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Old 07-18-2017, 01:25 PM   #11
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6 adults? Coolers? Weight needs to be moved forward.
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Old 07-18-2017, 09:34 PM   #12
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RandR,

What props are you running? When I do get on plain (with a lighter people load) it doesn't happen until ~25-27mph, but my top speed is ~40-45mph.

mmwjr,
Hopefully this weekend (weather permitting) I will do the RPM/Speed checks with just me and my wife on board. Then time permitting I will load it up with ~6 adults and repeat. Sorry, don't have this data yet and I know this is crucial to analyzing the problem.

Others, I have played with trim tabs and outdrive trim at various positions with no real help. The trim tabs do a great job keeping the boat level as needed, so I know they are functioning properly. Also, once on plain I have played with the outdrive trim and they also function properly (get a slight bump up in speed when at WOT and trim the outdrives up a little from full down. I have also played with rolling on the throttle verses WOT straight away and it seems the more throttle the better, but not the fix. Compression was good when I bought the boat, had tuned up and that helped a little early on, have fresh fuel filters, clean bottom, just normal gear loaded, clean flame arresters, and checked to ensure throttle cables were opening the throttle plates in carb fully (they were fully open). My son-in-law just bought a 32' 2005 Rinker with twin 350's and with more people and gear on board than I'm talking about jumps right up on plain, but tops out at 38-42mph.
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Old 07-18-2017, 10:41 PM   #13
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When you say your boat is "not planing," what specifically is it that you are describing? Is the bow pointed way up in the air and the stern squatting into the water and bogging down? That would be typical of a boat that can't get out of the hole and is stuck on its own bow wave.

Your boat is "on plane" at any speed where it is moving across the surface of the water faster than its hull speed, which for a 3300 SCR is around 7 knots (8 mph). From 8 to around 15 mph, you are moving at semi-displacement speed. Beyond that, you are skipping over and outrunning your bow wave, which is pretty much the definition of "planing." So if you can get the boat up to 25 mph, it is "on plane," even if it doesn't feel like it. At 20mph with a 33 foot waterline if you were not planing your bow would be pointed essentially vertically into the sky and your engines would be straining gigantically to maintain that attitude. My boat may feel like it's going slow and bogging, but is still planing at 16 knots (a difficult speed for me to maintain unless I'm facing head currents).

If you can get to 40-45 mph at WOT, then I don't think you really have serious engine or outdrive problems. That's fairly respectable. I think I've had my boat doing 36 knots....ONCE.

You've got more horsepower than your son-in-law's Rinker in a similar-sized boat (roughly 12,000 lbs dry weight with a 32' waterline and 11' beam). You even have the same amount of deadrise as the transom (17-18 degrees). So it should be at least as fast.

Have you checked that the Bravo 3 outdrives are actually working as they are supposed to? Both props on each turning at full power and balanced?
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Old 07-18-2017, 11:28 PM   #14
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ertyqway,

Thanks for the reply. You raise a good point that when the boat is lightly loaded (i.e. my wife and I) and I can get on plain is ~10-15 seconds, but once on the boat moves really fast, so no serious engine or outdrive issues . With 6 full size adults the stern squats down and the bow is really high (tough to see over) - ~10-15mph and it just will not push through this and get on plain (i.e. 20-25mph).

What do you mean when you say, " are the outdrives actually working as they are suppose to"? How would you test if both props are turning at full power? I haven't had them balanced.
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Old 07-18-2017, 11:44 PM   #15
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I'm not really sure what I mean. ;-)

Bravo 3s use two counter-rotating props. Are they both rotating at the same speed? Are they running without vibration and in balance? That kind of thing.

The additional detail you give on problem tells me it's probably a loading issue. When you've got a bunch of people in the cockpit, you're heavily stern-weighted. In that situation, you need to shift your trim tabs down a fair bit more to get on plane. This may be exaggerated if you also have additional weight items in the cockpit or engine compartment (e.g. a built-in generator). Move as much weight as you can to the nose of the boat (storage compartment under the forward berth when you know you're going to have a bunch of people on board.

.... or tell some of your guests to get out on the bow pulpit to get the nose down. ;-)
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Old 07-19-2017, 01:44 AM   #16
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I don't know the exact numbers. But I can check next time I get to the Marina. They are stainless steel
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