porpoising

[Pecker]

got a brand new skeeter 17' w/ yamaha 115 four stroke that porpoises at all trim angles except when tucked under all the way, only 4200 rpm.<br />will flatter prop help porpoising, ( i know it will help rpms )or do i need to have dealer lower motor?

 

[DJ]

Re: porpoising

Porpoising is a true sign of too much weight aft (rear).<br /><br />Props can help, but probably not the answer. Engine height probably won't help either.<br /><br />Solutions:<br /><br />Move some weight forward. Batteries, etc.<br /><br />Trim tabs.<br /><br />Engine fin (cavitation plate).

 

[DJ]

Re: porpoising

Read the posts on this "Boats" page from topic starter "Sivart". "Boat Bouncing".

 

[cinder1995]

Re: porpoising

A hydro-foil solved that problem for me.

 

[Pecker]

Re: porpoising

I just left this boat with the dealer to correct.<br />The Skeeter engineer told the dealer to lower the motor and put on a prop with less pitch.<br />I'm supposed to pick the boat up in a couple of days.<br />If that doesn't solve it, I may go with a hydrofoil.

 

[Dodgerdavn]

Re: porpoising

Hello,<br /><br />Don't mean to hijack this question, but I have a similar problem. My Reniell 170 will porpoise when I try higher speeds. When I trim the motor up, it gets worse. What causes this? Should I move weight towards the front?<br /><br />Thanks!,<br />Dave

 

[Pecker]

Re: porpoising

Dave:<br /><br />When I get the boat back I'll let you know what they did to correct it. Right now it looks like a lesser pitch prop and lowering the motor may solve it with my boat, but I'm going to wait to hear from the dealer before I offer any suggestions for you.<br /><br />Whenever I get the boat back I'll let you know

 

[Dodgerdavn]

Re: porpoising

Cool Beans,<br /><br />I have an I/O, so I think moving the motor is out of the question. Pitch of the prop? That's an idea. I am SOOOO new to this! I had my boat up to about 35 mph and I thought, holy smokes, this is fast enough! My cousin had the boat up to 55 mph. Screw that! I just don't want to spill my beer.<br /><br />Can a trim tab be installed? Would that help?<br /><br />Later,<br />Dave<br /><br />

 

[chris in va]

Re: porpoising

You need a hydrofoil. It really does help with the bounce, if takes off a couple mph top end. I can plane out my 19' Caravelle at 15mph with the sucker on!

 

[Dan180cc]

Re: porpoising

Pecker,<br /> I had the same problem with my boat, Sea-Pro 180 center console the first time I took it out.<br />I had purchased a 140 4 stroke Johnson which is actually lighter than the 115 4 stroke option.<br />It would porpoise at all trim levels above full down. I found the problem at its worse with 1/2 a tank of fuel about 20 gallons. On my boat the fuel tank is below the center console. The problem started out small but got worse the longer you drove. You mentioned changing props.<br />This is what fixed my boat but before you do it do some homework on props. They can change the way your boat drives big time. Going down in pitch should give you a better hole shot but it will raise the rpm's at w.o.t. 300 rpm increase per inch reduced on my boat. If you increase the pitch expect less hole shot with a 300 rpm decrease at w.o.t. but increase in top end speed and more bit. I went from a 14x17 prop to a 14x21 and got rid of all of the proposing problems increased top end to 55 mph from 46 mph. I can now use the trim to the full extent. Your dealer should have a couple of different used props that <br />you can try before any holes get drilled in your motor or transom. Problem like porpoising can be improved or fixed by doing several differnet things and no two boats/motors are exactally the same. There is a lot of good advise on this board dealing with all types of problems do a few searches on porpoising, bouncing, hydrofoils and trim tabs. Good luck. Dan

 

[Pecker]

Re: porpoising

Thanks Dan,<br />The dealer just called and my boat is ready. I'll get it on the water this afternoon and tomorrow I'll post the results. The dealer put a 17 pitch prop on (down from a 21). He says the problem is solved. I 'll know for sure this evening.