Performance Boats Forum banner

1 - 20 of 34 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter #1
I purchased a 1978 Nordic Bubbledeck from my father-In law last summer, and I have been totally stoked on the boat with one exception. The darn thing has a serious porpoise problem at higher speeds from about 60 to the current top speed of about 75. I guess the problem was much worse at one time. My father-in law had a lot of work done to get it where it is at today. The guys at Jet Boat Plus in Havasu City blueprinted the bottom put on a droop snoot and made a custom ride plate for it. The motor is a BBC I believe bored to a 468 ci, Dominator pump, dual 750's with tunnel ram. The intake grate is stock and I was thinking of going to a loader grate. It doesn't really have a shoe, the ride plate is one piece and where it attaches to the boat it kind of looks like a shoe but I don't think it functions as one. The ride plate is not really adjustable, I believe it was at about 1.5 degrees up and I shimmed it down to zero with no significant results. I'm thinking now that I need to go the other way and maybe go to an adjustable plate. I would like to get a loader grate and maybe go to a straight snoot. I don't really know if I need a shoe and I don't really want to add weight to the bow. I know the boat will go faster than 75 but I just want a smooth ride at 75-80. When I put the place diverter all the way down it is much better but it plows and I don't get the speed I want. I've heard that the place diverter should be adjusted so you are putting a rooster about 3-5 feet off the water. Please help me out, this is an amazing ride and I just want to smooth it out a bit more. Thanks in advance for any assistance.
 

·
21 Daytona
Joined
·
5,291 Posts
Good luck
I helped a friend try to stop his for years
We could get it close but never cured

We are actually going to put it back together once more after changing everything and adding several lavers of glass to make the rear 1/3 of the boat stronger







Sent from my iPhone
 

·
Registered
Joined
·
536 Posts
have you tryed it without the "rideplate",and droop. I've looked in to rideplates without shoe and have learned it really can't be done & work properly,may be doing more harm than good. Some boats just don't like a droop.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #7
I've taken the ride plate off and tried it like that and it was worse. Haven't tried without the droop, like I said it was once much worse without the ride plate, droop, and refinished/blueprinted hull. It feels as if the boat wants to come up higher and then either looses suction or has resistance and drop back down. Sometimes in rough water with the diverter all the way up I can get a smooth ride at close to top speed.
 

·
Banned
Joined
·
41 Posts
have you tryed it without the "rideplate",and droop. I've looked in to rideplates without shoe and have learned it really can't be done & work properly,may be doing more harm than good. Some boats just don't like a droop.


could you post a sideshot of the pump so we can see what that cradle looks like and a sideshot of your rideplate... could be bent?? Have you tried adjusting the plate? Looks like someone put alot of time into that setup, you should call jetboatplus and see if they still remember the boat? Also put a straightedge on the biting edge in relation to keel and also see if you might have developed a hook in the boat again by checking that with the straightedge also. just a thought. :happy:
work with what you have there before investing in another part that might not help.:shhh:
 

·
21 Daytona
Joined
·
5,291 Posts
looks like you have on of those "add on " ride plates. I've seen a couple of these before,( a homemade shortcut to add a ride plate).
problem is it really doesn't give you any adjust ability on how much water you're feeding the pump.
First thing I would do is remove the intake and have it machined for a shoe and ride plate or replace it with one already machined.

when you re install it make sure you set it at the correct angle, this will depend on which intake you have.
with a shoe you can adjust the opening on the intake, probably overcharging the intake currently.

I was told Nordics were built with a Hook into the bottom, we removed the hook my friends, currently we have a new intake from MPD ready for install.
but his project has been on hold for a couple years. Once we put it back together I'm confident it will run out lots better.
 

·
Registered
Joined
·
513 Posts
porpoise

I found that the porpoise issue is usually related to a weight balance problem. Have you tried moving the engine? Does the boat act differently with more or less people in it? I had a porpoise problem in my boat and ended moving the engine to solve the problem.

Good Luck
 

·
Registered
Joined
·
1,379 Posts
Throw a bag or two of water softener salt, or something of equal weight in the back of the boat against the transom, (about 50 or 60 lbs on each side), and see how it reacts. Then report back here.

Duane HTP
 

·
Registered
Joined
·
7,464 Posts
Very curious about the shoe and ride pate as well as the area (bottom) surrounding the actual intake casting trying to understand the Plate and how it is attached/inletted hard to tell from the current pics , some more pictures would be useful been dealing with a similar problem and have made progress by eliminating the droop on it altogether so you may be on the right track by considering a straight snoot or even a standard nozzle adaptor Tom
 

·
Registered
Joined
·
44 Posts
78 nordic

I have the same boat..I have droop with wedge..boat runs smooth as can be..I have bbc..if I can help you out I will..I could take some pics of my setup...also I could measure placement of motor..boat was setup when I got it..like I said it jumps up and runs perfect...
 

·
Registered
Joined
·
10 Posts
Discussion Starter #18
Wow, lots of posts here in such a short period of time!! You guys are awesome and I really appreciate the willingness to help. I will try to get some more pics up soon. Rush, I would love to see what your setup looks like. The hook has been removed from the hull, like I said the hull (aft ~8ft) has been blueprinted and refinished with that grey coating. The ride plate is extra long because I think the guys who did it tried an aftermarket one first and it was still pretty bad so they built a custom one. I have talked to the guys at jet boat plus, the boat is posted on their website, and they are friends with my father-in law. I thought about taking it down to them in Havasu and dropping it off for the installation of a real shoe and adjustable ride plate with a cradle. I live in Chico California, north of Sacramento and Havasu is a trek, but was thinking about hitting up the Nordic Regatta as well so who knows. I don't even know if the boat needs a shoe as I'm probably right around 500hp. What about a loader grate, could that help? Thanks for all the interest and help.
 

·
Banned
Joined
·
41 Posts
I have talked to the guys at jet boat plus, the boat is posted on their website, and they are friends with my father-in law. I thought about taking it down to them in Havasu and dropping it off for the installation of a real shoe and adjustable ride plate with a cradle. I live in Chico California, north of Sacramento and Havasu is a trek, .

check with jim at performancejet in sebestopol, shouldnt be to far away from you. knows his stuff. From the looks of that plate it looks bent. Again, alot of time was spent somewhere so i would talk to the guy that set that up directly and pick his brain. good luck.:yes:
 
1 - 20 of 34 Posts
Top