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porpoising issue.............
http://www.mudmotortalk.com/mmt_v2/viewtopic.php?f=4&t=2310
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Author:  Texas Heat [ Sat May 30, 2009 9:29 am ]
Post subject:  porpoising issue.............

Have 32 HP Generac PD on a 16 56 Go Devil Hull. First time we took the boat out, ( single person driving the boat) boat started to porpoise. Added a passenger and problem went away. Have ran the boat since that day and yet to have it happen again until this morning. Lake was pretty calm. Crossing over another boats wake at WOT it started to porpoise again. Tried to trim the motor up/down but that did not fix it. Was me ( 190 lbs) dog, (70 lbs). Full tank of fuel up front and nothing has been added as far a weight goes. Moved dog to the back and still same problem. Was told I might have to weld up some wedges to the transom to permanently fix this issue but have no clue HOW to go about that! Any one run into this problem before and offer a solution?

Author:  River [ Sat May 30, 2009 10:07 am ]
Post subject:  Re: porpoising issue.............

Eric, you got two choices.


More weight up front or wedges.


They are pretty easy to do, anyone that can weld aluminum can fix you up.

Author:  Crews [ Sat May 30, 2009 10:20 am ]
Post subject:  Re: porpoising issue.............

I used to have those problems with my little godevil boat... I opted for wedges, and couldn't be happier. Get a piece of 3x3 aluminum angle, and then cut you two pieces of it that are 3" long. Rip one side of the angle down.... that will be the back of the wedge that is perpendicular to the bottom of your hull. I made mine a little less than 1/2" tall (from the bottom of the boat.) I put my 2 3" wide wedges right in front of the transom, as far out to the sides as I could. That being said, if I had to do it all over again, I would have moved them in a little bit just so they wouldn't interfere with the bunks. Some folks put them on with epoxy first to test them out, then weld them on if it works. I just got them tacked on, ran it, then went ahead and got them completely welded on. We ran a couple of beads at the front of the wedge, then blended it down so there wasn't any sharp edges catching water or stumps. They worked like a champ for me... trim tabs kinda create drag, these wedges create lift. I'm no expert, but feel free to pm me and I'll tell you anything else I know. I still have some angle, if you need me to make you some.

Author:  Texas Heat [ Sat May 30, 2009 3:08 pm ]
Post subject:  Re: porpoising issue.............

Crews, do me a favor and take some photos for me. I do not have any buds that can weld aluminum so will have to take to welding shop. Need to get a trolling motor bracket welded up so could do them both while he has the boat! Thanks!

Author:  Texas Heat [ Sat May 30, 2009 3:14 pm ]
Post subject:  Re: porpoising issue.............


Author:  dog walker [ Sat May 30, 2009 4:21 pm ]
Post subject:  Re: porpoising issue.............

You can make the wedges and put them on with jb weld and try them out and then you can adjust the height if needed or pop them off if they hurt the performance.Get the right size then weld them up.

Author:  tbuc [ Sun May 31, 2009 8:40 pm ]
Post subject:  Re: porpoising issue.............

You could back off on the throttle for a few seconds and it will go away and then open her up again. If it's just happening when you hit another boat's wake and only when the water is calm and you're by yourself, I'd not worry about doing a whole lot to it. But that's just me. But it sounds like you rarely have this problem. So why go to the trouble of modifying your boat for something that rarely happens?

I've got a 1644 GD with a 35 hp GDSD on it and it will porpoise a little at times, but I just back off a hair and it's fine again. I originally thought I'd have to put wedges on it, but after running it a few times I see no need. It will porpoise in the same situation you described. But backing off for a couple seconds to let it settle down is all it takes after crossing another boat's wake.

Author:  SwampSnyper [ Mon Jun 01, 2009 7:13 am ]
Post subject:  Re: porpoising issue.............

Sounds like you got your boat riding perfect on the water. You want your set up to be right at the level of porpoising with the lightest load. The reason it only does it on occasion is probably because you are going with the current and/or with the wind giving you a little bit more speed to create the porpoising. I'd leave it alone. Maybe slide the icechest all the way to the front or make the dog stay in the front when it starts to happen.

Author:  Crews [ Mon Jun 01, 2009 7:35 am ]
Post subject:  Re: porpoising issue.............


Author:  Sand Man [ Mon Jun 01, 2009 7:46 am ]
Post subject:  Re: porpoising issue.............

put the dog up front and it shouldn't be an issue.

Author:  T-mac [ Mon Jun 01, 2009 8:57 am ]
Post subject:  Re: porpoising issue.............

more beer....in cooler....up front 8-)

Author:  Texas Heat [ Mon Jun 01, 2009 9:05 am ]
Post subject:  Re: porpoising issue.............

Roger that, guess I will just deal with it and see how it goes.

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