CONTINUOUSWAVE

If each Dauntless is loaded with 1000lbs of persons and/or gear, do the draft numbers cited below change? Hypothetically could the 13' Dauntless draft increase 4" and the 18' Dauntless increase 1" such that each hull equally has a draft of 13"?

Model         13 Dauntless     18 Dauntless
Length	      13-feet 9-inch   18-feet 6-inch
Beam	      6-feet	       8-feet
Draft         9-inches         12-inches
Dry Weight    650-lbs          2,000-lbs
Capacity      1,010-lbs        2,600-lbs
Swamp Cap.    1,700-lbs        4,000-lbs

Buoy wrote:If each Dauntless is loaded with 1000lbs of persons and/or gear, do the draft numbers cited below change? Hypothetically could the 13' Dauntless draft increase 4" and the 18' Dauntless increase 1" such that each hull equally has a draft of 13"?

Yes, hypothetically. Whether 1000 lbs would truly equalize the drafts of the two vessels could be calculated by a naval architect. But we do know (because the Dauntless 18 displaces roughly 3 times what the Dauntless 13 displaces) that the draft of the 13' Dauntless hull would increase more than the draft of the 18' Dauntless hull when the same amount of paylod is added to each and evenly distributed throughout the boats. (This would be true while the vessels are in displacement mode, but not necessarily while planing.)

If each Dauntless is loaded with 1,000-lbs of persons and/or gear, do the draft numbers cited below change?

Yes, of course. Any buoyant object will increase its draft as weight is added.

Hypothetically could the 13 Dauntless draft increase 4-inches and the 18 Dauntless increase 1-inch such that each hull equally has a draft of 13-inches?

Possibly. Here is how you can work out the answer:

An approximation of the volume of water displaced by the hull can be made by using the length and beam dimensions or some fraction of them to approximate the waterplane area of the hull. Use that area and add 1-inch of vertical to create a volume. Calculate the weight of water displaced by that volume. This should give you an approximation of the increase in draft with increasing weight.

For example, consider a boat with a length of 15-feet and a beam of 5-feet. Since the hull is not a true box shape, we use a factor of 66-percent to approximate the hull shape. The waterplane area is this

15 x 5 x 0.66 = 49.5-feet^2

If this hull increases in draft by 1-inch (0.083-feet), the volume of water displaced will be 4.125-feet^3.

The density of water at 70-degrees-F is 62.3-lbs/feet^3. This means that each inch increase in draft creates a buoyant force of

4.125-feet^3. x 62.3-lbs/feet^3 = 257-lbs.

Apply this same analysis to the two hulls you ask about. This should give a reasonable estimate.