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  1. #1
    Petty Officer 2nd Class
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    B'ham, AL, USA
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    Default Boat porpoising...

    I recently bought a used 17 foot boat called a vector with a 200 Suzuki outboard on it.When I take it out it always wants to porpoise real bad. I've tried different trim settings, and it is better when trimmed in but it still does it and the boat slows down when trimmed it. Somebody told me the motor height maybe wrong. I think the cavitation? plate is like 5 or 6 inchs above the bottom of the boat.Also I'm running a stainless prop that has 23 stamped in the side and when I get to 6000 rpm the engine starts to cut out. I guessing I have the wrong prop. Anybody know what kind of prop I should get.

  2. #2
    Senior Chief Petty Officer
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    Jul 2003
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    west virginia
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    Default Re: Boat porpoising...

    i had a problem with porpoising last weekend, i had to set the trim pin coser to the transom because i was 6hrs from home. i never had a problem with it until i started raising the motor up! a couple days ago i set the motor back down.

  3. #3
    Seaman
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    Jun 2003
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    Vancouver, British Columbia, Canada
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    65

    Default Re: Boat porpoising...

    Try some trim tabs. That will and should help solve the problem.Do a search for a product called "smart tabs" I hear they work greatAlso weight distribution may cause porposing as well. Try more weight in the front of the boat.Any other thoughts?

  4. #4
    DJ
    Guest

    Default Re: Boat porpoising...

    what200,Five or six inches seems kind of high. What kind of boat is this? I'm not familiar with "Vector" boats.As mentioned, porpoising is usually caused by too much weight, in the stern.At 6K rpm. you may be up against your rev limiter. Check with a Suzuki dealer to see what the max rpms are.If you do end up lowering your engine a notch or two, your rpms will decrease.

  5. #5
    Captain
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    Jun 2003
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    Boston, MA
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    3,983

    Default Re: Boat porpoising...

    You can also try a hydrofoil like Doel Fin or Stingray as well. I use both hydro foils and trim tabs. You can start with a foil for like $30 then add tabs if they foild doesn't completely solve the problem.

  6. #6
    Petty Officer 1st Class
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    Sep 2001
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    Mobile, Alabama
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    225

    Default Re: Boat porpoising...

    what200 Is that a Hydrostream, model Vector??If so, look at the pad and see if it has a slight hook in it.Possibly 5" is to high. Does it have a water cooling pressure gage, does the lower unit have a low water pick-up?Hydrostream has a web site that can help you with the set-up of your boat. Also visit Scream & Fly for good go-fast info.Good Luck,Gold Bear

  7. #7
    Cadet
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    Aug 2003
    Location
    Bonita, Ca
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    7

    Default Re: Boat porpoising...

    A Permatrim hydrofoil will stop your problem. http://www.johnfjensen.com/permatrim_hydrofoils.html

  8. #8
    iboats.com Partner Jdeagro's Avatar
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    Default Re: Boat porpoising...

    Porpoising is a problem caused by weight balance. It is sometimes corrected or reduced by triming the motor as far down as possible. This method uses the prop to push up on the stern and rotate the boat forward applying more pressure on the bow to keep it down. Frankly, i do not believe in using the prop to correct boat handling and attitude problems, it is for propelling. If the motor is too high ( the cavitation plate on the motor should be even +/- 1" with the bottom of the hull V) the ability to trim the motor down and under the stern will be impossible. Therefore little or no help!Using a hydrofoil to lift the stern will help push the bow down, and can minimize porpoising depending on when the porpoising begins to occur. For example if the porpoising starts at 24 mph the amount of stern lift at that speed may not be enough to stop the porpoising. The hydrofoils provide increasingly more lift as the speed increases. If the boat is fast enough and the hydrofoil large enough the lift at higher speeds ( 35+mph) can cause too much bow down pressure which will eliminate the porpoising but create bow steering and excessive lean in turns, and lower top speed, and less fuel efficiency.Chek the motor height, check the max trim angle down, and look into trim tabs or Smart Tabs on this site.Trim tabs are adjustable to the water conditions (either manualy or automatic)and therefor do not cause other problems while trying to correct another. And they do not use the prop energy to correct handling issues. Translates into better fuel economy at any speed.
    Get SX Smart Tabs cosmetic blems for an extra $20 off (only $99.95) exclusively at iboats.com
    link: http://www.iboats.com/Nauticus_SX_Sm...2485--dz.54646

  9. #9
    Petty Officer 2nd Class
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    B'ham, AL, USA
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    Default Re: Boat porpoising...

    I tried it again recently but with a different prop this time. This prop has 28 stamped in it. It still wanted to porpoise a lot.Here's a pic of how high the motor is: I'm guessing the plate is about 7 or 8 inches above the bottom It kinda seems to me that a fin will be out of the water at speed. Are you guys sure that will help?

  10. #10
    Petty Officer 3rd Class
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    Jul 2003
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    Jacksonville, FL
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    Default Re: Boat porpoising...

    From what you are saying and by the looks of the picture, it looks like someone set your outbourd up to try and run it like a surface drive. What I think is happening is that you are only getting the bottom half or less of the prop in the water when up on plane. The prop starts slipping causing the bow to start to rise. This alows the prop to get more bite as more is submerged causing the boat to lift out of the water again. It just keeps sliping and grabing over and over causing it to porpoise. This is just my opinion however. I think if you lowered the motor untill the cav plate was level with the bottom of the boat, you would fix most of it and also increase your top speed. The motor wouldn't be so apt to free rev as high, hitting the rev limmiter also.Again this is just my opinion.

  11. #11

    Default Re: Boat porpoising...

    if it's a Hydrostream Vector you won't get anywhere until you put NITROUS on that Suzi. They won't turn over 6000 unless you put it on the juice. Won't need no afterplanes, plates, trim tabs. Motor will last about 30 seconds so be ready to fly, but it'll be a short trip.Good luck Dude

  12. #12
    Petty Officer 2nd Class
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    B'ham, AL, USA
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    Default Re: Boat porpoising...

    Uncle Tony must give you all your outboard advice. Hey, it might last 40 seconds if you can find those fiber reeds for me. So how's the hydrasprouts project going for ya?Well, anyway, I got fed up and changed motors, but it still wanted to porpoise. Anymore ideas??

  13. #13
    Cadet
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    Sep 2003
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    Canada
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    Default Re: Boat porpoising...

    Foils are for fishing boats...slow one's.......( . )( . )..........

  14. #14
    Senior Chief Petty Officer
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    west virginia
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    Default Re: Boat porpoising...

    what200, i think you'd be happy with smart tabs, they will solve your porposing problem without comprimising speed.

  15. #15
    Commander
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    Apr 2002
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    NW FL
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    2,426

    Default Re: Boat porpoising...

    Man...that is a HUGE casting platform on the front of that boat Seriously, Smart Tabs transformed my boat. For the money, I recomend that for problems of porpoising or problems getting on/maintaining plane try the Smart Tabs first, and you will solve the problem. It is a rare thing that I buy something that turns out to be far better than I had hoped, but Smart Tabs were just such a purchase.

  16. #16
    Admiral walleyehed's Avatar
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    Back to Goodland, KS again
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    Default Re: Boat porpoising...

    Kim, I think your reply should be disregarded, as well as your signature.............. You might take another look at your reply if you think hydrofoils only help the "slow" ones.

  17. #17
    Cadet
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    Sep 2003
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    Canada
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    Default Re: Boat porpoising...

    Yeah, whatever.......lmao

  18. #18
    Lieutenant Commander flashback's Avatar
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    Default Re: Boat porpoising...

    Im no expert, but all info I have seen or heard says the plate should be even with the bottom of the boat. This gives the prop clean water to run in. seems to me with the plate as high as it is in your photo, that the water is disturbed by the hull before it gets to the prop, which could cause the prop to intermittently grab then slip which would cause the boat to porpoise. also the engine would over rev and reach its limit. surface running props are different from the one I see in the photo...........
    The Devil to pay, and no pitch hot!

  19. #19
    Senior Chief Petty Officer
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    Toronto Ontario Canada
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    Default Re: Boat porpoising...

    What 200 those boats up here were called Canadian Edition with same model names like VooDoo Vector and V-King, I used to hang with a couple of guys that had a vector and v-king, both boats porpoised but could driven out with adjusments made to engine height using a hydrolic jack plate, I can't tell if your boat as one from the pics, If not you will need one to get smoothed out, or go with less ponies, These were very much a high performance boat, and have to be rigged out correctly, or they will not perform and handle the way they should. Its like driving a corvette on a slalom course with snow tires. It ain't going to do to well.

  20. #20
    Cadet
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    Sep 2003
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    B.R.,La
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    Default Re: Boat porpoising...

    A better answer.Try puttiing the prop shft even with the bottom of the pad (the flat part of the boat bottom).Don't worry about where the ventilation plate is,it isn't in the water when the boat is on step. The porpoising is caused by dragging the lowwr unit too low below the boat. The prop you have looks to be a Ron Hill Yamaha Drag copy. The boat will porpoise slightly when trying to "cruise". This wheel is made for balls to the wall running. You may consider a thru the hub prop such as a Laser II.The Yammy is designed to give stern lift and run semi-surfaced,the Laser II will provide some more bowlift and can also be run close to surfacing. How much setback does your lackplate have? I would think your Voyager would like 6-8".All the fins and trim tabs in the world will not help your problem. Your rig is a HiPerformance boat that is designed to run on the pad. All the doddads that these guys are recommending will look silly flapping in the wind. Take the time to get to know your rig. Hydrostreams take a little getting used to,as all pad V-battoms are.When you start raising your motor,keep an eye on the water pressure. You shouldn't have to go anymore that 1" above the pad to get your rig handling properly.

  21. #21
    Cadet
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    Sep 2003
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    North
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    Default Re: Boat porpoising...

    what200, I recommend trying a left hand prop.

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