Audiofn

How much HP do you have for your motors? Are they 420hp 502's or? If they are 420's then IMO you are spinning way to much prop. Try a 23 or 25 at most. 23 on mine was more user friendly for day to day but my 25's gave me a little more top end. Thing is to get that top end I really had to trim it out like crazy. I can not imagine any more pitch then that. Try a plus 23. Again this is assuming a 420hp motor or close to it.

TomZ

iTrader: (2)

The 502s are the 415 variety (415, 425, 430 depending on who you ask... regardless... more torque than a 420). I had 23 Mirages on her, and she'd peg the rev limiters. Best I could get out of her speedwise was 65-66. Again, she would bang the limiter way too early hence the move to the 27s that I had access to.

I did some testing this evening... results in the next post.

TomZ

iTrader: (2)

Took the boat out this evening and here are some observations... I took a voice recording after my testing, and for the most part, below are my findings.

Fully tucked in, the indicator is at the slash between 0 and 1.

Getting on plane is no issue.

Tests conducted at 3-3200 rpm.

If I run the trim up in large bursts, I get ridiculous porpoising. The boat will porpoise so bad that she'll begin to get the drives out of the water enough to unload the props.

Restarted the test...

If I slowly bump up the trim, I can alleviate the severe porpoise, but I mean it has to be a "tap tap" on the buttons. If I miss, she starts the cycle all over, and I have to tuck the drives in to get her under control. With this method I can get to neutral, but the steering becomes extremely vague. Steering inputs are delayed, and she feels loose. Looking out the back, she's throwing a steady prop stream with a near parallel pattern out about 100 feet behind the boat.

Neutral is at the slash between 4 and 5.

I can get beyond the neutral point, but I have to tap the trim incrementally, and increase the throttle. I took her to about 4200 with this method but ran out of room.

I think two things are hurting me.... nose cones and props.

Thoughts?

stlliberator

iTrader: (1)

At 3200 if you trim the boat too much it will ALWAYS porpoise. There isn't enough power to carry the nose. There is no need to trim it that much as those rpm. When I'm at those rpms I hardly ever will get the trim past 1-2... I use more input with the tabs.

I think your your indicators are wrong. It should not throw a rooster tail at neutral trim. Almost scientifically impossible actually cause the prop shaft is neutrality inline with the bottom of the boat which actually is still at a downward angle cause of the way the boat runs in the water. If it is feeling loose that means the boat is starting to lift, but it shows Ike feel really lose at 3200rpm. Not going fast enough to get these heavy pigs out of the water at 40-50mph..my boat actually has a slight twitchy feeling at these speeds and any steering input is very noticeable.

Nose cones should not cause a porpoise.

TomZ

iTrader: (2)

I just got back in from looking it over again. Using a straight edge, the drives are level/neutral at 4-5 on the indicators. We looked it over THREE TIMES. All three times, same results.

To clarify... I never said the boat was throwing a rooster tail. The propeller stream was in the water (as you would expect to see behind the boat while running). I have never produced a rooster tail with this boat even with the trim up at the edge of the indicators.

I agree on the twitchy feeling. That's exactly what I'm experiencing. On another front, I found that the steering is very loose at the transom assembly. We held the tillers and tested movement; the drives are tight, and the play is at the actuator. I'll need to get in there and investigate/fix.

I'll post more later... I'm late leaving the office for an appointment.

Audiofn

Tom, Quick question was the condition this bad when you had the 23's? You will NEVER see a rooster tail with a 311 and TRS drives. If you do make it go away because you are about to blow your drive. ;-) I am almost positive you have a set of props that do not agree with your boat. The fastest props I had for my 311 were 25 mirage pluses that were labbed by BBlades. They got me to 72mph best speed and 70 all the time on GPS. That is about the best you will see with one of these boats. I may still have them and could work something out with you if you want to try them or even buy them. They won't work on my 353. have you tried a WOT run yet to see what it will do? It must be so slow out of the hole with the 27's. I know going from the 23's to the 25's was a huge difference on my boat as far as speed out of the hole.

TomZ

iTrader: (2)

I'm definitely interested in the props... if you could shoot me a PM with details, I'm sure we can work something! Thanks!

I've never seen a rooster tail with this boat. Best I've had her to speeswise is 69.8 on GPS... this was in a light chop out in the Currituck Sound (NC). She doesn't seem too slow out of the hole; I'll time her next time, but she gets right up fairly well and is comparable to the Cig Bullet when it had the same props. I'm sure the torque of the 502s is helping a great deal. The 23s planed a little quicker, but not by much. I only ran them a couple of times before I swapped... the boat porpoised similarly.

Audiofn

Your old props were 23 mirages? So odd. Would be interesting to see if maybe you have more rocker then most in your hull. If you put your strait edge on the bottom of the boat is it flat or is there rocker or hook? Also just grasping at straws but turning props in or out and have you checked your drive alignment? Just for reference my boat was a 98 with 420hp 454's so we should be almost the same numbers and performance. I am on my way out door so have to run but did you say you had nose cones on there? I had my boat with and with out nose cones and I felt it was better with out them. I believe I was turning in but will have to try and make sure of that for you.

RGPIII

If you know someone with a set of bravo 1 4 blades I would suggest trying those for sure. You will love the difference the 4 blades make. Also are your props spinning in or out? mine porpoised pretty bad when i bought it. the props were spinning in. since the switch to spinning out, the boat is much more stable, and rides so much better. I can trim up with no porpoise until about 4-5 at 3200 rpm.

TomZ

iTrader: (2)

I'll break out the straightedge to check it out. How far forward should I be looking? There is no hook in the hull; I've already check that. She's perfectly flat for the first three feet.

The props are turning out.

I have not checked alignment (I mentioned in another thread that I would), but I've gotten information from all over the place about what it should be. They are set very much toe-in at this point (by my eye), but the prop streams seem to be where they're supposed to be; I'll check this weekend. If I'm reading right, I should be slightly toe-out (1/8 to 1/4 inch) on the bullet compared to the prop shaft. I read something where Formula changed their set up to dead even/parallel, but I only read that in one place.