Hydrive OBKIT1-XT vs SeaStar PRO
High-horsepower outboard steering - 350 hp singles and multi-rigs
At the top of the outboard tree the two brands split philosophically. SeaStar PRO chases the performance single - higher pressure, faster wheel, Kevlar hoses, and no published twin rating at all. OBKIT1-XT is built for load: heavier horns, wire-retained lock nuts, 350 hp singles and multi-engine transoms to 1,200 hp - with the commercial rating the PRO doesn't claim.
Side by side
Published manufacturer figures only. Where a maker doesn't publish a number, the table says so.
Max power (single)
Hydrive OBKIT1-XT
350 hp (required fit for the Yamaha 350)
SeaStar PRO HK7500A-3
350 hp (300 hp on Dometic's current HK7500-4 copy)
Multi-engine rating
Hydrive OBKIT1-XT
1,200 hp total across twins/multi-rigs
SeaStar PRO HK7500A-3
Not published - PRO is marketed for single-engine boats
Wheel turns lock-to-lock
Hydrive OBKIT1-XT
5.5 (4.4 with 402 helm)
SeaStar PRO HK7500A-3
4.25
System pressure
Hydrive OBKIT1-XT
Not published per kit
SeaStar PRO HK7500A-3
1,500 psi relief (vs 1,000 psi standard SeaStar)
In the box
Hydrive OBKIT1-XT
401 helm with the 211BH-XT cylinder - full kit contents confirmed at quote
SeaStar PRO HK7500A-3
HH5770-3 2.0 cu in PRO helm, HC6345-3 PRO cylinder, fluid; Kevlar hose kits in HK75xx variants
Commercial use
Hydrive OBKIT1-XT
Commercial-rated (Admiral series)
SeaStar PRO HK7500A-3
None published - positioned as recreational/performance
Power steering option
Hydrive OBKIT1-XT
Pairs with POWERKIT-M12 electro-hydraulic assist
SeaStar PRO HK7500A-3
SeaStar Power Assist or the separate Optimus EPS system
Warranty
Hydrive OBKIT1-XT
2 years, commercial and leisure use alike
SeaStar PRO HK7500A-3
2 years, limited to 1 year for commercial, rental or income-producing use (Dometic warranty, Form 340124 Rev B)
| Specification | Hydrive OBKIT1-XT | SeaStar PRO HK7500A-3 |
|---|---|---|
| Max power (single) | 350 hp (required fit for the Yamaha 350) | 350 hp (300 hp on Dometic's current HK7500-4 copy) |
| Multi-engine rating | 1,200 hp total across twins/multi-rigs | Not published - PRO is marketed for single-engine boats |
| Wheel turns lock-to-lock | 5.5 (4.4 with 402 helm) | 4.25 |
| System pressure | Not published per kit | 1,500 psi relief (vs 1,000 psi standard SeaStar) |
| In the box | 401 helm with the 211BH-XT cylinder - full kit contents confirmed at quote | HH5770-3 2.0 cu in PRO helm, HC6345-3 PRO cylinder, fluid; Kevlar hose kits in HK75xx variants |
| Commercial use | Commercial-rated (Admiral series) | None published - positioned as recreational/performance |
| Power steering option | Pairs with POWERKIT-M12 electro-hydraulic assist | SeaStar Power Assist or the separate Optimus EPS system |
| Warranty | 2 years, commercial and leisure use alike | 2 years, limited to 1 year for commercial, rental or income-producing use (Dometic warranty, Form 340124 Rev B) |
Whatever the manufacturer's warranty says, both brands also carry Australian Consumer Law guarantees that can't be excluded - and for goods under $100,000 those apply to business buyers too.
Where OBKIT1-XT wins
- A published multi-rig rating: 1,200 hp across the transom. SeaStar PRO publishes no twin or counter-rotating rating at all.
- Built for load, not just speed - heavier horns and wire-retained lock nuts, and it's the required Hydrive fit for the Yamaha 350.
- Commercial rating and the 2-year commercial warranty carry over from the Admiral series.
Credit where due
- A genuinely quicker wheel at 4.25 turns lock-to-lock, backed by a 1,500 psi relief and mandatory factory-swaged Kevlar hoses - the right recipe for a 70 mph bass or race boat.
- Mercury Pro XS engines are steered to PRO by Mercury's own guidance in SeaStar's application tables.
Our verdict
For a US-style performance single - bass boat, flats boat, tournament rig - SeaStar PRO's fast wheel and 1,500 psi hardware are exactly its design brief. For Australian big-water boats, twin and multi-rig transoms, or anything working commercially, OBKIT1-XT's published 1,200 hp multi-engine rating and commercial warranty are the numbers that matter.
Questions we get asked
Which kit for twin 300s?
OBKIT1-XT - it's rated to 1,200 hp total across a multi-engine transom, and pairs with Hydrive's POWERKIT-M12 power steering for fingertip effort. SeaStar PRO publishes no twin rating at all; SeaStar's own twin answer is the standard HK6400, published at 600 to 700 hp combined depending on the generation of their documentation.
More comparisons
- Hydrive COMKIT1 vs SeaStar HK6400
- Hydrive COMKIT6 vs SeaStar BayStar
- Hydrive OBKIT1 vs SeaStar HK6400
- All Hydrive vs SeaStar comparisons
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