36Envision

I was out driving a 35 OL today with twin 425 HP HO's and bravo X drives. I could only get 4200 RPM out of the engines and 62 MPH top end from the boat.......shouldn't these motors and boat push about 5000 RPM's and ~72 MPH? Either the boat isn't running right or gauges are reading wrong. Thoughts??

I thought the boat handled OK but it liked to hop a bit in the choppy water and bang around a bit. I guess I expected the boat to handle a bit better in the snot and choppy stuff; water wasn't even half as bad as the next couple days will be!!!

offshorexcursion

iTrader: (5)

I agree that something is not right but It could be anything! have you driven this boat before? Is it yours? Give us more info, prop pitch, etc

Keith Atlanta

Were the tabs up? Did you trim it all the way out?

A.O. Razor

What pitch where you running? 26" B1's would be the number for that setup I think.
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36Envision

Not my boat. I've been in it and driven it twice, all day, two days in the boat. Trimmed up and tabs up not more than 4200 RPM's and 62 MPH. 26" bravo I with X drives I believe is correct. It is a 100% stock boat. The boat may be running right and gauges are reading wrong, no idea since it isn't mine.

bajaholic

If you are full on fuel, coolers, people etc, this may diminish the speed, Are you using wish-o-meter or GPS?

As far as running, use a little tab and play with the drive angle, this will help your handling, There is a sweet spot, you just need to find it. Also if they are stock props, they are not that far off for the RPM's It may have a low x as well?

That is why people play with the props etc...

A.O. Razor

Just found this.

Test Results
Test Power: 2 x 425-hp MerCruiser Mag
RPM MPH Knots Total GPH MPG NMPG Stat. Mile NM KM KPH LPH KPL dBA
700 4.7 4.0 3.5 1.34 1.17 224 195 360 7.56 13.2 0.57 68
1000 6.3 5.4 6.0 1.04 0.91 173 151 278 10.14 22.7 0.44 77
1500 9.7 8.4 9.8 0.98 0.85 163 142 262 15.61 37.1 0.42 88
2000 16.6 14.4 16.7 0.99 0.86 165 144 266 26.72 63.2 0.42 82
2500 19.3 16.8 19.7 0.98 0.85 163 142 262 31.06 74.6 0.42 84
3000 37.2 32.3 23.8 1.56 1.36 259 226 417 59.87 90.1 0.66 87
3500 48.8 42.4 32.4 1.50 1.31 250 218 402 78.54 122.6 0.64 89
4000 55.9 48.6 42.8 1.31 1.14 218 189 351 89.96 162 0.56 92
4500 64.2 55.8 54.5 1.18 1.02 196 170 315 103.32 206.3 0.5 93
5000 72.5 63.0 67.0 1.08 0.94 180 157 290 116.68 253.6 0.46 97

Speeds measured with Stalker ProSports radar gun.


Test Conditions
Time To Plane 3.4 sec.
0 to 30 7.1 sec.
Test Power 2 x 425-hp MerCruiser Mag
Transmission Bravo I
Ratio 1.5 : 1
Props 15 1/4 x 28P Bravo 1 4-blade
Load 3 persons, 1/2 fuel, no water, minimal gear
Climate 88 deg., 59% humid.; wind: 8 mph; seas: 1' chop

So if it's running 26" props, something is way off. Apparently 28" are the stock props. Do you know what the drive ratio is or seen the condition of the props?

36Envision

Boat had 2 of us in it and my wife probably only counts as a half person at 5'1" and 110 lbs! 3/4 fuel level, nothing else in boat, played with trim/drives all day and was in 1'-2' chop. Still 4200 RPM and 62 MPH on "wishometer". Props are actually 28" I was wrong on 26" in prior post. Props are not banged up. I did find out last night the boat has been in storage for 2 full years!! Could be the root of the problem??

A.O. Razor

If the boat has been in storage for that long, I would think there could be a fuel delivery problem. How are the fuel filters/water seperators and is it fresh fuel in the tank? If it was me, I would change all filters, sparkplugs, oli and impellers. Then check if the fuel pressure is ok. If there is something blocking, fuel pressure will be too low for the high rpm's. Check tach's and throttle system too. The interesting thing is, that it is both engines. If it was engine related, it would most likely be one engine and not both, therefore I'm thinking if both engines can't get enough fuel from the tank, they would both starve at the same rpm's.

A hook in the bottom from improper storage can also cause bad handling and slow speed.

Anyone else got an idea?