It is currently Tue Jul 08, 2025 12:12 pm




Reply to topic  [ 12 posts ] 
 porpoising issue............. 
Author Message
MMT Member

Joined: Wed Jan 14, 2009 9:34 am
Posts: 49
Post 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?


Sat May 30, 2009 9:29 am
Profile
MMT 1000 Club
User avatar

Joined: Wed Jan 14, 2009 8:34 am
Posts: 1092
Location: Unaffiliated, SETX group has caused me to renounce my Texas Citizenship
Post 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.

_________________
"Democracy is two wolves and a lamb voting on what to have for lunch.
Liberty is a well-armed lamb contesting the outcome of the vote."-Benjamin Franklin


Sat May 30, 2009 10:07 am
Profile
MMT 1000 Club

Joined: Wed Jan 14, 2009 9:07 pm
Posts: 2260
Location: Lafayette
Post 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.

_________________
24x60 Dual Prodrives


Sat May 30, 2009 10:20 am
Profile
MMT Member

Joined: Wed Jan 14, 2009 9:34 am
Posts: 49
Post 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!


Sat May 30, 2009 3:08 pm
Profile
MMT Member

Joined: Wed Jan 14, 2009 9:34 am
Posts: 49
Post Re: porpoising issue.............


Sat May 30, 2009 3:14 pm
Profile
MMT Elite Member
User avatar

Joined: Tue Jan 13, 2009 6:08 pm
Posts: 5282
Location: Meraux,La.
Post 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.


Sat May 30, 2009 4:21 pm
Profile
MMT Member

Joined: Sun Jan 18, 2009 11:16 am
Posts: 47
Location: Minnesota
Post 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.


Sun May 31, 2009 8:40 pm
Profile
MMT F.E.
User avatar

Joined: Tue Jan 13, 2009 8:43 pm
Posts: 823
Location: SORRENTO, LA
Post 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.

_________________
1948 Aucion's SS Edition Bateau with a stock 35GTR


Mon Jun 01, 2009 7:13 am
Profile
MMT 1000 Club

Joined: Wed Jan 14, 2009 9:07 pm
Posts: 2260
Location: Lafayette
Post Re: porpoising issue.............

_________________
24x60 Dual Prodrives


Mon Jun 01, 2009 7:35 am
Profile
MMT F.E.
User avatar

Joined: Thu Jan 15, 2009 9:57 am
Posts: 994
Location: Fort Worth, TX
Post Re: porpoising issue.............
put the dog up front and it shouldn't be an issue.

_________________
"Fight 'em until hell freezes over. Then fight 'em on the ice!"


Mon Jun 01, 2009 7:46 am
Profile
MMT Addict

Joined: Tue Jan 13, 2009 4:53 pm
Posts: 605
Post Re: porpoising issue.............
more beer....in cooler....up front 8-)


Mon Jun 01, 2009 8:57 am
Profile
MMT Member

Joined: Wed Jan 14, 2009 9:34 am
Posts: 49
Post Re: porpoising issue.............
Roger that, guess I will just deal with it and see how it goes.


Mon Jun 01, 2009 9:05 am
Profile
Display posts from previous:  Sort by  
Reply to topic   [ 12 posts ] 

Who is online

Users browsing this forum: No registered users and 129 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to: