Trailer Porpoising

CaptainDucky

CaptainDucky

Petty Officer 3rd Class
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Apr 24, 2010
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Took the boat out a few days ago for the first time since last year. Last year I was using a Ford f150 and not having any problems with the trailer going down the highway. However, this time out we have acquired a 2000 Chevrolet Suburban with a heavy duty towing package on it from the in-laws. They actually never pulled anything other than a camper and never seemed to complain about anything. My trailer that I have actually pulled with a Chrysler Town and Country and Chrysler Aspen have never given me any problems. Going to the lake the other day you couldn't even tell the boat was behind us and it launched beautifully and then it was one of the best retrievals ever. Chalk that up to the Suburban, but on the way home it was porpoising and giving me fits on the highway. Never really got over 55mph and it almost made me seasick. So my question is what would have caused this situation? I acquired this boat and trailer over 4 years ago from my grandfather and he used a buick or pontiac car to launch it. So the Suburban should not be doing this. Any help would be awesome!
 
C

Chip Chester

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Apr 17, 2012
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Re: Trailer Porpoising

Might be worth a check to see if you have an extra 800 pounds of water in the back of the boat. Note that it's possible it's not visible in the bilge...
 
CaptainDucky

CaptainDucky

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Re: Trailer Porpoising

Chip Chester said:
Might be worth a check to see if you have an extra 800 pounds of water in the back of the boat. Note that it's possible it's not visible in the bilge...
Click to expand...

Bilge is cleaned out as of today. However there was not 800 lbs of anything back there on way home. I'm thinking that the angle of boat and maybe hat for the heaviness of suburban that there isn't enough weight on tongue. Would moving boat toward suburban be beneficial?
 
C

Chip Chester

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Re: Trailer Porpoising

I have an '03 Suburban 2500, which has rear leaf springs with the 'helper' spring. It really doesn't kick in until almost 800 lbs. tongue weight. My boat tongue weight is about 150. Haven't noticed trailering issues with the heavy truck/light trailer combo. Do you have coil spring rear suspension? Autoride? What's your tongue weight/trailer weight? I suppose if there's very little movement by the Suburban on a bump or dip, there could be a sort of oscillation that's set up in the trailer that may not exist with a lighter suspension tow vehicle.
 
NYBo

NYBo

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Re: Trailer Porpoising

Is the trailer level when hooked to the Suburban?
 
K

KD4UPL

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Re: Trailer Porpoising

I suspect you need more tongue weight. The other vehicle you mention towing with would have had much lighter rear springs and were okay with the small amount of tongue weight you have. The Suburban, apparently, has stiffer rear springs and needs more tongue weight. Can you move the boat forward on the trailer?
 
scottmm73

scottmm73

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Re: Trailer Porpoising

NYBo has a very valid question. A lot of people who haul trailers disregard this bit of information (albeit safety information). This is why you see all different sizes of draw bars (the thing the ball is attached to). If you are pulling a trailer that is not level, center of gravity is affected and this will definitely affect the ride.

http://www.etrailer.com/faq-ballmount.aspx
 
M

mommicked

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Re: Trailer Porpoising

I would add to also check the condition of the shock absorbers. I had trailor porposing issues on my 98 Chevy S-10 a few years ago and found the shocks were shot. Replaced the rears w Bilstien gas charged shocks and it is much better handling when towing now, more stabil and no occilation? between truck and trailor on bumps or hitting the bottom of a hill like before.
 
O

Outsider

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Re: Trailer Porpoising

and maybe hat for the heaviness of suburban that there isn't enough weight on tongue.

If tongue weight wasn't a problem going to the lake, it's unlikely tongue weight would be a problem coming from the lake. Unless something significantly changed in tongue loading ... ;)
 
J

Jlawsen

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Re: Trailer Porpoising

If tongue weight wasn't a problem going to the lake, it's unlikely tongue weight would be a problem coming from the lake. Unless something significantly changed in tongue loading ...
Click to expand...

Yep that's what had me confused at first until I thought about fuel consumption during the day. If the fuel tanks are mid-ships or forward and were full on the way up but empty on the way home the tounge would be light. Moving the winch post up towards the hitch a couple of inches will probably cure the problem.
 
04fxdwgi

04fxdwgi

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Re: Trailer Porpoising

mommicked said:
I would add to also check the condition of the shock absorbers. I had trailor porposing issues on my 98 Chevy S-10 a few years ago and found the shocks were shot. Replaced the rears w Bilstien gas charged shocks and it is much better handling when towing now, more stabil and no occilation? between truck and trailor on bumps or hitting the bottom of a hill like before.
Click to expand...

^^^^^ #1... Just went thru this myself and it was the shock absorbers. Replaced them w/ new HD units and problem went away completely.
 
CaptainDucky

CaptainDucky

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Re: Trailer Porpoising

Thank you for all replies. I will try all these suggestions and let ya know
The one thing about the gas is that there was more in it coming home than going out since I stopped and got it. The tank is in rear.

Thanks again
 
Captain Caveman

Captain Caveman

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Re: Trailer Porpoising

Depending on the size of your gas tank, you may have added just enough weight to the boat that it teetered towards the back meaning that you removed the weight from the tongue. Suppose it's a 25 gallon tank and 6lbs/gallon that's 150lbs that might have been added behind the axle. That could cause some porposing, causing the bow of your boat to buck while trailering. Try either shifting more of the weight forward in your boat or as someone else stated, moving the winch tower forward another couple inches.

As an aside, depending on how far you tow, you might consider filling up just before you hit the water so that you aren't towing all of that extra weight and thereby lowering your MPG.
 
jbetzelb

jbetzelb

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Re: Trailer Porpoising

Sounds like the added fule tipped the toung weight a little. A hundred pounds in the bow and see if it goes away would prove it before you try to move the whole boat forward a little.
 
CaptainDucky

CaptainDucky

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Re: Trailer Porpoising

Ok...so i took it to a lot that I can see if it is level. Here is what I did....
I started out by measuring distance from ground to top of coupler while attached to the suburban and it measured 19" . Then I leveled out the trailer to where it looked level (not looking at boat, but at trailer itself compared to Suburban) and measured this and it came up to 20". I have already turned a 2" drop ball mount around to get it where it is. Should I add some washers to make up the extra inch, or spring for a new receiver ball mount in the 3" drop size?
 
R

rparde

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Re: Trailer Porpoising

I wouldn't use the washer's. Before I made any purchases I would throw some weight in the front and go for another driv e. Sounds like tongue weight to me.
 
CaptainDucky

CaptainDucky

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Re: Trailer Porpoising

rparde said:
I wouldn't use the washer's. Before I made any purchases I would throw some weight in the front and go for another driv e. Sounds like tongue weight to me.
Click to expand...

So if I've read everything correct here it seems as though the suburban is meant to pull a heavier tongue weight than I have since all the other vehicles mentioned weren't rated as heavy. Would that be correct?

We will load font end with canopy and coolers then and see what happens tomorrow.

Thanks
 
CaptainDucky

CaptainDucky

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Re: Trailer Porpoising

Captain Caveman said:
Depending on the size of your gas tank, you may have added just enough weight to the boat that it teetered towards the back meaning that you removed the weight from the tongue. Suppose it's a 25 gallon tank and 6lbs/gallon that's 150lbs that might have been added behind the axle. That could cause some porposing, causing the bow of your boat to buck while trailering. Try either shifting more of the weight forward in your boat or as someone else stated, moving the winch tower forward another couple inches.

As an aside, depending on how far you tow, you might consider filling up just before you hit the water so that you aren't towing all of that extra weight and thereby lowering your MPG.
Click to expand...

I fill up just before lake. there is just left over gas.
Also the tank is no where near 26 gallons. But I do appreciate your advice.
 
CaptainDucky

CaptainDucky

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Re: Trailer Porpoising

Just got to thinking though. If I put more weight in front nose will go down even more. Will it still be a better ride though?
 
J

Jlawsen

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Re: Trailer Porpoising

CaptainDucky said:
Thank you for all replies. I will try all these suggestions and let ya know
The one thing about the gas is that there was more in it coming home than going out since I stopped and got it. The tank is in rear.

Thanks again
Click to expand...

Well then, that actually does answer the question. The added fuel weight in the rear is what set it off but it shouldn't have. With the difference being only an inch, If the added weight in the bow during the next trip out doesn't help, try getting a good set of gas shocks for the rear of the Suburban. The Suburbans are setup to handle the weight and still have a nice cushy ride for the rear seated passengers. You'll still have a decent ride with heavy duty gas shocks but they won't allow you to bounce nearly as much. If that doesn't do it you might need to go to coil overs or even air bags.

If you're wondering why I'm not on the tounge weight band wagon, it's because I don't think that's the problem now. I'm not there with you to check it myself so I can't be 100 pct sure but I think I'm guessing pretty close.
 
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