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Hi all, I have a 2004 Horizon H210. It's got the 300bhp 350MAG motor and Bravo II (I think) drive. I currently have a Mercury Mirage Plus 15 1/4" 19 Pitch 3 blade stainless prop. I know this must be the wrong prop as the couple of times I have tried the boat at max rpm I have hit 6,000 rpm (don't worry only for a couple of seconds). I know the max range is 4,600-5,000. From memory I was hitting about 37 knots GPS. I also have a Hi Five prop that came with the boat (can't remember the specs) but with this on I could only hit about 35 knots GPS before I would go over the max rpm.

Can anyone advise what the standard prop was on this model. I generally use it for days out fishing, anchoring up and playing in the water. I do have a wake tower and will be using it to wakeboard and pull tubes too this summer.

Any help appreciated. I am in Australia but am thinking it will be far cheaper to ship a prop from the states. I take it when I have the correct prop with the throttle wide open I should be hitting just under 5,000 rpm? What sort of speed should I be getting too?

Thanks,

Mike

I don't know the specifics about an H210 with 300HP, so take my answer as a guess, to be considered with other peoples answers:

I would think that you should get at least 43 knots (50 mph) with that boat/engine combo. If your 19p prop is maxing out rpm at 35 knots, then you need 23% more pitch to get to 43 knots at the same RPM. What would calculate to 23.4" pitch. Therefore it sounds like you need a 23p prop, or even a 25p.

That sounds like a lot of pitch for a cruiser, so it makes me wonder if you have a non-standard gear ratio in the drive. Many boats reach 40+ knots (46+ mph) on a 19p prop, or 43+ knots (50+ mph) on a 21p prop.

_________________

"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

I have a 2005 210 horizon. The spec sheet for the 2005 (prob same for the 2004 since the boats are nearly identical) says the 350 mercruiser OEM prop was 14.5 x 19. Should run bout 48-51 mph (bout 42-44 knots) according to the spec sheet. Are you sure your tach is operating properly? It seems to me that 6000 rpm is pretty high with the prop you are running. My faria tach with hour meter got a little flaky at times this summer. Would read high. I could tell from the sound of the motor that I was not over-revving. Then I noticed that my rpm at idle was also high. Couple taps of the gauge and I could get it to dance back and forth a little. I will be looking to replace this gauge this spring. Might you have a similar issue?

_________________
Seth




2005 210 Horizon
5.0L GXi
"Don't Think Twice"

That's a good point about the tachometer. It it was somehow indicating in 6-cylinder mode instead of 8-cylinder mode, it would read 33% high.

I just looked up an App for Android phones that is an "Acoustic Tachometer". I don't know if it works. You input number of cylinders, and 4-stroke engine, and it 'listens" to the engine and displays RPM. It it works, it would be a nice way to check your tachometer for free.

_________________

"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

Just look up "prop" on this forum. We have truly beat the subject to death. I also have a prop-slip calc posted on many of them. Basically get a tach, check your gear ratio, use your GPS and plug away with the calc. Historically speaking, you should be using a 19 or 21p prop; and that would be a Bravo 1, so either 1.65 or 1.5:1 ratio, and a slip of about 18%. 5400-5600 RPM @ WOT; expect 48-52 MPH.
Good luck!

_________________
Walt B
"Debt-Charged"
Black '07 H210SS
6.2L Bravo One turning a 21P HIFive
Wakeboard Tower with Perfect Pass Stargazer version
Missouri River; Kansas City, Mo.