Pontoon boat weight help


Mar 12, 2017
Hi all
I am trying to figure out my load capacity for an old pontoon boat I am refurbishing, The boat is a 1970 Kayot 22 foot. The pontoons are steel and measure 19" diameter with 20' of round tube and 3' of cone. I can do the calculations for the buoyancy but what I don't know is the weight of the tubes.
Thanks for the help.


Petty Officer 1st Class
May 10, 2018


Mar 15, 2013
I can't think of an easy way to weigh the logs if they are already attached. But after it is in the water with just the basic boat you can mark the water line on the logs and do some estimates from that. For example, if the water line is right at the center of the log at the stern and two inches below the center at the bow, you can approximate the water line for the whole log as about one inch below the center. You can then either use Google to find the formula for the area of the bottom 8.5" of a 19" circle, or just guestimate it to be about 45% of the total cross-sectional area of the log. That area times the length of both logs gives you the volume of water displaced. Convert that volume of water to weight and that is what your boat weighs. The other 55% of the logs' displacement is what you have to carry any additional load. How much of a safety factor you'll want to leave is your call. If it were my boat, I'd want at least half the volume of the logs left for load and safety factor.


Lieutenant Commander
Jun 2, 2013
Ive seen toons so overloaded waterline is about at bottom of the the deck...if you start to sink, toss out the fattest person..

1960 Starflite

Petty Officer 2nd Class
Jun 23, 2011
Ive seen toons so overloaded waterline is about at bottom of the the deck...if you start to sink, toss out the fattest person..
I can tell you that a storm came up quickly on our lake and we were having a party on our favorite island. Two pontoon boats 40 people to get back to land.
I had 22 people on my 24' Harris Floteboat but the deck was still barley above water, Toons were no where in sight. It was only a 1/3rd mile trip back to mainland. Besides on our lake in this area, we could have waded back.


Sep 16, 2013
I've seen the front lights on one of our older boats 2' underwater...

That same boat carried it's 6 gallon tanks on racks located on top of the pontoons on either side of the motor. I woke up one morning and saw one of the tanks floating to one side of the boat, which was tied up at the dock, some how. I don't remember doing that. It wasn't until a few minutes later I realized that the tank was mine, and it had literally floated off it's rack. The only thing securing it was the fuel line. The other tank was found on a beach about a mile away.

Yes, lakefront pontoon owners have been known to party occasionally. The pontoon boats are often pretty basic and can be treated as beach toys. Just don't flip one upside down. That can take some serious work to undo..... pretty dangerous actually.