porposing

dolsen

Seaman Apprentice
Joined
Aug 17, 2002
Messages
36
I have a 16 ft north river revenge 40hp honda tiller. When solo it porposes even trimmed all the down. I was wondering if i could pull the trim pin out and get a little more trim? i suspect if i could get just a hair lower it would help if not eliminate the porposing.Oh and it has pt&t.
 

Jetcraft17

Recruit
Joined
Nov 5, 2002
Messages
3
Re: porposing

I had a 60 horse outboard on my 17 foot sled and it porpoised, too. I removed the pin and always had the power trim all the way down. That still didn't do the trick, especially when I had a full tank of gas. It has a 30 gal tank, all the way to the back. I stowed as much gear forward as I could, even carrying a spare battery up front-just for the weight. Eventually, I bent the trim tab down. The bottom of the aluminum boat is extended past the transon a few inches and can be bent down to force the bow down. The boat stopped porpoising after that and I didn't have to be as careful as to where I put my heavy stuff after that. If your North River has this tab, I'd give it a try. My tab runs the entire width of the boat, but I only bent the middle 2 feet. And only adjust a little at a time. I bent mine only 1/8 to 1/4 of an inch, and that was all it took. Finally, if this area is painted, beware, because I cracked the paint near the joint just from the movement of the metal. I was one happy boater, though after my boat finally ran right, and safer, too.<br /><br />Let us know how it goes?
 

dolsen

Seaman Apprentice
Joined
Aug 17, 2002
Messages
36
Re: porposing

Thanks Jetcraft mine does extend out an inch or so. did you bend a foot on either side of the centerline?First ill try pulling the pin and also a full tank of gas {14 gal. step tank}Yesterday was its maiden voyage and im very impressed with the handling especially the tracking.I upgraded from a smokercraft lodge merc 25.No comparison.I just cant wait till nov 23rd. Watch out sturgeon.Thanks again.
 

Jetcraft17

Recruit
Joined
Nov 5, 2002
Messages
3
Re: porposing

Yes, I bent the tab all the way from the center, out about a foot on each side. I don't know if you understood, but I porpoised more with a full tank of fuel. To help stop the porpoising, try less weight in the rear, more up front. If your tank is up front, then by all means, fill the tank. <br /><br />Congrats on your new boat. It's definetely a step up and a much safer boat for the Columbia. I fish out there too. Fishing the coast and duck hunting now. Good luck.
 

Jack Shellac

Lieutenant Commander
Joined
Aug 7, 2002
Messages
1,661
Re: porposing

Not familiar with your type of boats, but on a deep-V, when all else fails, a four blade propellor will usually help with porpoising.
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: porposing

A fin will also help if not cure it altogether. On a small motor like that one of the small inexpensive ones will work just fine.<br /><br />Bending the "tab" on the hull is a neat idea. I would do it like we do on larger boats. We stay away from the middle and create "hook" or tabs toward the outside and work our way in.<br /><br />Good luck!
 

jetdriven

Seaman
Joined
Aug 25, 2002
Messages
70
Re: porposing

My stern-heavy 14' boat porpoised and rode terribly rough until I spent $150 on a set of SmartTabs trim tabs that use gas-charged shocks. They are maintenance free and self-adjusting. These are well-worth it. If you don't want to spend this much, the above post recommending a hydrofoil fin for the motor is a good investment if you don't have one already.<br />Best of luck
 

dolsen

Seaman Apprentice
Joined
Aug 17, 2002
Messages
36
Re: porposing

Thanks for all the tips.If i pull the trim pin i can trim down about a half inch ,its pretty mild porposing and think that might help, but it seems that than the motor actually lowers to the point of touching the trim motor, im wondering if that will hurt anything? and also my step tank ,which is located just aft of bow platform is 14 gal and i was running about ten gal ,the extra 25 to 30 ibs of fuel will also help i hope.again this happens when im by myself and im sure a passenger onboard would alleviate the problem.Just waiting for a day off and some decent weather to coincide to test.Thanks again.
 

workinoffsho

Cadet
Joined
Aug 30, 2002
Messages
12
Re: porposing

Jetdriven is correct about the Smart Tabs they are well worth the money. I have a custom Aluminum mod V skiff with a 90hp Johnny with a dolfin and I run an 18 gal tank and battery in the back. Before putting the tabs I maxed out at 30mph since installing I'm running in the mid 40's. I still had to do a little shifting of weight forward to ride like I wanted. You can buy the tabs from Bass Pro, West Marine and other boat supply stores for $150. Hope this helps and good luck. Happy Boating
 

John Carpenter

Petty Officer 1st Class
Joined
Nov 1, 2002
Messages
336
Re: porposing

You might want to check and make sure that your motor is mounted at the correct height. The cavitation plate should be about level with the bottom of the boat.
 

rdmoore

Cadet
Joined
Jun 9, 2003
Messages
14
Re: porposing

True Story. A few years back , I was looking for a smaller boat than my<br />Four Winns cuddy, mainly for taking the family out on small lakes for water<br />skiing and tubing. After looking around a bit, I purchased a Stingray 180<br />RX bowrider. It seemed to meet our space and performance needs and seemed<br />like a real value for it's cost. And it was, except for one glaring fault.<br />At anything less that W.O.T and speeds below 35-40, it would porpoise<br />horribly unless you kept the trim fully down. Because you had to drive with<br />bow always plowing the water, instead of planing as it was designed to,<br />cornering was very unpredictable, gas mileage suffered and handling in<br />general was poor. It got to be so bad, my wife refused to drive it when I<br />wanted to ski. Having owned many other boats that you could trim at any<br />speed (once on plane), I knew this was not correct and tried to work with<br />first my dealer, then Stingray the company, to get this corrected. To make<br />a long story short, lets just say they both were an absolute joke. All I<br />had to show for months of effort of trying to go through the proper<br />channels, was countless unanswered phone calls and e-mails, wasted trips to<br />the dealer, money wasted on another prop, a lot of frustration and the<br />first hand knowledge (after trying other 18 & 19 foot Stingrays out) is<br />that they all porpoise just as badly! Many other disgruntled owners had<br />also contacted me with this same issue, after I started asking for help on<br />various boating forums. But just as I was convinced this is a flaw in the<br />design and was putting the boat up for sale, I learned of the smart tabs<br />from Nauticus. I contacted the company, who was very helpful and promised<br />they would completely fix my porpoising problem. After all I had gone<br />through with the shallow answers and promises from my dealer and Stingray,<br />I was extremely skeptical, but I went ahead and ordered a set, figuring it<br />was a lot cheaper than buying another boat. Got them a few days later and<br />installed them in about an hour.<br />Let's just say the results were far beyond my highest hopes. There is<br />absolutely no more porpoising. None whatsoever, no matter what speed or<br />trim the motor is at. Additional benefits are that the thing planes almost<br />instantly, it virtually doesn't even lift the bow at all! You feel like<br />you're in a car, not a boat when you take off! Because of this the hole<br />shot improvement is amazing. Heavy slalom skiers I could not pull out of<br />the water previously, now are no problem. Gas mileage is improved and the<br />thing corners predictably and rides much better. I even called the owner of<br />the company and thanked him personally. That was 2 years ago, and I can<br />truly say I am now 100% satisfied with this same boat I was so disgusted<br />with before the smart tabs installation, and can't even imagining using it<br />without the smart tabs. I hear so much about boaters looking for<br />performance improvements with expensive engine and prop modifications, <br />or complicated hydraulic or electric trim tabs, <br />when they could just add a set of these and get better performance<br />improvements (except top speed, that was not affected) at a fraction of the<br />cost. Several of my boating friend have installed them after they heard of<br />my success, with similar positive results. So go ahead and give them a try,<br />you won't regret it. Feel free to e-mail me if you have any questions.
 
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