Russ Johnson...1990 HST with Mercury
This 1990 HST was purchased in January of 1999 - I am the third owner. The hull was originally ordered from HydroStream to hold an OMC V8, so it is heavy; with driver (205lbs), ½ tank of fuel and the 2.5 it weighs 1950lbs.
Since purchasing the boat I have rewired, added pyrometers, and replaced most of the gauges, steering cables and fuel tank. I fabricated the trim gauge, setback plate, whale tail and added a 2 gallon catch-can with Holley Red fuel pump, onboard charger, fittings for 2" hoses so they are mounted to the cowl, and a windshield just enough to keep the wind out of my face.
I worked on setup the first summer ending up at 15" back and 1-½" above the pad for top speed. It is necessary to use the trim and jackplate all the time to keep porpoise out. At speeds below 70 the bow needs to be held very high if you want to keep the performance up.
In September I installed a new 300X. After three weeks of small problems it now runs great. I’m still trying to find the sweet spot for setback. I started at 11" after calculating the weight difference and the boat had a tendency to climb up on the prop and rock and at 105 MPH it’s not a good feeling. I came in to 6". The boat gets out of the hole with less bow rise, but is much harder to keep the porpoise out. It can start at 85 where as with the 11" setback it never happened over 72. Time to try a little more. There is always something to do.
So far the 300X is at least 10 mph faster all the time and it pulls harder and has more top end. The torque is tremendous - anytime you want to catch the bow (rollers or boat wakes) all you do is step on it a little and it lets the bow down softly. So far I have seen 104 MPH at 6470 rpm with still more dialing in to do.
I’d like to thank Mark for his interest in my boat and IHR.
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