Porpous issues

« **on:** June 23, 2010, 11:55:50 AM »

This is what I got:

76 sanger super jet
Berkely pump
Droop
Place diverter

I am having a hard time getting the boat to not porpous. This happens throuout the speeds (slow & fast). It gets to the point at higher speed that the boat will loose contact atvthe back causing the pump to suck air. I made a ride plate the goes about 2" past the bowl and got the angle damn close to what I was told by JBP. What am I missing here, it's just not doing what I want... I am looking for some experianced advise.

Thanks-

« **Reply #1 on:** June 23, 2010, 12:03:46 PM »

get rid of the droop and put either a straight snoot style droop on it or one of the Place HPH units.

« **Reply #2 on:** June 23, 2010, 12:05:01 PM »

i dont know what it is with sangers and porpoise issues! seems like alot of people are chasing their tails with them...it only seems to be the jets though! i would do a search and see how everyone else is set-up! have you tried it without the droop at all?

« **Reply #3 on:** June 23, 2010, 12:21:35 PM »

Yes, It was a problem before the droop. I guess I will continue to adjust the ride plate. What about making it longer? Smaller adjustment should be more obvious right...

« **Reply #4 on:** June 23, 2010, 12:24:19 PM »

Another problem I am having is getting the transom to seal up. I used a GE silicone but it removed the paint from my bowl and all fell off. I know it was clean because it was new and I am agro when it come to that shit-

« **Reply #5 on:** June 23, 2010, 01:24:43 PM »

Quote from: Luckie Stiff on June 23, 2010, 12:03:46 PM

get rid of the droop and put either a straight snoot style droop on it or one of the Place HPH units.

What is the reason for taking the droop off?

« **Reply #6 on:** June 23, 2010, 01:29:43 PM »

Well since it happened before and after the droop, nevermind.

« **Reply #7 on:** June 23, 2010, 04:55:42 PM »

Be sure and inspect the intake area of the bottom of the hull, look for cracks and such around the epoxy joints (for reasons of flexing in the pump) this flex could be causing both the difficulty in getting a good seal (silicone blows for this BTW) and the porpoise problem...

I would try some wedging, but not the traditional method of adding wedge, try up wedging about 7* if not already....You will have to play around with it to get an idea of what it will do...

Also make sure you don't have too much weight in the ass end of the boat.

Do you have a loader? This may give issues also.

GT

« **Reply #8 on:** June 23, 2010, 08:05:40 PM »

Quote from: GT Jets on June 23, 2010, 04:55:42 PM

Be sure and inspect the intake area of the bottom of the hull, look for cracks and such around the epoxy joints (for reasons of flexing in the pump) this flex could be causing both the difficulty in getting a good seal (silicone blows for this BTW) and the porpoise problem...

I would try some wedging, but not the traditional method of adding wedge, try up wedging about 7* if not already....You will have to play around with it to get an idea of what it will do...

Also make sure you don't have too much weight in the ass end of the boat.

Do you have a loader? This may give issues also.

GT

No loader, I will try wedging. What should a guy use if silicone is not the best choice?

Thank you for the input, I appreciate it.

« **Reply #9 on:** June 23, 2010, 09:31:32 PM »

Quote from: Jetboatunderground on June 23, 2010, 08:05:40 PM

No loader, I will try wedging. What should a guy use if silicone is not the best choice?

Thank you for the input, I appreciate it.

Semi permanent

http://www.shop3m.com/60980042810.html?WT.mc_ev=clickthrough&WT.mc_id=shop3m-AtoZ-Marine-101-Sealant

Pretty damn permanent...

http://www.shop3m.com/60980045581.html

A loader will help out IMHO.

GT

« **Reply #10 on:** June 24, 2010, 05:16:46 PM »

Do you have a diverter yet? Most people with Sangers use the diverters to get rid of the porpoising. It works with mine and thats what I have read in the past.

« **Reply #11 on:** June 24, 2010, 05:51:53 PM »

Quote from: Leadsled on June 24, 2010, 05:16:46 PM

Do you have a diverter yet? Most people with Sangers use the diverters to get rid of the porpoising. It works with mine and thats what I have read in the past.

He states he has a diverter in his first post.

« **Reply #12 on:** June 24, 2010, 07:09:32 PM »

Which Place Diverter do you have?

Old or new style? The old style (has a Berkeley style nozzle) will kick your ass....

Just my humble opinion.

« **Reply #13 on:** June 24, 2010, 07:11:29 PM »

When you say try to wedge the pump how do you do that?

« **Reply #14 on:** June 24, 2010, 07:19:44 PM »

Quote from: dirtbag1 on June 24, 2010, 07:11:29 PM

When you say try to wedge the pump how do you do that?

Yank it's underwear clean up it's ass

Hee Hee..

Where the Droop mounts to the bowl, you can install aluminum (or carbon fiber. even plastic) wedges to angle the entire Droop. Standard wedges are 7* so you can use two and clock them to get the desired amount of up or down angle.

It sounds wrong as hell, but he should wedge "up"...

GT

« **Reply #15 on:** June 24, 2010, 09:16:19 PM »

Quote from: Jetboatunderground on June 23, 2010, 11:55:50 AM

This is what I got:

76 sanger super jet
Berkely pump
Droop
Place diverter

I am having a hard time getting the boat to not porpous. This happens throuout the speeds (slow & fast). It gets to the point at higher speed that the boat will loose contact atvthe back causing the pump to suck air. I made a ride plate the goes about 2" past the bowl and got the angle damn close to what I was told by JBP. What am I missing here, it's just not doing what I want... I am looking for some experianced advise.

Thanks-

Mike , gotta a hunch that the boat may end up needing some trim plates at the back to help control this my last Sanger was similar (bounding porpoise) and what finally helped it was a small amount of "hook" (created by the plates) at the stern Tom

« **Reply #16 on:** June 25, 2010, 09:05:40 PM »

Quote from: GT Jets on June 24, 2010, 07:09:32 PM

Which Place Diverter do you have?

Old or new style? The old style (has a Berkeley style nozzle) will kick your ass....

Just my humble opinion.

New style

« **Reply #17 on:** June 25, 2010, 09:07:40 PM »

Quote from: jet boat performance on June 24, 2010, 09:16:19 PM

Mike , gotta a hunch that the boat may end up needing some trim plates at the back to help control this my last Sanger was similar (bounding porpoise) and what finally helped it was a small amount of "hook" (created by the plates) at the stern Tom

I am going to try calling you Saturday if you are around-

« **Reply #18 on:** June 25, 2010, 09:34:21 PM »

Quote from: Jetboatunderground on June 23, 2010, 11:55:50 AM

This is what I got:

76 sanger super jet
Berkely pump
Droop
Place diverter

I am having a hard time getting the boat to not porpous. This happens throuout the speeds (slow & fast). It gets to the point at higher speed that the boat will loose contact atvthe back causing the pump to suck air. I made a ride plate the goes about 2" past the bowl and got the angle damn close to what I was told by JBP. What am I missing here, it's just not doing what I want... I am looking for some experianced advise.
Thanks-

Do you have any pics of the ride plate you made ? How long, how wide, how thick, how is it mounted to the hull, how/where are you adjusting it, did you add any bracing to it to stop flexing ?

What angle do you have it at ?

Did your boat have the short wide factory plate with 2 turnbuckles to adjust it ?

« **Reply #19 on:** June 27, 2010, 06:03:40 AM »

Could we get some pics of the back of the boat, the pump, ride plate and the hull itself? Sangers seem to have used a couple different style bottoms on thier Superjet

« **Reply #20 on:** June 29, 2010, 08:09:13 AM »

Quote from: jrork on June 27, 2010, 06:03:40 AM

Could we get some pics of the back of the boat, the pump, ride plate and the hull itself? Sangers seem to have used a couple different style bottoms on thier Superjet

« **Reply #21 on:** June 29, 2010, 08:19:04 AM »

Where's the other turnbuckle?

Ray

« **Reply #22 on:** June 29, 2010, 12:55:44 PM »

Took it off to measure it. I am too close to maxing out the threads so I'm getting longer ones-

« **Reply #23 on:** June 29, 2010, 02:10:44 PM »

Aiight. I gonna take a stab at this, since it's been cess-pooling here a bit anyway, and an idiots opinion is better than no opinion. (My mamma taught me that....good huh?)

First, I think you're right, the ride plate is inducing a "false" rocker to the boat, its WAY to high. Looks like it needs to come down maybe as much as an inch at the rear.

Second, I would hook those turnbuckles back up to the fasteners on the transom, right beside the bowl. Just me, and splitting hairs here on it, but there's going to be flex no matter where, but there, it's triangulated better, for one, and if the entire pump is flexing, it may offset that somewhat.

Other than that, yeah, trim tabs might be the way to go.

Ray

« **Reply #24 on:** June 29, 2010, 06:16:40 PM »

X2, those boats had the little factory plate to control the porpoising issue (it was probably set downward from the factory). With that longer plate you have made it way more sensitive to plate angle. And with a plate that wide it will take way less angle to have the same affect as a standard ride plate. You just need to keep adjusting it down until your issue stops. Once you get it close, a 1/4 turn on those turnbuckles will make or break the setup, been there done that.

A plate angled up will create a low pressure area under itself and try to pull the plate down (bringing the bow up). If you dont have the thrust/speed to hold it up there, it falls back down and starts all over again (porpoising).

You might also want to add a couple pieces of angle to the top of the plate (front to back) to make sure it doesnt flex. If the plate flexes it will change shape at different speeds and you will be chasing your tail trying to figure out whats going on.

Jetboatunderground

Luckie Stiff

Nordie

Jetboatunderground

Jetboatunderground

Jetboatunderground

Luckie Stiff

GT Jets

Jetboatunderground

GT Jets

Leadsled

TJS Nordic

GT Jets

dirtbag1

GT Jets

jet boat performance

Jetboatunderground

Jetboatunderground

propless

jrork

Jetboatunderground

IRRebel

Jetboatunderground

IRRebel

propless