46 



BIOLOGICAL SURVEY OF 



Large gasoline tanks are set low and placed in zinc-lined 

 sinks 'with drainage outlets to below water line in case of 

 leakage. Ventilation for all this part of the boat is from two 

 ventilators rinming down from the top of the bridge deck and 

 then out of an opening at the stern. This entire space under 

 the decks can be flooded at a moment's notice with carbon 

 dioxide gas from a large tank carrying 300 pounds pressure 

 and piped to all parts of the hold. I mention this as quite 

 important because when dredging and moving slowly, by 

 touching up the engine now and then, there is always a forma- 

 tion of gasoline vapor which must be taken care of. This 

 danger of explosion was also taken care of by placing Ober- 

 dorfer mufflers on the carburetor, thus preventing the escape 

 of anv back-fire flame. 



Fig. 11 Typical shore Frenchmans Bay. 



The large open cockpit shown in figure 12 approximates 

 16 feet long, 9? feet wide at the forward end and 61 feet wide 

 at the stern, giving something over 130 square feet of space. 

 The floor is heavily planked and sealed and made self -bailing 



