Trailer balance and tongue weight

[Rick Macdonald]

My 1995 H23.5 has the factory trailer. When the trailer is empty, I can just barely lift the tongue (I'm not strong). With the boat on the trailer (right up to the rubber block on winch stand) and with the Honda 9.9 still on the transom (about 115lbs), I can lift it easily. With the engine off, I can still lift it easier than when the trailer is empty.

It feels like maybe 70 pounds with the engine, 120 lbs without the engine, and 160 lbs for the empty trailer.

Clearly, the center of gravity of the boat is behind the axle!

I did have the axle replaced when I bought the boat. Could they have moved it forward? I hadn't thought of looking, and now, 7 years later, I might not be able to tell. The boat is 90 minutes away so I can't check.

If I'm doing the math right, I'd have to move the axle back 17 inches to add 200 pounds to the tongue. That doesn't seem right. There's no way they could have moved the axle very far or the wheels would not fit in the wheel wells.

It's 213 inches from the axle to the hitch. To get 200 more pounds at the hitch:

(213 in)(200lbs) = (2500lbs)(x)
17 in = x

I'm guessing the boat is 2500 lbs. After I had the axle replaced, I drove the rear wheels onto a truck weigh station while still attached to the hitch (but the truck rear wheels off the scale) and it read 3300 lbs (without the outboard, and pretty empty because I had just bought it and was only half way home when a bearing disintegrated).

I can't believe the 17 inches. I think the math is right, but I haven't factored in the weight of the trailer itself. That would certainly contribute if you moved the axle, but I don't know how much.

To check the math, lets say the engine is 8 feet behind the axle (I didn't measure but estimated it from some web pictures below). What difference at the tongue does the 115lb engine make 96 in behind the axle?

(96 in)(115lb) = (213 in) (x)
52 lbs = x

That's close. I said it feels like 120 lbs with the engine off, and 70lbs with the engine on, and that's 50 lbs difference. The empty trailer feels like 160 lbs. If I stand on the swim ladder with the engine on, the trailer jack almost floats off the ground. I weigh 155 lbs.

(96 in)(155lbs) = (213)(x)
70 lbs = x

which means with my estimate of 70 lbs to lift it there would now be no weight at the tongue and the jack stand lifts off the ground. So, this math does seem to work.

Looking at web pictures of 23.5's on trailers, the axle is always pretty well under the little aft window. I'm guessing my axle couldn't be out more than an inch or two.

http://www.timshel.ca/lake/pics/wl-1.jpg (Mine, but at an angle)
http://www.buyusedboatsforsale.com/uploads/medium/25596-sailboats.jpeg (random web picture)

 

[Bob 04 H260]

I do not know your boat but have trailered sailboats on fairly long trips (1800 miles one way). I think smaller boats were not designed to be hauled with a 4 stroke motor hanging on the transom, it removes too much weight off the ball and may damage the boat eventually.
On many boat trailers the axle can be moved back and forth along the trailer frame, (the fenders move with the axle) in order to adjust teh tongue weight.
I have been surprised how much weight I have been able to add to my boats over the years, I weigh them when I buy them and then again a few years later and the boat has gained 1000 lbs some how ???
One important factor when towing a boat is to adjust the trailer hitch on the truck in order to keep the bow down. When a big truck passes a boat the wind will lift the weight off the ball if bow is level or higher up. If the drivers window is open you will hear the trailer come up on the ball, the trailer will then do a little wiggle and then settle down. If you do not have enough tongue weight it could cause the trailer to go into sway. If the boat has the bow down a passing truck will increase the tongue weight and improve the stability of the rig, and no wiggle.
You may also be able to move the post that supports the winch forward along the trailer frame and allow the whole boat to move closer to the ball to increase tongue weight.
If you can rearrange the gear in your boat to increase the tongue weight it maybe the easiest solution.
good luck, Bob

 

[Rick Webb]

Doubt They Moved the Axle

The axle brackets are welded on. Someone may have moved the winch post though it is held on with u bolts. Somewhere I have the formulas for determining the axle weights and center of balance for rolling stock. I'll look. You can use a bathroom scale to figure out the tongue weight. Since you have issues you may want to weigh the whole rig again to be sure.

Before I changed mine over to a tandem axle I remember the stern bouncing on the ground a couple of time after I washed it down real good the lazzerettes filling with water and I stepping onto the swim ladder to climb up. Figure ten gallons in each eight pounds per gallon so an extra 160 pounds to bring the tongue weight close to zero and then me not putting much weight on to lift the tongue in the air. I'm guessing my tongue weight at about two hundred pounds on the single axle with a motor that is forty pounds lighter than yours.

The trailer is close to 1,000 pounds the empty boat is supposed to be 2,000 so a boat with motor and everything on it has to be over 3,500 pounds which is what the axle is rated for the tires a little more. So your tongue weight should be at least 350 pounds.

 

[Rick Webb]

I Found This

http://www.hnsa.org/doc/pdf/fm55_17_army_cargo.pdf

Page 17-4

 

[Rick Macdonald]

Thanks Bob and Rick for the replies.

My talk of the engine on the transom was just to illustrate balance and verify the calculations. I certainly wouldn't drive farther than the launch ramp like that.

Since I bought the boat, I bought a new mini-van and installed a hitch just this year. I'll have to check to see if it's level or bow down or what. I need to get the tongue weight up first so the back of the van is down to where it will rest.

The U-bolts for the winch post could at most be moved forward 2 inches due to a welded loop on the side that the brake line passes through. Assuming it's in the right place now, I'd be afraid to move it as that would change the position of the bunks supporting the hull, which could be a problem.

Rick, if you weigh 165 then you were lifting the tongue with 400 lbs at the stern. Mine lifts with 270. I am talking about a completely empty boat. No engine, no gas tank, no battery, no porta-pottie. Just about 5 lbs of life jackets, a boat hook, a broom and a mop.

I can see if I were making an actual road-trip, I should load the boat, get out the bathroom scale, and then start shifting the load around. I see now the position of the load added will make more of a difference than anything else.

Rick - thanks for the cool document! 440 pages!

 

[Rick Webb]

Bathroom Scale Tongue Weight

Your tongue weight should be about three hundred pounds. I don't think bathroom scales go that high. What you do is put a board across a scale and another block of wood so that the board is level. Place the wheel on the tongue jack in the center between the scale and the block and multiply the reading on the scale by two.

Sounds like you could move the motor from the transom to the ladder on the tongue and be all set but what a pain in the ass.

 

[Rick Webb]

Checked My Post

Looks like it is on the other side of the ring for the brake line about three inches from the pin to extend the tongue.

Might be the issue right there.

 

[Rick Macdonald]

I've gone through a bunch of pictures but don't have a good view of the trailer. It will be a few weeks before I'm back at the boat, so I'll have to wait. I have other pictures to check as well; maybe I'll find a good one.

 

[Rick Macdonald]

Picture of trailer tongue

Rick,

Here is a picture of my winch post. Is this in a different location than yours?

 

[Rick Webb]

Looks Like it is Further back than Mine

The front of my winch post is three or four inches from the end of the tube

 

[Rick Macdonald]

Re: Looks Like it is Further back than Mine

Interesting! I might look at moving it forward then. I'll take some better pictures next time I'm up at the lake (in a few weeks).

BTW, does your winch have a 2-inch strap (or rope or cable)?

 

[Rick Webb]

Strap

I was thinking of going to a cable and then adding a block at the bow eye and bringing the cable bac to the post to get it up the additional few inches.

 

[bad co]

I have heard alot in here reguarding the trailer problems / I bought my boat exactly 1 year ago I drove 1,000 miles to get mine and really didnt have any troubles towing it what so ever it seemed to track fine was easy to back up ect . only thing I hated was the surge brakes didnt work and the sound of the hitch everytime from a dead stop or backing up made that slam sound. other then that the boat towed fine with the stock trailer. dont know if it made a difference but did and still do tow it with a 2004 ford f-250

 

[George H260]

Good discussion. I agree the TW should be from 8-10 percent of total weight to be safe.
Any or all of the following should help:
1. Move cargo forward
2. Remove engine
3. Move winch foward
4. Move axle back.
Here's a homemade way of weighing the tongue: