The R31 showed up as a 2025 model and we never posted it. FLIBS 2024, 2025 model year. It is still current. It is not the homepage “just arrived” boat; that is the R26 this August. Factory line on the R31 is “Built For Weekends That Last Longer.” For once the tagline matches the spec card: 31′ 5″, 9′ 10″ beam, 160 gallons, Yacht Certified, head standard, and the power list is twins only.
It sits between the R26 / R8 pack and the R33. Wider than the 8′ 6″ boats. Wider even than the A29’s 9′ 0″. This is the first sterndrive in this week’s stack that is not a single-engine conversation on the spec list. Volvo twins with joystick, Merc twins with Axius, 300 to 430 hp each. No Monsoon line on the R31 spec list I pulled, so I am not adding one.
Factory specs
- LOA (w/ swim platform): 31′ 5″
- Beam: 9′ 10″
- Deadrise at transom: 21 degrees
- Fuel: 160 gal
- Freshwater: 18 gal
- Capacity: Yacht Certified
- Head: yes (pump-out Porta Potti standard; VacuFlush optional)
- Dry weight, w/ twin engines (options not included): 9,500 lbs
- Draft, twin engines, drive up / down: 26″ / 44″
- Engines: twin Volvo Penta 300–430 hp each (joystick), twin MerCruiser 300–430 hp each (Axius)
Nine thousand five hundred pounds, twins, 160 gallons. That is a different club than the R4. Bridge clearance is printed at 5′ 4″ windshield-only and 9′ 1″ with hardtop, which is the covered-slip number some of you will care about more than horsepower. Head on the standard list is a pump-out Porta Potti with a sink console; Thetford Vac is optional. Dual Garmin 943 is the standard glass cockpit. Extra-wide electric helm seat is standard. I am not dumping the prep-galley, Seakeeper, hull-side window, and hardtop-awning catalog. Those are options on the factory page. Seakeeper 1 is on that list; Cobalt’s interior copy claims up to 95 percent roll reduction. That is their claim. I have not been on an R31 in a beam sea, so I will not second it.
Naming, because Coastal will confuse people. This post is the sterndrive R31. There is also an R31 Surf and an R31 Coastal. The Coastal product page is titled R31 Coastal. The homepage still says “R31 Coastal Edition.” The October 7, 2025 press said R31 OB. Same outboard boat, 32′ 8″ LOA, still a homepage feature, not this week’s launch. If you bought the sterndrive, you bought the 31′ 5″ twin. If you bought the Coastal, you bought a longer boat with Yamahas or Mercurys on the transom. I will get to Coastal in another round. Today is the sterndrive we skipped in 2025.
I used to think 31 feet was getting out of “day boat.” Then I remembered the 343. The R31 is still a bowrider with a giant cockpit, not a cabin cruiser, but the tank and the twins are how Cobalt is selling longer weekends. Walk-around video is on their site. I would rather walk around one in a slip. If you took delivery last year and we never asked, that is on me.
If you bought one, send pictures to editor@mycobalt.net. Seattle-area rides still welcome. Owner feature, your photos. Listing the boat it replaced? $25 / $50. This is not a for-sale post.
Photo: Cobalt Boats. Specs from cobaltboats.com, August 2026.
