Trailer porpoise while towing.

Discussion in 'Trailering' started by beeker, Jul 11, 2017.

  1. beeker

    beeker New Member

    16
    Nov 21, 2016
    Ok.
    03 185 sport
    4.3 v6 190 hp. Alpha one
    Need a remedy for trailer porpoise. Using extende cab chev.pulling single axle trailer with 3100 lb 185. Im second owner and boat has always been on this trailer and appears to be set up correctly. Boat extends about 8 inches past bunks at the rear. Does have room to move front roller/crank fwd some. Had dual axle with other boats previously and no problems. Does someone have a solution to this problem . Afraid strap is going to break or bunks split. Other note,good shocks on p.u. Thanks
     
  2. Westie

    Westie Active Member

    Oct 16, 2008
    Calgary
    2001 260 Sundancer towed with the power of an IFORCE V8
    7.4 L Bravo III
    Having the boat extend 8" past the bunks is not set up correctly. The end of the boat should be even with the end of the bunks.
    What is your tongue weight, it sounds like it may be low.
     
  3. beeker

    beeker New Member

    16
    Nov 21, 2016
    Ok.
    03 185 sport
    4.3 v6 190 hp. Alpha one
    Thanks for the reply.not sure of tongue wt.,but will check. Is there a percentage of total wt.? Like 10%
     
  4. outlaw32

    outlaw32 Member SILVER Sponsor

    71
    Mar 15, 2014
    St Petersburg Fl
    340
    496 V drives
    need to have boat against front roller. So need to understand tongue weight like stated below and adjust boat and front roller so boat is against it.
     
  5. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    If it's the trailer that came with the boat from Sea Ray, the transom should NOT be sticking out past the bunks. If you have the bow eye snugged up tight underneath the roller (should always be tight), then something has been changed. As Westie said, too much weight aft (which provides too little tongue weight) will cause swaying. I assume you mean swaying (left to right), not porpoising (up and down). However, very, very little tongue weight can also cause bouncing on the draw bar.
     
  6. beeker

    beeker New Member

    16
    Nov 21, 2016
    Ok.
    03 185 sport
    4.3 v6 190 hp. Alpha one
    No, trailer pulls with no sway at all But porpoises up/down front to back when you pass over a swell or dip in road like at an intersection crossing at 50 60 mph on two lane road
     
  7. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    Most likely, you're just keeping the speeds low enough and haven't experienced the sway, yet. Or, there's "just" enough tongue weight to limit the sway. It's a pretty normal thing, though, to experience (and the porpoising) when there isn't enough tongue weight.
     
  8. beeker

    beeker New Member

    16
    Nov 21, 2016
    Ok.
    03 185 sport
    4.3 v6 190 hp. Alpha one
    Going out this w/e ,I'll ck the tongue wt. ,and adjust boat
    further onto the trailer and re- ck tongue wt. Thanks ,all info is greatly appreciated
     
  9. Cincy Aquaholic

    Cincy Aquaholic Active Member

    Mar 15, 2009
    Cincinnati
    290 SS - 2016 Ford F250 Powerstroke
    Twin 5.7 with Bravo 1's
    Depending on the number of axles you should have 7-10% as your tongue weight I believe. I have one of these weigh safe hitches because i tow alot and use a cargo trailer for hauling my RZR and gear and I like to make sure the weight distribution is right..

    https://www.weigh-safe.com/
     
  10. GJarrett

    GJarrett Member

    579
    Oct 3, 2006
    South Carolina
    '99 240 Sundancer
    5.0 MPI
    +1, tongue weight too low. Needs to be 7%, up to 10% okay with lighter boats and tow vehicle capable of handling the tongue weight.
     
  11. NotHerDecision

    NotHerDecision Well-Known Member PLATINUM Sponsor GOLD Sponsor

    Jun 28, 2016
    Houston, Texas
    2001 Sea Ray 460 Sundancer
    2014 Seadoo 155 LTD
    2105 Seadoo 130 SE
    2013 Mercury Dinghy
    Cummins 6CTA 8.3L
    I was also told 10-15% tongue weight. Keep this in mind as well. I think it's probably a lack of tongue weight but it could be worn rear suspension on your truck.


    Sent from my iPhone using Tapatalk
     
  12. GJarrett

    GJarrett Member

    579
    Oct 3, 2006
    South Carolina
    '99 240 Sundancer
    5.0 MPI
    I also grew up using 10-15% as a guide, but that was for much lighter trailers than the boat/trailer I am currently hauling. Our boat did not have a trailer when I went to buy it so I had a trailer custom fit for it to tow it home. The guy who set up the trailer had something like 30+ years experience and set it for 7% tongue weight. I had a lengthy discussion with him about that, but it does make sense for heavier trailers. My boat is 6,500 lbs on the trailer; 15% would put a half ton tongue weight on my SUV which there is no way I would be comfortable doing that. I've now towed for four years and several thousand miles and at 7% it behaves wonderfully and has never even begun to try to sway.

    If the OP has a 3,100 lb load I agree 10-15% will work just fine. No way the boat should be hanging off the bunks like that; move the bow roller up to allow the transom to line up with the bunks and it will probably fix the problem.
     
    Last edited: Jul 12, 2017
  13. beeker

    beeker New Member

    16
    Nov 21, 2016
    Ok.
    03 185 sport
    4.3 v6 190 hp. Alpha one
    Thanks guys will move roller ,adjust boat and ck tongue weight. I'll let you know.
     
  14. Leardriver

    Leardriver Member

    122
    May 24, 2016
    Denver, CO
    2004 270 Sundeck 8.1 Bravo III
    5.0, 5.7, 6.2 8.1 Bravo III over the years
    My complaint with single axle trailers is that they are noticeably more bouncy.
     
  15. Espos4

    Espos4 Active Member

    384
    Jan 1, 2017
    Long Island NY
    2007 240 Sundeck
    350 MAG Bravo 3 W/DTS
    I agree with the heavier tongue weight. That is a relatively light boat for a full size pick up truck. 15% will give you 450 or so lbs on the tongue which can be easily handled by your truck.
     
  16. beeker

    beeker New Member

    16
    Nov 21, 2016
    Ok.
    03 185 sport
    4.3 v6 190 hp. Alpha one
     
  17. beeker

    beeker New Member

    16
    Nov 21, 2016
    Ok.
    03 185 sport
    4.3 v6 190 hp. Alpha one
    Took it out this past w/e, moved front roller
    assembly forward when loading the boat
    Bunks now end at transom
    This increased tongueweight and improved towing. Thanks for everyone's input
     

Share This Page

Show Sidebar