Water Weight, The hulls absorb water from the inside and the bag the factory puts around the floatation blocks can fill with water.



A dealer showed me years ago that your normal TheMightyHobie18 with a little water in the hulls weighs ~440-450 Lbm. If the bag around the floatation blocks in the hulls has water in it the boat can go 500 or so.



Try

making sure it doesn't leak

storing it slightly bow up

Covered

Drain plugs and ports open