Finding The Center Of Gravity Of A Boat

[SoapPeddler]

We pulled our boat out of the water this weekend its now parked on the new trailer we purchased earlier in the summer. After parking it in the yard to clean it up before taking it to the storage facility, I noticed that something didn't look right. The boat sits way forward on the trailer. The front of the 'toons hang off of the bunk by about three feet and there is about two feet of bunk sticking out from that back of the 'toons.







I can move the boat to the back of the bunks and move the upright that holds the winch back so it is against the front of the deck, but it looks to me like that will shift too much of the weight behind the trailer axle.

Is there a way to locate the center of gravity for the boat so that I can make sure it is slightly forward of the trailer axle?

[Woody]

If you move the boat too far back, you will not have enough tongue weight, and it will not pull well, and will possibly sway. I think the "rule of thumb" is to have at least 10% of the total weight on the tongue.

[SoapPeddler]

If you move the boat too far back, you will not have enough tongue weight, and it will not pull well, and will possibly sway. I think the "rule of thumb" is to have at least 10% of the total weight on the tongue.

I've read that in this forum before, but how do you find the spot placement that gives you 10% of the weight forward?

[dockholiday]

Looks like it needs to be slid back to almost near the ends of the bunks. Then see what the tongue weight is, and work from there. It would also support the weld on the nose cone at that position.
doc

[IMHB]

Slide the boat back so that you have 2 inches of pontoon bunks showing.
Then check your tongue weight.
I am guessing, from looking at the picture, that it will be good to go.
Let us know how things turn out..
Harry

[Bamaman]

Everyone's saying the same thing:

Move the boat to the back of the bunks.
Move the winch/bow support back.
Check the weight on your hitch/trailer ball. Is it 10% or more of the total boat/trailer weight? It should be.

You might have to go to a truck scale to find out the weight of your boat/trailer. Our city dump will let you use their scales for free. My wife's bathroom scale will weigh her, so it should also work on the trailer hitch.

I'm a walking expert on bad decisions. I've had a couple of trailer loads in my rear view mirrors swinging 45 degrees back and forth--potential roll overs. I'll never be caught with a light trailer hitch load again. I'm also a believer in using proper tow vehicles--preferably a full size pickup truck or van to pull any load over 3500 lbs. I'm a big believer in surge brakes on any trailer over 3500 lbs.

[WoodenPontoon]

When I first launched my boat, I had too much tongue weight and had to move my boat backwards as well. Your setup does look too forward.

You can easily calculate your tongue weight by taking 2 weights on a truck scale.
First pull over the scale so that your tongue jack is near the edge of the scale. Have the weight taken while the trailer is attached to the hitch. Next lower the jack, raise the trailer off of the tow vehicle and take a 2nd weight, which will be the trailer weight. The difference between the 2 numbers is your tongue weight.

Good Luck.
Dan

[hyper]

hell, move the boat back so that the rear of the logs are at the rear of the bunks. Then move the front stop back to meet the front of the boat. Go drive it. If it pulls good you are ready to go and I bet it does. If it doesnt then use a scale to see why, but i bet it will be fine once you move it back where it should be. The trailer builder builds these traliers and postiion the axel to compensate for this. Let us kow how it works when you move it. I bet you will be happy and your boat will look right sitting on the trailer.

[Ray Jr.]

I would slide it back too. If it is too light on the tongue then try to slide the axle back, to increase tongue weight.

[Leisure Kraft]

Move the boat to the back of the bunks.
Move the winch/bow support back.
Check the weight on your hitch/trailer ball. Is it 10% or more of the total boat/trailer weight? It should be.

Make sure that you have one or two helpers--they may need to jump onto the tongue as you move the pontoon boat back.

If it were me, I'd get the scale ready and put a block on it. Weigh the block by itself first.

You should know the dry weight of the pontoon boat itself. Calculate 6lbs/gallon for the fuel in the tank. Add the weight of the trailer by itself plus any gear. That's the total weight. Find 5% of that total weight. Find 10% of that total weight. This is your tongue weight range.

Now back to the pontoon boat, I'd winch it slowly forward while someone's monitoring the weight (remembering to subtract the block's weight). Remember that you may not have a full fuel tank when you're doing this. If that's the case, try to split the weight difference between 5-10% and you should be safe.

If the tongue weight is too heavy then you're lifting weight from your towing vehicle's front. If the tongue weight is too light the trailer will fishtail down the road. If you aim for 7.5% of the total weight then you're probably good for both empty- and full-fuel situations.

It's a good idea (and the law) to use straps on the stern side when trailered; specifically they said that it needs to be properly secured. And depending upon the state, you may be required to have trailer brakes depending upon the max weight.

[lakerunner]

Slide it back and drive it, any swaying will be noticed.

Does your axles sit on their own frame mount? Most are these days. If so you can move them back a bit if you need to, just be sure you square them before you clamp them down.
I feel you will be just about right when you move it back

[GregF]

When I first set up my boat on the trailer I had it sitting so it was just about evenly balanced with about 40 pounds on the tongue. I set the hitch wheel on a bathroom scale and started cranking up on the winch until it was a tad over 200 pounds. Then I moved the winch post back until it was on the stop.
Over the years I tweeked it forward and back a little but 210-220 seems to be just about right for a light 20' boat (no furniture) on a single axle trailer.
It tows great at Florida interstate speeds.

It is also just about all I can dead lift but I am old.

[belercous]

Checking the weight on the tongue is the best measure to be sure. On that size boat one should be able to lift the tongue although it may take two people to move it around on level ground.

The boat may look like it's sitting too far forward but the engine weighs a lot more than an open deck. Factor in some fuel in the tank & your C.G. may not be as far forward as one might think. It also does look like the trailer is made for a bit longer boat though.

[hyper]

looks like the trailer is the right one for this boat, but the front stop is slid all the way foward. Move it back to the correct position and take a picture of it. You axel is back more than the half way mark of the "loaded" area. Move the boat back and you are done. Problem fixed!

[GregF]

The other possibility is that you can move the axle on the frame. Some are on a frame that has a couple different holes drilled for different positions.