01 What makes it unique
East to West lists the 2027 Blackthorn 3780FK at 12,769 lb dry, a GVWR of 15,500 lb, a net carrying capacity of 2,731 lb and a pin weight of 2,375 lb. Its dry weight plus its carrying capacity comes to exactly its GVWR.
It is 42' 7" long and 13' 5" high. East to West prints its tanks as 64 gal fresh, 132 gal grey, 88 gal black.
Every number on this page was read on 8 Nov 2026 from East to West’s own 2027 Blackthorn floorplan page for the Blackthorn 3780FK, whose heading names the model year 2027.
How the 3780FK differs from the other seven Blackthorn floorplans. Most distinctive first. Sibling pages may cover other model years than this one (2027). How these ranks are worked out.
- Cargo capacity as a share of GVWR, 17.6%: smallest of eight; next is the 3820DSL (17.8%).
- Pin weight, 2,375 lb: heaviest of eight; next is the 3820DSL (2,350 lb).
- Length, 42 ft 7 in: longest of eight; next is the 3880RBDB (42 ft 1 in).
- Exterior height, 13 ft 5 in: tallest of eight; next are the 2990MK, 3750LK and three others (13 ft 4 in).
- Cargo capacity, 2,731 lb: second-smallest of eight, between the 229RK (2,621 lb) and the 3820DSL (2,911 lb).
- Dry weight, 12,769 lb: third-heaviest of eight, between the 3750LK (12,619 lb) and the 3880RBDB (13,019 lb).
- GVWR, 15,500 lb: fourth-lowest of eight, between the 2990MK (14,180 lb) and the 3750LK (16,120 lb).
- Pin weight as a share of dry weight, 18.6%: shared with the 3865FLR; of eight, five smaller and one larger, nearest the 3820DSL (17.5%) and the 2990MK (20.1%).
- Grey tank, 132 gal: largest of eight, level with the 3820DSL and 3880RBDB; next is the 3750LK (108 gal).
- Black tank, 88 gal: largest of eight, level with the 3820DSL and 3880RBDB; next are the 229RK, 279BH and three others (44 gal).
Next to the 3750LK (2026 page), the nearest lighter floorplan by dry weight, the 3780FK is 150 lb heavier by dry weight, has a GVWR 620 lb lower, has 770 lb less cargo capacity, has a pin weight 255 lb heavier, is 1 ft 9 in longer, stands 1 in taller, has a grey tank 24 gal larger and has a black tank 44 gal larger; the two publish the same fresh tank.
Next to the 3880RBDB (2026 page), the nearest heavier floorplan by dry weight, the 3780FK is 250 lb lighter by dry weight, has a GVWR 720 lb lower, has 470 lb less cargo capacity, has a pin weight 155 lb heavier, is 6 in longer and stands 1 in taller; the two publish the same fresh tank, grey tank and black tank.
02 Full specifications
Dimensions
- Exterior length
- 42' 7"
- Exterior height
- 13' 5"
- Exterior width
- 96"
- Interior height
- Not published by East to West
Weights
- Dry / unit base weight (UVW)
- 12,769 lb
- GVWR (max loaded)
- 15,500 lb
- Net cargo / payload (CCC)
- 2,731 lb
- Hitch / pin weight
- 2,375 lb
Capacities
- Fresh water
- 64 gal
- Grey water
- 132 gal
- Black water
- 88 gal
Running gear
- Hitch type
- Fifth wheel (pin box)
- Tire size
- Not published by East to West
Sleeping & layout
- Sleeps
- Not published by East to West
- Sold under each badge (as printed)
- East to West sells the same floorplan as the Tandara 381FK: its 2027 Blackthorn and Tandara pages print the same dry weight, cargo capacity, pin weight, length, height, width and tank sizes. The Blackthorn page also prints a GVWR; the Tandara page prints none. Each page on this site is built from its own maker page.
- Model year (as printed)
- page title “2027 Blackthorn 3780FK Floorplan - East to West”
- Weight basis (as printed)
- UVW footnote: “*Estimated Average based on standard build optional equipment.”
- Awning
- 20'
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
Weight budget
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 (15,500 lb) and the upper loaded pin estimate (3,875 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 Blackthorn floorplan family
The Blackthorn floorplan below was added from East to West’s 2027 Blackthorn floorplan page; every Blackthorn floorplan on this site, every model year, is listed on the Blackthorn hub.
| Floorplan | Nominal |
|---|---|
| Blackthorn 3780FK | 42' 7" |
The Blackthorn floorplan below was added from East to West’s 2027 Blackthorn floorplan page; every Blackthorn floorplan on this site, every model year, is listed on the Blackthorn hub.
04 Notes on this floorplan
What East to West does not publish for the Blackthorn 3780FK
East to West prints no tire size, interior height and sleeping capacity for this model, so none is given. Nothing is filled from a sibling model, a different model year or a dealer listing.
Read the label on the trailer
The weight label every RV trailer carries by law (49 CFR 571.110 and 571.120) governs the towing decision, not this page.
05 How it compares
06 Loading it for a trip
A full 64-gallon fresh tank is about 531 lb of water (water counts as cargo: 49 CFR 571.120 S10.4.2), 19% of the 3780FK’s 2,731 lb cargo capacity, leaving 2,200 lb. Across 8 Blackthorn floorplans the water share runs 14% to 20%, and 1 gives up more than this one. Nearest on that share: Blackthorn 3820DSL at 18% and Blackthorn 229RK at 20%. Your own unit’s figure is on the label inside its entry door (49 CFR 571.120 S10.4.3).
07 Where this floorplan sits
Closest sibling: the Blackthorn 3820DSL, nearest on the published figures. It differs on 5 of the 8 fields both publish (this plan first): length 42 ft 7 in vs 41 ft 11 in; dry weight 12,769 lb vs 13,439 lb; GVWR 15,500 lb vs 16,350 lb; cargo capacity 2,731 lb vs 2,911 lb; hitch weight 2,375 lb vs 2,350 lb. They match on fresh tank, grey tank and black tank.
| Blackthorn plans | This plan | Position, low to high | Range |
|---|---|---|---|
| GVWR (lb) | 15,500 | 4 of 8 | 9,945–16,350 |
| Dry weight (lb) | 12,769 | 6 of 8 | 7,324–13,439 |
| Cargo capacity (lb) | 2,731 | 2 of 8 | 2,621–3,876 |
| Hitch weight (lb) | 2,375 | 8 of 8 | 1,145–2,375 |
| Length | 42 ft 7 in | 8 of 8 | 28 ft 1 in–42 ft 7 in |
| Grey tank (gal) | 132 | 6–8 of 8 | 88–132 |
| Black tank (gal) | 88 | 6–8 of 8 | 44–88 |
Either side of it by GVWR: Blackthorn 2990MK is 1,320 lb lighter (14,180 lb GVWR); Blackthorn 3750LK is 620 lb heavier (16,120 lb GVWR).
| Nearest Blackthorn siblings | Length | Dry (lb) | GVWR (lb) | CCC (lb) | Hitch (lb) | Fresh (gal) |
|---|---|---|---|---|---|---|
| Blackthorn 3780FK | 42 ft 7 in | 12,769 | 15,500 | 2,731 | 2,375 | 64 |
| Blackthorn 3820DSL | 41 ft 11 in | 13,439 | 16,350 | 2,911 | 2,350 | 64 |
| Blackthorn 3880RBDB | 42 ft 1 in | 13,019 | 16,220 | 3,201 | 2,220 | 64 |
| Blackthorn 3750LK | 40 ft 10 in | 12,619 | 16,120 | 3,501 | 2,120 | 64 |
| Blackthorn 3865FLR | 41 ft 11 in | 12,444 | 16,320 | 3,876 | 2,320 | 64 |
| Blackthorn 2990MK | 35 ft 0 in | 10,864 | 14,180 | 3,316 | 2,180 | 64 |
All 8 Blackthorn floorplans: Blackthorn line hub.
| Other lines, nearest by GVWR | GVWR (lb) | Dry (lb) | Sleeps | Length |
|---|---|---|---|---|
| 3780FK | 15,500 | 12,769 | — | 42 ft 7 in |
| Bighorn Traveler 32RS | 15,500 | 10,803 | 4 | 36 ft 2 in |
| Brookstone 374RK | 15,500 | 13,020 | — | 42 ft 2 in |
| Chaparral 367BH | 15,500 | 12,328 | — | 42 ft 6 in |
| ElkRidge 37RED | 15,500 | 11,848 | 6 | 41 ft 7 in |
| Mesa Ridge 371MBH | 15,500 | 12,665 | — | 42 ft 5 in |
| Milestone 370FLMB | 15,500 | 12,520 | 8 | 44 ft 2 in |
Against the 3780FK: the Bighorn Traveler 32RS is 6 ft shorter.
08 Common questions about the 3780FK
How much does the 3780FK weigh?
12,769 lb dry; 15,500 lb GVWR, the most it may weigh loaded.
How much can the 3780FK carry?
2,731 lb, 18% of its GVWR (median across 491 fifth wheels here: 19%). A full fresh tank uses 531 lb of it.
What is the pin weight of the 3780FK?
2,375 lb as published, 19% of the dry weight (median across 727 fifth wheels here: 19%).
What size tow vehicle does the 3780FK need?
A tow rating of at least 15,500 lb, plus payload for the loaded pin weight, passengers and cargo.
What are the tank capacities on the 3780FK?
Fresh 64, grey 132, black 88 gallons. Off hookups, fresh water runs out first.
How long is the 3780FK?
42' 7" overall, tongue or pin box included.
From the figures above.
09 What this page publishes, and what it does not
11 of the 18 fields this catalogue tracks are published for the 3780FK. Not published: interior height, sleeps, slide count, axle count, tire specification, refrigerator, air conditioning.
Sourcing rules: methodology.
10 Manuals & documents
Sources: easttowestrv.com (linked below); the full source note is at the foot of the page.
11 NHTSA safety record
NHTSA holds 3 recall campaigns and 6 owner complaints (model years 2005 on) against the Blackthorn line (a recall and a complaint are not the same thing).
Too few reports to show a pattern. 6 complaints have been filed on this line — not enough to say what fails most often. They cover structure, tires and electrical system.
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 Blackthorn line page.