of the body
- Fresh tank A 52 gal
- Heat pump Monoblock lying flat, low side intake and outlet
- Fresh tank B 26 gal, linked to tank A
- Air exchanger ERV core and exhaust fans
- Dry bay by the door Hoses, shore cable, leveling blocks, chocks
- Dry bays, north cap Tools, spares, filter media, waste pails
The battery sits mid-body, near the axles. Tank contents sit low and central for when the trailer is parked; they do not affect towing balance, because the tanks travel empty. Tank shapes are custom, sized at about 70% of each compartment.
Storage
Two people with about two weeks of dry food need roughly 40–55 ft³ of storage. None of it needs floor area. Overhead bins run the length of both walls above the windows, from 84 in up, where the upper wall leans in, and lockers fill the space behind the sloping lower walls in the front room. Together with the dry service bays they hold about 47 ft³, plus the bedding in the couchbed's pull-out.
A hanging wardrobe would be the one item that takes floor: about 24 × 22 in in the front room, for about 20 ft³.
Open: the couchbed's pull-out does not fully nest under the seat. Its 27¾ in depth meets the sloping lower wall, which leaves about 16 in at the floor and 22 in at the pull-out's top, so the space under the couch is already used. The pull-out needs a tapered back or a two-part base.
| Needs | ft³ | Goes in |
|---|---|---|
| Clothing and shoes | 12–15 | Overhead bins above the couch and the front-room lockers |
| Bedding | 4–6 | Couchbed pull-out, by day |
| Pantry: two weeks of dry food | 5–7 | Overhead bins above the sink |
| Dishes, cookware and small appliances | 2–3 | Overhead bins above the sink and under the sink |
| Towels, toiletries, cleaning and laundry supplies | 3–4 | Bath bins and under the sink |
| Outdoor gear: chairs, mat, boots, jackets | 6–8 | Front-room knee-wall lockers |
| Hoses, shore cable, leveling blocks, chocks | 3–4 | Dry bay by the door, under the floor |
| Tools, spares, filter media, waste pails | 4–6 | North-cap dry bays, under the floor |
| Office, electronics and papers | 1–2 | Desk and bins |
| Spaces above and below the floor | ft³ | Where |
|---|---|---|
| Overhead bins, both walls | 22 | 84 to about 103 in above the floor, 14 in deep at the bottom, n 31–171, above the windows and the door |
| Bath bins | 3 | Above both bath windows |
| Front-room knee-wall lockers | 9 | Behind the 75° lower walls, below about 29 in: west n 112–171, east n 118–138 |
| Under the sink | 3 | Beside the Fotile plumbing and drinking-water filter |
| Dry service bays | 10 | By the door and in the north cap |