311...porpoise...
09-19-2016, 11:14 AM
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311...porpoise...
My 89 311 has 330hp and I bought a set of hydromotive 24 pitch 4 blades and put them on before I ever ran the boat. So wide open full of fuel it only turns 4000 rpm...but once it gets lighter on fuel I can turn the motors too around 4200. Problem is once I start trimming out it had a horrible porpoise...I guess either the boat just isn't fast enough to run through the bouncing or the props are causing it. Who has ran bravos on their boat? Any issues with them? Also boat only runs 60mph wide open. Thinking I may need to drop to a 22 pitch. Problem is I love the cruise speed with the 24s and it comes on plane with no issues...
09-19-2016, 11:30 AM
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If you porpoise while trimming out, I would just trim back in a bit until it stops . . .
You also might be a little over propped, since your RPM is not quite up to spec.
You also might be a little over propped, since your RPM is not quite up to spec.
09-19-2016, 10:53 PM
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My 292 does the same thing. I just tested some hydro 24's on mine so see if I would lose the porpoise but nope- same as the bravo's. The Mirages porpoised the least of all the props I've tested. Now the big difference is I've got 1300 hp now, so once I hit 55 I start trimming up. Then the boat gets loose and really feels great. At 60 the boat is just starting to come to life. find a set of 23 Mirages and test them out. Get a set of non-pluses. Your hull will like them better than the Mirage Plus props. That should allow to you get close to the 4500 rpm mark. You are over propped now.
09-23-2016, 06:40 PM
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