01 What makes it unique
The Momentum 381MS is a fifth-wheel toy hauler 43 ft 11 in long with a 15 ft garage, on three axles with three slide-outs and a 60-gallon fuel station. It is on Grand Design’s Momentum roster for 2027.
Grand Design’s page lists an unloaded vehicle weight of 17,722 lb, a GVWR of 23,500 lb and a pin weight of 3,726 lb. It publishes no cargo carrying capacity, so none is printed or computed here. Tanks are 140 gal fresh, 52 gal grey and 104 gal black, and it sleeps 6.
Grand Design’s page names the 351MS and 350G as comparison floorplans.
How the 381MS differs from the other eleven Momentum fifth wheels. Most distinctive first. Each rank counts only the siblings that publish that field, and a figure most of them share is left out.
- Pin weight, 3,726 lb: third-heaviest of twelve, between the 392M (3,650 lb) and the 395MT and 396DB (3,760 lb).
- Pin weight as a share of dry weight, 21%: fourth-largest of twelve, between the 325G (20.9%) and the 394G (21.3%).
- Dry weight, 17,722 lb: fifth-heaviest of twelve, between the 394G (16,400 lb) and the 392M (18,114 lb).
- Length, 43 ft 11 in: sixth-longest of twelve, between the 363G (41 ft 7 in) and the 399M (44 ft 10 in).
- Grey tank, 52 gal: smallest of twelve, level with the 320G, 350G and 351MS; next is the 395MT (78 gal).
- Black tank, 104 gal: largest of twelve, level with the 320G, 350G and 351MS; next is the 395MT (78 gal).
- GVWR, 23,500 lb: highest of twelve, level with the 392M, 395MT and two others; next is the 394G (22,500 lb).
- Sleeping capacity, 6: shared with the 320G, 325G and two others; of twelve, two smaller and five larger, nearest the 350G and 399M (5) and the 394G, 395MT and 396DB (7).
Next to the 394G, the nearest lighter floorplan by dry weight, the 381MS is 1,322 lb heavier by dry weight, has a GVWR 1,000 lb higher, has a pin weight 226 lb heavier, is 1 ft shorter, has a fresh tank 42 gal larger, has a grey tank 52 gal smaller, has a black tank 52 gal larger and sleeps one fewer; the two publish the same exterior height and slide-out count.
Next to the 392M, the nearest heavier floorplan by dry weight, the 381MS is 392 lb lighter by dry weight, has a pin weight 76 lb heavier, is 2 ft shorter, has a grey tank 52 gal smaller, has a black tank 52 gal larger and sleeps three fewer; the two publish the same GVWR, exterior height, fresh tank and slide-out count.
02 Full specifications
Dimensions
- Exterior length
- 43 ft 11 in
- Exterior width
- 8 ft 5 in
- Width, slides out
- 14 ft 3 in
- Exterior height
- 13 ft 6 in
- Chassis
- 101″ wide body · 5-side aluminum cage
- Garage / flex length
- 15 ft
Weights
- Dry / unit base weight (UVW)
- 17,722 lbs
- GVWR (max loaded)
- 23,500 lbs
- Net cargo / payload
- Not published by Grand Design
- Hitch / pin weight
- 3,726 lbs
Capacities
- Fresh water
- 140 gal
- Grey water
- 52 gal
- Black water
- 104 gal
- LP gas
- 60 lbs · 2 tanks
- Refrigerator
- 20 cu. ft.
Construction
- Chassis
- 101″ Wide Body Super Chassis w/ drop-frame storage
- Body
- 5-side aluminum cage · 101″ wide body
- Sidewalls
- High-gloss gel coat · frameless tinted windows
- Roof
- Worry-Free composite w/ lifetime warranty · walk-on
- Underbelly
- Fully enclosed and heated underbelly and storage area
Running gear
- Hitch
- Fifth-wheel (in-bed) · MORryde® pin box
- Suspension
- MORryde® Independent Suspension 2.0 w/ disc brakes
- Leveling
- 6-point hydraulic
- Tires
- Heavy-duty H-rated · 17.5″ H-rated aluminum wheels
- Spare
- 17.5″ undermount
- Tire size
- ST215/75R17.5 LRH
- GAWR, as Grand Design lists it
- 21,000 lbs
Garage
- Garage / flex length
- 15 ft
- Ramp
- Ramp door w/ Keyed Alike™ latches
- Tie-downs
- 2,500 lb rated flush-mount tie-downs
- Fuel station
- 60 gal · dual tank
Galley & systems
- Refrigerator
- 20 cu. ft. 12-volt
- Air conditioning
- 30,000 BTU
- Furnace
- 35,000 BTU
- Water heater
- On-Demand
- Solar
- 330W roof-mounted panel · 50 AMP controller w/ Bluetooth · inverter prep · 2 USB dock ports
- Shower
- 48 X 30
Sleeping & layout
- Sleeps
- 6
- Slides
- 3
- Awnings
- 2
- Hitch type
- Fifth-wheel (in-bed)
- Primary bed
- 60 X 80 Queen Bed (King Opt.)
How these published figures sit against the rest of the catalogue: fifth wheel pin weight and payload; fresh, grey and black tank sizes; camper trailer size chart.
Drawn to scale
Size, with end view
Holding tanks
Axles, wheels and nose shape are schematic; not a floorplan. Data: dataset.
Towing it
Check your vehicle. Enter the ratings from your owner’s manual and the door-pillar placard.
Compares your figures with this page’s published GVWR (23,500 lb) and the upper loaded pin estimate (5,875 lb, a rule of thumb). Your vehicle’s placard and the trailer’s own weight label govern.
Loaded range: 15–25% of GVWR on the pin, a rule of thumb, not a measurement of this unit. No truck ratings or hitch classes (why; NHTSA, DOT HS 809 433). The range starts at the published figure, because loaded is never lighter than that.
03 The Momentum floorplan family
Momentum is Grand Design's toy-hauler family, and it spans four rosters across both tow types. The full-size Momentum fifth wheel is the flagship — a 101-inch wide-body coach on MORryde independent suspension with disc brakes, carrying a 60-gallon dual fuel station. The Momentum G-Class fifth wheel sits below it on MORryde CRE3000 suspension and a Rotoflex pin box with a 30-gallon fuel station, and the G-Class travel trailer puts that same garage behind a bumper pull. The Momentum MAV is the compact end — the lightest and cheapest way into a Momentum garage, and the one roster with no fuel station at all. The 381MS on this page is highlighted; each other profiled plan links to its own page. The full MY2027 catalogue runs to 28 floorplans across the four rosters; eight are profiled in depth here and the rest are catalogued on the line hub with their weights.
| Floorplan | Roster | Type | Length | Garage | Sleeps | Notable |
|---|---|---|---|---|---|---|
| 351MS | Momentum | 5W | 39′ 11″ | 11 ft | 6 | 11 ft garage, sleeps 6, 3 slides |
| 344M | Momentum | 5W | 39′ 11″ | 11 ft | 6 | Entry Momentum — lowest GVWR of the ten, tightest payload |
| 381MS | Momentum | 5W | 43′ 11″ | 15 ft | 6 | 15 ft garage, sleeps 6, 3 slides |
| 392M | Momentum | 5W | 45′ 11″ | 17 ft | 9 | Sleeps nine, longest fifth-wheel garage in the family |
| 395MT | Momentum | 5W | 46′ 4″ | 14 ft* | 7 | 14 ft* garage, sleeps 7, 3 slides |
| 396DB | Momentum | 5W | 46′ 4″ | 10 ft 10 in | 7 | 10 ft 10 in garage, sleeps 7, 3 slides |
| 399M | Momentum | 5W | 44′ 10″ | 12 ft 6 in | 5 | 12 ft 6 in garage, sleeps 5, 3 slides |
The full-size Momentum is Grand Design's luxury fifth-wheel toy hauler and the top of the family — a 101-inch wide-body coach on MORryde independent suspension with disc brakes, a 60-gallon dual fuel station and a 20-cubic-foot refrigerator. Pin weights here are factory dry figures and a toy hauler's real loaded pin climbs hard once the garage is full — weigh the loaded coach against your truck's payload and rear-axle rating. The other Momentum fifth-wheel floorplans are catalogued on the line hub.
04 Notes on this floorplan
15 ft garage, 60-gallon fuel station
Garage / flex length and fuel station as printed on the 381MS page.
Pin 3,726 lb on 17,722 lb UVW
Grand Design’s pin weight is 21.0% of its unloaded weight; the loaded figure is higher.
30,000 BTU A/C, 35,000 BTU furnace
Climate equipment as Grand Design lists it for the 381MS.
140 fresh / 52 grey / 104 black
Tank capacities in gallons, from the 381MS page.
05 How it compares
Named by Grand Design’s 381MS page as a comparison floorplan: UVW 15,760 lb, GVWR 19,000 lb, 39 ft 11 in.
Named by Grand Design’s 381MS page as a comparison floorplan: UVW 13,400 lb, GVWR 18,000 lb, 39 ft 9 in.
Every current Momentum floorplan, all four rosters, side by side.
07 Where this floorplan sits
Closest sibling: the Momentum 351MS, nearest on the published figures. It differs on 4 of the 8 fields both publish (this plan first): length 43 ft 11 in vs 39 ft 11 in; dry weight 17,722 lb vs 15,760 lb; GVWR 23,500 lb vs 19,000 lb; hitch weight 3,726 lb vs 3,000 lb. They match on sleeps, fresh tank, grey tank and black tank.
| Momentum fifth-wheel plans | This plan | Position, low to high | Range |
|---|---|---|---|
| GVWR (lb) | 23,500 | 8–12 of 12 | 16,400–23,500 |
| Dry weight (lb) | 17,722 | 8 of 12 | 12,603–19,170 |
| Hitch weight (lb) | 3,726 | 10 of 12 | 2,300–3,760 |
| Length | 43 ft 11 in | 7 of 12 | 35 ft 6 in–46 ft 4 in |
| Fresh tank (gal) | 140 | 5–12 of 12 | 98–140 |
| Grey tank (gal) | 52 | 1–4 of 12 | 52–104 |
| Black tank (gal) | 104 | 9–12 of 12 | 52–104 |
| Sleeps | 6 | 3–7 of 12 | 5–9 |
Either side of it by GVWR: Momentum 394G is 1,000 lb lighter (22,500 lb GVWR); Momentum 392M matches it at 23,500 lb GVWR.
| Nearest Momentum fifth-wheel siblings | Length | Sleeps | Dry (lb) | GVWR (lb) | CCC (lb) | Hitch (lb) | Fresh (gal) |
|---|---|---|---|---|---|---|---|
| Momentum 381MS | 43 ft 11 in | 6 | 17,722 | 23,500 | — | 3,726 | 140 |
| Momentum 351MS | 39 ft 11 in | 6 | 15,760 | 19,000 | — | 3,000 | 140 |
| Momentum 395MT | 46 ft 4 in | 7 | 19,100 | 23,500 | — | 3,760 | 140 |
| Momentum 396DB | 46 ft 4 in | 7 | 19,100 | 23,500 | — | 3,760 | 140 |
| Momentum 350G | 39 ft 9 in | 5 | 13,400 | 18,000 | — | 2,600 | 98 |
| Momentum 399M | 44 ft 10 in | 5 | 19,170 | 23,500 | — | 3,406 | 140 |
All 24 Momentum floorplans: Momentum line hub.
| Other lines, nearest by GVWR | GVWR (lb) | Dry (lb) | Sleeps | Length |
|---|---|---|---|---|
| 381MS | 23,500 | 17,722 | 6 | 43 ft 11 in |
| Solitude 414LJMJ | 23,500 | 19,000 | 6 | 42 ft 10 in |
| Riverstone 442MC | 23,845 | 18,591 | 6 | 43 ft 9 in |
| Model G 3950 | 23,000 | 18,700 | 8 | 45 ft 5 in |
| Cyclone 3913 | 21,000 | 15,435 | 8 | 46 ft 5 in |
| Nightfall 397NHD | 21,000 | 15,674 | — | 45 ft 0 in |
| Sandstorm 4017GX | 21,000 | 15,674 | — | 45 ft 0 in |
Against the 381MS: the Solitude 414LJMJ is 1 ft shorter; the Riverstone 442MC is 345 lb heavier; the Model G 3950 is 500 lb lighter and 2 ft longer and sleeps 2 more.
08 Common questions about the 381MS
How much does the 381MS weigh?
17,722 lb dry; 23,500 lb GVWR, the most it may weigh loaded.
What is the pin weight of the 381MS?
3,726 lb as published, 21% of the dry weight (median across 411 fifth wheels here: 19%).
What size tow vehicle does the 381MS need?
A tow rating of at least 23,500 lb, plus payload for the loaded pin weight, passengers and cargo.
How many people does the 381MS sleep?
It is rated to sleep 6. 5 of the 12 Momentum fifth-wheel floorplans that publish a count sleep more.
What are the tank capacities on the 381MS?
Fresh 140, grey 52, black 104 gallons. Off hookups, fresh water runs out first.
How long is the 381MS?
43 ft 11 in overall, tongue or pin box included.
From the figures above.
09 What this page publishes, and what it does not
14 of the 18 fields this catalogue tracks are published for the 381MS. Not published: cargo capacity (CCC), interior height, axle count, tire size (a description is published, a size is not).
Sourcing rules: methodology.
10 Manuals & documents
Sources: granddesignrv.com (linked below); the full source note is at the foot of the page.
11 NHTSA safety record
NHTSA holds 19 recall campaigns and 201 owner complaints (model years 2005 on) against the Momentum line. They are counted separately: a recall is a confirmed defect with a remedy, a complaint one owner’s unverified account.
What to look at on a used one. Across the 201 complaints filed on this line the most-reported components are structure (41%), unknown or other (19%) and suspension (10%).
Reports that name the 381MS
2 of those records name this floorplan specifically rather than the line as a whole.
| Type | Date | Reference | What it says |
|---|---|---|---|
| Recall | 6 May 2025 | 25V281000 | Steps that detach while in use increase the risk of injury. |
| Complaint | 6 Aug 2024 | ODI 11606828 | I was made aware of Grand Design’s Technical Service Bulletin 24-001 concerning issues with undersized and/or missing lag screws possibly be on some models of their fifth wheel campers. I… |
Recall coverage here is not complete, and complaints are owners’ unverified reports (how this record is built). Check a specific VIN at NHTSA before you buy. Full tables are on the Momentum line page.