Still porposing

[tahitijet]

Ok I dropped the ride plate from 5* up to 1.5* up. in .5* increments The porpoise got better each time but never really cleared up. I installed a MPD loader this week and Jack told me 1.5 was way to low and i needed to get back up around 4*. So i put the loader on and plate to 4* up. Boat handled the mild chop better but on smooth water still porpoises at speeds over 50mph. I still have to keep the place diverter in full down to have any amount of driveability. even 1 notch up starts a porpoise. Seems like even at full down the bow is ridding really high.
Anyone have any thoughts?
thanks

[Cas]

what's the bottom of the hull like? any hook or rocker?

[tahitijet]

No.. bottom is blueprinted.. jack seems to think that may be some of my problem because i got it to straight.
boat also has Wedge 2* up, Berk Droop, back cut shoe, and setback pump (intake is set at 4*).
Also another thing i noticed that i thought would clear up with the loader but didn't is the porpoise gets so bad that it will cavitate very easy.
I'm Thinking 2 things.. the boat is running to high in the water and is carrying the Bow to much. At full down diverter the bow seems to have a up angle to it. I'm thinking if i could get the boat to carry the bow at that height with the diverter straight it would allow the transom to settle down a little instead of having all that help from the down angle pushing up on the transom and down on the bow. Not to mention it would probably be a lot quicker. with out all the extreme angle changes.
thanks

[RCB19]

Try taking that 2* up wedge out. Or will this cause your droop & diverter to drag in the water? Most boats need to wedge the droop down for best performance.

[Squirtin Thunder]

Is this a drag boat ???
If not, I will tell you that 4* up is way too much, on most hulls you will get a porpoise and then add 2* up wedge. Holy hell, your trying to drive the thing to the moon. Here is my recommendation: Set your rideplate at 2*, put your 2* wedge so that the big part is on top, this is called down wedge. I will bet my bottom dollar that this cures your problem or atleast makes a night and day difference. If it helps try 3* down wedge, now remember to have your GPS with you at all times during this testing process.
Good Luck !!!
Jim

[Cas]

yep, gotta agree with the last 2 posts. I was thinking ride plate at 2º and removing the wedge as a place to start or at least see what happens. As Jim said, have your GPS with you so you can see what each change does to your mph.

[*BN*]

Same thoughts we discussed on the phone.

[MikeF]

Same thoughts we discussed on the phone.
Was gonna say that earlier. He might need some of those trim tabs to settle it down.
Looks like it could use some training wheels. ;) :D

[olbiezer]

u got to get that nozzle down i agree with the other posts to reverse your wedge and start over again on the plate ...but start at level not 4 up

[flat broke]

Ok I dropped the ride plate from 5* up to 1.5* up. in .5* increments The porpoise got better each time but never really cleared up. I installed a MPD loader this week and Jack told me 1.5 was way to low and i needed to get back up around 4*. So i put the loader on and plate to 4* up. Boat handled the mild chop better but on smooth water still porpoises at speeds over 50mph. I still have to keep the place diverter in full down to have any amount of driveability. even 1 notch up starts a porpoise. Seems like even at full down the bow is ridding really high.
Anyone have any thoughts?
thanks
How fast is the boat at WOT and does it porpoise at that speed? As other's stated, pull the wedge and see what happens, if the issue persists, flip the wedge for down angle and document all of your changes in a journal noting water conditions, speeds and RPMs. One thing to note is that you may find that your max WOT speed is best when the boat has a midrange porpoise, so it may come down to you deciding which is more important. I don't think that all by itself slackening the 4* setting on the plate is the magic bullet that will cure your ill.
Good luck with it.
Chris

[tahitijet]

Ya BN i talked with Jack today and he brought up a few points that we talked about. I'll be ordering tabs from him next week (he said to set them up exactly how you told me you did).
Flat broke not sure how fast since adding the droop and plate i haven't been able to get rid of the porpoise enough to drive it.. It starts in the 50's and begins cavitating in the 70's and the porpoise gets so bad you almost bounce out of the boat.
my feeling was always the wedge was hurting me but if I flip it I think i'll be draggin my hardware. I guess i'll start buy just pulling it out and seeing what happens.
I'm curious about the 2* on the plate everyone is recomending now.. Everyone i've every talked to and guys with similar boats have always said 4-5 up on v-bottoms..
Jack also brought up a very big point that i was worried about last year but forgot all about till today. When i did my setback.. I moved the motor back. That in combo with the bottom being to flat he thinks is a major factor. I guess i'll be moving the motor forward 4" and mine as well add a jet-a-way while i'm at it.
thanks

[MikeF]

Jack also brought up a very big point that i was worried about last year but forgot all about till today. When i did my setback.. I moved the motor back. That in combo with the bottom being to flat he thinks is a major factor. I guess i'll be moving the motor forward 4" and mine as well add a jet-a-way while i'm at it.
thanks
BN, How far from the transom is your engine measuring from the inside/bottom of your hull? Are your hull bottoms identical? Trying to ask the right questions. :)

[stillgoin]

Had this problem a couple of weeks ago. Took out 4 deg wedge. made all difference in world. Still had enough up in droop and diverter to adjust for a nice ride at all speeds. I just don't have the roost that hits the clouds anymore.

[*BN*]

IMHO,
His problem is compounded by the amount of transom lift he has in the hull.
If he try's to trim the hull for the proper bow rise, the transom is not being planted due to the lifting strakes under his hull. in other words he doesn't have the power to carry the entire hull as high as the hull "wants" to ride.
If he were to add the plates in the back and just put them dead flat with the hull on insides and down a 1/16" on the outsides this should "allow him" to use the ride plate plate and diverter to "plant the transom". (4 degree up on the plate and approx. 6 degrees up on the nozzle)
I had exactly the same problem described above and between 70-90 mph it would porpoise out of the water. JUST adding the plates and lowering the outer edges of the plates a 1/16" solved all the problem. Could make 94 mph passes from Roadrunner to Bransons ALL day long (About a mile).

[Squirtin Thunder]

Who in their right mind wants to run 94 mph in a Tahiti ???
That's scary shit !!! :2purples:

[*BN*]

Who in their right mind wants to run 94 mph in a Tahiti ???
That's scary shit !!! :2purples:
I think most of us here have both left and right minds.....it makes it easier.
Those of you with only the right mind, please stay on the BEACH! :eat:

[XClutchboy725]

Let us know how the tab deal turns out. I think I have the same problem. :cry:

[tahitijet]

Thanks guys this is great info.
IMHO,
If he try's to trim the hull for the proper bow rise, the transom is not being planted due to the lifting strakes under his hull. in other words he doesn't have the power to carry the entire hull as high as the hull "wants" to ride.
I don't think it's a lack of power issue. :rollside:
Did you sale your boat? Do you know where the motor was placed? just curious to compare. I know the rear nuts on the loader sit flush with the flexplate cover on mine. I pulled a 455 olds out of the boat when i got it and dropped the 540 in 4 years later. So i have no clue if the motor is anywhere near proper for chevy placment in these boats.
Who in their right mind wants to run 94 mph in a Tahiti ???
The bottoms on both mine and BN's boats were copys of the southwind bottom. I think the only differance between my bottom and BN is i have full length strakes closest to the intake and I Think his were cut off ahead of the intake. Pending getting this porpoise taking care of which We will We should be running right in the 90's

[*BN*]

Thanks guys this is great info.
I don't think it's a lack of power issue. :rollside:
Do you know where the motor was placed?
The bottoms on both mine and BN's boats were copys of the southwind bottom. I think the only differance between my bottom and BN is i have full length strakes closest to the intake and I Think his were cut off ahead of the intake.
TJ, Don't get me wrong when I say not enough power...... trust me it would have taken a Blown Fueler to carry my hull at the attitude it wanted to run. That is to say there are ways to get the hull to run really high in the water but it takes mega power. Somebody probably could post a pick of Going Places at 160mph. That hull is really high but also has a earth mover bucket for a loader. LOL
I will find a pick of my motor location.
Yes, my center strakes were removed approx 12" forward of the intake.

[tahitijet]

ok well I've made probably a dozen small changes to the boat since i started playing.. Removing the wedge made the most noticable differance no doubt.
I removed the wedge all together, went to 4* up on the plate and the boat ran better. boat would run good at 2 notches up on the diverter at 3 it would run great and you could feel it speed up and release from the water but any slight change in the water would start a porpoise. I dropped the ride plate in 1/2* increments down to 2*.. at about 3* it worked best with 2 notches up on the diverter.. it would take almost all water conditions with no porpoise at cruise .. any other setting(below or above on the diverter) or at increased speed it would cause a bad porpoise.
By the way at about 4 notches up on the diverter handle is where it throws a 4-5 foot roost
This boat definatly does not like 2* up on the plate. At 2 up it would bow steer and porpoise at the same time??????
I"m going to put the wedge back on and wedge it down this time start over at 4* up and work down and see if i can work this out or at least get it close before the trim tabs get here.
The amount of differance it made from wedge 2 up to no wedge 2 down is looking promising. The transom definatly feels more planted and i can't feel the hardware dragging anymore and the left pull is gone. Thanks everyone for the advice

[Old Guy]

I would try a longer ride plate. Also make sure the ride plate is flat and can't bend.