need some porpoise advice

[FHI-prez]

I have a '78 Borum which I'm sure no one has a clue what it is. It seems to be a splash of the Taylor SS bubbledeck. The boat is not light by any means, but I don't know the exact weight. I have a place diverter on the E pump and the stock cavitation plate.
Here is the problem. The boat rides superb at WOT, but tends to porpoise at cruising speeds. I'm gonna put the shoe/rideplate on it this winter which may help the porpoise but I won't know till I try it. I've also been looking at the possibility of a droop, but I'm thinking that MAY worsen the porpoise as most if not all droops have a 4 deg up angle built into them. It seems that the "snoot" that Duane and Hi-tec sells would be a better option, but I really don't know for sure. The down side is that I don't think with approx. 550hp I need the billet snoot, costing $550 for the kit. I'd like to know if there is a cast version of the snoot, or a droop with no 4 deg up built in. When I'm cruising I have to angle the PD down to keep it from porpoising (almost all the way down). At this point, I'm thinking about just doing the ride/shoe thingy and see how that works, but I wanted to get opinions on the droop or snoot. Also, I realize that E-pumps in stock trim can't accept a snoot/droop but I have an Agressor bowl on it that can. I also realize that every boat is different and set up varies likewise. I was just hoping to get a good direction to go before I start tossing money into the lake.
Sorry, this post is getting longer by the minute, BUT what do you guys think about putting "wings" on the sides of the ride plate? I've been thinking about putting some angled "wings" welded to the sides about 3" long and angled with the slope of the V in the keel. I think it would work great, but I've not seen anyone else do it, so that makes me wonder. To clarify, the wings would basically make the width of the rideplate 6" greater and would follow the contour of the keel to keep them from dragging in the water. I've seen many people put angle on the sides of the rideplate probably just to keep the plate from flexing in the middle, but I've never seen anyone put extensions on a rideplate to make it wider. It wouldn't be easy as they would have to step up first to get them on plane with the keel, then follow the V for a couple of inches.
Well it makes sense in my head anyway, not sure if I described it very well tho. :hammerhea
Lemme no your thoughts!
Regards,
Nick
:)

[MudPumper]

You might want to check the bottom for hook and rocker. There is a good article in this months ***boat about it.

[FHI-prez]

You might want to check the bottom for hook and rocker. There is a good article in this months ***boat about it.
Yeah i should have mentioned that as well, but I have checked it and it's pretty damn flat with a little bit of a rocker in it. I'm sure I could flip it and improve on the bottom at least to some degree, but I'm not considering that at option right now. I'm gonna work with what I have in this regard because from all measurments it's pretty good and I seriously doubt that even making it perfect would have any affect on it in cruising speeds. I'd be much more likely to make it perfect if I was concerned about absolute top speed, or if the porpoise showed itself at WOT.
I guess that's why I have the questions I do in this thread. Almost without fail people ask the questions I have in the above post, but only in regard to top speed. I'm concerned with cruising efficiency. The boat is plenty fast, I just need to make it more friendly at 30 mph.
Thanks,
Nick

[Squirtin Thunder]

And make sure you feed them !!! :eat:
Jim

[Mohavekid]

Have you tried adjusting the stock cavitation plate up or down to see if you can lessen the porpoise?
I have the same problem on my Sanger, and adjusting the plate helps some, but does not eliminate the problem.
I think a longer ride plate and the shoe kit from Duane will provide some lift at the rear to reduce the problem. I'm planning to try that this winter.
Good luck.

[Squirtin Thunder]

The longer plate makes a big difference.

[roostwear]

For what it's worth, here's what I'd do. On my E pump, the biggest difference was from the plate, not the shoe. My speed increased about 3 mph with the combination, but if I did it again, I'd make a longer plate and get the cradle from Duane. The difference in the ride is dramatic. Where I used to cringe crossing a wake, now it just cuts through, and I'm sure it is because of the plate.
I'd put the money into a Place diverter, and make a new plate.
My .02

[Squirtin Thunder]

For what it's worth, about 3 mph with the combination,
My .02
$$$$$$$$

[FHI-prez]

I'm gonna shoe and plate it regardless. I know it can't hurt. I'll probably put "wings" on the plate as well to see how it acts, if it gets too goofy at WOT I'll cut em off if I have to. Knowing me, I'll probably put a droop on it at the same time so I'll have no idea what did what. :rollside:
I can adjust the stock cavitation plate down from plane and it does lessen the porpoise at crusing speeds, but that is a poor band-aid at best. I noticed a little difference just in the weight of the aluminum heads compared to the iron ones, so I'm pretty sure I need to get the transom lifted more to solve the cruising problem. It really only becomes problematic in reletively calm water. In a decent chop it goes away for the most part. I just want to get the boat set up so the PD can be put in the middle without it porpoising like a damn dolphin. I'll get it, just wondered if anyone had input on different droops, or ride plate wings. I'll guess I'll have to be the guinnea pig on the rideplate wings.
Nick

[TRG]

I'll probably put "wings" on the plate as well to see how it acts, if it gets too goofy at WOT I'll cut em off if I have to.Nick
What would wings help in a boats attitude?
Not stirring the pot just have never heard of doing this!
A few months ago i did some work on a challenger, and it was fitted with an "E" pump, and the "RIDE PLATE" had a flat area asthe sides lifting.
i could not come up with a reason why the pump had that!
Todd

[FHI-prez]

I'm thinking that wings would just add that much more lift to the transom of the boat, now how much lift and how it would affect the ride is completely a trial and error thingy I suppose.

[Nubbs]

I'd like to know if there is a cast version of the snoot, or a droop with no 4 deg up built in.
I've seen people use a 4 degree wedge upside down with the droop. That cancels out the 4 degrees up of the droop.

[ttmott]

Nick,
The porpoise is completely due to the "rocker" on the bottom as the boat has no pad on which to ride. Most boats of earlier years intentionally had hook so the boat would be stable. Has someone added glass or was the boat stored wrong (for many years)? Your boat's condition is very unusual. If you are going to install a shoe and ride plate you might as well get the bottom straightened out as the intake structure needs to be removed. I spent weeks getting the bottom straight on mine.
Tom

[Mohavekid]

Tmott, the porpoise he has is not too uncommon on an "e" pump boat.
The "e" pump and motor sit about 6 inches further back in the boat than a typical Berk pump. The change in weight location contributes to the problem. On my boat, a change in weight distribution front to rear makes a real difference in the amount of porpoise. The bottom of my boat is straight as can be, with no hook or rocker.

[roostwear]

Nick,
The porpoise is completely due to the "rocker" on the bottom as the boat has no pad on which to ride. Most boats of earlier years intentionally had hook so the boat would be stable. Has someone added glass or was the boat stored wrong (for many years)? Your boat's condition is very unusual. If you are going to install a shoe and ride plate you might as well get the bottom straightened out as the intake structure needs to be removed. I spent weeks getting the bottom straight on mine.
Tom
The "intake" on an E pump isn't removeable, it is molded into the hull.
I don't know how fast this boat is now, or how much HP it is making, but I'd be willing to guess the shoe is a waste of money at this point. The diverter is the best upgrade imho, and a longer plate will do wonders. Then again, look at my boat..... who am I to say what's the best money spent? :D

[Squirtin Thunder]

Mike,
Give yourself more credit man. You did one hell of a job on that whole shoe and ride plate deal. I think there was alot more to be had with it though. Your ride attitude was much better and that in turn will alow more speed. You walked us all through a very interesting intake modification. You payed close attention to the details and you should be proud of the way it turned out. I have talked to alot of people and the intake cracking was not your falt. Thouse E-pump boat are kind of a ****ed up deal. They are kind of like the Panther deal. Things just never were right from the get go. Like I said you saw a change with more fine tuning you may have been able to find a bit more MPH.
Jim

[Mohavekid]

Intake cracking?
I have not heard this before, what happened?

[FHI-prez]

The "intake" on an E pump isn't removeable, it is molded into the hull.
I don't know how fast this boat is now, or how much HP it is making, but I'd be willing to guess the shoe is a waste of money at this point. The diverter is the best upgrade imho, and a longer plate will do wonders. Then again, look at my boat..... who am I to say what's the best money spent? :D
Of course the intake is removable on a E pump. It's just not interchangable with other pumps. The hull is molded to recieve the odd shaped intake, but it gets glued and bolted in like any other pump.
The diverter is a must for my boat for sure. It works very nicely to set the attitude right. I have about 525 hp and she runs low 70's on gps. There is no way in hell I'd go through the trouble to strip the boat, flip it, and change the bottom, when my goal has nothing to do with top speed. It just so happens to be that it want's to porpoise at the most common cruising speed about 30 mph. The porpoise goes away at around 36 mph and never comes back, no matter how high you put the PD. It's really not that big of a deal, I was just looking for a little more lift in the transom and maybe making the boat more efficient for cruising/skiing with a rideplate and possibly a droop. The ride plate I get, no rocket science there. What I don't get is the droop and what it's supposed to accomplish. There is no way a droop will lift a transom if it has 4 deg wedge built into it, it would push the transom down lifting the bow. It seems Duane's snoot would be much better, at least for my situation.
The only reason why I'd put a shoe on it would be to set the ride plate down that much lower to lift the transom and stablize the ride.
The fact that the boat has a 28 gal fuel tank in the bow might have something to do with it as well. :jawdrop:
Nick

[roostwear]

Intake cracking?
I have not heard this before, what happened?
At FC2, I noticed the pump housing developed 2 cracks in the bottom. I guess the good thing was that I was only running on 7 cylinders, and never went faster that 68 mph. I'm thinking there was a pre-existing condition, and the greater intake pressure brought it out. I have some repairs to make this winter. :rolleyes:

[Mohavekid]

Good thing you noticed the cracks, blowing out that housing at speed would suck.
Are you going to replace the intake piece or try to weld up the cracks in yours?

[roostwear]

The intake on an E is all one piece... there is no set-in "intake" like a C, G or R. I'm going to try welding it up. If it works, great. If not, I'll wind up replacing the housing. A true PIA, but I'm not going 50 anymore... stuff is gonna break. The good thing about an E over the others is that if the housing blew out, at least I wouldn't sink. :D

[Squirtin Thunder]

The intake on an E is all one piece... there is no set-in "intake" like a C, G or R. I'm going to try welding it up. If it works, great. If not, I'll wind up replacing the housing. A true PIA, but I'm not going 50 anymore... stuff is gonna break. The good thing about an E over the others is that if the housing blew out, at least I wouldn't sink. :D
Amen to that !!! I would hate to hear about that fate for the Circus Boat !!!