Hydrive COMKIT1 vs SeaStar HK6400
Bullhorn hydraulic steering for single outboards to 200 hp
COMKIT1 is Hydrive's value bullhorn kit and the natural cross-shop against SeaStar's standard front-mount kit. The biggest practical difference isn't in the spec table - it's what's in the carton: COMKIT1 arrives with 15 m of tubing, fluid and a bleeding kit, while the SeaStar HK6400 kits ship without hoses, which are bought separately.
Side by side
Published manufacturer figures only. Where a maker doesn't publish a number, the table says so.
Max power (single)
Hydrive COMKIT1
200 hp (COMKIT1-PRO: 300 hp)
SeaStar HK6400A-3 / HK6400-4
350 hp
Max power (twin, counter-rotating)
Hydrive COMKIT1
400 hp total (PRO: 600 hp)
SeaStar HK6400A-3 / HK6400-4
700 hp combined
Dometic's current HK6400-4 page quotes 600 hp combined; the A-3 literature quotes 700. Both SeaStar figures are the maker's own.
Cylinder mount
Hydrive COMKIT1
Bullhorn (511BH) over the splashwell
SeaStar HK6400A-3 / HK6400-4
Front mount (HC5345-3) on the engine pivot plate
Wheel turns lock-to-lock
Hydrive COMKIT1
5.4
SeaStar HK6400A-3 / HK6400-4
5 (4.9 on HK6400-4)
In the box
Hydrive COMKIT1
501 helm, 511BH cylinder, 15 m tubing, 2 L ULTRA-15 fluid, fittings, bleeding kit
SeaStar HK6400A-3 / HK6400-4
HH5271-3 helm (1.7 cu in), HC5345-3 cylinder, 2 qt fluid - hoses sold separately
Commercial rating
Hydrive COMKIT1
COMKIT1-PRO variant is commercial-rated
SeaStar HK6400A-3 / HK6400-4
Not published for this kit
Warranty
Hydrive COMKIT1
2 years for leisure use (commercial terms confirmed at quote)
SeaStar HK6400A-3 / HK6400-4
2 years, limited to 1 year for commercial, rental or income-producing use (Dometic warranty, Form 340124 Rev B)
Designed and supported from
Hydrive COMKIT1
Designed and manufactured in Adelaide, South Australia
SeaStar HK6400A-3 / HK6400-4
Dometic Marine, head office Richmond BC, Canada - per-product build location not published
| Specification | Hydrive COMKIT1 | SeaStar HK6400A-3 / HK6400-4 |
|---|---|---|
| Max power (single) | 200 hp (COMKIT1-PRO: 300 hp) | 350 hp |
| Max power (twin, counter-rotating) | 400 hp total (PRO: 600 hp) | 700 hp combined |
| Dometic's current HK6400-4 page quotes 600 hp combined; the A-3 literature quotes 700. Both SeaStar figures are the maker's own. | ||
| Cylinder mount | Bullhorn (511BH) over the splashwell | Front mount (HC5345-3) on the engine pivot plate |
| Wheel turns lock-to-lock | 5.4 | 5 (4.9 on HK6400-4) |
| In the box | 501 helm, 511BH cylinder, 15 m tubing, 2 L ULTRA-15 fluid, fittings, bleeding kit | HH5271-3 helm (1.7 cu in), HC5345-3 cylinder, 2 qt fluid - hoses sold separately |
| Commercial rating | COMKIT1-PRO variant is commercial-rated | Not published for this kit |
| Warranty | 2 years for leisure use (commercial terms confirmed at quote) | 2 years, limited to 1 year for commercial, rental or income-producing use (Dometic warranty, Form 340124 Rev B) |
| Designed and supported from | Designed and manufactured in Adelaide, South Australia | Dometic Marine, head office Richmond BC, Canada - per-product build location not published |
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 COMKIT1 wins
- Everything to steer the boat is in one carton - 15 m of tubing, 2 L of fluid, fittings and the bleeding kit. The SeaStar HK6400 kits ship without hoses.
- Australian designed and made in Adelaide, with factory support and published seal kits for every helm and cylinder - spares don't cross an ocean.
- A clear upgrade path on the same cylinder: COMKIT1-PRO swaps in the Admiral 401 helm for a 300 hp single / 600 hp twin rating, and Hydrive rates it for commercial use.
- The bullhorn mount keeps the cylinder above the splashwell - nothing bolts to the engine's pivot plate, and it clears engines where front-mount access is tight.
Credit where due
- Higher headline ratings: SeaStar's literature for this kit quotes 350 hp on a single, and 600 to 700 hp across counter-rotating twins depending on which generation of the documentation you read.
- The front-mount cylinder lets twin engines tilt independently.
- Enormous OEM and aftermarket presence worldwide - SeaStar is the default fit on many imported hulls.
Our verdict
For a single outboard up to 200 hp, COMKIT1 gets you steering in one carton while the HK6400 still needs hoses chosen and added - and COMKIT1-PRO covers the 300 hp class with a commercial rating. If you're pushing past 300 hp on a single, or want SeaStar's higher published twin figure, their rating runs above COMKIT1 and we'd spec you into an Admiral kit or SeaStar accordingly - talk to us either way.
Questions we get asked
Does the SeaStar HK6400 kit really come without hoses?
Yes - Dometic's own product page describes the HK6400 kits as supplied without hose, with SeaStar hose kits bought separately to suit the run length. Hydrive's COMKIT1 includes 15 m of tubing, fluid, fittings and a bleeding kit in the carton.
Can I use COMKIT1 on a 250 hp outboard?
Not COMKIT1 itself - it's rated to 200 hp on a single. Step up to COMKIT1-PRO (300 hp single, 600 hp twin, commercial-rated) or the Admiral OBKIT1, which uses the same bullhorn mounting style.
Is either kit hard to fit yourself?
Both are within reach of a competent DIY installer. Hydrive's kit includes the bleeding kit and cut-to-length tubing, and we're on the phone in Mornington if you get stuck - (03) 5973 6444.
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