porposing bow issue?? - Maxum Boat Owners Club

spud123 · 08-16-2010, 10:35 PM

i have a 2008 maxum 2900se twin bravo3 ,305 cu in . no problems getting up on plane, no problems using trim tabs to get a side to side level ride, if i am going above 25mph @ 3300rpm , i have a hard time keeping the bow tilted up using the outdrive tilt controls . i am only trying to cruise at a more efficient angle so i don't push the water.
the engine tilt gages barely regester off zero degree angle . i have tried giving more rpm when the porposing starts but not really helping?? any ideas.

seapuppy · 08-17-2010, 01:51 AM

well..with a b3 drive at the pivot shaft..there is a spacer down there that is called a celery stick...it prevents the drive from coming down too far...
what that limits is the amount of up trim needed to free up the boat and get the bow up...one or two hits on the drive trim button and your cavitating...have the shop change the setting of the celery stick...
with that said....when you trim the drive up in some conditions and loads..the boat will porpose at certain speeds...
My 2700 did that too with full up tabs and the drive trimmed up some which caused it to porpose like crazy...so..what is the fix...bump the drive down or drop the trim tabs a touch or two until the bouncing stops....

SP

tackleshep · 08-17-2010, 03:44 PM

Have you tried putting a couple of fat women in the bow? Just saying

seapuppy · 08-17-2010, 05:14 PM

don't forget to post pictures of the mod to your bow....(ie women

)

Sp

dragoy · 08-17-2010, 08:47 PM

Lets not turn this into any kind of Green Peace post,,, (I.E. save the whales,,,) LOL On a more serious note, I have noted the same with my 2700 SCR. Like SP said, just a slight touch on the outdrive trim (down) takes care of it.

Nils

cj · 08-17-2010, 11:02 PM

My 2400scr does the same thing, even worse after i added and extended swim platform. Running a bit of tab helped a bit but really slowed me down..........I decided to try......now don't hate me.....but i put on a fin and it totally cured the porpoising issue. Now I can run a full 42mph with the tabs up and trim for the conditions. My last boat had over 700hrs on it with a fin when i sold it, and the fin never caused me any drive "strain" issues like everyone talks about on the forums, only four little holes.....just my two cents...
Cheers

ed & inge · 08-18-2010, 07:30 AM

hai cj,

what sort of a fin did you install ?

txs, ed

cj · 08-18-2010, 02:03 PM

I installed one of those hydrofoils on the leg. Can't recall the brand name?
Cheers

capav8r · 08-24-2010, 03:03 AM

My 2600SE (2006) does the same thing if I try to go too fast!! If I pull the tabs all the way up and trim the drive up much at all, it will start to bounce even on glass. Leaving the tabs down some and leaving the drive most of the way down stops/prevents it. Right on the edge of starting to bounce, I show 42 on the speedometer. 350 mag efi/bravo 3.

Also, well before reaching the up limit on the drive, I get a vibration from the drive. Any idea what that is? Cavitation? I bought the boat with 19 hours on it and it has done it since I have owned her. It was out of warranty, so would have taken it in but since it is out of warranty, I just don't trim it high enough to vibrate. I would hate to think that it is a u joint....

ss3964spd · 08-24-2010, 02:30 PM

Definately sounds like a u joint Cap.

Dan

seapuppy · 08-24-2010, 05:15 PM

you need to have the alignment checked...if the engine and drive isn't pretty much straight..it will vibrate....

SP

iceman · 08-24-2010, 07:11 PM

I also have an '06 2600SE, and I've noticed vibration at times. The first time I thought it was a helicopter overhead! It's happened a few times and seems to go away on its own. Now I'm wondering if I need to have it looked at by a mechanic. Is a U-Joint a big $$$ job? Something I need to get fixed immediately, or can I let it ride for awhile?

seapuppy · 08-24-2010, 08:07 PM

the way to tell if your u-joint is going out is to crank it over in a hard turn....all the way over...if your hear growling or noise in the back of the engine only in turns..it's a u-joint.....bout the only thing to do is pull the drive and replace the u-joint....it's not a hard job and will only take about 2 hrs to do with a good mechanic....

parts are about 50 bucks and the time for the mechanic to pull the drive..take the old one out and stick the new one in...a little beating and cohersion maybe needed but it doesn't take long..

SP

iceman · 08-24-2010, 08:43 PM

Thanks SP, I'll try that next time we're out. Do we need to be at planing speed, or is displacement speed good enough to hear the noise?

Didn't see your note about alignment earlier, guess I can have that checked. I'm hoping I can wait until the off season.

capav8r · 08-25-2010, 02:20 AM

Thanks SP, it does not make any noise or have any perceivable vibration at full turns under power. Only when I trim up too much. I did check the length of the rams the last time I had it on the trailer and they were dead on spec. I would estimate that the vibration starts about half way to the limit stop.

ss3964spd · 08-25-2010, 02:43 PM

Quote:

Originally Posted by seapuppy

the way to tell if your u-joint is going out is to crank it over in a hard turn....all the way over...if your hear growling or noise in the back of the engine only in turns..it's a u-joint.....SP

Thought that was the test for the gimbal bearing Steve?

seapuppy · 08-25-2010, 04:36 PM

nope...gimble bearings give a growling noise that gets worse in a turn at slow speeds....you can always tell a gimble bearing is going out when it starts to growl...

SP

ps...I found out the hard way that mine were going out.....

spud123 · 09-03-2010, 07:16 PM

thanks for all your suggestions, i found the fix. well at least for my 2900se, before i accelerate from idle i lower the trim tabs 5-6 indicator lights. once i am up on plane i have a lot more ability to raise the bow using the engine trim with out the bow porpoising .

swampy2646 · 09-21-2010, 04:14 PM

two 75lb. sand bags in my front v birth helped with my 1991 2500 scr