Porpoising

[BarryTurano]

I really do not know because I was not the original owner. It was a 96 Johnson. I doubt if was more than 200 to 225. I don't know how big Johnson's were made in 96. The max it could be would be 250. The boat is rated for 300 hp max.
Thank you for your interest and help.
Regards,
Barry

[nautiduck]

Barry do you have any pics of the transom area with the boat out of the water? Also where does the cav plate on the lower unit sit height wise compared with the bottom of the hull at the transom.

[jawz12]

I have had this problem since I bought the boat, "porpoising". The boat runs very smooth until I hit a wake at that point it starts to porpoising. The only way I can stop it is to slow down drastically. Even if I am not going fast I still have the same problem. It almost seems that there is not enough weight forward. Also the bow comes up high if I throttle up slow. What I need to do is to throttle up fast get up on a plane then back down. This is the first center console I have owned. Is this normal? Or does anyone have any ideas how to end this.
Thanks,
Barry

first,gotta check the height of the engine on the transom...have some one operate the boat,you go to the stern and look at the engine-cavitation plates-water should be just below the cavitation plates-if the cavitation plates are in the water,you will need to raise the engine...you don't state the engine "ventilates",this would be the engine free revs-this is usually caused by the engine being too high on the transom...
second:
trim,where is the engine ? trimmed out far ?? if you're trimming the engine out too far,then trying to counter act this with the tabs-this will happen...i don't know your skill level running a boat.most of the problems like this are caused by operator error...try trimming the engine full down,and leaving it there,see if this stops the problem.if it does,install a set of these...

http://www.cook-mfg.com/accessories.html

transom wedges...i've installed a few of these,mostly on contenders,to stop a ventilation problem...

[BarryTurano]

Thanks for the replies. Here is what I can tell you. The cavitation plate is in line with the keel, it is below the transom step. When running the motor is trimmed all the way down then backed off 1 to 11/2 marks on the trim Yamaha gauge. My tabs are all the way down. I can run level and flat until I hit a wake at about 4400 rpms or more that is about 26 mph. That is when the fun begins. The only way it stops is for me to come off the throttle. I am going to run the boat and check the cavitation plate as to it's relative position to the surface.
I have spoken with Edgewater. They do acknowledge this problem, saying it was worse on a single engine boat.

Here is their reply:
The answer from Edgewater

Barry,
This boat did require some use of the tabs to help prevent this issue. Make sure the trim tabs are down, this will keep the bow down and prevent the porpoising. You can leave the tabs down a little to help get the boat up on plane quicker as well! This issue was more pronounced with a single engine rather than duals. Hope this helps!
Best regards,


I am going to look into a different prop, something with a stern lift. I am also thinking about adding a PermaTrim to the motor. I just need to do this slowly so I don't over compensate and have a constant bow down.

Attached is a old photo of the hull showing the reverse step at the transom.
Thanks,
Barry

[BarryTurano]

Well here is an update regarding this. No sure cure but it's getting closer. The engine height is good. The trim is fine. Did find that the stbd. tab is a little sticky some times it will not come down. Checking to see if they are extending fully. Mechanic has told me that the reverse step in the hull is not helping because there is no water to lift the transom. Probably going to try some type of hydro foil. From there it will be a 4 blade prop. I'll let you all know as things progress.

[Allenf]

I fish on Lake Livingston here in east texas and alot of times the lake will be as slick as glass and as I open up my fiberglass boat, I too have had the same problem with the porpose effect, however I tried one simple thing, and it actually stopped it totally.

Wax the bottom of your boat regularly. By waxing the boat is keeps a slick surface and it actually keeps the boat gliding on the plane of the water instead of the slamming up and down of the porposing effect.

Hope this helps all the fisherman out there to get to your fishing places faster.

[nautiduck]

Barry where are your tabs mounted? Are they on the transom or mounted down on the step?

[BarryTurano]

Mounted on the step. Boat runs a lot better with the 4 blade and the DoelFin. Porposing is no longer an issue.