Pontoon Float or Boat Draft CalculationThis calculator assumes that a pontoon float or boat consists of two or more pontoons tiedtogether by some form of structure, which is decked over to form a platform for people and gear.

Assumptions:Dpontoon 27in Diameter of the pontoon pontoon 54.07

lbfft

Unit weight of the pontoonLpontoon 48ft Length of the pontoon

DLstruct 2747lbf Weight of platform, hardware, etc.Npontoon 2 Total number of pontoons

Unit Weight of waterFresh: 62.4Salt: 64

water 62.4lbf

ft3

Calculations:DLvessel pontoon Lpontoon Npontoon DLstruct

DLvessel 7937.72 lbf Total weight of the pontoon boat (unloaded)

Vpontoon Dpontoon

2

2

Npontoon Lpontoon Calculate the total volume of the pontoons

Calculate the Recommended Maximum Gross Loadper: "Construction Standards for Small Vessels (2010)"TP 1332 E - Section 4

GLvesselVpontoon water DLvessel

2

GLvessel 7940.29 lbf Recommended Maximum Gross Load - Passengers & Gear

Volume of waterdisplaced by just thepontoon boat weight

DLVolDLvesselwater

DLVol 127.21 ft3

Volume of waterdisplaced by pontoonboat + peaple + gear

GLVolDLvessel GLvessel

water GLVol 254.46 ft3

End area of submergedpontoon, pontoon boatweight

DLAreaDLVol

Npontoon Lpontoon DLArea 1.33 ft2

End area of submergedpontoon, pontoon boatweight + peaple + gear

GLAreaGLVol

Npontoon Lpontoon GLArea 2.65 ft2

In this next section, we need to use calculated values to pick values from a table. Table is attached at the end of this worksheet.

inTableDLDLArea

Dpontoon2

inTableLLGLArea

Dpontoon2

inTableDL 0.26 Find this number in the table, under the column area/D2. Pickthe value of d/D from the column to the left of your value, andenter it below.

Find this number in the table, under the column area/D2. Pickthe value of d/D from the column to the left of your value, andenter it below.

inTableLL 0.52

outTableDL 0.37 This is the number you picked off the table, in the d/D columnand from the same row as the value for inTableDL

This is the number you picked off the table, in the d/D columnand from the same row as the value for inTableLL

outTableLL 0.63

dDL outTableDL Dpontoon Multiply the value found above by the pontoon diameter tofind the submerged depth or draft of the pontoon boat underjust it's own weight.

dLL outTableLL Dpontoon Multiply the value found above by the pontoon diameter tofind the submerged depth or draft of the pontoon boat underjust it's own weight.

Results:dDL 9.99 in Submerged depth or draft of the pontoon boat under just it's own weight.

dLL 17.01 in Submerged depth or draft of the pontoon boat with passengers and gear.