Gas mileage went down suddenly

I have a’97 Johnson fast strike that seems to be using more gas than usual the last 3 or 4 times I’ve been on the water. The engine is running perfectly normal. This morning I had 1/4 of a tank, 20 gallon tank, and I made a 4-5 mile run from my last stop to the boat ramp and was pushing e when I got back to the ramp. Any suggestions on possible causes?

check your boat for water in the hull

1/4 tank in 20 gal. tank is 5 gals. Most fuel tank senders are not spot on accurate when getting low. I would fill the tank and see how much fuel was left in the tank when you put it back on the trailer. That will tell the story.

I made 2 or 3 trips to the lake with mine at or below a 1/8. I wanted to see how low it would go before I ran out. Boat was new to me and not sure about the gauge. I never did run it out. I got tired of carrying a gas can with me. In my Ranger I could pretty much predict by the gauge when I needed to switch tanks but it would run for quite a while on E.

I usually can fish a day trip on a full tank and predict very close to amount for fill up on way home, very close depending on wind where I went and boat loading. Same for % of batteries used and left.